Simple and rapid high-pressure liquid chromatographic determination of papaverine in plasma

Pharmacokinetics and bioavailability of papaverine HCl following intravenous, peroral, rectal, vaginal, topical and buccal administration in beagle dogs

This in vivo study was designed to obtain bioavailability data and a definite pharmacokinetic profile of papaverine HCl in Beagle dogs following intravenous (IV), peroral (PO), rectal, vaginal, topical, and buccal administration of different papaverine HCl formulations. Blood samples were analyzed by high-performance liquid chromatography. The pharmacokinetic parameters were determined using either a curve fitting program (RESID) or a compartment model independent program (AUC-RPP). The plasma concentration-time profiles show that papaverine HCl pharmacokinetics is best described by an open two-compartment model. The absolute bioavailability of papaverine HCl was determined to be 57.2 per cent, 25.2 per cent, 53.2 per cent, 3.2 per cent and 7.5 per cent, respectively, following P.O., rectal, vaginal, topical and buccal administration.

Determination of minoxidil in bulk drug and pharmaceutical formulations by ion-pairing high-performance liquid chromatography

An ion-pairing liquid chromatographic method with UV detection is described for the determination of minoxidil in bulk drug, compressed tablet, and topical solution formulations. The chromatographic system consists of a microparticulate octadecylsilica column and a mobile phase composed of sodium dioctylsulfosuccinate in aqueous methanol (pH 3). The bulk drug and the topical solution samples are prepared by the dissolution of the drug in internal standard solution. Sample preparation for the compressed tablet formulation involves dissolving the drug from an aliquot of pulverized sample and centrifuging to remove insoluble excipients. Quantitative recovery of minoxidil from formulation excipients was demonstrated; assay precision was less than 1% CV.

Papaverine disposition in cardiac surgery patients and the effect of cardiopulmonary bypass

Cardiac surgery involving cardiopulmonary bypass (CPB) causes substantial physiologic changes which may potentially alter the pharmacokinetic properties of drugs used during and after the procedure. Studies with fentanyl have implied a relationship between prolonged elimination half-lives following CPB and decreased liver perfusion during and after the procedure. To further test this hypothesis, the effects of CPB on the pharmacokinetics of papaverine, a coronary vasodilator currently being added to the cardioplegic solution to prevent vasospasm, were studied. The drug was given to two groups of patients, one (n = 6) undergoing surgery with and one (n = 5) without CPB, the latter serving as controls. Plasma papaverine concentrations declined biexponentially in the control patients with a mean elimination half-life of 1.30 +/- 0.25 h, total plasma clearance of 13.8 +/- 3.75 ml/min/kg, volume of distribution of 1.52 +/- 0.45 l/kg and volume of distribution, steady-state, of 0.992 +/- 0.530 l/kg. For the CPB group, only half-life was estimated, and averaged 2.77 +/- 0.28 h, significantly greater (p less than 0.01) than that in the controls. These results further confirm the increased half-lives seen with other hepatically cleared drugs following CPB and have implications in the clinical management of patients given drugs eliminated in this manner.

Plasma levels of ethaverine after oral administration to humans

Fourteen healthy human subjects received a 200 mg oral dose of ethaverine hydrochloride as an elixir. Blood samples were obtained for 12 h after dosing. Plasma ethaverine concentrations were determined using a paired-ion, reversed-phase high performance liquid chromatographic method. Individual plasma concentration-time profiles were fitted to a two-compartment model with first-order absorption. The ethaverine was rapidly absorbed, based on a time of maximum plasma concentration of 0.75 h, a time-lag of 8.4 min, and an apparent first-order absorption half-life of 8.6 min. The mean terminal elimination half-life was 3.3 h.