The in vitro activity of azithromycin (AZM), a new macrolide, was compared with those of erythromycin (EM), oleandomycin (OL), clarithromycin (CAM), josamycin (JM) and rokitamycin (RKM).
AZM possessed broad antibacterial spectra together with potent activity against gram-positive bacteria. AZM demonstrated superior potency against gram-negative bacteria such as Escherichia coli, Shigella spp., Salmonella spp. and Acinetobacter calcoaceticus in comparison with EM, OL, CAM, JM and RKM. AZM also showed a high activity against Haemophilus influenzae, Neisseria gonorrhoeae and Moraxella catarrhalis.
In a killing-kinetics experiment, AZM at four times its MIC demonstrated the bactericidal effect against Staphylococcus aureus and H. influenzae.

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The in vitro and in vivo antibacterial activities of azithromycin (AZM) were compared with those of erythromycin (EM), clarithromycin (CAM), josamycin (JM), midecamycin acetate (MDM), kitasamycin, rokitamycin, ampicillin, cefaclor (CCL) and ofloxacin (OFLX). In addition, in vitro resistance emergence tests were also conducted.
AZM demonstrated broad-spectrum against gram-positive bacteria and produced a significant improvement in potency against gram-negative organisms as compared with other macrolides. The AZM MIC for 90% of the strains (MIC₉₀) against methicillin-susceptible Staphylococcus aureus was 2-and 4-fold less than that of EM and CAM, respectively. The MIC₉₀ of AZM against Streptococcus pneumoniae was equivalent to that of EM and 2-fold less than that of CAM. AZM was the most active antibiotic against Neisseria gonorrhoeae, Vibrio cholerae and Vibrio parahaemolyticus among the macrolides; with tested MIC₉₀ values of 0.20, 1.56 and 1.56μg/ml, respectively. It was four and eight times more potent than EM and CAM against Haemophilus influenzae (MIC₉₀, 3.13μg/ml). In a killing-kinetics experiment, AZM, at its MIC, showed better bactericidal activity against Staphylococcus aureus than EM and an activity similar to that of CAM. It also showed the best bactericidal effect for S. pneumoniae. In the in vitro emergence of resistance experiment, the increase in the AZM MIC for 80% of the strains (MIC₈₀) was one dilution for S.aureus. Furthermore, the MIC₈₀ of CAM, JM and OFLX for S.aureus increased by two dilutions while the MIC₈₀ of EM and CCL for S.aureus increased by three dilutions. Thus, among the drugs tested the MIC80 increase rate for AZM, namely resistance emergence, was the lowest.
In the therapy of experimental acute systemic infections in mice, AZM exhibited lower activity than CCL and CAM against S.aureus, and demonstrated the lowest ED₅₀ against Streptococcus pyogenes and _S.pneumoniae. The number of organisms recovered decreased more significantly following treatment with AZM than with CAM or OFLX in murine models of S. pneumoniae lung infection and H. influenzae lung infection (p<0.01).
Because of its excellent pharmacokinetics, as shown by the serum and lung T_1/2 of AZM being 8-and 10-times longer than those of CAM, AZM produces greater in vivo efficacy.

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Eighty percent minimum inhibitory concentrations (MIC₈₀) of azithromycin (AZM) were>100, >100, >100, 0.20, 3.13, 0.10, >100, >100, 0.78, 6.25, 25, >100 and 0.20μg/ml against 18 to 77 clinical isolates of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), coagulase-negative staphylococci, Streptococcus pyogenes, Streptococcus pneumoniae, Streptococcus agalactiae, Enterococcus faecalis, Enterococcus faecium, ampicillin-resistant Haemophilus influenzae, Escherichia coli CS2 (R⁺), Acinetobacter calcoaceticus, Campylobacter coli and Campylobacter jejuni, respectively.
Approximately 32% of clinical isolates of MSSA were resistant (higher than 12.5μg/ml) to erythromycin (EM) and cross resistant to AZM.
AZM, as well as EM and clarithromycin, showed moderate synergy in bactericidal effect with whole blood cells and lysozyme.
Synergy with complement in producing its bactericidal effect was markedly demonstrated in the case of S. aureus.
The S. aureus organisms were well phagocytosed and rapidly digested by cultured murine macrophages in the presence of a higher than 1/4 MIC of AZM.

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The in vitro activity of azithromycin (AZM), a new macrolide, was compared with those of erythromycin (EM), clarithromycin (CAM), ampicillin (ABPC), and cefaclor against anaerobic bacteria and a fastidious facultative anaerobe, Gardnerella vaginalis. Against Ureaplasma urealyticum, AZM, EM, CAM, and minocycline (MINO) were involved for susceptibility testing. AZM had broad spectrum against grampositive and gram-negative reference strains of anaerobes, inhibiting many anaerobic bacterial strains at 3.13μg/ml or less. AZM was as active as or less active than EM against clinical isolates of Peptostreptococcus spp. and gram-positive rods. AZM was very potent against Mobiluncus spp. Although AZM had weak activity against the Bacteroides fragilis group, this compound had very strong activity against Prevotella bivia and Prevotella intermedia, the activity which was more than those of cefaclor and ampicillin. The influence of inoculum size upon antimicrobial activity was seen in AZM as well as EM and CAM. The activity of AZM was effected by medium pH; lowering pH from 7 to 6 rendered MIC 4 time or more higher. In a mouse model of intraabdominal infection with B. fragilis and Escherichia coli, AZM was as active as CAM. AZM was less active than CAM, comparable to MINO, and more active than EM against U. urealyticum. These results suggest that AZM is more effective than EM on anaerobic infections and ureaplasmal infections.

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The in vitro and in vivo activities of azithromycin (AZM), a new macrolide antibiotic, were evaluated in comparison with those of erythromycin (EM), clarithromycin (CAM), josamycin (JM), rokitamycin (RKM), amoxicillin (AMPC), cefixime (CFIX), and cefaclor (CCL). In addition, ofloxacin (OFLX) was used as a comparative drug in a partial experiment.
AZM had a broad and potent antibacterial spectrum against Gram-positive and Gram-negative bacteria, including Haemophilus influenzae, Neisseria gonorrhoeae, Moraxella catarrhalis, Escherichia coli, Shigella spp., Salmonella spp., andAcinetobacter calcoaceticus.
AZM showed bacteriostatic action against Staphylococcus aureus and Staphylococcus epidermidis, and concentration-dependent bactericidal activity against Streptococcus pneumoniae, E. coli, Klebsiella pneumoniae, and H. influenzae.
Morphological observation with a scanning electron microscope and transmission electron microscope demonstrated that AZM produced the remarkable thickness of the cell wall of S. aureus and the elongation cells of E. coli, K.pneumoniae and H. influenzae.
Therapeutic efficacy of AZM against systemic infection in mice was superior to those of EM, JM, and RKM against S. aureus, Streptococcus pyogenes and S.pneumoniae. Although AZM was slightly inferior to CAM against S.aureus, it was superior to CAM against S. pyogenes and S. pneumoniae with ED₅₀ about 3 fold lower than those of CAM. AZM showed good protective activity against abscess formation induced by S. aureus in mice. It was superior to those of EM, OFLX and CCL, and similar to that of CAM.

