Microzide
Application of LC and HPTLC-densitometry for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide.

El-Gindy A, Ashour A, Abdel-Fattah L, Shabana MM.

Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt.

Two methods are described for the simultaneous determination of benazepril HCl and hydrochlorothiazide in binary mixture. The first method was based on HPTLC separation of the two drugs followed by densitometric measurements of their spots at 238 and 275 nm for benazepril HCl and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F(254,) using ethyl acetate-methanol-chloroform (10:3:2 v/v) as mobile phase. Second order polynomial equation was used for the regression line in the range 2-20 and 2.5-25 microg/spot for benazepril HCl and hydrochlorothiazide, respectively. The second method was based on HPLC separation of the two drugs on reversed phase, ODS column at ambient temperature using a mobile phase consisting of acetonitrile and water (35:65 v/v) and adjusting to pH 3.3 with acetic acid. Quantitation was achieved with UV detection at 240 nm based on peak area with linear calibration curves at concentration ranges 10-60 and 12.5-75 microg ml(-1) for benazepril HCl and hydrochlorothiazide, respectively. The two proposed methods were successfully applied to the determination of both drugs in laboratory prepared mixtures and in commercial tablets. No chromatographic interference from the tablets excipients was found.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11275425&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Spectrophotometric determination of benazepril hydrochloride and hydrochlorothiazide in binary mixture using second derivative, second derivative of the ratio spectra and chemometric methods.

El-Gindy A, Ashour A, Abdel-Fattah L, Shabana MM.

Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522, Egypt. ghada74 ismailia.ie-eg.com

Different spectrophotometric methods are presented for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical tablets. The first method depends on second derivative (2D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The second derivative amplitudes at 214.8 and 227.4 nm were selected for the assay of benazepril hydrochloride and hydrochlorothiazide, respectively. The second method depends on second derivative of the ratio spectra by measurement of the amplitudes at 241.2 and 273.2 nm for benazepril hydrochloride and hydrochlorothiazide, respectively. Chemometric methods, classical least squares and principal component regression, were applied to analyze the mixture. Both the chemometric methods were applied to the zero and first order spectra of the mixture. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures and in commercial tablets.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11275437&dopt=Abstract hydrochlorothiazide Microzide



Microzide
The Antihypertensive Properties of the Angiotensin-Converting Enzyme Inhibitor Moexipril Given Alone or in Combination with a Low Dose of a Diuretic.

Drayer JI, Stimpel M, Fox A, Weber M.

G.H. Besselaar Associates, Princeton, USA.

The antihypertensive characteristics of the angiotensin-converting enzyme inhibitor moexipril were evaluated in 413 patients with baseline setting diastolic blood pressures between 95 and 114 mm Hg. The study was double blind, with patients randomized to placebo or to differing doses of moexipril alone or in combination with a low dose of hydrochlorothiazide. Compared with placebo, moexipril 3.75 mg daily was not different, but single daily doses of 7.5, 15, and 30 mg were significantly more effective (as measured at trough, approximately 24 h after dosing) in decreasing the diastolic blood pressuring during an 8-week treatment period. The dose-response relationship indicated that no additional blood-pressure-lowering effect occurred above 15 mg daily. Hydrochlorothiazide 12.5 mg was not significantly more effective than placebo, but the combinations of the diuretic with moexipril doses of 3.75, 7.5, and 15 mg all produced significant antihypertensive actions. Interestingly, the 3.75-mg moexipril--hydrochlorothiazide combination was equally as efficacious as the higher doses. The combinations were all more effective than their respective moexipril and hydrochlorothiazide monotherapies. There were no meaningful laboratory changes except for decreased potassium concentrations in the patients on diuretic alone; this effect was attenuated in the low-dose moexipril combination. Only 14 of the 413 patients who entered the double-blind study period (3%) discontinued treatment because of adverse experiences. Thus, moexipril is a well-tolerated drug that has clear antihypertensive efficacy as a single agent in once-daily doses of 7.5--30 mg. When combined with hydrochlorothiazide 12.5 mg, it is effective in daily doses as low as 3.75 mg.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11854821&dopt=Abstract hydrochlorothiazide Microzide



Microzide
A comparative study of modified starches in direct compression of a poorly water soluble drug (hydrochlorothiazide).

Okafor IS, Ofoefule SI, Udeala OK.

Dept. of Pharmaceutics and Pharmaceutical Technology, University of Jos, Nigeria.

The direct compression properties of four modified starches in hydrochlorothiazide (HCTZ) tablets were studied. The starches were obtained locally from common plant sources and were modified through physicochemical treatment. Each modified starch was used as the only filler-binder-disintegrant in the formulation of hydrochlorothiazide tablets containing 25 mg of the drug. The tablets were produced by the direct compression technology. Sta-Rx 1500, a directly compressible starch, was used as basis for comparison. Evaluated tablet properties included weight and drug content uniformity, hardness and friability as well as disintegration time and dissolution profile. The modified starches exhibited species specificity in terms of the tablet properties. The weight, drug content and disintegration time for all batches of tablets were within acceptable limits. Proper ranking of the starches on the basis of specific tablet properties was used to highlight their differences.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11338775&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Spectrophotometric and HPTLC-densitometric determination of lisinopril and hydrochlorothiazide in binary mixtures.

El-Gindy A, Ashour A, Abdel-Fattah L, Shabana MM.

Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, 41522, Ismailia, Egypt. ghada74 ismailia.ie-eg.com

Different spectrophotometric and HPTLC-densitometric methods are presented for the simultaneous determination of lisinopril and hydrochlorothiazide in pharmaceutical tablets. The spectrophotometric methods include third derivative (3D) ultraviolet spectrophotometry with zero crossing measurement at 217.4 and 233.4 nm, second derivative of the ratio spectra with measurement at 214.3 and 228.0 nm; both classical least squares and principal component regression were applied to the UV absorption and first derivative spectra of the mixture. The HPTLC method was based on separation of both drugs followed by densitometric measurements of their spots at 210 and 275 nm for lisinopril and hydrochlorothiazide, respectively. The separation was carried out on Merck HPTLC aluminum plates of silica gel 60 F254, using chloroform-ethylacetate-acetic acid (10:3:2 by vol.) as mobile phase. The linear and second order polynomial were used for the regression equation of lisinopril and hydrochlorothiazide, respectively.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11377075&dopt=Abstract hydrochlorothiazide Microzide