Cefodizime (CDZM), a newly developed injectable cephem antibiotic, was given to 8 healthy male volunteers with ages 23-28 years (mean: 24 years) and body weights 54-73 kg (mean: 64 kg). 4 volunteers received 2 g b.i.d., intravenous infusion for 5 days, and 4 volunteers had 4 g b.i.d. for the same duration. We studied changes in bacterial flora and drug levels in feces, as well as changes in susceptibility of isolated microbes to CDZM, cefmetazole, cefotaxime (CTX) and cefoperazone. Adverse drug reactions and changes in laboratory findings were also investigated. The following results were obtained.
1. In fecal flora for the 2 g b.i.d. group, on day 3 of treatment Enterobacteriaceae were identified in only 2 of the 4 cases. Individual microbe counts decreased or fell below detection limit (10² cells/g) on day 3 of treatment. Colony forming units (CFUs) of Enterobacteriaceae on day 5 of treatment were similar to those on day 3. After the end of treatment, its CFUs increased. The mean CFU of Enterobacteriaceae on day 10 after the end of treatment increased to about the same level as before dosing. However, some microbes did not revert to pretreatment levels. Of other Gram-negative bacilli, Pseudomonas sp. increased in one case transiently on day 3 of treatment. After day 3 of treatment, its CFU decreased. Gra -positive microbes showed various changes. Mean CFU of yeast like organism (YLO) increased between day 3 of treatment and day 3 after the end of treatment and its mean CFU decreased on day 10 after the treatment. As for anaerobes, CFUs of Bacteroides fragilis group organisms and overall anaerobes showed no distinctive changes. Clostridiun difficile were detected in two cases. In one case, C. difficile was noted at levels between 1.1 × 10³ cells/g and 2.0 × 10⁶ cells/g at the following sampling times: days 1 and 3 of treatment and days 3, 5, 10 and 20 after the end of treatment. In other case, it was noted at levels of 1.8 × 10⁵ cells/g on day 20 after the end of treatment. D-1 toxin was detected in one case before dosing, and in three cases (the concentration of D-1 toxin was 250 ng/g or 500 ng/g) on day after treatment.
Enterobacteriaceae in fecal flora of 4 cases given 4 g b.i.d. frequently decreased or fell below detection limit on days 3 and 5 of treatment and day 3 after the end of treatment. Individual microbes for the 4 g b.i.d. group showed a similar tendency, but the influence of the drug on this group was stronger than that on the 2 g b.i.d. group. After the above mentioned period Enterobacteriaceae increased gradually, and the mean CFU returned to approximately that on day 1. However, some microbes did not revert to pretreatment levels. Of other Gram-negative bacilli and Gram-positive microbes showed no distinctive changes. CFU of YLO increased on days 3 and 5 of treatment and day 5 after the end of treatment, followed by a gradual return to the pretreatment CFU level. Of anaerobes, B. fragilis group showed a slight decrease on day 3 of treatment in some cases. Overall CFUs of anaerobes showed no distinctive change. C. difficile was detected in one case at 1.3 × 10⁵ cells/g, 1.0 × 10⁴ cells/g and 3.0 × 10⁴ cells/g on day 3 before treatment, day 1 of treatment and day 3 after treatment, respectively. In another case, C. difficile was isolated at 1.3 × 10⁶ cells/g, 4.0 × 106 cells/g and 1.0 × 107 cells/g on day 5, 10 and 20 after the end of treatment, respectively. D-1 toxin was detected in one case before dosing, and it was detected in two cases (the concentration of D-1 toxin were 250 ng/g-1,000 ng/g) on day after treatment.
2. Fecal levels of CDZM were determined using bioassay for 3 of the 2 g b.i.d. group on day 3 or 5 of treatment. The levels ranged from 1.5-2,025, μg/g.

