In vitro observations on the suitability of new rifamycins for the intermittent chemotherapy of tuberculosis.
The bactericidal activity of six new rifamycin derivatives--rifabutin (RBU), FCE 22250 (F22), rifapentine (RPE), CGP 29861 (C29), CGP 7040 (C70) and CGP 27557 (C27) and rifampicin (RMP)--have been measured against log phase and, as a better test of sterilising activity, against stationary phase cultures of Mycobacterium tuberculosis, H37Rv. The order of activity of 1.0 and 0.2 mg/l rifamycin against log phase cultures was RMP greater than RPE & C27 greater than RBU & C29 greater than C70. The order of activity of 1.0 and 0.4 mg/l, adjusted for stability of the rifamycin, against stationary phase cultures was F22 & RMP greater than RBU greater than RPE greater than C27 & C29 greater than C70. Viable counts were done during and after pulsed exposures of 6, 24 or 96 h to C29 and RMP. The curves were similar though C29 was less bactericidal and the lag period before recovery was 1-2 days longer. F22, having high bactericidal activity against stationary organisms and a long half-life, was considered likely to be the most effective sterilising drug.
Dickinson
J M
JM
Department of Bacteriology, Royal Postgraduate Medical School, London.
Mitchison
D A
DA
D000995:Antitubercular Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D017828:Rifabutin; D012293:Rifampin / Q000031:analogs & derivatives / Q000494:pharmacology; D012294:Rifamycins / Q000494:pharmacology*
D000995:Antitubercular Agents; D012294:Rifamycins; C055682:CGP 7040; C055683:CGP 27557; C055684:CGP 29861; D017828:Rifabutin; C041560:FCE 22250; D012293:Rifampin; C018421:rifapentine