The antimicrobial activities of amoxycillin (α-amino-p-hydroxybenzylpenicillin), a new semisynthetic penicillin synthesized in the chemistry laboratories of Beecham Research Laboratories, were studied in in vitro.
The results obtained are summarized as follows.
(1) The antibacterial effects of amoxycillin against St. aureus, E. coli, Salmonella and Shigella isolated from clinical specimens were almost identical to those of ABPC, while about twice of those of ABPC against P. mirabilis.
(2) Amoxycillin was hydrolyzed by β-lactamases isolated from gram-positive and-negative bacteria, and the relative rate of hydrolysis was similar to that of ABPC.

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The present authors compared the antibacterial activity of amoxycillin (AMPC) and that of ampicillin (ABPC) on 629 strains in total consisting of hemolytic Streptococcus, intestinal flora (E. coli, Klebsiella, Enterobacter, Citrobacter and Proteus group), 8 species of Pseudomonas genus, and 5 species of other non-glycolitic enzymatic Gram-negative bacilli, which were all isolated from the clinical materials in Clinical Laboratories, Juntendo University Hospital, from the latter half of 1972 to April 1973. As to Proteus group, Pseudomonas genus and non-glycolitic enzymatic Gram-negative bacilli, the antibacterial activity was compared as well with that of carbenicillin (CBPC), sulbenicillin (SBPC) or cephaloridine (CER). The antibacterial activity was measured to a high concentration as 1, 600 mcg/ml.
1) AMPC showed a strong antibacterial activity against hemolytic Streptococcus, while there observed numerous strains of intestinal flora and other Gram-negative bacilli of which the growth was not inhibited by the concentration of 100 mcg/ml, although a difference was noticed according to species. There observed, however, fairly many strains which were inhibited the growth at 200-1, 600 mcg/ml. The antibacterial activity against Proteus group, Pseudomonas aeruginosa and P. maltophilia, was inferior to the cases with CBPC and SBPC, exactly as in the case with ABPC.
2) There exists approximately a relationship between the antibacterial activity of AMPC and ABPC, while the antibacterial activity of AMPC is somewhat stronger than ABPC against hemolytic Streptococcus and Proteus group.

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Amoxycillin had a broad spectrum of antibacterial activity similar to that of ampicillin against anaerobic bacteria.
Many strains of anaerobic cocci were sensitive to concentrations of 0.39 mcg/ml or less. Almost strains of anaerobic rods were sensitive to concentrations of 3.13 mcg/ml or less.
Bacteroides fragilis were relatively insensitive to amoxycillin as well as to ampicillin.

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Amoxycillin, a new synthetic penicillin developed by Beecham in 1970, was evaluated microbiologically in comparison with ampicillin (ABPC) of an analogous structure, and the following results were obtained.
Firstly, there was no remarkable difference between this agent and ABPC in the experiments in vitro on antibacterial activity (MIC), antibacterial spectrum, sensitivity of Staphylococci and Escherichia coli isolated clinically, influence of various factors (pH, amount of inoculated bacterium, serum protein) on antibacterial activity, and stability to β-lactamase which is derived from penicillin-resistant Staphylococci and Escherichia coli isolated clinically. However, the authors obtained the first evidence from the experiment on the bactericidal effect of this agent and ABPC on the growth curve of Escherichia coli that this agent is quick in activity and about twice as effective as ABPC, and this fact will be the key to further morphological and biochemical studies on the mechanism of antibacterial activity of this agent.
Next in the experiments in vivo, it was confirmed that this agent is twice higher than ABPC in the concentration in the blood and organs of the mouse. Further, the therapeutic trials of experimental infections in mouse revealed the superiority of this agent to ABPC.

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Amoxycillin is a new synthetic penicillin derivative developed by Beecham Group Ltd. (England). Presented in this paper are the results of our study in which amoxycillin was compared with aminobenzyl penicillin (ABPC) as to in vitro and in vivo antimicrobial activity and pharmacokinetics.
1. Amoxycillin was found broadly effective against Gram-positive and -negative bacteria, but was ineffective against β-lactamase producing strain of Staph. aureus, strain of Prot. vulgaris and strain of Ps. aeruginosa. The antibacterial spectrum of amoxycillin was the same as that of ABPC.
2. As for the effect of various factors on the antimicrobial activity, it was remarkable that the activity of amoxycillin tended to increase with increasing acidity of the medium. The activity of the compound was not significantly influenced by the presence of serum, size of inocula or kinds of medium.
3. Repeated subculture of Staph. aureus and E. coli in BHI broth containing increasing levels of amoxycillin resulted in a stepwise development of resistance which was relatively slow for both strains.
4. The activity of amoxycillin proved bactericidal in the growth of Staph. aureus and E. coli.
5. Amoxycillin-serum binding rate was 16 to 25% when determined by the methods of diffusion, equilibrium dialysis and gel filtration.
6. As was the case with ABPC, amoxycillin was found unstable to β-lactamase produced by Staph. aureus and E. coli.
7. In the studies with mice experimentally infected with Staph. aureus, Str. pyogenes, D. pneumoniae, E. coli, Prot. mirabilis and K. pneumoniae, amoxycillin was more active than ABPC by oral administration.
8. After oral administration, amoxycillin produced markedly high drug concentrations in the blood and tissues of mice and rats than did ABPC.
9. Amoxycillin was excreted into urine at higher concentrations and into bile at lower concentrations than ABPC.
10. From the result of bioautogram, an antimicrobial compound in urine was identified as unchanged amoxycillin.

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General pharmacology of amoxycillin, a new synthetic penicillin antibiotic, was investigated.
1. An oral dose of amoxycillin 4000 mg/kg was essentially without effect on the barbiturate sleep, electroshock convulsion and pain response to tail pinch in mice, and on the body temperature, blood pressure, heart rate, ECG pattern and urine volume in unanesthetized rats.
2. An oral dose of amoxycillin 1000 mg/kg produced no effect on the blood pressure, heart rate and intestinal motility in unanesthetized dogs.
3. At concentration of 5×10^-4g/ml, amoxycillin had no effect on the spontaneous motilities of isolated rat uterus and rabbit ileum, and on the contraction of guinea-pig ileum induced by acetylcholine, histamine, and barium chloride, and of rat stomach induced by serotonin.
4. At concentration of 4 per cent, amoxycillin had no local irritating and local anesthetic effect on the rabbit eye.

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Comparative studies in man and animals proved that the serum levels of orally given amoxycillin are about twice as high as those of ampicillin. The physiological availability of amoxycillin was also shown to excel that of ampicillin by its greater urinary recovery and higher tissue levels. It was experimentally proved that the higher serum and tissue levels of amoxycillin are by no means due to the delayed urinary excretion or to the decreased distribution volume but to the increase in the net absorption from the gastrointestinal tract.
Urinary excretion of penicilloic acid, a metabolite, was studied in healthy volunteers who were given these antibiotics orally. The amount of urinary penicilloic acid derived from amoxycillin was shown to be larger than that from ampicillin. This finding was justifiably confirmed by animal experiments, in which, this greater urinary excretion was evidently shown to be caused by the profuse absorption, and not by the unstableness in the living system.
The biotransformation product, reported in one of our previous papers, was shown to form also by incubation of amoxycillin with rat kidney homogenate.

