The absolute oral bioavailability of selected drugs.

Oral bioavailability is best defined as the rate and extent to which an active drug substance is absorbed and becomes available to the general circulation. This concept is discussed, along with several popular methods for determining absolute oral bioavailability. The absolute oral bioavailability of numerous drugs is reviewed and interspecies comparisons are made. In general, absolute oral bioavailability does not correlate well between species, though relative comparisons might be made.