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Antimicrobial activities of sulbactam (SBT) with ampicillin (ABPC) or with cefoperazone (CPZ), in other words, the effects of SBT, an β-lactamase inhibitor, against β-lactamase producing strains of clinical isolates, were studied using microdilution broth method.
1. β-Lactamase producing strains such as Staphylococcus aureus, Branhamella catarrhalis, Haemophilus influenzae, Escherichia coli and Klebsiella pneumoniae decompose benzylpenicillin (PCG) which is one of substrates of the acidimetry disc method and show a strong reaction, while they do not decompose cefazolin (CEZ), another substrate, showing no or weak reaction. Thus, it is suspected that β-lactamases produced by these organisms are mainlypenicillinase (PCase).
MIC-distributions of ABPC and CPZ against these clinical isolates which seemed to produce PCase shifted to lower MIC ranges with MIC's reduced to 1/4 or below when 0.025 to 0.39 μg/ml of SBT was added.
2. It appears that β-lactamase produced by Proteus vulgaris may be oxyiminocephalosporinase (CXase), because P. vulgaris showed strong reaction on CEZ, but moderate reaction on PCG In the acidimetry disc method.
MIC-distribution of ABPC and CPZ against P. vulgaris shifted to a lower range with MIC's of 1/4 or below when 0.20 to 0.39 μg/ml of SBT was added.
3. All the test strains of Pseudomonas aeruginosa showed strong reaction on CEZ but only 56% of the test strains showed reaction on PCG. It appears that the β-lactamases which showed strong reaction on CEZ is cephalosporinase and is encoded in chromosome, while those β-lactamase that showed strong reaction on PCG is encoded in a plasmid which was acquired secondarily by P. aeruginosa.
MIC-distribution of CPZ against P. aeruginosa shifted to a lower range with MIC values of 1/2 or below with the addition of SBT at 1.56 μg/ml.
4. It appears that the synergy of SBT with ABPC or with CPZ against the PCase or CXase producing strains may occur in the presence of SBT at a concentration far less than that reported previously.

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We performed abdominal hysterectomy and administered aztreonam (AZT) for prophylaxis of postoperative infections, and investigated influences of the antibiotics on vaginal bacterial flora. Theobtained results are summarized as follows.
1. Patients administered with AZT were studied (n =48) for bacteria isolated from their vaginae preoperatively and at the 7th and the 14th days postoperatively. Groups of patients administered with cephalothin (CET), cefamandole (CMD) and latamoxef (LMOX) were also studied for comparison.
2. In the AZT group, the rate of isolation of aerobic Gram-positive bacteria was high (68.8-81.4%) whereas those of aerobic Gram-negative and anaerobic bacteria were low.
3. When changes in isolation frequencies of bacteria from the subjects preoperatively to postoperatively were compared, the following tendencies were observed: increase in the rate of aerobic Gram-positive bacteria was larger in the LMOX group than in the AZT group whereas decrease in the rate of aerobic Gram-negative bacteria was largest in the LMOX group followed by the AZT group then by the CMD group. Rates of decrease of anaerobic bacteria showed similar tendencies to the latter. Isolation rates of Candida sp. showed the largest increase in the LMOX group, followed by CET, CMD then AZT groups.

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Cardiotoxic effects of ME2303 were studied upon interval intravenous administrations to rats in comparison with those of doxorubicin (ADR).
ME2303 at two dose levels of 3 and 9 mg/kg/day or ADR at a dose levels of 3 mg/kg/day was injected once a week for 3 weeks to female Sprague-Dawley rats (SPF) of 5-weeks of age. ADR depressed body weight gain, decreased food intake and increased water intake. Microscopic observation on the myocardial tissues revealed that ADR caused necrosis and cell infiltration, edema and disarrangement of myofibrils in some of ADR-treated rats. On the other hand, ME2303 showed no significant effects except that some decrease of food intake was observed at a dose level 9 mg/kg/day. No changes in left ventricular functions were observed in perfused hearts isolated from ADR- or ME2303-treated rats. However, about 133 ng/g of ADR remained in the hearts even at 1 week after the final administration whereas ME2303 or its metabolites were not detected, suggesting that ADR may cause disturbance of ventricular function and more cardio myopathy after a longer term than 1 week following the final administration.
These results suggest that the cardiotoxicity of ME2303 is weaker than that of ADR in rats.