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The antigenicity of amoxycillin and its cross reactivity with ampicillin and benzylpenicillin were studied and the following results were obtained.
1. Amoxycillin was shown to have no sensitizing activity in rabbits even after oral administration for as long as 30 consecutive days.
2. When injected into experimental animals, amoxycillin bound covalently with carrier protein and produced specific antibodies, hemagglutinin antibodies, precipitin antibodies and PCA antibodies.
3. The extent of cross reaction between amoxycillin and ampicillin was 1/4 to 1/8 that of the homologous penicillin system in passive hemagglutination and its inhibition tests and hapten inhibition of precipitation.
4. The cross reactivity of amoxycillin to benzylpenicillin was weaker than that of ampicillin.

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The results obtained from a laboratory and clinical study of amoxycillin, a new semisynthetic penicillin with antimicrobial spectrum similar to ampicillin, were summarized as follows :
1) Antimicrobial activity of amoxycillin against 59 clinical isolates of Staph. aureus, 13 of E. coli, 4 of Klebsiella and 5 of Ps. aeruginosa was found to be similar to that of ampicillin.
The cross-resistance of Staph. aureus was demonstrated between amoxycillin and ampicillin.
2) The three to five times higher concentrations in serum and tissues of rats were obtained with amoxycillin in contrast to ampicillin 2 hours after oral administration of 100 mg/kg of the drugs.
3) Serum concentrations and urinary recovery of amoxycillin in patients suggested that the drug was comparatively well absorbed after oral administration.
4) Forty-four of 54 patients with various infections responded satisfactorily to amoxycillin. Eight patients failed to respond to the treatment. The remaining was unassessable.
The overall cure rates were 90.6% in the respiratory tract infections and 73.7% in the urinary tract infections.
As to the bacteriological responses, the overall success rate was 68.0% in 25 patients assessed.
Acute pneumonia responded satisfactorily to amoxycillin treatment, although the bacteriological responses were assessable only in a few patients. Out of 12 patients assessed clinically, 10 cured. Two failures were due to ampicillin resistant Staph. aureus and Candida.
5) No significant changes due to amoxycillin were found in the hematological and biochemical investigation carried out during and after amoxycillin treatment.
6) Side effects were observed in 11 out of 54 patients. They were similar to other oral penicillins and mainly gastrointestinal disturbances (7 patients) and skin rashes (2 patients).
The medication was discontinued in 1 patients because of gastro-intestinal disturbances and in one because of skin rash.

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The results of some studies on amoxycillin were summarized as follows :
1. Amoxycillin (10 mg/kg) was administered orally to rats in order to determine the concentrations in tissues (liver, kidney, lung, blood). The concentrations in all the determined organs were higher than those after the administration of ampicillin in the order of liver, kidney, lung and blood. Ampicillin gave the peak value one hour after and amoxycillin two hours after.
2. As the result of well controlled studies with 19 cases of respiratory infections, especially bacterial pneumonia, no significant difference was seen about the efficacy among amoxycillin-1g, amoxycillin-2g and ampicillin-2g groups. In some of the cases treated with amoxycillin 1g, the efficacy corresponding to that by ampicillin 2 g was recognized. The efficacy in each case corresponded with the result of sensitivity test to pathogenic bacteria.
3. Administration of amoxycillin 1.5 g for 20 days was effective to endocarditis relapsed after the use of ampicillin. No relapse was observed after the administration of amoxycillin.
4. As for side effect, skin rash was seen in each one case of amoxycillin-2g and ampicillin-2g groups. No abnormality in liver function and renal function was seen in any case during the medication.

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Several experiments were performed on amoxycillin (AMPC), a new ampicillin (ABPC) derivative, and the results were as follows.
1) Indicator organisms and assay procedures were studied for determining AMPC levels in human serum and urine. The following organisms and assay procedures were proved to be available and to show much the same results.
Indicator organisms Assay procedure
B. subtilis ATCC 6633
Sarcia lutea PCI 1001} Cup method
Strept. hemolyticus S-8
B. subtilis ATCC 6633} Superposition assay method
2) No significant difference was observed between the serum levels of AMPC determined by the standard curves obtained with serum dilution and those with phosphate buffer.
The serum levels were examined in 3 healthy volunteers after a single dose of 500 mg of AMPC by using superposition assay method and the standard curve with phosphate buffer.
The serum levels reached the peak of 4.8-14 mcg/ml at 2 hours, decreasing to 0.8-4 mcg/ml at 4 hours and 0.2-1.3 mcg/ml at 6 hours. These values were about 2 times higher than those of ABPC.
3) The urinary recovery rates were 23.5-364%, that is about 2 times higher than those of ABPC.
4) The tissue concentrations of AMPC in rats were far higher than those of ABPC.
5) AMPC was given to 5 patients with acute pneumonia. The results were effective in 4 patients and undetermined in 1. In the latter AMPC was withdrawn due to skin rash.

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On amoxycillin, a new derivative of ampicillin, several investigations were performed and the following results were obtained.
1. The sensitivities of amoxycillin against clinical isolates of Staphylococcus aureus and some Enterobacteriaceae were similar to those of ampicillin.
2. The biliary level following oral administration of amoxycillin to rabbits was equal to that of serum, whereas the urinary level reached about 90 times higher than that of serum.
3. Each organ level following oral administration of amoxycillin to mice was found 1.4 to 4.2 times higher than that of the same dose administration of ampicillin.
4. Bioautograms of bile and urine of rabbits given amoxycillin and the mixture of amoxycillin with bile or liver homogenate of untreated rabbit in vitro were investigated, and the results were discussed.
5. Clinically amoxycillin was administered to ten patients with various kinds of infectious diseases, and good effects were obtained in eight of them. Except that exanthema was noticed in one case, there were no side effects in any other cases.

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Laboratory and clinical investigations were performed on amoxycillin, a new synthetic penicillin similar to ampicillin, and the results were obtained as follows.
1) Antibacterial activity
Antibacterial activity of amoxycillin was investigated on each 50 strains of Staph. aureus, E. coli and Klebsiella. The growth was inhibited at less than 12.5 mcg/ml in 21 strains (42%) of Staph. aureus and 44 strains (88%) of E. coli, while almost all strains of Klebsiella were resistant at more than 100 mcg/ml.
2) Absorption, excretion and concentration in organs
a) Blood concentration
Peak of blood concentration was 2.2 mcg/ml and 7.2 mcg/ml respectively on 2 nd hour after 250 mg or 500 mg of amoxycillin were administered once orally to healthy adults. When 500 mg of ampicillin were cross overed to the same cases, the peak of blood concentration was 2.9 mcg/ml on 2 nd hour, indicating thus the peak of blood concentration of amoxycillin is almost twofold higher than that of ampicillin when the same dose was administered.
When amoxycillin was administered orally after meal, the peak of blood concentration lowered some-what than in the case of the administration at an empty stomach, though the influence of meal was more slight than with ampicillin.
In the cases of renal function disorder, the half life time of blood concentration who prolonged remarkably with amoxycillin, and this tendency was observed too with ampicillin.
b) Excretion in urine
Amoxycillin was administered orally at a dose of 500 mg, and the excretory ratio in urine was about 60% within 6 hours, indicating thus a higher value compared to 42% with ampicillin.
c) Concentration in organs
Concentration in organs was measured with amoxycillin in rats, and the value was the highest in liver, lowering in order in kidney, spleen and lung.
3) Clinical results
Amoxycillin was administered at a dose of 1-2g per day for 9-17 days to 8 cases in total consisting of 5 cases of respiratory organs infection and 3 cases of urinary tract infection, and the effectiveness was obtained in 6 cases.
No serious side effect was noticed so far except 2 cases of eruption.