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The in vitro activity of azithromycin (AZM), a macrolide antibiotic, against gram-negative bacteria was evaluated in comparison with those of erythromycin (EM), clarithromycin (CAM), cefoperazone (CPZ) and ciprofloxacin (CPFX). In this study, Escherichia coli, Klebsiella pneumoniae and Haemophilus influenzae were used as test strains.
AZM showed concentration-dependent bactericidal activity against all the strains tested. Morphological observation with a phase-contrast microscope demonstrated that AZM produced elongation and swelling of cells in E. coli, K. pneumoniae and H. influenzae at around each MIC. At high concentrations, bacteriolysis was observed. AZM had a postantibiotic effect against E. coli, K. pneumoniae and H. influenzae, similar to CPFX. The bacterial ATP of E.coli was reduced after exposure to 1 MIC of AZM, and its activity was similar to that of 4 MIC of EM and 4 MIC of CAM and superior to that of 4 MIC of CPZ and 4 MIC of CPFX.

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The in vitro activities of azithromycin (AZM) against a reference strain and 20 clinical isolates of Chlamydia trachomatis were compared with the activity of two macrolides, three quinolones and minocycline.
The minimal inhibitory concentrations (MIC;μg/ml) for the isolates were as follows: AZM, 0.063 to 0.125; erythromycin, 0.125 to 0.25; clarithromycin, 0.008 to 0.016; sparfloxacin, 0.031 to 0.063; tosufloxacin, 0.125 to 0.25; ofloxacin, 0.5 to 1.0; and minocycline, 0.031 to 0.063. The results for the reference D strains were similar to those for the 20 clinical isolates.
The minimal lethal concentrations (MLC) of all antibiotics except AZM were 8 to 16 times higher than the respective MIC, while the MLC of AZM against D strain was only 2 times higher than its MIC. The effects on MLC of the duration of the presence of each drug were also studied.

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The in vitro and in vivo activities of azithromycin (AZM) were compared with those of erythromycin (EM), clarithromycin (CAM), josamycin (TM), midecamycin acetate (MDM), rokitamycin and cefaclor. MICs of AZM for Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumoniae were generally two to eight-fold higher than those of EM and CAM. AZM was two to eight-fold more active than EM and CAM against Neisseria gonorrhoeae, Moraxella catarrhalis and Haemophilus influenzae.
Neither growth media nor inoculum size had any marked effect on the in vitro potency of AZM or EM. The presence of horse serum enhanced the activity of both AZM and EM. An alkaline medium decreased the MIC values of AZM and EM, while an acidic medium increased MIC values.
AZM showed clear bactericidal activities against S. aureus at two-fold its MIC and against H. influenzae at its MIC. MBC₉₀ of AZM for S. aureus and S. pyogenes were six and eight dilutions higher than its MIC₉₀, when incubated with antibiotics for 24h. However, when the incubation time was increased to 48 or 72h, MBC₉₀ of AZM decreased and were equal to the MIC₉₀.
The rates of in vitro emergence of resistance to AZM were similar to those of EM and CAM in S. aureus, S. pyogenes and H. influenzae.
Therapeutic activities of AZM against systemic murine infections with S. aureus, S. pyogenes and S. pneumoniae were greater than those of EM and MDM, even though EM and MDM exhibited greater in vitro potencies. In a murine model of respiratory infection with H. influenzae, AZM significantly reduced the recoverable pathogen counts as compared with CAM.

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We compared the in vitro activity of azithromycin (AZM), against fresh clinical isolates, with that of erythromycin (EM) clarithromycin (CAM) roxithromycin (RXM) josamycin, midecamycin acetate and cefaclor.
The activity of AZM against methicillin-susceptible Staphylococcus aureus (MSSA) was 2-4-fold lower than those of EM and CAM, but similar to that of RXM, Although EM-susceptible MSSA were highly sensitive to AZM, EM-resistant isolates exhibited cross resistance to AZM, CAM and RXM. Six (33.3%) of 18 methicillin-resistant S. aureus isolates were inhibited by 0.78μg/ml of AZM. The sensitivity patterns of Staphylococcus epidermidis and other coagulase-negative staphylococci were similar to those of MSSA.
AZM showed high activities against Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus sanguis, Streptococcus anginosus, Streptococcus constellatus, Streptococcus MG-intermedius and Streptococcus intermedius, with MIC₉₀s of 0.10 0.39μg/ml. The activity of AZM against Streptococcus pneutnoniae was comparable to that of RXM.
AZM was the most potent, among the antibiotics tested, against Moraxella catarrhalis. AZM had a 4-8-fold greater activity against Haemophilus influenzae than EM and CAM. AZM showed moderate activity against Enterobacteriaceae, which was minimally susceptible to the other macrolides.
The activities of AZM against anaerobes, such as Peptostreptococcus spp., Propionibacterium acnes, Bacteroides spp., Prevotella spp. and Fusobacterium spp., were nearly equivalent to those of EM and CAM.

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We compared the therapeutic efficacy of azithromycin (AZM), in several localized infection models, with those of clarithromycin (CAM), tosufloxacin (TFLX) and cefaclor (CCL). Local delivery of AZM and CAM to infection sites was also studied.
In a rat pouch infection with Staphylococcus aureus, 30mg/kg doses of AZM at 0, 6 and 24h postchallenge reduced the CFU by approximately 99% from the initial inoculum. Although the MIC of AZM was 4 and 16 fold higher than that of CAM and TFLX, respectively, AZM demonstrated greater therapeutic efficacy than CAM and TFLX.
In a murine model of subcutaneous infection with Streptococcus pyogenes, 25mg/kg (twice a day) doses of AZM at 1 and 2 days post-challenge produced a 99% reduction of CFU as compared to an untreated control. These effects of AZM were much greater than those of CAM, even though CAM exhibited greater in vitro potency.
In a murine respiratory infection model with Haemophilus influenzae, a single dose of AZM (50 mg/kg) at 4h post-challenge significantly (p<0.01) reduced the CFU as compared with CAM and the untreated control. AZM produced more than 40 times higher concentrations in lungs than in serum, and the lung concentrations exceeded the MIC for the pathogen until at least 48 h post-dosing. Lung concentrations of AZM in infected mice were significantly (p<0.01) higher than in non-infected mice.
These results suggest that AZM may have good clinical efficacy in localized human infections because of its high, and prolonged, levels in tissues.

