Objectives: The present study, the first clinical pharmacokinetic report of the immune response modifier imiquimod, was conducted to assess the effect of food on the oral absorption of imiquimod, to characterize its pharmacokinetics, and to estimate its oral bioavailability.
Subjects and methods: Sixteen healthy male volunteers completed this open-label, randomized, three-period crossover study. Subjects received a 100 mg oral dose of imiquimod after fasting in one period, after a standarized, high fat meal in another, and a 30 mg subcutaneous dose in the third period.
Results: The oral bioavailability of imiquimod was on average 47%, and independent of whether imiquimod was administered with or without food. Oral imiquimod was absorbed in both fasted and non-fasted states with an absorption half-life of approximately 1 hour. However, there seemed to be a delay in the initiation of the absorption process when food was administered, which translated in to a Tmax of approximately 2.6 hours while fasting and one hour later in the non-fasted state. Imiquimod was rapidly eliminated with a half-life of approximately 2.5 hours and a total body clearance of approximately 970 ml/hxkg. Although equivalence could not be established due to the large intersubject variability, no significant differences in rate (Cmax) and extent (AUC) of oral absorption were observed between the fasted and non-fasted states. In addition, the Cmax, AUC and bioavailability values for individual subjects were consistent between both oral treatments.
Conclusion: This study suggests that food does not have a major effect on the rate, extent of absorption or bioavailability of oral imiquimod, and thus, it is suitable to administer imiquimod orally in either the fasted or non-fasted states.