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I. On the susceptibility of 50 strains of Staphylococcus aureus which were clinically isolated, the peak of MIC of amoxycillin was 6.2 mcg/ml and similar to that of ampicillin. On the susceptibility of 50 strains of E. coli which were clinically isolated, the MIC of amoxycillin was 3.2 to 6.2 mcg/ml and that of ampicillin was the same.
II. The serum concentrations and the urinary excretions of amoxycillin were examined in 6 healthy subjects in the fasting and non-fasting state to whom 250 mg were administered.
The absorption and the urinary excretion was delayed in the non-fasting state in comparing with that of fasting state (Table 5, 7, Fig. 3).
The peak of serum concentrations given 500 mg of amoxycillin after meal was 5.1 mcg/ml after 2 hours which was about twice of that of cases given 250 mg after meal (Table 4, 5 Fig. 1).
The serum concentrations given 500 mg of amoxycillin after meal was about twice of that of ampicillin (Table 4, 6 Fig. 2).
The urinary excretion of amoxycillin 250 mg or 500 mg was 54.7 % to 68.6 % during 6 hours following the administration, although urinary excretion of cases given 500 mg of ampicillin was about 40% (Table 4, 5, 6, 7).
III. On the therapeutic efficacy of amoxycillin to bacterial infections, including pneumonia (5), lung abscess (1), acute exacerbation of chronic bronchitis (5), acute bronchitis (2), and urinary infections (6), clinical response was good in 9 cases of 13 cases of respiratory infections, and in 3 cases of 6 cases of urinary infections. The reason of the low percentage of effective cases may probably be attributed to the associated severe underlying diseases in most of our cases.
In less severe cases, there was a tendency to be effective with smaller dosis of amoxycillin, such as 0.75mg daily, than that of ampicillin probably because of high blood concentration of amoxycillin.
There were 2 cases who had slight eruptions as the side effects of amoxycillin.

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Amoxycillin, a new synthetic penicillin for oral use, was investigated for its antibacterial activity as well as its clinical use in pneumonia and lung abscess. The results obtained were as follows.
1) The minimal inhibitory concentration of amoxycillin was determined by plate dilution method against Staphylococcus aureus (16 strains), Streptococcus hemolyticus (7 strains), E. coli (17 strains), Klebsiella (6 strains) and Pseudomonas aeruginosa (4 strains) isolated from lesions. As compared with ABPC, there was no difference in minimal inhibitory concentration against these strains.
2) Amoxycillin was administered orally at dose of 1-2 g/day to 4 patients with pneumonia and 1 patient with lung abscess, and 3 cases of them proved to be effective and one ineffective. Ineffective case was Mycoplasma pneumonia. Drug administration was stopped in one case.
3) As side effects, slight increase in GOT and GPT was observed in one case of lung abscess to which amoxycillin was administered at dose of 2 g for 2 weeks.

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From the laboratory and clinical studies on amoxycillin, the following results were obtained.
1) There was little difference between amoxycillin and ampicillin as regards the MIC against St. aureus, E. coli, Klebsiella and Proteus.
2) Serum level of amoxycillin reached following an oral administration of 250 mg early in the morning at fasting, was almost the same as that of ampicillin following an oral dose of 500 mg.
3) There was little difference between after meal and at fasting as regards the serum level, and it is considered that food has little influence upon serum level.
4) Nine cases of infections in the field of internal medicine were treated with amoxycillin, and in 8 of them good responses were obtained (88.9%).
5) No serious side effects were observed except for anorexia and nausea in one case.
6) Examination of the peripheral blood and liver and renal function tests revealed no abnormalities except for the abnormal values characteristic of the diseases.

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Serum concentrations of amoxycillin after a single oral administration of 500 mg were kept at a high level in patients with severely impaired renal function. Peak serum levels were 10.5-19.0 mcg/ml in eight patients with creatinine clearance below 35 ml/mm. except one case, and 4.9-6.3 mcg/ml in three patients with 53-73 ml/min.. Serum half lives of amoxycillin were 6.6-11.7 hours and 1.5-4.0 hours in the patients with renal failure and others.
In clinical observations of eight cases with infections of liver, bile duct, urinary tract and lung, the treatment with amoxycillin showed good results for 6 cases, fair for 1, poor for 1. As side effect, diarrhea was observed in one patient with urinary infection.

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1) The antibacterial activity of amoxycillin against 77 bacterial strains of 8 species isolated from clinical sources was determined by the agar dilution method.
All of 7 Salmonella strains, all of 3 Proteus mirabilis strains, 6 of 8 E. coli strains, 33 of 39 Staph. aureus strains and 2 of 2 Streptococcus faecalis strains showed high sensitivity with the MIC less than 3.1 mcg/ml. While, the sensitivity of Klebsiella, Proteus (except mirabilis) and Yersinia enterocolitica were proved to be lower. All of 5 Pseudomonas strains, 1 of 8 E. coli strains and 1 of 8 Proteus strains showed the resistance with the MIC more than 100 mcg/ml.
2) The active concentration of amoxycillin in the body fluids was assayed by the thin-layer cylinder-plate method using B.subtilis PCI 219 as a test organism to the lower limit of 0.02 mcg/ml.
Blood levels during the oral administration of 500 mg 6-hourly and of 1000 mg 6-hourly were 2.2-3.6 and 2.5-5.2 mcg/ml, respectively. Urine level during the oral administration at the dose of 500 mg 6-hourly was 344 mcg/ml and the recovery was 58.5%. A peak of bile level after a single oral administration of 500 mg was 62 mcg/ml.
3) Oral administration of amoxycillin was found to be effective in a case of acute bronchitis caused by Haemophilus influenzae and a case of pulmonary abscess. Transient rash occurred as side effect in both cases.
No side effect was noticed in a case given 4000 mg daily for 22 days.

