Phase I pharmacokinetic study of a new 3-azinomethyl-rifamycin (rifametane) as compared to rifampicin

An open randomized cross-over study was conducted in 8 healthy male volunte ers to study the pharmacokinetic pattern and the safety of a 300-mg single oral dose of a new 3-azinomethyl-rifamycin (USAN rifametane, SPA-S-565) com pared with 300 mg of conventional rifampicin. The pharmacokinetic profiles of rifametane were significantly more favorable than those of rifampicin. T he serum peak value was 7.82 mu g/ml for rifametane a nd 4.04 mu g/ml for r ifampicin (p < 0.001); the elimination half-life was 10.58 h for rifametane and 1.89 h for rifampicin (p < 0.001); area under the serum concentration curve from 0 to infinity was 142.3 mu g.h/ml for rifametane and 19.9 mu g.h /ml for rifampicin (p < 0.001); the mean residence time was 18.05 h for rif ametane and 3.93 h for rifampicin (p < 0.001). Rifametane showed a good saf ety profile after the 300-mg single oral dose. Three volunteers developed a mild headache, metallic taste and slightly elevated temperature for 3-4 h, which subsided without medication. Clinically or statistically significant changes in laboratory parameters were not found between baseline and post- treatment values.