The polarographic determination of some thiazide diuretics in compound tablets

The derivative spectrophotometric and IP-RP-HPLC determination of the Lometazid tablets

In this paper the second-derivative spectrophotometric and ion-pair reversed-phase high performance liquid chromatographic methods for the simultaneous determination of some diuretic ingredients are described. Optimal conditions of both techniques for the quantitative analysis of the two-component diuretic mixture of the Lometazid tablets were settled. The second-derivative order of the spectra in sodium hydroxide with the wavelength modulation was used. For the determination of amiloride hydrochloride the 'zero-crossing' technique was applied, but for methyclothiazide the peak amplitude had to be corrected. In the ion-pair RP-HPLC technique tetrabutylammonium hydroxide was applied as an ion-pairing agent using acetonitrile-phosphate buffer (45:55 v/v) as a mobile phase. The validation was done of both proposed methods.

Spectrophotometric study of polythiazide-palladium (II) complex

A quantitative spectrophotometric method using Pd(II) chloride as analytical reagent for the determination of polythiazide in pharmaceutical preparations is described in this study. It has been found that polythiazide reacts with Pd(II) chloride in the pH range 3.6-5.8, forming a red, water-soluble (1:1) complex with maximum absorbance at 527 nm. At the optimum pH of 4.8 and an ionic strength mu = 0.1 M, the conditional stability constant of the complex is found to be log K' = 4.77. The molar absorptivity at 527 nm is 3.2 x 10(3) l mol-1 cm-1. Good agreement with Beer's law was found for polythiazide concentrations up to 2.2 mmol l-1. The nominal percent recovery of polythiazide was 99.5% (n = 20). The simplicity, selectivity and sensitivity of the method described is suitable for rapid and accurate determinations of polythiazide in tablets.

Liquid chromatographic determination of guanethidine salts and hydrochlorothiazide using electrochemical detection and ion-pair techniques

A high-performance liquid chromatographic method with amperometric detection utilizing oxidation at the glassy carbon electrode is reported for the quantitative determination of a guanethidine (1)-hydrochlorothiazide (2) mixture. The drug mix is difficult to analyze by a single assay procedure due to large differences in the chemistry and chemical structure of the compounds. The drugs are best separated on an octadecylsilane column using 30:70 acetonitrile:0.05 M aqueous sodium dihydrogen phosphate containing 0.02 M sodium pentanesulfonate (pH 2.5) as the mobile phase at a 1.0 mL/min flow rate. Using a cell potential of +1300 mV versus Ag/AgCl and procaine hydrochloride as the internal standard, calibration curves were established for 1 monosulfate or sulfate and 2 in the 0.5-10 and 1.25-25 micrograms/mL range, respectively. Accuracy and precision of the assay are in the 1.7-6% range. The procedure is shown applicable to the analysis of a combination dosage form and is also useful for either drug in a single component dosage form.

Application of conventional (DC) and differential pulse polarography (DPP) to the quality control of benzothiadiazines in tablets. Simultaneous determination of hydrochlorothiazide and dihydralazine sulphate in mixtures with minimization of interaction by the use of a zero covariance in the calibration

A previous study of the polarographic behaviour of 14 benzothiadiazines having diuretic properties enabled possible reaction mechanisms to be proposed and gave the opportunity to determine the best conditions for analytical application. The results obtained with benzthiazide as an example of the unsaturated compounds, bendrofluazide as the dihydro compound, and hydrochlorothiazide determined together with dihydralazine are reported. The electroactivity of these last two substances was made the object of a mathematical study for the correction of reciprocal interference.

Simultaneous determination of hydrochlorothiazide and triamterene in capsule formulations by high-performance liquid chromatography

A stability-indicating, high-performance liquid chromatographic method is presented for the simultaneous determination of hydrochlorothiazide and triamterene in two-component capsule formulations. An aliquot of the sample is dissolved in a mixture of acetonitrile and aqueous acetic acid, mixed with m-hydroxacetophenone as an internal standard, and chromatographed on octadecylsilane bonded to microparticulate silica using 80% acetate buffer (pH 5.0, 0.004 M)-15% acetonitrile-5% methanol as the mobile phase. The relative standard deviations are +/- 1.1-1.6% for hydrochlorothiazide and +/- 1.7-2.2% for triamterene for two formulations. Recoveries of the two drugs added to placebos ranged from 98.4 to 101.7%.

High-pressure liquid chromatographic analysis of polythiazide in pharmaceutical tablet formulations

A high-pressure liquid chromatographic method was developed for the quantitative determination of polythiazide in pharmaceutical tablet formulations after extraction of the powdered tablets with a water-acetonitrile solvent. Analysis is a accomplished by comparison of peak areas after chromatography.