The pharmacokinetics and cardiovascular pharmacodynamics of HP 749 (besipirdine HCl) and metabolite P86-7480 in the conscious monkey.

Abstract

HP 749 was absorbed slowly in the conscious monkey after single oral doses (10, 20, and 40 mg/kg), with gradual metabolism to the N-despropyl metabolite, P86-7480. The tmax was 2 to 4 hours after dosing, with nonlinear increases in Cmax and the AUC0-4th for HP 749. The calculated elimination half life (t1/2) after oral administration was 7.4 +/- 2.1 hours; however, absorption appeared to influence the terminal phase because the t1/2 after intravenous administration of 10 mg/kg was 1.5 hours. Plasma concentration of HP 749 2 minutes after intravenous bolus was 26.08 micrograms/mL. The HP 749 was rapidly distributed (t1/2 alpha = 0.064 +/- 0.033 hours) after intravenous administration, and displayed a VZ of 2.6 +/- 0.85 L/kg. The CL of HP 749 was 20.8 +/- 6.9 mL/min/kg, whereas renal clearance (CLR) of unchanged drug was only 0.13 +/- 0.04 mL/min/kg. Thus, only about 1% of the administered dose was excreted unchanged by the kidney. The P86-7480 also was rapidly distributed and eliminated after an intravenous bolus, but was less extensively distributed than HP 749. HP 749 administered either as an intravenous bolus or orally caused a significant pressor effect soon after dosing. A significant tachycardia resulted from intravenous administration, but not after oral administration of the drug. An intravenous bolus of P86-7480 (0.1 mg/kg) resulted in an immediate increase in MAP and decreased heart rate. The duration of these cardiovascular events was significantly shorter after intravenous administration of P86-7480 than with intravenous or oral administration of the parent drug.(ABSTRACT TRUNCATED AT 250 WORDS)