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We established a microbiological assay method and modified shepard's high-performance liquid chromatography (HPLC) method for the quantitative determination of azithromycin (AZM).
In the bioassay method, the AZM concentration was determined by using Micrococcus luteus ATCC9341 as a test organism and antibiotic medium No.11 as a test medium.
In the HPLC method, the concentrations of AZM and its metabolites in body fluids were determined by HPLC combined with an electrochemical detector. AZM and its metabolites were well separated from organic components, and good linear calibration curves were obtained.
The serum concentrations of AZM in healthy male volunteers after oral dose were determined by HPLC and bioassay. The results showed a high correlation (correlation coeffect: 0.998).

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Azithromycin (AZM) is an antimicrobial agent of a new class known as azalides, which contains a nitrogen atom in the macrolide aglycone ring. AZM has greater stability than erythromycin in the presence of acids and also has an enhanced spectrum of activity, with significantly greater activity against gram-negative organisms than, erythromycin (EM) while retaining activity against gram-positive organisms. In this study we investigated the pharmacokinetics of AZM in experimental animals following oral administration.
1. The effect of dose was examined at 10, 20 and 50mg/kg of AZM in rats. At these doses, mean peak serum concentration was attained 3-4h after dose, mean elimination half-life (T_1/2) was 20-23h, and each values were approximately the same irrespective of the dose. Cmax and AUC were roughly dosedependent at these doses.
2. Following on oral dose given to male and female rats, no significant differences were observed in pharmacokinetic parameters between male and female.
3. Following an oral dose of ¹⁴C-AZM to rats, radioactivity was rapidly the distributed throughout the body, and almost all the tissue concentrations were higher than the plasma concentration.
High tissue concentrations were observed at immune systems such as spleen, thymus, lymph node and bone marrow at 120 h after dose.
4. Radioactivity in milk amounted to about 10 times that in blood at 2 h after dosing, but completely disappeared by 168 hours.
5. Whole-body autoradiography was carried out in the male mice using ¹⁴C-AZM orally. Radioactivity was observed in most tissues at a level higher than that in blood at 2 hr after dosing. At 72 hr after dosing, radioactivity was observed in gastric mucosa, spleen, thymus and testis.
6. Following oral dose of ¹⁴C-AZM to rats, urinary, fecal and respiratory recovery were 13.3%, 80.3% and 3.1%, respectively, and 26.9%, 58.7% and 3.5% after intravenous dose.
7. Biliary excretion of ¹⁴C-AZM in rats was 8.1% at 48 hr after dose. Entero-hepatic circulation of AZM was observed; 3.6% of intraduodenally injected radioactivity was reexcreted into bile.
8. AZM was mainly excreted as unchanged compound in urine, feces and bile of rats after oral administration.
. Protein binding of AZM was 10-23%, irrespective of the drug concentration, and much lower than that of the other 2 macrolides.

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The distribution of azithromycin (AZM) in the infection site, following an oral dose of 20 mg/kg, was studied in mice with localized Staphylococcus aureus infections.
1. Autoradiograms of [¹⁴C] AZM showed that the radioactivity was well distributed to infection sites, and that the degree of radioactivity in the infection site was higher than in non-infected regions, suggesting that AZM was selectively distributed to infection sites.
2. Micro-autoradiograms of [³H] AZM showed that radioactive silver grains were presented with phagocytic cells in granulation tissues, such as neutrophils and macrophages, suggesting that AZM in vivo had apparently penetrated into phagocytic cells.

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The general pharmacological actions of azithromycin (AZM) were examined in animals. Oral administration of AZM caused loss of huddling behavior, response to tail pinch and pinna reflex in one of five mice at 300mg/kg, but the effect was not dose dependent. Increasing doses up to 500mg/kg slightly suppressed gastrointestinal propulsion. In rats, AZM reduced gastric secretion at 300mg/kg (intraduodenal dosing: i. d.). In anesthetized dogs, AZM (i. d.) induced transient and slight increases in blood pressure, heart rate and respiration at more than 40mg/kg, but intravenous dosing of 10mg/kg did not affect the hemodynamic responses to autonomic agents or carotid occlusion. No other effects of AZM were found in the central nervous system, autonomic and somatic nervous systems, isolated smooth muscles, renal excretion or blood system.
Thus, AZM seems to be a highly safe macrolide antibiotic.

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Phase I studies of azithromycin (AZM) were conducted in healthy male volunteers to evaluate its safety and pharmacokinetics.
In the single-dose study, 125, 250, 500 and 1000mg of AZM were administered in the fasting state.
In the multiple-dose studies, 250 or 500mg of AZM were administered once a day, at 24-hour intervals for 3days.
No side effect, without mild abdominal pain in 3 patients, was observed and abnormal laboratory findings attribute to AZM was not observed during these 2 studies.
The serum concentrations after single oral doses of 125, 250, 500 and 1000mg of AZM in the fasting group showed dose-dependency, and peak levels were 0.09, 0.24, 0.58 and 0.74μg/ml, respectively, about 2-3 hours after administration.
The elimination half lives at 48-168 hours following single dosing ranged approximately between 62 to 68 hours, no dose-dependency was observed.
In the serum concentration following multiple dosing, no accumulation was observed.

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A phase I multiple dose studies of azithromycin (AZM) was carried out in healthy male volunteers to evaluate safety and pharmacokinetics.
No appreciable change was observed in the pharmacokinetics of AZM during repeated oral dosing.
Safety was assessed by physical examinations, including ophthalmological and hearing acuity tests performed prior to and after administration. No clinically significant changes were observed in any of the safety parameters. There were no side: effects, other than mild to moderate headache, abdominal pain, upper abdomen pressure sensation, loose stools and diarrhea, observed in two patients and there were no abnormal laboratory findings attributable to azithromycin.
We conclude that AZM was generally well tolerated, and there were no clinically significant adverse effects.
Azithromycin is potentially useful antimicrobial agent which merits further clinical study.

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The effect of meal fasting state or after meal on the 500mg oral administration of azithromycin was investigated using a cross-over design study with 8 healthy male volunteers.
Time of maximum concentration (Tmax), maximum concentration (Cmax), area under the concentration-time curve (AUC), and elimination half-life (T_1/2) of serum azithromycin concentrations showed no statistically significant difference between after-meal and fasting. Total urine excretion rates also showed no statistically significant difference.
No abnormal findings in clinical symptoms definitely attributable to azithromycin were found throughout these studies.