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The laboratory and clinical studies have been carried out on amoxycillin, a new semisynthetic penicillin, an improved drug of ampicillin, developed by Beecham Research Laboratories, Great Britain, And the following results were obtained.
1) No remarkable difference was noticed between the antibacterial activity in serum of amoxycillin and that of ampicillin against the standard of strains Staphylococcus aureus, Gram-negative bacilli (Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeruginosa).
2) The concentration of amoxycillin in blood and organs after it was administered orally to rats, exhibited twofold or more compared with that of ampicillin.
3) As to the excretion of amoxycillin in bile at the perfusion of extirpated liver of rat, no distinct difference was observed between that of ampicillin in a viewpoint of the total amount of excretion. The transition of excretion amount following time elapsed, was similar to that of blood concentration.
4) Amoxycillin was applied clinically to 11 cases of internal infections at a grade slighter than middle, consisting mostly of respiratory apparatus infection, and the results obtained were effective in 6 cases, ineffective in 2 cases and undecided in 3 cases.
From the above results, the indications of amoxycillin should be looked for in the infections at slighter than middle grade, and a serious consideration must be given to the side effect, especially allergic reaction. The investigation should be pursued sufficiently on the dose and dosing method of amoxycillin.

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Antibacterial spectrum of amoxycillin was similar to that of ampicillin. Sensitivity of amoxycillin to various clinical isolates was as follows : 0.3-10. 0 mcg/ml in 17 out of 18 strains of Staphylococcus, less than 10 mcg/ml in 8 and 20-40 mcg/ml in 6 respectively out of 14 strains of E. coli, and more than 160 mcg/ml in all of 2 strains of Pseudomonas, 2 strains of Proteus and 4 strains of Klebsiella.
Amoxycillin was administered orally at an empty stomach at a dose of 250 mg to healthy adults, and the blood concentration exhibited a peak of 3.29 mcg/ml after 2 hours, and 0.2 mcg/ml after 6 hours. In the same cases, the drug was recovered in urine at 61.5% on an average within 6 hours.
Amoxycillin was applied at a dose of 1-2 g daily for 7-19 days to 13 cases of the internal infections, and the results were obtained as follows : effective in all 4 cases of pneumonia, in all 2 cases of acute cystitis, in all 3 cases of acute pyelitis, and in 3 out of 4 cases of cholecystitis except 1 undecided case. As to the side effect with amoxycillin, there observed 1 case of eruption and 1 case of gastroenteric trouble.

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1) Antibacterial activity : Staph. aureus strains showed quite similar M. I. C. of amoxycillin (AMPC) to those of ABPC, i. e. higher than those of PC G, MPIPC or nafcillin. AMPC and ABPC showed similar activities (M. I. C. ≤25 mcg/ml) against E. coli and Proteus strains.
2) Blood levels and urinary excretion : Cross over tests using four volunteers revealed that oral administration of 250 mg AMPC gives rather higher blood levels than that of 500 mg ABPC. Urinary recovery rate of AMPC was higher than that of ABPC; amounts recovered from urine after 250 mg dosage of AMPC were often larger than those after 500 mg dosage of ABPC.
3) Clinical trials : Twelve cases of respiratory tract infections (bronchopneumonia 3, bronchitis 5, bronchitis with pharyngitis 1, and tonsillitis 3) as well as one case of pyelonephritis were treated with AMPC (mostly 1 g/day, 4-23 days). Eight of the cases responded with good results, four with fair results, although one of them showed no response to the treatment.
The results obtained suggest the usefulness of the drug, especially for the treatment of the gram-negative bacilli infections.

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Amoxycillin (α-Amino-p-hydroxybenzylpenicillin) is a new semisynthetic antibiotic developed by Beecham Research Laboratories, Great Britain. Its in vitro antibacterial activity and its absorption from digestive tract after the oral administration to humans, were investigated in comparison with ampicillin, and the treatment effect was investigated on several kinds of infections. The results obtained are as follows.
1) Antibacterial activity : The amoxycillin sensitivity was measured on 34 strains of Staphylococcus isolated from lesions, and 14 strains exhibited the MIC of less than 6.25 mcg/ml, while there existed 11 resistant strains of more than 100 mcg/ml. As to Escherichia coli, 17 out of 23 strains were inhibited the growth by 3.12-25 mcg/ml of amoxycillin, though 5 strains were resistant at more than 100 mcg/ml. This antibacterial activity of amoxycillin was almost the same degree as that of ampicillin which was measured simultaneously, and a cross resistance was observed between two drugs.
2) Absorption and excretion : Amoxycillin (250 mg and 500 mg) and ampicillin (500 mg) were administered orally at an empty stomach and after meal to 12 healthy adults, and the transition of blood concentration and the excretory amount in urine were compared by a cross over method. As the results, a peak of blood concentration after administered at an empty stomach, demonstrated 4.49 mcg/ml with 250 mg of amoxycillin, 7.23 mcg/ml with 500 mg of amoxycillin, and 4.02 mcg/ml with 500 mg of ampicillin. That is, amoxycillin showed the blood concentration of 1.8 fold higher than that of ampicillin with the same dose, and thus amoxycillin may show almost the same blood level with a half dose of ampicillin. As for the peak of blood concentration after meal, it was 2.62 mcg/ml with 250 mg of amoxycillin, 6.36 mcg/ml with 500 mg of amoxycillin, and 2.90 mcg/ml with 500 mg of ampicillin, and thus the blood concentration was suppressed remarkably by intake of meal with ampicillin, whereas the peak value of blood concentration was not remarkably influenced by intake of meal with amoxycillin, though the absorption was a little delayed there.
As to the recovery ratio in urine within 8 hours, when the drug was administered at an empty stomach, it was 41.9% with 500 mg of ampicillin, while 50.3% with 250 mg of amoxycillin and 46.1% with 500 mg of the same drug, showing thus slightly higher values with amoxycillin. On the other hand, when the drug was administered after meal, the ratio lowered to 33. 9% with ampicillin, while 55.0% with 250 mg of amoxycillin, and 48.0% with 500 mg of the same drug, exhibiting thus no fall.
That is to say, amoxycillin is absorbed from digestive tract far better than ampicillin, and the effect of meal intake is more slight as well.
3) Clinical result : Amoxycillin was administered orally at a dose of 0.5-2g per day to 1 case of acute pharyngitis, 1 case of chronic bronchitis, 1 case of bacterial pneumonia, 1 case of primary atypical pneumonia, 1 case of pulmonary purulent inflammation, 1 case of cholecystitis and 7 cases of acute cystitis, totalling 13 cases. The results obtained were remarkably effective in 3 cases, effective in 7 cases, ineffective in 2 cases, and undecided in 1 case.
As to the side effect with amoxycillin, no remarkable one was observed, except 1 case in which the administration was interrupted due to an eruption 4 days after the beginning of administration, and another 1 case in which a temporary rise of transaminase was noticed after 2 weeks of administration.

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The laboratory and clinical studies have been carried out with amoxycillin (AMPC), a new broad-spectrum semisynthetic penicillin, and the following results were obtained.
1) The in vitro antistaphylococcal activity of AMPC was almost the same as that of ampicillin (ABPC) and slightly superior to that of carbenicillin (CBPC), while the activity against gram-negative rods of AMPC was slightly inferior to that of CBPC.
2) As for the AMPC serum concentration, a peak was over 10 mcg/ml in two adults after they received orally 500 mg of AMPC. The above mentioned values are markedly higher than those of the same amount of ABPC.
3) AMPC was administered orally for 11 to 14 days at a daily dose of 250 mg or 500 mg four times to three cases of respiratory infections. As the result, the clinical effect was obtained by AMPC without any side effect.

