[Pharmacokinetics and metabolism of gallopamil]

Despite its almost complete absorption following oral administration, gallopamil has an absolute bioavailability of only 15% due to an extensive hepatic first-pass metabolism. During multiple oral dosing bioavailability increases to approximately 25% indicating a partial saturation of first-pass metabolism. Since the half-life time of gallopamil is on average 3-6 h a minimum of three times daily dosing of the instant-release 50 mg tablet is required in order to maintain therapeutic plasma concentrations. The sustained-release 100 mg tablet which recently became available has a relative bioavailability comparable to the instant release preparation. Due to the delayed drug liberation therapeutic plasma concentrations are maintained for 24 h following once or twice daily administration of this drug preparation.