Pharmaceutical Applications
The diethyl amide of rifamycin B, formulated as the sodium salt for parenteral administration. It exhibits high activity against Gram-positive organisms and M. tuberculosis typical of the group. MICs for Gram-negative bacilli are of the order of 20–50 mg/L.
It is absorbed orally and is rapidly eliminated through the bile, achieving concentrations sufficient to inhibit Gramnegative bacilli. In contrast to rifampicin, it can be administered as the sodium salt by intramuscular injection. A dose of 150 mg produces mean plasma levels of about 1 mg/L. The plasma halflife is about 2 h. The same dosage produces concentrations over 1 g/L in bile and c. 40 mg/L in the gallbladder wall.
Toxicity and side effects are similar to those of other rifamycins. It has been used in staphylococcal infections and infections of the biliary tract. It is unsuitable for the treatment of tuberculosis because of insufficient distribution to the tissues.
