High-performance thin-layer chromatography for the determination of nimesulide in human plasma, and its use in pharmacokinetic studies.

A rapid and sensitive high-performance thin-layer chromatographic assay has been developed for the measurement of nimesulide in human plasma. Its use for pharmacokinetic studies has been evaluated. The method includes a single-stage extraction procedure without the use of an internal standard. Analysis was performed on plasma containing known amounts of the drug, on drug-free plasma, and on plasma containing an unknown quantity of the drug. Known amounts of extract and nimesulide (100 and 200 ng, as external standard) were spotted on precoated silica-gel 60F254 plates by means of a Camag Linomat IV autosampler. Quantification was achieved using a Camag TLC scanner 3. The recovery of the method was 97.10 +/- 2.22%. The method was applied for the determination of plasma levels and pharmacokinetic parameters of nimesulide after oral administration of two formulations (100 mg) in healthy volunteers. The method is a sensitive, economical, rapid and specific assay for nimesulide in human plasma, and is suitable for pharmacokinetic studies after therapeutic doses.

High-performance thin-layer chromatographic method for the detection and determination of lansoprazole in human plasma and its use in pharmacokinetic studies.

A rapid and sensitive high-performance thin-layer chromatography (HPTLC) method has been developed for the measurement of lansoprazole in human plasma and its use for pharmacokinetic study has been evaluated. Detection and quantitation were performed without using an internal standard. A single stage extraction procedure was followed for extracting lansoprazole from plasma and a known amount of the extract was spotted on precoated silica gel 60 F254 plates using a Camag Linomat IV autosampler. Lansoprazole was quantified using a Camag TLC Scanner 3. The recovery study of authentic analytes added to plasma at 0.05 to 0.25 microg/ml was 95.37+/-2.15% and the lowest amount of lansoprazole that could be detected was 20 ng/ml plasma. The method provides a direct estimate of the amount of lansoprazole present in plasma. The method was used for the determination of plasma levels as well as pharmacokinetic parameters of lansoprazole after oral administration of two marketed preparations to healthy volunteers.

High-performance thin-layer chromatography for the determination of cetirizine in human plasma and its use in pharmacokinetic studies.

A rapid and sensitive high-performance thin-layer chromatography (HPTLC) assay has been developed for the measurement of cetirizine in human plasma and its utility for pharmacokinetic study has been evaluated. In the proposed HPTLC method, protein-bound cetirizine was freed by proteolysis of plasma proteins by incubating the plasma with 0.35% pepsin and then extracting with 2 mL pH 5.0 phosphate buffer, followed by 4 mL chilled chloroform. The chloroform layer was separated and concentrated. An aliquot of the extract was then spotted on precoated silica-gel 60 F254 plates using a Camag Linomat IV autosampler. Quantification was with the help of a dual-wavelength TLC scanner. The proposed method had a recovery of 98% and the lowest amount of cetirizine that could be detected was 50 ng. The method was applied for the determination of the plasma levels and pharmacokinetic parameters of cetirizine after oral administration of two marketed preparations in healthy volunteers and the pharmacokinetic parameters determined by the proposed method were in agreement with previously reported values.

Sensitive high-performance thin-layer chromatography method for detection and determination of ranitidine in plasma samples.

A high-performance thin-layer chromatographic procedure has been developed for the determination of ranitidine, a H2-receptor antagonist, in plasma. The detection and quantification were performed without using internal standards. A single-stage extraction procedure was followed for extracting ranitidine from plasma, and a known amount of the extract was spotted on precoated silica gel F254 plates. Ranitidine was quantified using a Shimadzu CS930 dual-wavelength TLC scanner. The method provides a direct estimate of total ranitidine present in the plasma.

Detection and determination of total amlodipine by high-performance thin-layer chromatography: a useful technique for pharmacokinetic studies.

A novel analytical method for determination of the total plasma levels (free and protein bound) of the calcium channel blocking agent amlodipine has been developed using a high-performance thin-layer chromatographic (HPTLC) procedure. Detection and quantitation were performed without internal standards. In previously described methods for the estimation of amlodipine by gas chromatography and high-performance liquid chromatography, only the free levels in plasma and serum were quantified at 7% of the total amlodipine level, with the remaining 93% bound to plasma protein and tissue. The present method employs proteolysis of the plasma proteins by incubating plasma for 2 h in pepsin solution. After proteolysis amlodipine is extracted and a known amount of the extract is spotted on precoated silica-gel 60 F254 plates using a Camag Linomat IV autosampler. Amlodipine was quantified using a dual-wavelength TLC scanner. The method provides a direct estimate of the total amlodipine present in plasma.

Detection and determination of free and plasma protein-bound astemizole by thin-layer chromatography: a useful technique for bioavailability studies.

A thin-layer chromatographic (TLC) procedure has been developed for the determination of astemizole in plasma as the free and as protein-bound substance. The detection and quantification were performed without using internal standards. In earlier described methods for the estimation of astemizole by high-performance liquid chromatography and radioimmunoassay, only free levels in plasma were quantified, at 3.3% of the total astemizole, with the remaining 96.7% bound to plasma protein and tissue. Our method employs proteolysis of plasma proteins by incubating plasma for 2 h in pepsin. After proteolysis the astemizole is extracted, and a known amount of the extract is spotted on precoated silica gel F 254 plates. Astemizole was quantified using a Shimadzu CS-930 dual-wavelength TLC scanner. The method provides a direct estimate of total astemizole present in the plasma.

Experimental model for the study of antidiabetic effect of ayurvedic metallic preparations.

To Substantiate the claims of Ayurvedic classics, animal experimentation with modern technology has been carried out in this paper. Various methods have been described for induction diabetes Mellitus or any other disease. Now it is the duty of an Ayurvedist to select the suitable method on the guidelines of Ayurvedic aetiology to produce a condition stimulating to Prameha (Madhumeha) and the best suitable method (Folin-Wu) for estimating the sugar content of blood is adopted. Besides this one must do experiment in all species and should confirm the finding by clinical evaluation. Side by side toxicity studies are also necessary.

Isolation of (-)-Epicatechin from Pterocarpus marsupium and its Pharmacological Actions.

(-)-Epicatechin has been isolated from the bark of PTEROCARPUS MARSUPIUM Roxb (Leguminosae). This flavonoid compound was tested for its activity on central nervous system, isolated frog heart preparations and blood sugar levels of rats. Preliminary acute toxicity studies were also carried out. It was observed that (-)-epicatechin did not have any effect on central nervous system of rats and mice, (-)-epicatechin had shown both positive chronotropic and inotropic effects on frog hearts, the effect of which is blocked by propranolol. The compound in higher doses caused hyperglycemia in rats and this effect is also blocked by propranolol, showing adrenergic type of activity. (-)-Epicatechin was found to have no untoward effect even in higher doses.

Functional beta cell regeneration in the islets of pancreas in alloxan induced diabetic rats by (-)-epicatechin.

(-)-Epicatechin (1), a naturally occurring flavonoid compound was found to have reversed the diabetogenic action of alloxan in albino rats (2). (-)-Epicatechin administration in doses of 30 mg/kg (i.p.) twice daily for 4-5 days in alloxan induced (150 mg/kg, i.p.) diabetic albino rats (either sex), has brought down the high blood sugar levels to normal values. Concurrent histological studies of the pancreas of these animals showed regeneration of the beta-cell population of the islets which were earlier necrosed by alloxan. Immunoreactive insulin (IRI) studies showed that the regenerated beta-cells of the islets of pancreas are functional in nature.