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Amoxycillin, a new synthetic penicillin, was studied in the basic and clinical point of view, and the followings were revealed.
1. The susceptibility of various strains of microorganisms to amoxycillin was about the same as that to ampicillin.
2. Amoxycillin is absorbed easily from the intestine, and the equal concentration to ampicillin in blood was seen after giving a half dose of ampicillin. The peak of amoxycillin concentration in blood was seen in 2 hours after administration, and that of ampicillin was in 4 hours. Urinary excretion was rich in amount, and the drug was detected in the urine soon after giving orally. The recovery rate of amoxycillin in the urine 6 hours after 500 mg single oral administration was 40.4%, while that of ampicillin was 28.8%.
3. The concentrations of amoxycillin in the various tissues of rats resembled to those of ampicillin which was reported already, i. e. high concentration was seen in the kidneys and the liver, while the concentration in the lungs was lower than in the serum.
4. In the therapeutic point of view, 6 cases with pulmonary infectious diseases were treated with amoxycillin; and the results were satisfactory in 5 cases. No adverse reaction was seen.

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One of the characteristics of amoxycillin is said that its absorbency from digestive tract is better than that of ampicillin, and that the blood concentration of amoxycillin is nearly twofold as that of ampicillin. In the purpose to investigate how this good absorbency reflects on the clinical effect, 16 institutions throughout the country have performed the comparative test of the effectiveness by 3 administration methods; amoxycillin 1 g per day, amoxycillin 2 g per day, and ampicillin 2 g per day.
The treated patients consisted of 95 cases of pneumonia and 8 cases of pulmonary purulent inflammation. Having excluded the drop out cases due to various reasons, a statistical analysis was made on the results obtained from cases of pneumonia amoxycillin 2 g in 30 cases, amoxycillin 1 g in 24 cases, and ampicillin 2 g in 16 cases.
The items tested were the symptomatic findings as temperature, pulse rate, respiratory frequency, cough, sputum (amount, Property, and odour), dyspnoea chest pain, breast râles, cyanosis, dehydration symptom and blood pressure, and the clinical test results as thoracic X-ray finding, arterial blood gas, leukocyte count and its classification, erythrocyte count, hemoglobin, hematocrit value, erythrocyte sedimentation rate, CRP, and electrocardiogram. The improvement degree classified by each item above described, was sought from the values obtained before the administration of drug, after 3 days of administration, and after 7 days of administration, and the investigation was made to confirm whether there is a significant difference among three drug methods. As to the finding of thoracic X-ray, the films of each case were collected at a certain place, and they were compared and judged following a fixed standard by a small committee composed of several doctors.
The investigation was made to confirm whether there is a significant difference among three drug methods by comparing the above improvement degrees classified by cases, the judgment results of clinical effects by each physician in charge, and the judgment results of effects in each case by the effect judgment committee composed of several doctors.
The effects classified by causative bacteria were not compared, as there were too few cases in which causative bacteria were determined exactly. The examination was made separately on the cases in which Mycoplasma pneumonia was diagnosed by measuring the value of Mycoplasma CF antibody.
Results : No significant difference was observed among three drug groupes drugs on the improvement degrees of each symptom and finding, although the only degree of CRP tended to be the best with 2 g of amoxycillin at a risk ratio of 10%, while the worst with 2 g of ampicillin. No significant difference was noticed in all the improvement degrees of other symptoms and findings.
No significant difference was observed among three drug groups on the results of effect judgment by each physician in charge and that by effect judgment committee either with all cases and with the cases excluded Mycoplasma pneumonia.
No significant difference was noticed as well among three drug groups on the appearance frequencies of side effects such as digestive tract disorder, allergic reaction, hepatic disorder and renal disorder.
The comparative investigation was not performed on pulmonary purulent inflammation, as the cases of the disease were too few.

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Amoxycillin (α-amino-p-hydroxybenzyl penicillin) is a new semi-synthetic penicillin with a broad spectrum of antibacterial activity similar to that of ampicillin.
From the fundamental and clinical studies on amoxycillin in the pediatric field, the following results were obtained.
1) In three children, the highest blood level after single oral dose of amoxycillin of 250 mg averaged 2.52 mcg/ml in two hours after administration, and the blood level in 6 hours after administration was 0.06 mcg/ml. Cumulative urinary excretion in three cases was 80.0%, 59.4% and 46.7% of the given dose in 8 hours after administration, respectively.
2) Amoxycillin was administered to 20 children with various bacterial infections and found to be effective in 16 cases of them.
3) No particular side effects were observed.

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A series of investigations was carried out on amoxycillin (abbr. AMPC), a new synthetic broad spectrum penicillin, in the field of pediatrics, and the following results were obtained.
1) The peak of blood concentration after the oral administration of AMPC was twice higher than that with a same dose of ABPC, and the ratio of AMPC excretion was distributed between 36-56.2% until 6th hour.
2) AMPC was administered at a dose of 20 mg/kg/day for 5-7 days to the patients of scarlet fever, and the patients cured completely. The result was better than that obtained by the oral administration of ABPC or cephalexin, as well as the reelimination of bacteria was suppressed remarkably.
3) The sensitivity of AMPC was examined on Streptococcus A group isolated from pharyngeal mucous membrane of scarlet fever patients, and the MIC was distributed between 0.025-0.05 mcg/ml, and no resistant strain was found.
4) AMPC was administered at a dose of about 20 mg/kg/day for 3-4 days to the acute infection of upper respiratory tract (acute tonsillitis, lacunar tonsillitis, etc.), at a dose of about 25 mg/kg/day for 5-10 days to the infections of lower respiratory tract (acute bronchitis, bronchopneumonia, etc.), and a satisfactory therapeutic result was obtained in all the patients.
5) The cases treated by AMPC counted 73 patients (38 cases of capsule group and 35 cases of granule group), totalling 7 kinds of disease. The clinical effective ratio obtained was approximately 100%. No difference was noticed between the clinical effects with capsule and those with granule.
6) The GI disorder was investigated during the administration of AMPC capsule or granule, as well as the effect on blood and hepatorenal functions before and after the AMPC administration, and no abnormal finding was encountered throughout the cases treated.

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Absorption and excretion of amoxycillin, a new derivative of ampicillin, was studied, and its clinical effects were evaluated in the treatment of acute bacterial infections in children.
1) Blood concentration of amoxycillin after its oral administration and urinary recovery rate were higher than those of ampicillin.
2) A daily dose of 30 to 40 mg/kg of amoxycillin was given orally for 7 to 14 days to 9 subjects with urinary tract infection, 9 subjects with tonsillitis, and 1 subject with colitis. Its effect was estimated to be good or excellent in all subjects except for 2, i. e., each one of urinary tract infection and tonsillitis. Its overall efficacy rate was 89.5%.
3) No adverse reactions of significance were noted during the treatment with this antibiotic.
4) Based on the above results, it was concluded that amoxycillin is a potent new antibiotic.

