The pharmacokinetics of melphalan in patients with multiple myeloma: an intravenous/oral study using a conventional dose regimen

The pharmacokinetics of melphalan have been studied after intravenous and oral dosing (10 mg) in 6 patients with multiple myeloma. After intravenous administration, mean plasma t0.5 alpha was 8.0 +/- 2.3 min, t0,5 beta was 63.3 +/- 8.7 min, and total systemic clearance was 510.4 +/- 57.9 ml/min. After oral administration, the drug was rapidly absorbed (lag-time = 18.4 +/- 3.7 min, absorption rate constant = 0.0547 +/- 0.0166 min-1, Tmax = 59.3 +/- 6.6 min), but there was considerable variation in its bioavailability (61.5 - 102.0% mean 78.3 +/- 6.3%). Variability in drug absorption may be responsible, at least in part, for variation in response to this drug.