Pharmacology of methicillin.
The pharmacology of a new antibiotic methicillin, 6(2:6-dimethoxybenzamido)-penicillanic acid, which is effective against staphylococci resistant to penicillin G, has been investigated. It is free from acute and chronic toxic effects, except that some pain may be caused following intramuscular injection. It is poorly absorbed orally, but after intramuscular injection the concentrations in the serum and in tissues are very similar to those found with penicillin G. It is excreted by the kidneys both by renal tubular secretion and glomerular filtration. It is also excreted in the bile in very high concentrations, the ratio of concentration in the bile to the blood being approximately 2.5 times that of penicillin G. From a study of the metabolism of the drug it is calculated that 75% is eliminated unchanged in the urine and that the remainder is probably destroyed after the excretion into the intestine via the bile.