[A new anti-mycobacterial agent, rifabutin]

This is a review of non-clinical and clinical study results of rifabutin (Mycobutin, RBT) which was approved as a new anti-mycobacterial agent 38 years after rifampicin (RFP) was approved in Japan. The anti-bacterial actions of RBT were similar to those of RFP, but its potency was stronger (4 to 32 times in MIC90). RBT showed excellent penetration in cells (9 times in neutrophil, 15 times in monocyte, against plasma concentration) and in tissues (5 to 10 times in pulmonary tissue). Clinical efficacy of RBT (150 mg, as well as 300 mg daily) was comparable to that of RFP 600 mg daily, in the treatment of newly diagnosed tuberculosis, drug-resistant tuberculosis, and the NTM diseases. In addition, RBT 300 mg showed significant prophylactic effect on the development of disseminated MAC infection in HIV positive subjects. Most of the adverse events of RBT were the same as those of RFP, including drug-drug interactions related to the induction of CYP3A4. The concomitant use of RBT (over 450 mg) with clarithromycin induces uveitis, which warrants special attention. It is expected that the efficacy and safety of RBT in Japanese subjects will be evaluated in Japan through the accumulation of clinical experience.