Basic and clinical studies on BMY-28100

We performed basic and clinical studies on BMY-28100, a new oral cephalosporin antibiotic, and the results were as follows. 1) Antimicrobial activity : The MICs of BMY-28100 against various clinical isolates were determined. The MIC₈₀ was 1.56 μg/ml for Staphylococcus aureus, 12.5 μg/ml for Enterococcus faecalis and Escherichia coli. 6.25 μg/ml for Klebsiella pneumoniae, >100 μg/ml for Enterobacter spp., Serratia marcescens, and Proteus vulgaris, 3.13 μg/ml for Proteus mirabilis, > 100 μg/ml for Citrobacter spp. and Pseudomonas spp. Its activity against Gram-positive cocci was stronger than that of cefaclor (CCL) and cefixime (CFIX). But against Gram-negative bacilli it was almost the same as that of CCL and much less than that of CFIX. 2) Serum concentration and urinary excretion : Serum concentrations of BMY-28100 were measured in four healthy volunteers given orally 500mg of BMY-28100 in a fasting condition. The peak mean serum concentration was 9.4 μg/ml after 1.4 h. T_1/2 was 1.7 h and the area under the curve (AUC) was 38.4 h-μg/ml. The mean 8-h cumulative urinary excretion rate was 89.5%. 3) Clinical efficacy : Three patients with pneumonia, 2 with bronchitis, 3 with tonsillitis, 3 with pharyngitis, 2 with cystitis, and 1 with furuncle were treated with BMY-28100 at a daily dose of 1.0-1.5g for 5-28 days. Clinical response was good in 8, fair in 4, poor in 1, and unknown in 1 patient. The clinical efficacy rate was only 61.5%, being especially poor in lower respiratory tract infection. Abdominal fullness with angular stomatitis and elevation of GPT were observed in one patient each.