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The pharmacokinetics of azithromycin (AZM) in patients with renal failure were investigated by dividing patients into a mild group (Group I: 50<creatinine clearance [Ccr]≤70ml/min), a moderate group (Group II: 30<Ccr≤50ml/min), and a severe group (Group III: Ccr≤30ml/min), based on Ccr values.
1) The times when the serum concentration reached its maximal level (Tmax) in Groups I, II and III were 2.0, 2.4 and 2.0 hours, respectively, after a single oral 500mg administration of AZM. Maximal serum concentrations (Cmax) in these groups were 0.557, 0.538 and 0.582μg/ml, respectively. The respective half times (T_1/2) were 34.1, 33.8 and 29.9 hours. There were no significant differences in any of the parameters calculated from the serum concentrations among the three groups.
2) The rates of AZM recovery from urine, 72 hours after administration, in the above groups were 4.48, 4.51 and 2.87%, respectively, showing a significant difference between Groups II and III.

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A newly developed antibacterial agent derived from azalide, azithromycin (AZM), was administered to a patient with respiratory infection to examine the concentrations in blood and sputum with time as well as its clinical usefulness. AZM at a dose of 500mg was administered once a day for 3 days to an infected patient with bronchiectasia. Sputum samples were obtained daily from days 1 to 14 to determine their AZM concentrations. The peak concentration in sputum appeared 6-8 hours after administration on days 1, 2 and 3, with values of 1.76, 5.62 and 7.42μg/ml, respectively. The ratio of concentration in sputum to that in serum 1-1.5 hours after administration ranged from 0.697 to 32.6. Clinical examination was carried out in 13 patients, including 4 cases of pneumonia, 1 of chronic bronchitis, 3 of bronchiectasia+infection, 2 of bronchial asthma+ secondary infection, and 1 of pulmonary fibrinosis+secondary infection. AZM was orally administered at a dose of 250 or 500mg, once a day, for 3 days. The result was evaluated as excellent in 2 cases and good in 11 cases, an efficacy rate of 100%.
Bacteriologically, 6 causative strains, including 2 of Streptococcus pneumoniae and 1 each of Streptococcus pyogenes, Enterobacter cloacae, Haemophilus influenzae and Haemophilus parahaemolyticus, were eradicated by AZM. However, 1 strain, including 1 of S. pneumoniae showed no changes. No adverse reactions or abnormal laboratory changes were observed during the study period.

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The in vitro antibacterial effect of azithromycin (AZM), a new macrolide antibiotic, on 3 clinically isolated strains, S. pneumoniae, M. catarrhalis and H. influenzae, was examined. The MIC₉₀ was revealed to be 0.78μg/ml for S. pneumoniae, 0.1μg/ml for M. catarrhalis, and 3.13μg/ml for H. influenzae. The utility and safety of AZM were examined in 11 cases of respiratory infection. The drug at a dose of 250 or 500mg was administered once a day for 2-4 days with the following results. Pathogens eliminated by AZM administration included all 3 strains of M. catarrhalis, 1 of 3 strains of H. influenzae and both of 2 strains of S. pneumoniae. Against I isolated strain of Pseudomonas aeruginosa, another antibacterial agent was used on and after 2 days of AZM administration; however, the bacteriological effect was unclear. The result was evaluated as good in 7 cases (2 of acute bronchitis, 2 of chronic bronchitis, 3 of old pulmonary tuberculosis+ infection), fair in 1 case (chronic pulmonary emphysema+ infection), poor in 2 cases (1 of acute pharyngolaryngitis, 1 of chronic bronchitis) and undeterminable in 1 case (acute aggravated case due to chronic panbronchiolitis), an efficacy rate of 70.0%. No adverse reactions were observed, while abnormal changes in laboratory values included elevated GOT, GPT, ALP, LDH and γ-GTP in 1 ease.

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The in vitro antimicrobial activity of azithromycin (AZM), a new azalide antimicrobial agent for oral use developed by Pfizer pharmaceutical company, and its therapeutic efficacy in the treatment of respiratory tract infections were evaluated. The minimum inhibitroy concentrations (MICs) of AZM, erythromycin (EM), clarithromycin (CAM) and roxithromycin (RXM) against 20 strains each of methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Pseudomonas aeruginosa, and 18 strains of Enterobacter cloacae were determined by the micro-broth dilution method using the Dynatech MIC 2000 system. As shown by the MICs obtained, AZM was less active against MSSA and MRSA, and more active against Enterobacteriaceae and P. aeruginosa than EM, CAM and RXM. Thirteen patients received a daily dose of 250 mg (6 cases) or 500mg (7 cases) of AZM per os for 3 days: 2 patients each with acute bronchitis and chronic bronchitis, 7 with acute pneumonia, 1 with Mycoplasma pneumoniae pneumonia and 1 with infection associated with old pulmonary tuberculosis. The clinical effects were excellent in 4 and good in 9 patients (efficacy rate: 100%). Eight strains were identified as causative organisms: 1 strain each of Haemophilus influenzae and S. aureus and 6 strains of Streptococcus pneumoniae. The 6 strains were eradicated but 1 strain each of S. aureus and S. pneumoniae persisted after therapy. Diarrhea occurred in 2 patients during AZM therapy and a transient elevation of serum transaminase was observed in another. These adverse reactions disappeared after completion of therapy. We conclude, from the above results, that AZM is one of the most useful oral antimicrobial agents and should be a drug of first choice in the treatment of respiratory infections.

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Fundamental and clinical studies of azithromycin (AZM) were carried out with the following results. In the fundamental study, the MICs of AZM against gram-positive bacteria [methicillin-sensitive Staphylococcus aureus (MSSA), Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus pneumoniae, Enterococcus faecalis] and gram-negative bacteria [Moraxella catarrhalis, ampicillin (ABPC)-sensitive Haemophilus influenzae, ampicillin (ABPC)-resistant H. influenzae, Acinetobacter sp.] were examined and compared with those of other macrolide antibacterial agents (erythromycin, clarithromycin, rokitamycin) as well as those of ofloxacin, tosufloxacin, clavulanic acid/amoxicillin, amoxicillin, cefotiam, minocycline and cefpodoxime. It was revealed that the drug has excellent antibacterial activity especilly against gramnegative bacteria as compared with other macrolide antibacterial agents. In the clinical study, AZM at a dose of 250-500mg was administered once a day for 3 days to patients with respiratory infection. The result was assessed as excellent in 10 cases and good in 3 cases, an efficacy rate of 100%. Except for slightly increased GOT, no adverse reactions were observed, indicating that the drug is effective and safe as an antibacterial agent against respiratory infection.