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The authors carried out the laboratory and clinical studies of amoxycillin. The results were as follows :
The sensitivity was determined by the plate dilution method with 28 strains of Coagulase-positive Staphylococci and 20 strains of E. coli.
The growth of 75% of the 28 strains of Staphylococci and 75% of the 20 strains of E. coli was inhibited at the concentrations of less than 6.25 mcg/ml. The activity of amoxycillin was similar to that of ampicillin against Coagulase-positive Staphylococci and E. coli.
The absorption and excretion of amoxycillin were compared with those of ampicillin in cross-over studies. The subjects were given orally a single dose of 250 mg and 500 mg.
The serum concentrations obtained with amoxycillin were about 3 times higher than those with ampicillin.
The urinary excretion of amoxycillin was slightly lower than that of ampicillin. In comparison of the serum concentrations of amoxycillin granules and capsules, the peak was reached 30 minutes and one hour after administration, respectively. The serum concentrations of the granules were very similar to those of the capsules.
Amoxycillin was effective in 9 of 11 patients with respiratory infections.
No side effects were observed in any patients except eruption in one.

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Effectiveness of amoxycillin granule was studied from therapeutic and bacteriological view points in 25 children suffering urinary tract infections.
The daily dose was 30 mg/kg body weight and was given in four divided portions for an average period of 18 days.
The overall effectiveness rate was 96% on therapeutic basis and 75% on bacteriological basis. In infections caused by E. coli, the rate was 91%, 73%, respectively. All the causative organisms isolated from nonresponsive patients were found to be suppressed only at a concentration of 100 mcg/ml or more.
Amoxycillin was found to be effective also in the limited number of infections caused by organisms other than E. coli. The marked bacteriological effect was obtained in 2 of 3 patients affected with Proteus and in one patient each with Citrobacter and Klebsiella.
No side effect was recorded except in one patient who developed diarrhea.
Deviations in GOT and GPT were recorded in 2 and 1, respectively. ALP and BUN were not affected.
As a result, we regard amoxycillin as a useful means for treatment of children's urinary tract infections.

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Fundamental and clinical studies have been carried out on amoxycillin in our Department, and the following results were obtained.
1) Antibacterial activity
Antibacterial activity of amoxycillin was measured on Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris, Pneumococcus, Enterobacter and Citrobacterisolated respectively from the lesions in surgical field. The results obtained exhibited to be almost similar to those of ampicillin, and there observed a wide antibacterial activity against both Gram-positive and -negative bacteria.
2) Absorption and excretion
Amoxycillin (500 mg and 250 mg) and ampicillin (500 mg) were administered orally once at an empty stomach to 3 cases of healthy adults, and both blood concentration and urinary excretion were measured. The blood concentration of each drug attained a peak on second hour of the administration, and yet the peak with 500 mg of amoxycillin was nearly twofold of that with the same dose of ampicillin, and the peak with 250 mg of amoxycillin was slightly higher than that with 500 mg of ampicillin. The excretory ratio in urine was 35.6% within 8 hours after 500 mg of amoxycillin were administered orally, the value being thus better in comparison with 25.5% in the case of an oral administration of the same dose of ampicillin.
As to the transference in bile, two antibiotics demonstrated to be nearly the same.
3) Result of clinical application
Amoxycillin was applied to 24 cases consisting mainly of acute pyogenic infections of soft tissue in surgical field, and the results obtained were remarkably effective in 5 cases, effective in 11 cases, slightly effective in 5 cases, ineffective in 2 cases and undecided in 1 case, effective ratio being thus 91.3% excluding 1 undecided case. The dose employed was mostly 750 mg daily, and a sufficient effect may be expected with this dose as the blood concentrations of the drug rise excellently. As for the side effect of amoxycillin, 1 case complained of a dizziness, which was alleviated however by the interruption of the administration.

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Amoxycillin was studied of fundamental and clinical bases.
The antimicrobial activity was found equal to that of ampicillin when coagulase-positive Staphylococci, E. coli, Klebsiella, Proteus group, and Ps. aeruginosa were used as test organisms.
The serum levels and urinary excretion were composed with those of ampicillin in two healthy volunteers who received a single oral dose of 250 mg under a cross-over design.
The peak serum level, attained 2 hours after administration, was 5.0 mcg/ml for amoxycillin and 2.7 mcg/ml for ampicillin.
Urinary recovery in the first 8-hour urine sample was 61% for amoxycillin and 44.5% for ampicillin.
Biliary levels were studied in 3 patients who underwent drainage from the common bile duct. A cross-over method was applied to two of them. The peak level and the time required were 2.3 mcg/m1 and 4 hours for amoxycillin and 2.4 mcg/ml and 5 hours for ampicillin.
Therapeutic effectiveness was comparatively studied in two groups : 7 patients with surgical superficial infection and 7 with biliary infection. The daily dose was 750 mg in the former and 1, 000 mg in the latter. Good response was obtained in 6 and 2 respectively. No side effect was recorded.

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The biliary excretion of amoxycillin was studied in 8 patients with common bile duct drainage for cholelithiasis. The concentration of the drug in bile was determined by the cup method using B. subtilis PCI-219. After single oral administration of 1, 000 mg of amoxycillin an average biliary level was 0.1±0.3, 2.2±3.0, 5.9 ±8.2, 10.1±14.2, 3.2±5.0 and 1.0±1.3 mcg/ml at 1, 2, 3, 4, 6, and 8 hours, respectively. The highest individual peak was 44 mcg/ml and the lowest 1.4 mcg/ml. No significant correlation between the biliary excretion and liver functions was found.
The serum level of amoxycillin was measured in 3 patients. An average peak was 7. 6±2.3 mcg/ml at 2 hours after administration. In two of these cases the biliary excretion was significantly correlated to the serum level.
Recovery rate of this drug in urine within 8 hours was 46±18% (N=3).
A cross-over test for biliary excretion of amoxycillin and ampicillin was done in 4 cases and almost the same results for biliary level of both drugs were obtained.
It was, therefore, concluded that amoxycillin must be as useful for biliary infections as ampicillin. A clinical application of amoxycillin to some cases with biliary inflammatory disease was presented.

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Double blind test was performed of amoxycillin (BRL2333), using ampicillin (ABPC) as placebo, on the clinical results in surgical field.
The treated patients consisted of acute purulent infections of soft tissue, of more than 16 years of age, and the dosage of amoxycillin was 250 mg×3 per day while that of ABPC the twofold for a week as a rule.
As the results, in respect of drug absorption, a nearly same blood concentration was obtained with amoxycillin at almost a half dose of ABPC as placebo, whereas in respect of clinical practice, amoxycillin proved to demonstrate an efficacy without any statistically significant difference at a half dose of ABPC. As for the side effect, no difference was observed between two drugs, without any obstacle to be disputed.

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Amoxycillin, the molecular constructure of which was shown in Fig. 1, the solubility in Table 1, and the antibacterial spectrum in Table 2, was administered orally to twelve volunteers. The dosage was 500 mg and after the administration, the blood levels and the concentrations distributed into the bone marrow were assayed by band culture method (OKUBO).
The experimental results are demonstrated in Table 3, Fig. 2, and Fig. 3. The blood levels were much higher than those of ampicillin.
As for the ratio of the concentrations in the blood and bone marrow, the experimental results are indicated in Table 4; this shows that the ratio increases in the course of time after the administration.

