Rifametane (SPA-S-565) is a semisynthetic derivative of rifamycin (a natural antibiotic produced by Amycolatopsis rifamycinica). It was being evaluated for treatment of bacterial infections. A phase I study showed that administration of rifametane is safe with minor, reversible adverse events such as mild headache, metallic taste and slightly elevated temperature for 3 to 4 hours. Rifametane has anti-tuberculosis activity and was suggested to be a good candidate for phase II clinical trials.