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Fundamental and clinical studies of azithromycin (AZM) an azalide antibiotic, were performed.
The minimum inhibitory concentration (MIC) of AZM was determined using 39 strains of sputumderived penicillin-sensitive Streptococcus pneumoniae (PSSP), penicillin-insensitive S. pneumoniae (PISP) and 8 strains of blood-derived S. pneumoniae. The MIC₅₀ and MIC₈₀ of AZM against PSSP derived from sputum were 0.05μg/ml and >100μg/ml, respectively. These values against PISP were 0.78μg/ml and >100μg/ml, respectively, almost equal to those of erythromycin. The MIC₅₀ and MIC₈₀ of AZM against blood-derived S. pneumoniae were 0.05 and 0.39μg/ml, almost equal to those of clarithromycin. The clinical effect of AZM was examined in 41 cases of respiratory infection, including 2 of acute bronchitis, 10 of pneumonia, 1 of mycoplasma pneumonia, 18 of chronic bronchitis, 3 of bronchiectasis infection, 1 of diffuse panbronchiolitis+infection, 3 of bronchial asthma+infection, 1 of pulmonary emphysema+infection, and 2 of pulmonary fibrosis+ infection. The drug was administered at a dose of 250 or 500mg once a day for 3 days as a rule. The result was evaluated as excellent in 9, good in 19, fair in 7, poor in 3 and undeterminable in 3, for an efficacy rate (excluding the undeterminable cases) of 73.7%(28/38). Although no adverse reaction due to AZM was observed, abnormal changes in laboratory values were noted: increased eosinophils, decreased potassium and increased potassium levels in 1 case each.

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A clinical study on the utility of 3-day treatment with azithromycin at a dose of 250 or 500mg once a day was carried out in 10 cases of respiratory infection. Microbiologically, 3 strains, Enterobacter agglomerans, Enterobacter cloacae and Haemophilus influenzae, were successfully eradicated, but Klebsiella oxytoca only decreased. All these strains were judged as the responsible pathogens. Thus the efficacy rate was 80.0%. Although no adverse reaction was observed, slightly elevated γ-GTP was noted in 1 case.

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Azithromycin (AZM), a new oral azalide antibiotic, was p.o. administered to 5 aged patients with various disturbances of renal function at a single dose of 500mg, to examine its blood concentration and urinary excretion rate. The degree of renal disturbance was graded as mild (Group I) in 1 case, moderate (Group II) in 1 case and severe (Group III) in 3 cases for comparison of the pharmacodyna-mics in individual groups. As a result, the elimination half-life in blood was revealed to be 45.4hr in Group I, 30.5hr in Group II and 29.7hr in Group III (mean values). The area under the blood concentration time curve (AUC) was 3.83, 4.21 and 4.66μg·h/ml in Groups I, II and III, respectively. The excretion rate in accumulated urine samples of up to 120 hours after administration was 5.57% in Group I, 5.53% in Group II and 4.62% in Group III. AZM was used in 6 patients with respiratory infection, including 1 case of chronic bronchitis, 2 of bronchiectasia+infection and 3 of bronchial asthma+infection. The result was evaluated to be good in all 6 cases. There were no adverse reactions or abnormal laboratory values thought to be due to the drug during the study period. Thus the drug was considered to be a useful agent for treating respiratory infection.

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The antimicrobial activities of azithromycin (AZM), a new azalide antibiotic, against clinically isolated strains of major respiratory pathogenic bacteria and standard strains of Chlamydia spp., were investigated and compared with those of other antibiotics.
Eleven cases with respiratory tract infections were treated with AZM and the clinical efficacy and safety of the drug were evaluated.
1) In vitro activities (MICs) of AZM against Gram-positive bacteria, such as Staphylococcus aureus and Streptococcus pneumoniae, were inferior to those of clarithromycin (CAM) and roxithromycin while activities against Haemophilus influenzae and Moraxella catarrhalis were superior to those of the other drugs tested.
2) MICs of AZM against standard strains of Chlamydia psittaci, Chlamydia pneunwniae and Chlamydia trachomatis were 0.125μg/ml, superior to that of erythromycin but inferior to the MICs of CAM and minocyclines.
3) The clinical efficacy of AZM at treatment dosages of 250-500 mg once daily for 3 days in 11 cases with respiratory tract infections, was evaluated as excellent in 4 cases, good in 6 cases and fair in one case. No clinical adverse reactions or severe abnormal changes in laboratory examinations were observed.

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The antibacterial potential of azithromycin (AZM), a new oral azalide antibiotic, in the treatment of respiratory pathogens as well as its clinical effect on respiratory infections were examined in this study, with the following results. The MIC of AZM against clinically isolated strains from patients with respiratory infections was 0.39->100μg/ml (MIC₉₀>100μg/ml) for Staphylococcus aureus, 0.05-25μg/ml (MIC₉₀ 25μg/ml) for Streptococcus pneumoniae, 0.025-0.1μg/ml (MIC₉₀ 0.1μg/ml) for Moraxella catarrhalis and 0.39-3.13μg/ml (MIC90 1.56μg/ml) for Haemophilus influenzae. The clinical results in 8 patients with respiratory infection (1 with acute bronchitis, 1 with pneumonia, 1 with chronic bronchitis, 2 with diffuse panbronchiolitis, 2 with bronchiectasis+infection and 1 with chronic pulmonary emphysema+infection) were rated excellent in 1 and good in 7 cases, an efficacy rate of 100%. The pathogenic bacterium was detected in 4 cases, including mixed infection of S. aureus+S. pneumoniae, S. pneumoniae, E. coli and H. influenzae in 1 case each. All of these bacteria were eradicated completely after AZM administration.

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To 10 inpatients with respiratory infection (mean age: 73.4 yr), azithromycin (AZM) was administered at a dose of 250 or 500 mg once a day for 3 days to determine its blood concentration. Although determination of blood concentration with time failed in individual subjects, the blood concentrations that were successfully determined coincided well with the results obtained by extrapolation from changes in the blood concentration in the Phase I successive administration test of AZM.
To 21 patients with respiratory infection (1 case of acute bronchitis, 5 of pneumonia, 5 of chronic bronchitis, 3 of bronchiectasia+infection, 3 of old pulmonary tuberculosis+infection, 2 of pulmonary emphysema+infection, 1 of bronchial asthma + infection, 1 of pulmonary emphysema+pulmonary tuberculosis+infection), the drug was orally administered at a dose of 250 or 500mg once a day for 3 days to examine its clinical effect and safety. Except for 1 not evaluated case, the clinical result was assessed to be excellent in 8, good in 7 and fair in 2, and poor in 3 cases. Bacteriologically, 2 strains, 1 of Streptococcus pneumoniae and 1 of Haemophilus influenzae, were isolated. These were completely eradicated by AZM administration. As for adverse reactions due to AZM administration, diarrhea appeared in 1 case, increased eosinophils in 4 and elevated ALP in 1.

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A newly developed antimicrobial agent, azithromycin (AZM), was evaluated in vitro and in vivo. The following results were obtained:
1) Antimicrobial activity: Minimal inhibitory concentrations (MICs) against 571 clinical isolates of 16 different species were determined, and compared with those of 4 other drugs, erythromycin, clarithromycin, roxithromycin and josamycin. AZM showed excellent antimicrobial activities against Haemophilus influenzae and Moraxella catarrhalis. The MICs of AZM against these bacteria were equal to or lower than those of the other drugs tested.
2) Clinical efficacy and adverse reactions: 11 patients with respiratory tract infections were treated with AZM. The overall efficacy rate was 90.9%(excellent in 3 cases, good in 7, fair in 1). No adverse reactions or abnormal laboratory findings were observed in any case, indicating that AZM is a safe agent.