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Amoxycillin was given to twenty-two patients with bone and joint infections, whose ages and sex were demonstrated in Table 1 and the lesions were shown in Table 2. These lesions were thirty in all, and four were chronic osteomyelitis, seven were bed sores, two were suppurative arthritis, and seventeen were post-operative infections. As for the post-operative infections, most of them occurred after primary closure of compound fractures.
The organisms detected in these lesions were shown in Table 3, and most of them were Staphylococcus aureus and others were gram negative bacilli such as Proteus vulgaris, E. coli, etc. The sensibility of these organisms to various antibiotics, such as PC G, SM, KM, TC, CP, EM, MCI, MDI, and ABPC were also demonstrated in Table 3.
Table 4 shows the dosage and the administered period of amoxycillin. The therapeutic results were also indicated in this Table; they were excellent in seven, good in ten, fair in eight, and poor in five lesions.
Discussion was made about the clinical results of amoxycillin, and the author believes that sensibility of the infected organisms and the antibiotic concentrations penetrated into the lesions are the most important factors in these therapeutic results.

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From the fundamental and clinical studies of amoxycillin, a newly developed oral penicillin, the following results were obtained.
Concentrations in oral tissues were determined in rats. Concentrations in the tongue, masseter muscle, submaxi. gland, gingiva and mandibular bone marrow showed the movement parallel to that of blood concentration. Following administration of amoxycillin higher levels were obtained both in blood and tissues concentration than in the case of ampicillin, the reference drug.
Clinically, amoxycillin was tried on 29 patients with infectious diseases of oral region and it was remarkably effective in 8 patients, effective in 15 patients and ineffective in 6 patients. The effective rate was 80%. Bacteria which were found to be α-streptococcus were detected in 5 cases. Side-effects were observed in 2 cases, one was angular stomatitis and the other was gastro-intestinal disturbances.

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The authors have assayed the concentration in serum and oral tissues by means of superposition assay method in Wistar strain rats, after oral administration of amoxycillin.
Compared with the concentrations of ampicillin, the results were obtained as follows :
1) The serum concentration of amoxycillin reached to the maximum level after 2 hours, being later than ampicillin.
2) At the maximum level of the concentrations in oral tissues, those of amoxycillin were higher in the dental pulp, gingiva and submaxillary lymphonodi than those of ampicillin.
3) The concentrations of amoxycillin could be measured after 8 hours of single administration.

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Amoxycillin (α-amino-p-hydroxybenzylpenicillin) is a new semisynthetic penicillin with broad spectrum of antibacterial activity similar to that of ampicillin.
We report here the findings of amoxycillin in oral infections. Thirty patients were studied; all were out-patients at Tokyo Dental College. The standard regimen was 250 mg amoxycillin by mouth 6-hourly.
In clinical evaluation, 9 patients (30%) were superior and 18 patients (60%) were good. The other patients (10%) were not effective. The side effects were seen in 5 patients; nausea, anorexia, diarrhea and others.
Therefore, amoxycillin seems likely to prove effective in therapy of oral infections.

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A new antibiotic amoxycillin has been applied to the infectious diseases in the field of oral surgery and the results were obtained as follows :
1) Amoxycillin was administered orally for 3-11 days at a daily dose of 750, 1000 and 1500 mg to 22 cases of acute oral inflammation.
2) The results were excellent in 1 case, good in 10 cases, fair in 7 cases, poor in 3 cases and uncertain in 1 case. The overall effective rate was 85.7%.
3) No noticeable side effect was observed with amoxycillin.
4) No abnormality was observed in blood and urine findings, and in hepatic function after amoxycillin administration.

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Amoxycillin is a new semi-synthetic penicillin with a broad spectrum of anti-bacterial activity similar to that of ampicillin.
1) Bacterial activity : The test bacteria isolated from urinary tract infections were 53 in total, composed of 43 gram-negative bacteria, and of 10 gram-positive ones. Except penicillinase-producing strains of Staphylococcus aureus, strains of Pseudomonas, indole positive Proteus, Klebsiella and Alkaligenes, amoxycillin showed to be active against strains of E. coli, Proteus mirabilis, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus faecalis.
2) Clinical evaluations
A) Acute cystitis; A total of 50 patients with acute cystitis was treated with amoxycillin. The patients were divided into four groups. Fourteen patients of 50 received 375 mg of the drug daily, 10 was given 500 mg, 8, 750 mg and 18, 1000 mg. Each group demonstrated satisfactory therapeutic response, bacteriological cures being 88. 9%-100% with 3-4 days' treatment courses.
B) Chronic pyelonephritis ; Two of 4 patients were cured with 2, 000mg of the drug daily, infected by amoxycillin sensitive organisms, however, failed in the treatment of the two cases with the infections due to penicillin resistant strains.
C) Urethritis; Seven patients with acute gonorrheal urethritis were well cured within 3-7 days with the drug of the dosis of 500 mg-1000 mg daily and one non-gonorrheal urethritis exhibited also satisfactory result.
3) Side reaction : Except one case of skin rashes, no significant side reactions were encountered.

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A new broad-spectrum semisynthetic penicillin for oral use, amoxycillin, was studied both fundamentally and clinically. Results are summarized as follows.
1) Concentrations in urine and antibacterial activity of urine after oral administration of 250 mg of amoxycillin were equal or slightly higher than those obtained after oral administration of 500 mg of ampicillin.
2) Twenty-five cases of genito-urinary tract infections were treated with amoxycillin at the daily dose of 750 mg.
Satisfactory results were obtained in 20 cases with the overall effective rate of 80%.
3) Subjective side effect, nausea, was occurred only in 1 case.
4) It was considered that the daily dose of 750 mg of amoxycillin was sufficient for the treatment of acute urinary tract infections, but to determine the adequate daily dose of amoxycillin for the treatment of chronic urinary tract infections, further investigations should be carried out here after.

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The absorption and excretion as well as the effect of amoxycillin on urinary tract infections have been studied. The results obtained are as follows :
1) Serum level and urinary excretion
The peak serum level in volunteers after an oral dose of 500 mg occurred in 2 hours and was 9.52 mcg per ml. The level was still 1.93 mcg per ml in 6 hours.
The urinary excretion of amoxycillin over 6 hours period ranged from 56.7% to 61.4% of the dose.
2) Susceptibility of clinical isolates
The antibacterial activity against E. coli, Proteus mirabilis, Proteus vulgaris, Rettgerella, Pseudomonas, Klebsiella, Serratia and Staphylococci was found to be comparable to that of ampicillin.
3) Clinical trials
Of 40 cases of urinary tract infections treated with amoxycillin, 23 cases were responded remarkably, 9 moderately and 8 none. The effective rate was 80.0%.
4) Side effects
Of total 43 cases, 5 had side effect (11.6%); diarrhoea in one case and rash in 4 cases. The medication was discontinued only in one case of rash.

