title: In vitro and in vivo evaluation of A-56268 (TE-031), a new macrolide.
abstract: The in vitro and in vivo antibacterial activity of A-56268 (TE-031), the 6-O-methyl derivative of erythromycin, was compared with those of erythromycin and other reference drugs. A-56268 had the same spectrum of antibacterial activity as erythromycin. A-56268 was generally 1 log2 dilution more potent or equal to erythromycin against all organisms except haemophilus influenzae and Propionibacterium acnes, for which A-56268 was 1 log2 dilution and 3 log2 dilutions, respectively, less potent. The MBC of A-56268 and erythromycin was not significantly different from the MIC against Streptococcus pyogenes, Streptococcus pneumoniae, Staphylococcus epidermidis, and H. influenzae but was more than 2 log2 dilutions higher than the MICs for some Staphylococcus aureus strains. Human serum at a concentration of 50% did not change the in vitro potency of A-56268 or erythromycin. A-56268 was similar to erythromycin in being more active at pH 8.0 than at the physiologic pH of 7.3. The activity of A-56268 was synergistic with sulfamethoxazole against 4 of 12 strains of H. influenzae. In mouse protection tests, when administered orally A-56268 was more potent than erythromycin against H. influenzae, S. pyogenes, S. pneumoniae, and S. aureus. After subcutaneous administration the potencies of A-56268 and erythromycin were not statistically different from each other. A-56268 was more potent than erythromycin against Legionella infection in guinea pigs. The concentration of A-56268 in the serum and lung was higher than that of erythromycin after intraperitoneal administration. In A-56268 in the serum and lung was higher than that of erythromycin after intraperitoneal administration. In mice, the peak levels in serum of A-56268 and erythromycin were similar after subcutaneous administration and seven times higher for A-56268 after oral administration. The serum half-life of A-56268 was approximately twice that of erythromycin after administration by both routes.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D001424:Bacterial Infections / Q000188:drug therapy; D017291:Clarithromycin; D004338:Drug Combinations; D004357:Drug Synergism; D004917:Erythromycin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007279:Injections, Subcutaneous; D007700:Kinetics; D007875:Legionella / Q000187:drug effects; D007877:Legionnaires' Disease / Q000188:drug therapy; D008297:Male; D051379:Mice; D008826:Microbial Sensitivity Tests; D013420:Sulfamethoxazole / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D004917:Erythromycin; D017291:Clarithromycin; D013420:Sulfamethoxazole