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In order to investigate the single dose oral toxicity of BMY-28100 in juvenile animals, the drug was administered in single doses to 4-day-old and 14-day-old Crj: CD (SD) rats of both sexes at a dose of 2,000 mg/kg, and to 4-week-old beagle dogs of both sexes at doses of 500, 1,000 and 2,000 mg/kg by oral route.
The results obtained are summarized as follows:
1. In rats, decreases of the body weight gain were observed for male and female rats treated with the drug on postnatal day 4 through 5 days and 3 days after dosing, respectively. There were no apparent drug-related toxic signs. No deaths occurred during the observation period. Enlargement of the cecum was found in a few rats of both sexes administered the drug on postnatal day 4 or 14.
2. In dogs, watery-mucous diarrhea observed at 2 to 3 hours after dosing in all dose groups was not dose-related. This finding lasted in some dogs till 4 days after dosing. An increased incidence of emesis was induced in all males at 2,000 mg/kg and all females of all dose groups except one female at 2,000 mg/kg.Body weights increased normally for all dogs, but one male at 1,000 mg/kg showed a transient decrease in food consumption. No drug-related histopathological changes were found.
Based upon these results, BMY-28100 at 2,000 mg/kg induced no apparent toxic changes in the present experimental conditions. Therefore, the single dose oral toxicity of the drug in juvenile animals appeared to be very slight and generally similar to that in adults. The lethal doses were more than 2,000 mg/kg in juvenile rats and dogs.

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In order to investigate the repeated dose oral toxicity of BMY-28100 in juvenile rats, the drug was administered orally to 4-day-old Crj: CD (SD) rats of both sexes at daily doses of 250,750 and 1,500 mg/kg for 4 weeks.
The results obtained are summarized as follows:
1. Soiling around the anus apparently correlated to soft stool or diarrhea was observed at 750 and 1,500 mg/kg and the incidence appeared to be dose-related. Three deaths including l death due to cannibalization occurred at 750 and 1,500 mg/kg, but they were considered to have been caused by misadministration.
2.Slightly depressed body weight gains were noted in the 750 and 1,500 mg/kg dose groups during early dosing period.
3. Slightly increased averages of food and water consumption observed predominantly in the 1,500 mg/kg dose group at later dosing period and the recovery period were considered as incidental and unrelated to the treatment.
4.Though average values of some blood chemical parameters were slightly suppressed or elevated compared with those of controls at the completion of the dosing and recovery periods, these differences appeared to be generally within normal ranges and to be irrelevant to the drug treatment. No definitive drug-related changes were detected in hematological examinations and urinalyses.
5. The average absolute and/or relative organ weights of the brain, thymus, lungs and liver from male rats in the 1,500 mg/kg dose group were lower than those of the corresponding organs from controls. However, these findings were not considered to be toxicologically significant because no corroborative changes were detected microscopically.
6. Macroscopic and microscopic examinations demonstrated dilatation of the cecum in a dose-related fashion. This phenomenon has been reported with other antibiotics and appears to be drug-related and reversible caused by an alteration of the gut flora. There were no other microscopic changes that were considered to be related to the administration of the drug.
7. Electron microscopic examination revealed no drug-related changes in the liver and kidneys from rats of the 1,500mg/kg dose group.
Based upon these results, the no-effect dose level of BMY-28100 was estimated to be 250 mg/kg/day for both male and female juvenile rats in the 4-week repeated dose oral toxicity study if the finding of cecum dilatation was not considered.

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Three groups, each consisting of 3 male and 3 female juvenile beagle dogs, were orally given BMY-28100 for 4 weeks at dose levels of 50,160 and 500 mg/kg/day, respectively. Additionally, one male and one female dogs were added to each of the control and high dose groups in order to examine the recovery, and observed for 4 weeks after withdrawal of BMY-28100.
The results obtained are summarized as follows:
1. BMY-28100 provoked an increased incidence of emesis in the 500 mg/kg group during the treatment period.
2. BMY-28100 sporadically brought distention of the cecum containing considerable amounts of contents in dogs sacrificed after the 4-week administration period. However, no macroscopic or microscopic changes were observed in the cecum itself after removal of the contents. In the 500 mg/kg group, hypocellularity in the sternum bone marrow was observed in a male and a female, and thymic atrophy in a male.
3. No changes ascribed to BMY-28100 treatment were detected after the 4-week recovery period.
Based upon these results, the no-effect dose level of BMY-28100 was estimated to be 160 mg/kg/day, except for effects on the cecum.