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1) Minimal inhibitory concentration of amoxycillin (AMPC) was determined on 59 strains isolated from urinary tract infections by the plate dilution method. Most strains of Staphylococcus aureus, Escherichia coli and Proteus mirabilis were inhibited at the concentration of 6.25 mcg/ml or less and all of Proteus vulgaris and Pseudomonas were resistant to 100 mcg/ml of AMPC.
2) In a case with normal renal function, the blood level reached to the maximum (7.8 mcg/ml) in 2 hours after administration of AMPC 500 mg per os. In the same case, the blood level reached to the maximum (4.1 mcg/ml) in 2 hours after administration of ampicillin (ABPC) 500 mg per os. The maximum blood level of AMPC was about two times as that of ABPC.
3) The urinary recovery rate was 35.1% during 6 hours after administration of AMPC. The urinary recovery rate of ABPC was 27.6% during the same period.
4) Thirty-two cases with urinary tract infections were treated with AMPC, and excellent or fair effects were obtained in 19 cases. These results were similar to those of ABPC.
5) Side effects were observed in 2 cases of this series; one was skin eruption and gastrointestinal symptom and the other was gastrointestinal symptom.

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In order to test the value in urinary infection, a double blind trial was carried out using ABPC and amoxycillin, and the following results were obtained.
1. MIC of E. coli was usually shown 6.25 mcg/ml for ABPC and 12.5 mcg/ml for amoxycillin, respectively.
2. Clinical effectiveness was obtained from oral dosage of 0.75 g of amoxycillin per day, and it was almost corresponded to that from 1.5 g of ABPC.
3. Frequency and character of side effect caused by amoxycillin were generally the same to those observed by ABPC.

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Amoxycillin, a semisynthetic penicillin which is comparable to ampicillin in antibacterial spectrum and in vitro activity but yields higher concentrations in blood, was administered to ambulatory patients with urinary tract infections.
1) The therapeutic results were as follows : excellent 8 cases, good 2 cases, failure 11 cases, effective ratio 48%.
2) Clinical responses of 9 cases of uncomplicated urinary tract infections were as follows : excellent 7 cases, failure 2 cases, effective ratio 78%, while 12 cases of complicated urinary tract infections showed the responses as follows : excellent 1 case, good 2 cases, failure 9 cases, effective ratio 25%.
3) Bacteriologically, 11 out of 22 strains disappeared and the bacteriological effectiveness was 50%.
4) No serious side effects were observed except for gastrointestinal disturbances in 4 cases.

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Laboratory and clinical investigations were performed on a new penicillin for oral dose, amoxycillin.
1. Antibacterial activity
Antibacterial activity of amoxycillin was compared with that of ampicillin on 11 strains preserved in our Department and 109 strains isolated from urinary tract infections, and the MIC was presented to be equal or 1 tube lower. As to the strains isolated from patients, both gram-negative and-positive bacteria were inhibited the growth at a lower concentration of the drug.
2. Blood serum concentration
Blood serum concentration was measured after 250 mg of amoxycillin or 250 mg of ampicillin were administered orally singly after a meal and after 150 ml of water were drunk after the administration. The blood serum concentration was higher when the water was drunk after an oral administration of amoxycillin than when the antibiotic was administered singly.
3. Clinical result
Effective ratio demonstrated 76.5% in simple inflammation and 33.3% in complicated inflammation respectively with amoxycillin. As for the side effect of the antibiotic, no remarkable change was found objectively, except a drug rash was noticed only in 1 case.

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A new semi-synthesized penicillin, amoxycillin (AMPC) was given to 11 cases of acute bacterial simple cystitis. The result showed excellent in 8 cases, improved in 2 cases and poor in 1 case. Serum levels and urinary excretion of AMPC and ABPC after 500 mg oral administration in healthy adults were measured by thin layer cup method. AMPC indicated higher serum level and greater urinary excretion than ABPC.
No unfavorable side effect was noticed except oral eruption in a case.

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Amoxycillin was orally given to 27 patients with gonorrheal urethritis.
The daily dose was initially 1.5 g, but was reduced gradually through 1.0g to 0.75g or to 0.5g in the light of the high serum level which is twice that of ampicillin.
Satisfactory therapeutic results were obtained in 2 of the 3 patients who were given 1.5g, 6 of the 7 who were given 1g, 9 of the 12 who received 0.75 g. and 3 of the 5 receiving 0.5g.
The results of the present study suggest that patients with this disease should preferably be treated with 0.75 g rather than 0.5 g of this antibiotic for 3 to 5 days and observed for 7 days to ensure prompt relief from urethritic symptoms.

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The blood concentration of amoxycillin, a new ampicillin (ABPC) -like antibiotic, is reputated to be higher than that of ABPC. The present authors have investigated comparatively the clinical effect and side effect of two drugs by means of a double blind test on the cases of acute simple cystitis.
Amoxycillin (1 capsule containing 125 mg) and ABPC (1 capsule containing 250 mg) were administered at a dose of 2 capsules every 8 hours for 7 days respectively. The transition of subjective and objective symptoms were studied on 4-5 th day and 8 th day after the commencement of administration, as well as the relapse of disease was examined on 15 th day.
The criteria of the judgment of clinical effect is indicated in the table. The objects to be analyzed the results of the experiment reached 148 cases except some omitted ones, and the number of cases of two drugs was found to be just the same 74 by chance as clarified by opening the key.
The comparison between the homogeneicity of cases and the clinical result of two drugs was made Statistically by means of m×n contingency table and MANN-WHITNEY U assay method.
A majority of the cases consisted of women in both drug groups, and their ages ranged mostly 20's-40's years. On the first examination, the bacteria isolated from urine were mostly singly, and overwhelmingly numerous was Gram-negative coccus, in which E. coli occupied 82% in amoxycillin group and 75% in ABPC group.
The distribution of MIC was investigated on cultivated bacteria isolated against amoxycillin and ABPC, and the biphase was observed in both groups, a curve with a peak of 6.25 mcg/ml and an another one with a peak of 100 mcg/ml.
As for the clinical results, the remarkably effective cases on 4-5 th day were 57.7% with amoxycillin and 56.2% with ABPC, whereas those on 8 th day 82.5% with the former and 79.7% with the latter. The statistical examination was tried between two drugs, and no significant difference was observed.
As to the relapse ratio on 15 th day, it was 4.8% in amoxycillin group and 3.5% in ABPC group, exhibiting thus no significant difference between two drugs.
The side effect was investigated on 76 cases of amoxycillin group and 78 cases of ABPC group, and the appearance ratio was 10.5% (8 cases) in amoxycillin group and 15.4% (12 cases) in ABPC group, showing thus no significant difference between two drugs. The side effects consist mainly of eruption and gastro-intestinal disorder, and yet the patients who were obliged to interrupt the administration due to the side effect were 3 cases out of 8 cases in the former group and 7 cases out of 12 cases in the latter one.
In short, a quite similar result was obtained both with amoxycillin (a half of common dose of ABPC) or ABPC (a common dose) on the clinical effect, relapse and side effect in the treatment of acute simple cystitis.

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