Determination of apovincaminic acid in human plasma by gas-liquid chromatography

Determination of apovincaminic acid in human plasma by high-performance liquid chromatography using solid-phase extraction and ultraviolet detection

A new, simple and rapid high-performance liquid chromatography (HPLC) method with UV detection has been developed for the determination of apovincaminic acid in human plasma. Apovincaminic acid and internal standard were isolated from plasma samples by solid-phase extraction with OASIS HLB cartridges. The chromatographic separation was accomplished on a reversed-phase C(18) column and UV detection was set at 311 nm. The calibration curves were linear in the concentration range of 2.4-240.0 ng/ml, and the limits of quantification was 2.4 ng/ml. The precision and accuracy ranged from 0.84 to 8.54% and 91.5 to 108.3%, respectively. The developed method was subsequently applied to study the pharmacokinetics of apovincaminic acid in a group of 20 human subjects at a single oral dose of 10mg of vinpocetine tablet.

Determination of apovincaminic acid in human plasma by high-performance liquid chromatography

An isocratic high-performance liquid chromatographic method is described for the quantitative analysis of low concentrations of apovincaminic acid (AVA) in blood plasma. AVA, interfering plasma components and primidone (used as the internal standard) were separated on a reversed-phase column of LiChrospher 60 RP-Select B (125 mm x 3 mm i.d.; 5 microns) (Merck). A UV-Vis detector was used at a wavelength of 254 nm. Each chromatographic separation was completed in 14 min and the results showed a relative recovery which varied between 95.9 and 116%, a good overall precision (relative standard deviation, 7.00%) and sensitivity over a linear range of 5.00-300 ng ml-1 (R = 0.999) for AVA in plasma. The method was applied to the analysis of plasma samples obtained from healthy subjects treated with one single oral dose of 20 mg of vinpocetine. The results indicate the method to be suitable for pharmacokinetic studies.

Study on the absorption of vinpocetine and apovincaminic acid

The absorption of vinpocetine (Cavinton) and apovincaminic acid, compounds showing a marked difference in their physico-chemical properties, was studied in rats in in situ loop experiments by using radiolabelled compounds. In the case of apovincaminic acid, the investigations also involved the estimation of the portion of radioactivity excreted in urine and faeces after i.v. and p.o. administration of the compound. According to our results, it can be concluded that both vinpocetine and apovincaminic acid are absorbed from the gastrointestinal tract--apovincaminic acid mainly from the stomach, while vinpocetine is absorbed from the small intestine.

Determination of apovincaminic acid in serum by means of high-performance liquid chromatography

A high-performance liquid chromatographic method for the determination of low concentrations in serum of apovincaminic acid, the main metabolite of vinpocetine, is reported. The assay includes a two-step ion-pair extraction with tetrabutylammonium as counter ion. Recovery is ca. 40%. Separation is performed on a narrow-range 5 microns particle size octadecylsilane modified silica packing. Heptanesulphonic acid is the pairing ion in the eluent, and the ultraviolet detection wavelength is 224 nm. Yohimbine serves as the internal standard. The assay is fast, accurate and sensitive quantifying at least 5 ng/ml apovincaminic acid in serum. The method was applied to the analysis of serum samples from aged subjects, treated with a 20-mg dose of vinpocetine.

Effect of age on the pharmacokinetics of vinpocetine (Cavinton) and apovincaminic acid

The pharmacokinetics of vinpocetine and its main metabolite, apovincaminic acid (AVA), were studied in the aged. Vinpocetine was eliminated with a mean half-life of 2.12 +/- 0.51 h. Total plasma clearance (CL) and distribution coefficient (delta) of the parent drug were 2.2 +/- 0.9 l.kg-1.h-1 and 6.7 +/- 3.7 l.kg-1, respectively. The CL and delta of vinpocetine differed significantly from young subjects but the elimination half-life was not altered. Significant changes in the elimination half-life and plasma clearance of AVA were found, perhaps because of the physiological decrease in renal function.

Pharmacokinetics and metabolism of vincamine and related compounds

The pharmacokinetics and metabolism of vincamine, vinpocetine, methylene-methoxy-apovincaminic acid ester and eburnamine have been reviewed. The main route of elimination for vincamine, vinpocetine and methylene-methoxy-apovincaminic acid ester is ester cleavage and conjugation in the case of eburnamine. Vincamine and its derivatives show significant differences in metabolic pathway and their elimination is rapid in the species studied. Emphasis has been placed on the analytical methods used for monitoring these drugs in biological systems.

Pharmacokinetics of vinpocetine and its metabolite, apovincaminic acid, in plasma and cerebrospinal fluid after intravenous infusion

The pharmacokinetics of vinpocetine (ethyl apovincaminate, Cavinton) and its metabolite, apovincaminic acid, was studied in patients with cerebrovascular disorders. Vinpocetine (1 mg/kg) was infused intravenously over 25 min. The elimination half-life of the parent drug in plasma was 4.7+/-2.13 h. Total clearance of vinpocetine was 0.79+/-0.1 1 h(-1) kg(-1). The presence of vinpocetine in cerebrospinal fluid shows that the drug is able to pass through the blood-brain barrier and reach the central nervous system which is a possible site of action. The maximum increase of cerebral blood flow (25%) was measured at 32 min after the start of the infusion.

Pharmacokinetics of vinpocetine and apovincaminic acid in patients with impaired renal function

Effects of renal insufficiency on the pharmacokinetics of vinpocetine and its main metabolite, apovincaminic acid (AVA) were investigated in the present study. The elimination rate constant, half-life, clearance, area under the curve and volume of distribution were measured and compared with reported values for subjects with normal renal function. Previous investigations have shown that the elimination half life of vinpocetine was 2.54 +/- 0.48 hours and half-life of AVA was 3.66 +/- 1.56 hours in healthy volunteers after i.v. administration of 10 mg vinpocetine.

Derivatization reactions in the gas—liquid chromatographic analysis of drugs in biological fluids

Alkylation, acylation, silylation and other derivatization reactions applied to the gas chromatographic analysis of drugs in biological matrices are reviewed. Reaction conditions are discussed in relation to reaction mechanisms. Detector-oriented labelling of drugs, and derivatization with chiral reagents for the separation of enantiomers are surveyed. Data on the sample clean-up, derivatization and GLC analysis of more than 300 drugs and related compounds are listed.

Determination of apovincaminic acid in biological samples by high-performance liquid chromatography

A method is described for measuring the concentrations of apovincaminic acid and vincaminic acid (internal standard) in blood plasma and urine by high-performance liquid chromatography using ion pair extraction. The main metabolite of vinpocetine, apovincaminic acid, and vincaminic acid were extracted from 1 ml of plasma and urine into chloroform as an ion pair using tetrabutylammonium hydroxide as counter ion. Analysis was carried out on a reversed-phase column of RP-8 with acetonitrile-0.0075 M phosphate buffer (28:72) at pH 3.5 as mobile phase. The eluted derivatives were detected by UV absorption at 254 nm. The sensitivity of the method is 20 ng/ml for AVA in plasma and urine samples. The relative recovery of these compounds added to plasma was about 50%.