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We evaluated the usefulness of azithromycin (AZM), a new azalide derivative, in respiratory tract infections. The MIC₅₀, MIC₇₀ and MIC₉₀ (μg/ml) of AZM were 0.78, 3.13 and >100 against Methicillin sensitive Staphylococcus aureus (26 strains), >100, >100 and >100 against Methicillin resistant Staphylococcus aureus (22 strains), 0.10, 1.56 and 3.13 against Streptococcus pneumoniae (46 strains), 1.56, 3.13 and 6.25 against H. influenzae (41 strains), 0.05, 0.05 and 0.05 against Moraxella catarrhalis (45 strains), >100, >100 and >100 against Pseudomonas aeruginosa (46 strains), respectively. The activity were comparable with or superior to those of erythromycin and roxithromycin.
The pharmacokinetics of AZM were studied in three patientswith chronic respiratory infections. The maximum sputum level in the patient after 250 mg oral administration once per day were 0.24μg/ml. The maximum sputum level in other patients after oral administration of 500mg were 1.60μg/ml and 3.54 μg/ml. The maximum serum level were 1.84μg/ml at two hours after oral administration of 500mg.
9 cases with lower respiratory tract infections were studied for the clinical evaluation of AZM. AZM were given orally at 250 or 500mg per day for 3 days. The causative organisms were S. pneumoniae (1 case), H. influenzae (3 cases), M. catarrhalis (2 cases), Corynebacterium pseudodiphtheriticum (1 case) and Acinetobacter haemolyticus (1 case). AZM were clinically effective on the 8 cases of the 9. Only 1 strain of H. influenzae were not eradicated. No adverse reactions were observed.
We concluded that AZM is a very useful oral antimicrobial agent for the treatment of respiratory tract infections.

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The in vitro antibacterial activity of a newly developed macrolide antibiotic, azithromycin, was determined, and its clinical efficacy for respiratory infections was examined in this study. The results were as follows:
1. Antibacterial activity: Using 756 strains from 18 species isolated from clinical specimens (175 strains of gram-positive coccus, 50 strains of Moraxella catarrhalis, 325 strains of intestinal flora, 129 strains of glucose nonfermentative gram-negative bacilli, 51 strains of Haemophilus influenzae, and 26 strains of Bacteroides fragilis), the MICs (minimum inhibitory concentrations) of azithromycin were determined according to the method established by the Japan Chemotherapy Association for comparison with the antibacterial activities of erythromycin, rokitamycin, and clarithromycin. As a whole, the drug showed potent antibacterial activity against gram-negative bacteria, especially Haemophilus influenzae and Acinetobacter calcoaceticus, with no evidence of any resistant strain, although it showed an antibacterial activity almost equal to or slightly weaker than those of conventional macrolide antibiotics against grampositive bacteria.
2. Clinical results: Azithromycin was administered at a dose of 250 or 500 mg once a day for 3 days to 7 patients with respiratory infection. The clinical result was assessed as good in all cases. No subjective or objective adverse reactions or abnormal laboratory values due to the drug were observed.

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We performed a basic evaluation of azithromycin (AZM), a newly developed oral macrolide antibiotic, and clinically studied its application in the treatment of respiratory infections, with the following results.
1. Antibacterial activity
The minimum growth inhibitory concentrations (MICs) of AZM against 284 strains of 14 species isolated from clinical material were measured and compared with those of erythromycin (EM) roxithromycin (RXM) and clarithromycin (CAM), oral macrolides. Based on the MIC₉₀, AZM showed similar activity to those of EM and CAM against Gram-positive bacteria, and showed the strongest activity in these macrolides against Gram-negative bacteria.
2. Clinical efficacy
AZM was given to 4 patients with pneumonia, 1 patient with chronic bronchitis and 1 patient with acute bronchitis, orally at 250 or 500mg once a day for 3 days. The clinical response was excellent in 2 cases and good in 4. No adverse reactions or abnormal laboratory findings were observed.

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The efficacy of a newly developed macrolide antibiotic, azithromycin (AZM), in the field of surgery, was investigated basically and clinically by means of collaborative studies conducted in 18 major institutes and their affiliated hospitals throughout Japan. The following results were obtained.
1. Assessment of pharmacokinetics: AZM levels in gallbladder tissue were 8.42μg/g and 3.92-10.4μg/g about 24 hours and 48 hours, respectively, after a single 500mg administration.
Bile AZM levels reached the maximum level, 186-509 μg/ml, 2-5 hours after administration.
2. Clinical assessment: AZM was administered at a dose of 250mg (titer) or 500mg (titer) once a day for 3 days.
Seven patients were excluded or dropped out, such that clinical efficacy was eventually evaluated in 179 patients. These subjects consisted of 85 with superficial purulent diseases, 13 with mastitis, 25 with periproctal abscess, 45 with superficial secondary infection due to trauma, burn and operative wound, 6 with cholecystitis or cholangitis, and 5 with other infections.
The efficacy rate was 96.5%(82/85) for superficial purulent diseases, 76.9%(10/13) for mastitis, 84.0%(21/25) for periproctal abscess, and 75.6%(34/45) for superficial secondary infection due to trauma, burn and operative wound. The overall efficacy rate was 87.7%(157/179)
The eradication rate was 90.1%(109/121) for gram-positive bacteria, 85.7%(36/42) for gramnegative bacteria, and 93.6%(73/78) for 241 anaerobic strains of casual bacteria, which were isolated from 140 patients. The overall eradication rate was 90.5%(218/241).
Adverse reactions were observed in 6 of 181 patients in whom they were evaluated. They consisted of gastrointestinal symptoms in 5 patients and exanthema in 1. Abnormal changes in clinical laboratory test values were observed in 5 patients, and consisted of eosinophilia in 1, elevation of S-GOT and S-GPT in 1, elevations of S-GOT, S-GPT and γ-GTP in 1, elevations of S-GPT in 1, and elevations of AL-P and γ-GTP in 1.
These results suggest that AZM is very useful for infections in the field of surgery.