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Immunogenicity, eliciting antigenicity and cross-reactivity of new cephem antibiotics, BMY-28100 and cefepime, were studied by means of passive cutaneous anaphylaxis (PCA), passive hemagglutination (PHA) and active systemic anaphylaxis in guinea pigs, and of PCA in mice and the results were compared with those obtained with reference antibiotics. In addition, the direct COOMBS' reaction of the human blood was examined in vitro for the test antibiotics as compared with reference antibiotics. The results obtained are summarized as follows:
1. Immunogenicity
Immunogenicity of unconjugated antibiotics was examined using the corresponding conjugates with bovine γ-globulin (BGG) as eliciting antigen. When used as emulsions with FREUND'S complete adjuvant, cephalothin (CET) and benzylpenicillin (PCG) produced IgG₁ and IgM antibodies in guinea pigs. However, cefepime as well as cephalexin (CEX) did not produce these antibodies, and BMY-28100 showed slightly active sensitization only for anaphylactic shock. In BALB/c and C3H/He mice, BMY-28100 and cefepime failed to produce antibodies under the experimental condition while IgE antibody formation to CET was observed.
2. Eliciting antigenicity
Unconjugated CET and PCG provoked anaphylactic signs in guinea pigs sensitized with their conjugates with rabbit serum albumin (RSA). Cefepime, however, provoked no anaphylactic shock and BMY-28100 as well as CEX showed slight signs. In the other systems examined, no reactions were observed when elicited with BMY-28100, cefepime or the reference antibiotics.
3. Immunological cross-reactivity
BMY-28100 did not cross-react with the reference antibiotics. While the antiserum to the RSA conjugate of CET provoked weak cross-reaction on PHA with the BGG conjugate of cefepime, the antiserum to the RSA conjugate of cefepime failed to react with the BGG conjugate of CET. Other cross-reactivities of cefepime were not observed against the reference antibiotics.
4. In vitro direct CoomBs' reaction
BMY-28100 did not induce the COOMBS' reaction of the human blood in vitro at the testable concentration of 10 mg/ml. Cefepime or cefazolin (CEZ) caused no reaction even at a high concentration of 80 mg/ml, while CET and PCG caused a positive reaction at 10-40 mg/ml and 60 mg/ml, respectively.
As shown above, immunogenicity and eliciting antigenicity of BMY-28100 and cefepime were somewhat weaker than CET and PCG but similar to CEX, and cross-reactivities of the test antibiotics with these reference antibiotics were not observed in general. The ability of BMY-28100 to give a positive reaction in the COOMBS' test was weaker than that of CET, and that of cefepime was weaker than CET and PCG and equivalent to CEZ.
From these results, it was concluded that BMY-28100 and cefepime were immunologically rather inactive under the experimental conditions.

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General pharmacological properties of BMY-28100, a new semisynthetic oral cephalosporin, were studied in experimental animals. The obtained results are summarized as follows:
1. BMY-28100 had no effect on gross behavior and the central nervous system in mice and rats nor on EEG activities in rabbits.
2. BMY-28100 did not affect the smooth muscle isolated from rats, guinea pigs or rabbits nor did it influence ganglionic transmission in cats.
3. Effects of BMY-28100 on the atrium and heart isolated from guinea pigs were not obvious. Several parameters of the cardiovascular system were examined and found unchanged by administration of BMY-28100 to rabbits.
4. In the digestive system, BMY-28100 had no effect on charcoal meal transport in the small intestine of mice. In rats, however, gastric secretion was reduced at a dose level of 125 mg/kg or higher and bile secretion was enhanced at a dose level of 500 mg/kg.
5. BMY-28100 had no effect on neuromuscular transmission in rabbits and showed no local anesthetic activity in guinea pigs.
6. BMY-28100 decreased urine volume and urinary excretion of electrolytes in does-dependent manners in rats. Sulfobromophthalein excretion in rats was inhibited only at the highest does tested. BMY-28100 had no effect on blood coagulation and red blood cell resistance in rats or rabbits. BMY-28100 revealed no antiinflammatory activity in rats.
7. BMY-28167, a trans-isomer of BMY-28100, had no or weak effects on some of above test systems when compared with BMY-28100.
These results suggest that BMY-28100 has hardly any pharmacological properties leading to severe adverse reactions in clinical use.

