Determination of oral anti-diabetic agents in human body fluids using high-performance liquid chromatography

Pharmacokinetic-pharmacodynamic relationships of oral hypoglycaemic agents. An update

Oral hypoglycaemic drugs, sulphonylureas and biguanides, occupy an important place in the treatment of Type II (non-insulin-dependent) diabetic patients who fail to respond satisfactorily to diet therapy and physical exercise. Although the precise mechanisms of action of these compounds are still poorly understood, there is sufficient agreement that sulphonylureas have both pancreatic and extrapancreatic effects, whereas biguanides have predominantly extrapancreatic actions. By using labelled compounds or measuring the circulating concentrations, the main pharmacokinetic properties of oral hypoglycaemic agents have been assessed and, in some cases, their pharmacokinetic-pharmacodynamic relationships have been evaluated. A correlation between diabetes control and plasma sulphonylurea or biguanide concentrations is generally lacking at the steady-state, with the possible exception of long-acting agents; after either oral or intravenous dosing, the reduction of plasma glucose is usually related to the increased circulating drug concentrations. The toxic effects of oral hypoglycaemic drugs are more frequent in the elderly and in the presence of conditions that may lead to drug accumulation or potentiation (increased dosage, use of long-acting compounds, hepatic and renal disease, interaction with other drugs); however, a relationship between toxic effects and drug plasma levels has been reported only for biguanides.

Fluorometric determination of biguanides in serum by high-performance liquid chromatography with reagent-containing mobile phase

A simple post-column derivatization method for the fluorometric determination of biguanides (buformin and phenformin) in serum by high-performance liquid chromatography is described. The serum was treated with 4% perchloric acid to precipitate proteins, and the supernatant was directly injected into the column. Synthesized 9,10-phenanthrenequinonesulphonate (PSQ) was used as a fluorogenic reagent and added to the mobile phase. Biguanides were separated within 10 min on a Radial-Pak microBondapak C18 cartridge (10 microns, 10 cm x 8 mm I.D.) by reversed-phase ion-pair chromatography. They were then allowed to react with PQS in an alkaline stream and detected fluorometrically. This method was applied to the analysis of serum from patients with diabetes mellitus.

Effect of oral verapamil on glibenclamide stimulated insulin secretion

In order to study the effect of the calcium antagonist, verapamil, on glibenclamide stimulated insulin release, nine healthy fasted male volunteers were given 5 mg oral glibenclamide with either 120 mg oral verapamil or placebo in a double-blind crossover manner 1 week apart. Blood was withdrawn at intervals for drug, hormonal and glucose estimations. Concomitant administration of verapamil resulted in higher levels of glibenclamide at each time point (P less than 0.01) suggesting that verapamil interferes with glibenclamide metabolism. However, levels of plasma glucose, C-peptide, insulin and glucagon did not differ between the verapamil and placebo studies.

Drug level monitoring: chromatography of some minor groups of drugs

Some important facts about the chromatographic separation of a number of selected categories of drugs are summarized. The data refer to the chromatographic method of choice, stationary phase, mobile phase (carrier gas), detection procedure and (where available) method sensitivity. Also, fundamental instrumental parameters, namely injector, column and detector temperature, carrier gas and mobile phase flow-rate and gradient set-up are reported here. In all cases also the source material used for analysis is specified. The data are presented in table form, each table dealing with a particular category of drugs. The following categories of drugs are being dealt with: anthelmintics, antiarteriosclerotics, antibacterials, anticholinergics and cholinergics, anticoagulants, antidiabetics, antiemetics, antimycotics, antihistamines, antimalarials, antiparasitics, antiparkinsonics, antitussives, antiulcer drugs, antiviral compounds, appetite depressants and immunosuppressives.

Determination of gliclazide in human serum by high-performance liquid chromatography using an anion-exchange resin

A method for the routine clinical examination of serum gliclazide by high-performance liquid chromatography (HPLC) on a column packed with a macroporous anion-exchange resin, Diaion CDR-10, was developed. The elution was performed with acetonitrile-methyl alcohol-1.2 M ammonium perchlorate (4:3:7, v/v/v) at a flow-rate of 0.4 ml/min. The retention time of gliclazide was 15 min. It seems that the retention mechanism of gliclazide under the HPLC conditions described is not only ion-exchange mode but reversed-phase mode between the anion-exchange resin and the mobile phase. The detection limit of gliclazide was 0.2 microgram/ml in plasma. The coefficient of variation for the within-day assay was 5.0% (0.2 microgram/ml, n = 8). The decay curve of serum gliclazide in diabetic patients was determined.