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The efficacy, safety and usefulness of a newly developed oral macrolide antibiotic, azithromycin (AZM), for obstetric and gynecological infections were investigated both fundamentally and clinically, and the following results were obtained.
1. Assessment of pharmacokinetics
1) Serum
AZM concentrations in the cubital vein and the uterine artery reached 0.38 μg/ml or 0.02 μg/ml approximately in 4 or 61 hours, respectively after a single 500 mg administration of AZM.
2) Tissue
Concentrations in each genital organ examined reached a maximum level, 2.60-8.23 μg/g or 0.81-5.25 μg/g in 7 or 61 hours, respectively after the administration. The levels were 10 to 20 times higher in the genital organ tissues than those in the serum.
2. Clinical assessment
The efficacy rate was 96.0%(48/50) for intrauterine infection, 92.3%(12/13) for adnexitis, 100%(11/11) for mastitis, and 84.2%(16/19) for external genital infection. 98 patients, out of 107 given, could be evaluated for clinical efficacy, which was 93.9%(92/98). For evaluation of bacteriological efficacy were 72 patients subjected. 90 (82.6%) of 109 strains of causal bacteria were eradicated by the drug. Gastrointestinal symptoms were noted as one of the main adverse reactions, and were observed in 5 (4.7%) of 106 patients. Mild leukopenia was observed in 1 (1.0%) of 101 patients by clinical laboratory tests. All symptoms appeared temporary and mild. The rate of safety (proportion of patients in whom the drug was evaluated as being no problem) was 94.3%(100) of the 106 patients evaluated. The rate of usefulness judged by doctors was 91.9%(91 of the 99 patients evaluated.)
These results suggest that AZM is useful for intrauterine infection, uterine adnexitis, mastitis and external genital infection.

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Fundamental and clinical studies were conducted on azithromycin (AZM), a semisynthetic acid stable, macrolide antimicrobial drug, the structure of which is a 15-member lactone ring, in obstetrics and gynecology. The following results were obtained.
1) The MIC₉₀s of AZM against methicillin-susceptible Staphylococcus aureus (MSSA), methicillinresistant S.aureus (MRSA), Streptococcus agalactiae, Enterococcus faecalis, Escherichia coli, Bacteroides fragilis and Prevotella bivia were 0.20, 100, 0.10, 6.25, 25, 12.5 and 6.25μg/ml, respectively.
2) Concentrations of AZM in the blood and female genital organs after oral administration of 500mg of AZM were measured. The serum concentrations were 0.45-0.02μg/ml at 2.1-61.2 hours posttreatment. The concentrations in the portio vaginalis, cervix uteri, myometrium, endometrium, oviduct and ovary were higher than those in serum; the ranged from 10.8-0.03μg/g at 2.1-61.2 hours posttreatment.
3) Oral administration of 500mg once a day for 3 days was given to 5 patients with obstetric and gynecological infections (1: endometritis and adnexitis, 4: adnexitis), and 1000mg as a single dose was given to 2 patients with chlamydial cervicitis. The clinical efficacy was excellent in 1 patient and good in 1 with chlamydial cervicitis; good in 4 and poor in 1 with obstetric and gynecological infections. The bacteriological efficacy was eradicated in 2 patients with obstetric and gynecological infections and eradicated in 2 patients with chlamydial cervicitis. There were no adverse reactions or abnormal laboratory finidings.

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A clinical study of azithromycin (AZM), a new macrolide antibacterial agent, was performed in the field of obstetrics and gynecology with the following results. Against various genital infections in 26 cases, including 3 of endometritis, 3 of Bartholin abscess and 20 of nongonorrheal cervicitis caused by Chlamydia trachomatis, the drug was administered at a dose of 500mg once a day for 3 days in the former 2 groups and at a single dose of 500mg in the latter after informed consent had been obtained from individual patients. Except for 1 case each of endometritis and cervicitis, the clinical result was evaluated as effective in all cases, an overall efficacy rate of 92.3%. Bacteriologically, 29 strains, including 5 of gram-positive bacteria, 2 of gram-negative bacteria, 2 of anaerobic bacteria and 20 of C. trachomatis, were detected prior to drug administration. All except 1 strain each of Escherichia coli and C.trachomatis were eradicated after AZM treatment, for an overall eradication rate of 93.1%. In addition, no subjective or objective adverse reactions or abnormal laboratory values due to the administered drug were observed. From these results, AZM is expected to be a useful agent for treating genital infections in the field of obstetrics and gynecology.

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A multicenter clinical evaluation of azithromycin, a new 15-membered macrolide, was performed in terms of its efficacy, safety, and usefulness in the treatment of skin and skin structure infections. Azithromycin was administered at the dosage of 250mg or 500mg a day for 3 days after informed consent was obtained.
128 patients were enrolled. The clinical efficacy rate was 85.3%(99/116). The bacteriologic response rate was 73.4 %(58/79). Adverse reactions were seen in 6 out of 126 patients (4.8%). These were loose stool in 2 patients, stomachache in 1 patient, sense of abdominal fullness in 1 patient, heartburn in 1 patient, and aggravation of atopic dermatitis in 1 patient. Abnormal laboratory finding was observed in 1 (eosinophilia) out of 109 patients. Adverse reactions and abnormal laboratory finding were all minor in severity.
Skin penetration of azithromycin was examined in three skin surgery patients after a single oral administration of 500mg after informed consent was obtained. The concentration of azithromycin in the skin ranged from 2.66μg/g to 6.36μg/g (sampling time: 14-15h). The corresponding serum concentration ranged from 0.06μg/ml to 0.10μg/ml.
These results suggest that azithromycin penetrates well into the skin and will be effective, safe, and useful drug in the treatment of skin and skin structure infections.

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The possibility of applying azithromycin (AZM), a new macrolide oral antibiotic, in the fields of dentistry and oral surgery was examined clinically.
1) A clinical examination was performed by administering AZM at a dose of 250 or 500mg once a day for 3 days to 148 patients with infection in the fields of dentistry and oral surgery. The efficacy rate (scoring assessment) was 65.0%(13/20) during 250mg dosing and 90.7%(98/108) during 500mg dosing.
2) The efficacy rate in relation to individual diseases was 78.7%(37/47) for periodontitis, 90.0%(27/30) for pericoronitis and 92.2%(47/51) for osteitis of jaw.
3) The bacterial eradication rate (“disappeared” or “replacement of bacteria”) was 92.3%(60/65).
4) Skin rash was observed in 1 patient treated with 500mg of AZM and the overall incidence of adverse reactions was 0.7%(1/146). The incidence of abnormal laboratory values was 90%(12/134).
5) The safety rate (rate of “no problem”) was 91.1%(133/146).
6) The utility rate (rate of “more than useful”) was 82.2%(106/129).
7) Migration of AZM at a dose of 250 or 500mg into blood, oral tissues, or effusion standing in operative wound after oral surgical tooth extraction performed in 71 patients was investigated. The concentrations of AZM in the wound recorded during the period of 1.4 to 20.5hours after administration of 500mg single-dose AZM ranged from 0.01 to 0.95μg/ml. Oral tissue specimens were measured for AZM concentrations during the period of 3 to 28 hours after the administration, and the follwing results were obtained: 0.27 to 5.6μg/g in the gum, 0.57 to 14.1μg/g in the cystic wall tissue, and 0.06 to 2.50μg/g in other tissues such as tumor-laden oral tissue and maxilla.
The above results suggest that AZM is useful in the treatment of infections associated with dental and oral surgery.

