Pharmacokinetics of a more reliable Chloraminophene® formulation

The pharmacokinetics of two formulations of chlorambucil, Chloraminophene® capsules and Chloraminophene® tablets, were compared in 12 patients in a randomized cross-over study. Chlorambucil concentrations in plasma were measured by HPLC over a period of 24 h after drug intake. The peak concentration (C(max)) occurred earlier after administration of capsules than after administration of tablets [median (range)]: 0.50 (0.33-0.66) h vs 2.00 (0.66-4.00) h (p < 0.01). Although values of C(max) and the area under the plasma concentration versus time curve (AUC) were not significantly different, the two formulations were not bioequivalent. Tolerance was in both cases acceptable, with only a transient decrease in haemoglobin one day after last drug intake. The variability of chlorambucil pharmacokinetics tended to be less important for capsules than for tablets: 38% vs 71% and 35% vs 113% for C(max) and AUC respectively. Capsules are therefore likely to be more reliable than tablets for clinical use.