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The pharmacokinetics of BMY-28100 have been studied in rats and monkeys upon oral administrationof ¹⁴C-BMY-28100.
1. In rats administered with BMY-28100 at a single oral dose of 20 mg, /kg, the peak blood level of the drug was 6.30, ag equiv./ml at 1 hour after administration. Blood levels declined biphasically, thereafter.The AUC value was 37.0 μg equiv. · hr/ml, and was 97% of that observed after intravenous administration. This suggests that BMY-28100 is absorbed at a high absorption rate from the gastro-intestinal tract.
2. In monkeys administered with a single oral dose of 20 mg/kg, the peak blood level was 4.26 μg equiv./ml at 3 hours after administration. Thereafter, blood levels declined biphasically as did in rats. The AUC was 38.9 μg equiv.· hr/ml, which is similar to that observed in rats.
3. Urinary and fecal excretion after 20 mg/kg oral administration were 60.9% and 38.1%, respectively, in rats, and 40.3% and 51.2%, respectively, in monkeys.
4. Although absorption from gastro-intestinal tract was delayed by food intake, this did not affect the total amount absorbed in rats.
5. The absorption rates were similar in rats administered with 20 and 60 mg/kg, while a lower rate was obtained with 200 mg/kg.
6. In rats, biliary excretion was 28.5% of dose administered. Thirty-nine percent of the biliary radioactivity was reabsorbed from the intestinal tract.
7. No differences between sexes were observed in absorption and excretion in rats administered with the drug at 20 mg/kg orally.
8. In rats administered with 20 mg/kg, the radioactivity distributed rapidly to the whole body. High levels of radioactivity were found in gastro-intestinal tract, kidney, urinary bladder, aorta and liver. The radioactivity was removed rapidly from the tissues. Autoradiograms of the whole body were consistent with the measured tissue distribution. Relatively high levels of radioactivity were found in aorta, fascia, and ligament at 0.5, 1, 6, and 24 hours.
9. In vivo protein binding, which increased with time after administration, was 56.8 to 73.5% in rat and 36.3 to 58.6% in monkey. The in vitro protein binding at 0.4 to 50 μg/ml of drug concentration was 50.0 to 54.7% in rat, 32.3 to 35.0% in monkey, and 33.4 to 36.3% in human.
10. A stability test of ¹⁴C-BMY-28100 in plasma solution showed that the drug decomposed gradually into relatively polar compound (s). At 8 and 24 hours, the proportions of unchanged ¹⁴C-BMY-28100 were 53.2% and 5.9%, respectively.

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Studies were done in rats on placental transfer and excretion into milk of ¹⁴C-BMY-28100 upon single oral administration. Studies on absorption, distribution and excretion of ¹⁴C-BMY-28100 were also done upon multiple dosing.
1. Fetal tissue concentration of the drug reached a maximum at 6 hours after dosing on day 18 of gestation. The highest concentration observed was only 0.56 μg equiv./g in fetal kidney; The transfer of radioactivity into the fetus was low. Similar results were obtained from whole body autoradiograms performed in rats on day 12 and day 18 of gestation.
2. Concentrations of radioactivity in milk reached a maximum of 0.60 μg equiv./ml at 1 hour after administration, and gradually decreased thereafter. The maximum concentration in milk was 10% of the plasma concentration measured at the same time.
3. In the multiple oral administration study, 24 hours blood levels of radioactivity rose progressively with each dose, and reached a level 3.8 times higher than that observed with single dosing by the final (21st) administration. Tissue concentrations were relatively high in aorta, kidney and large intestine as were found upon single administration. However, the ratios of these levels between multiple and single dosing were lower than those observed in blood; 1.7, 3.6 and 2.9 for aorta, kidney and large intestine, respectively. Urinary and fecal excretion were constant after the 2nd administration.

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