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A clinical study of azithromycin (AZM), a new oral macrolide antibiotic, was performed with the following results. AZM at a dose of 250 or 500mg was administered once a day for 3 days to 5 patients, including 2 cases of pneumonia and 3 cases of chronic bronchitis. The clinical result was effective in 1 of 2 cases of pneumonia and 2 of 3 cases of chronic bronchitis, that is, 3 cases responded effectively and 2 cases did not respond. No adverse reactions were observed, and there was no evidence of abnormal laboratory changes.

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The clinical usefulness of azithromycin (AZM), a newly developed macrolide antibacterial agent, on various infections in the internal field was examined in this study. The drug was administered to 3 patients, 1 with mycoplasma pneumonia and 2 with acute tonsillitis, at a dose of 500mg once a day for 3 days. The result was evaluated as excellent, good and fair in 1 case each. No pathogenic bacterium was isolated in any case, so the bacteriological effect was unclear. Although no adverse reactions were observed, abnormally changed laboratory values were detected, including slightly elevated GOT, GPT and LDH in 1 case.

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The in vitro postantibiotic effect (PAE) of azithromycin, a newly developed macrolide antibiotic, was examined. The results were as follows:
The in vitro PAE of AZM against Staphylococcus aureus Smith, Streptococcus pneumoniae TW 228, and Haemophilus influenzae TW 644 were 0.6, 1.0, and 3.9 hours, respectively, at a dose of 2 MIC, and 1.1, 1.3, and 4.2 hours, respectively, at a dose of 4 MIC.
As compared with the control drugs, erythromycin (EM), roxithromycin (RXM), and clarithromycin (CAM), AZM had a shorter PAE against S. aureus Smith and S. pneumoniae TW 228 but a longer PAE against H. influenzae TW 644.
In the clinical study, AZM was administered to one patient with pneumonia, but another antibacterial agent was combined during the observation period. Thus the clinical effect was difficult to evaluate. Abnormal laboratory changes probably due to the drug were elevated GPT, ALP, and LDH.

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Azithromycin was administered to 10 patients with respiratory infection (2 with pneumonia, 3 with chronic bronchitis, 1 with bronchiectasis+infection, 3 with bronchial asthma+infection and 1 with organized pneumonia) at a dose of 250 or 500 mg once a day by oral route to examine its clinical effectiveness. 2 patients had an excellent response and the drug was good in 7 of the cases of respiratory infection and 1 undeterminable case. Furthermore, no adverse reactions were observed. In the laboratory findings, 1 patient showed a slightly elevated GPT value.

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A newly developed oral macrolide antibacterial agent, azithromycin (AZM), was administered to 2 cases of acute bronchitis, 1 of pneumonia and 1 of diffuse panbronchiolitis during the acute aggravation period, to examine its clinical effect and possible adverse reactions. The drug was administered at a dose of 250 or 500mg once a day for 1-3 days. The response was rated good in all 4 cases. As adverse reactions due to the administration of AZM, diarrhea appeared in 1 case. No abnormal laboratory values thought to be related to the administered drug were observed.

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Azithromycin (AZM) was administered to patients with respiratory infection to examine its clinical utility.
The subjects were 1 case each of pneumonia, bronchiectasis+ infection, and mycoplasmal pneumonia. AZM was orally administered at a dose of 250mg once a day for 3 days in 1 case and at a dose of 500mg once a day for 3 days in the remaining 2 cases.
Bacteriologically, 1 strain of Streptococcus pneumoniae was detected in 1 case, but it showed no change following the administration of AZM. The clinical result was assessed to be excellent in 1 case and good in 2 cases. No adverse reactions were observed, and there was no evidence of abnormal laboratory changes.

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Azithromycin (AZM), a newly developed macrolide antibiotic, was administered to 13 cases, including 1 of acute pharyngolaryngitis, 1 of acute tonsillitis, 7 of acute bronchitis, 1 of acute pneumonia, 1 of mycoplasma pneumonia, 1 of chronic bronchitis and 1 of bronchiectasis+ infection, to examine its clinical effect and safety. The drug was administered at a dose of 500mg once a day (t.i.d. in 1 case alone) for 3 days (7 days in 1 case alone). The result was evaluated as excellent in 4 cases, good in 7, fair in 1 and poor in 1 case. Diarrhea, thought to be due to the drug, was observed in 1 case, while abnormal laboratory values, including elevated GOT, GPT, Al-P, LDH and γ-GTP, were noted in 1 case.

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A newly developed macrolide antibiotic, azithromycin, was administered to 7 patients with respiratory infection to evaluate its clinical efficacy and safety. The subjects included 1 case of acute bronchitis, 2 of pneumonia, 2 of chronic bronchitis, 1 of bronchiectasis+infection and 1 of pulmonary histocytosis X + infection. The result was assessed as excellent in 1, good in 3 and poor in 3 cases. As for adverse reactions, loose stools and abdominal pain were noted in 1 patient, but disappeared on the following day without any treatment. The only laboratory abnormal change was elevated LDH in 1 case.

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The clinical effect of azithromycin (AZM), a newly developed azalide antibacterial agent, was examined, with the following results. The subjects were 7 patients, including 2 cases of acute bronchitis, 4 of chronic bronchitis and 1 of pneumonia. The result was evaluated as good in all 7 cases.
As for the bacteriological effect, Haemophilus influenzae isolated from 1 case of chronic bronchitis was eradicated by AZM. No adverse reactions or abnormal changes in laboratory values were observed throughout the study period

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The clinical effect of Azithromycin (AZM) was examined in 5 patients with respiratory infection. The drug was administered at a dose of 250 or 500mg once a day for 3 days. The clinical result was good in 4 cases and poor in 1 case with the efficacy rate of 4/5. No isolated bacterium was detected in all 5 cases. As for abnormally changed laboratory values, increased NAG and β₂-microglobulin and slightly elevated LAP were observed in 1 case each. In addition, no adverse reactions attributable to the drug administered was noted.

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Eight patients with respiratory tract infections were treated with azithromycin at a daily dose of 250mg or 500mg for 3 days.
Clinical efficacy was good in 7 and poor in 1. No subjective adverse reactions were recognized in any of these patients, though laboratory findings revealed slight elevations of GOT and GPT in one patient.

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A new azalide antibiotic, azithromycin, was administered to 8 patients with infection, including 2 with acute pharyngitis, 1 with acute pharyngolaryngitis, 2 with acute bronchitis, 1 with mycoplasma pneumonia and 2 with chronic bronchitis. The result was evaluated as good in all 8 patients, while the bacteriological effect was eradicated in 3 patients “decreased” in 1 and “unknown” in 4. No adverse reactions or abnormal laboratory findings thought to be due to the administered drug was observed.

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