Bioavailability of the sedative propiomazine after nasal administration in rats

The bioavailability of the sedative propiomazine after nasal administration in rats was evaluated. Two salt forms, hydrochloride and maleate, in saline and a test vehicle were administered in two doses (0.2 and 0.4 mg/kg). The composition of the test vehicle was propylene glycol (5%), polysorbate 20 (2.5%), polyethylene glycol 400 (20%) and water. The plasma concentration was determined by blood sampling up to 4 h after administration. The results indicated that nasal administration of propiomazine resulted in fast absorption followed by rapid reduction of the plasma concentrations. Maximum plasma concentrations were reached within 5 min in all groups. A rapid rate of absorption and elimination is an advantage for sedatives since a speedy onset of action is desirable and unwanted hang-over symptoms may be minimised. The mean absolute bioavailability of approximately 40% (mean range 38-51%) was equivalent for both the low and high doses of the hydrochloride salt and for the low dose of the maleate salt, but not for the high dose of the maleate salt. There were no differences in the bioavailabilities of the different vehicles studied. Copyright (C) 1996 Elsevier Science B.V.