Microzide
Effect of amiloride with or without hydrochlorothiazide on urinary calcium and saturation of calcium salts.

Leppla D, Browne R, Hill K, Pak CY.

To assess the therapeutic role of amiloride in calcium nephrolithiasis, seven patients with renal stones were evaluated before and after 1 month of treatment each with amiloride (2.5 mg twice daily), hydrochlorothiazide (25 mg, twice daily), and both drugs at the same dosages. Although amiloride alone reduced urinary calcium in only two patients, it caused a slightly more prominent decline in urinary calcium when added to hydrochlorothiazide treatment in five patients. The urinary saturation of stone-forming salts (brushite and calcium oxalate) decreased significantly during treatment with hydrochlorothiazide alone or in combination with amiloride. Although the decrease in brushite saturation was slightly more marked with the combined treatment, the reduction in calcium oxalate saturation was equivalent during the two treatment phases. Although serum potassium was significantly reduced during combined treatment with amiloride and hydrochlorothiazide, this reduction was not as prominent as that occurring during treatment with hydrochlorothiazide alone. The results suggest that the addition of amiloride to hydrochlorothiazide treatment in calcium nephrolithiasis may be advantageous, because of its stimulation, though slight, of the thiazide-induced reduction of urinary calcium and saturation of calcium phosphate and because it may avert the development of severe hypokalemia.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6619267&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Thiazides. VIII: Dissolution survey of marketed hydrochlorothiazide tablets.

Augsburger LL, Shangraw RF, Giannini RP, Shah VP, Prasad VK, Brown D.

The dissolution profiles of 50-mg hydrochlorothiazide tablets representing all approved manufacturers (at the time of the study) were determined in two vehicles [purified water and dilute (1:100) hydrochloric acid] by three methods (rotating basket at 150 rpm; spin filter at 300 rpm; paddle method at 50 rpm). The paddle method was preferred on the basis of overall ease of operation, reproducibility, and discrimination. The paddle data were validated in both vehicles on the same lots of tablets by a second laboratory. A standard of not less than 80% dissolution in 60 min by the paddle method in water is proposed for hydrochlorothiazide tablets.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6620141&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Blood lipids and antihypertensive drugs. The Oslo study.

Leren P, Eide I, Foss OP, Helgeland A, Hjermann I, Holme I, Kjeldsen SE, Lund-Larsen PG.

The treatment of hypertension has failed to achieve a reduction of the incidence of coronary heart disease. Recently, attention has been drawn to the effects of antihypertensive drugs on the metabolism of lipoproteins. Of the beta-blockers only pindolol was lipid neutral while propranolol, atenolol and oxprenolol lowered cholesterol and increased serum triglycerides. Hydrochlorothiazide did not influence blood lipids. Prazosin lowered serum LDL + VLDL cholesterol and total triglycerides. The combination of pindolol + prazosin lowered LDL + VLDL cholesterol and increased triglycerides. Propranolol + prazosin lowered HDL cholesterol, methyldopa + hydrochlorothiazide and hydrochlorothiazide + amiloride had no effect on blood lipids.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6632918&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Liquid chromatographic determination of methyldopa and methyldopa-thiazide combinations in dosage forms.

Ting S.

A liquid chromatographic (LC) method, using a reverse phase C18 column, an acetic acid-methanol-water mobile phase, and detection at 280 nm, was developed for the determination of methyldopa in tablets and oral suspensions and combinations of methyldopa with hydrochlorothiazide or chlorothiazide in tablets. A mixture of these 3 drugs was resolved in less than 8 min. Detector responses were linear for the following amounts (mg/mL) of drug injected: methyldopa 0.031-0.393, chlorothiazide 0.019-0.114, and hydrochlorothiazide 0.004-0.083. Recoveries from commercial dosage forms ranged from 99.1 to 100.9% for methyldopa, 99.2-100.4% for chlorothiazide, and 100.0-101.2% for hydrochlorothiazide. Replicate injections of methyldopa, chlorothiazide, and hydrochlorothiazide standard preparations alone or in combination gave overall relative standard deviations of less than 1.6% (n = 10). The results for methyldopa tablets by the proposed method were in agreement with those obtained by the USP XX method. The LC method detected as little as 0.6 micrograms 3-O-methylmethyldopa/mL and 0.5 micrograms 4-amino-6-chloro-1,3-benzenedisulfonamide/mL, which are sometimes found as contaminants of methyldopa and thiazides, respectively, and resolved methyldopa from its methyldopa glucose adduct, a substance found in methyldopa oral suspensions.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6643354&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Effects of hydrochlorothiazide combined with amiloride in atenolol-resistant hypertensive patients.

Corea L, Bentivoglio M, Verdecchia P.

Twenty hypertensive outpatients WHO stage I or II, with supine diastolic blood pressure greater than or equal to 95 mmHg at the end of a 4-week treatment period with atenolol (Tenormin) 100 mg daily, continued atenolol in free association with half a tablet of Moduretic (i.e., hydrochlorothiazide 25 mg + amiloride 2.5 mg) for a further 4 weeks. Atenolol monotherapy induced a drop of systolic blood pressure from 175.0 +/- 11 (mean +/- s.d.) mmHg to 158.7 +/- 6 mmHg (p less than 0.01), and of diastolic blood pressure from 113.5 +/- 8 mmHg to 102.7 +/- 5 mmHg (p less than 0.01). After 4 weeks with atenolol in association with half a tablet of Moduretic, systolic blood pressure further decreased to 145.7 +/- 8 mmHg (p less than 0.01), and diastolic blood pressure to 90.2 +/- 10 mmHg (p less than 0.01). Seven out of 20 patients remained with diastolic blood pressure greater than or equal to 95 mmHg despite the above combination therapy. In these patients, the doubling of diuretic dose (hydrochlorothiazide 50 mg + amiloride 5 mg) in combination with atenolol resulted in a further drop in systolic pressure (to 142.1 +/- 9 mmHg) and diastolic (to 92.1 +/- 6 mmHg) (both p less than 0.01). Plasma potassium concentration showed a slight and non-significant increase during atenolol monotherapy (from 4.4 +/- 0.5 mEq/l to 4.6 +/- 0.7 mEq/l; n.s.).(ABSTRACT TRUNCATED AT 250 WORDS)

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6678830&dopt=Abstract hydrochlorothiazide Microzide