1 Departments of Pediatrics, Neurology, and Pathology, College of Physicians & Surgeons, Columbia University, New York, NY 10032
Bioavailability is defined as the measurement of both the relative amount of an administered dose that reaches the general circulation and the rate at which this occurs. The most satisfactory method for measurement of bioavailability of a drug is by comparing the plasma level following oral administration of the drug in a given dosage to that following intravenous administration of the same dosage.1
As Koren correctly observes, most bioavailability studies have involved adults receiving a single oral test dose of theophylline following an overnight fast and then continuing with two to four more hours of fasting.2-6