Pharmacology: Pharmacokinetics: Azithromycin given orally is rapidly absorbed and about 40% bioavailable. Absorption from capsules, but not tablets or suspension, is reduced by food. Peak plasma concentrations occur 2 to 3 hours after an oral dose and 1 to 2 hours after intravenous dosage. Azithromycin is extensively distributed into the tissues, and tissue concentrations subsequently remain much higher than dose in the blood; in contrast to most other antibacterial, plasma concentrations are therefore of little diffusion into the Cerebrospinal fluid when meninges are not inflamed Data from animal studies indicate that Azithromycin crosses the placenta. Small amounts of Azithromycin are demethylated in the liver, and it is excreted in bile mainly as unchanged drug and a number of inactive metabolites have also been detected. About 6% of an oral dose (representing about 20% of the amount in the amount in the systemic circulation) is excreted in the urine. The terminal elimination half-life is about 68 hours.