Microzide
Double-blind study with thiazide in recurrent calcium lithiasis.

Scholz D, Schwille PO, Sigel A.

The effect of 25 mg. hydrochlorothiazide twice daily on the meta-phylaxis of recurrent calcium lithiasis was compared to placebo in a double-blind study during 1 year in 51 patients. A distinct and continuous decrease in urinary calcium excretion occurred only in patients given hyrochlorothiazide. On the other hand, both groups showed a slight increase in total serum calcium levels, unchanged values for ionized and ultrafilterable calcium, and decreased urinary excretion of oxalate during the study. The activity products of calcium oxalate and calcium phosphate also were decreased in both groups but remained within the metastable range. Spontaneous passage of renal stones occurred during treatment in 6 patients given placebo and in 6 treated with hydrochlorothiazide despite decreased urinary calcium excretion in the latter group. The findings show the specific effect of hydrochlorothiazide treatment to be a decrease in urinary calcium excretion in patients with calcium lithiasis, while other changes appear to be nonspecific effects of treatment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7176047&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Haemodynamics during long-term thiazide treatment in essential hypertension: differences between responders and non-responders.

Van Brummelen P, Man in't Veld A, Schalekamp MA.

1. Blood pressure, systemic haemodynamics, plasma volume, renin and aldosterone were measured during placebo treatment and after 1, 4 and 12 weeks of hydrochlorothiazide in 13 patients with uncomplicated essential hypertension. Nine of these patients were also studied after 24 and 36 weeks of treatment. 2. Mean arterial pressure was lowered significantly during hydrochlorothiazide treatment. In seven patients the fall in mean arterial pressure was lowered significantly during hydrochlorothiazide treatment. In seven patients the fall in mean arterial pressure was greater than 10% (responders); four of these were studied for 36 weeks. The remainder were considered non-responders. 3. Hydrochlorothiazide lowered cardiac output. The maximal decrease was observed after 12 weeks of treatment (P less than 0.01). In responders this was followed by a return to pretreatment values and a significant decrease in total peripheral resistance, whereas in non-responders cardiac output remained reduced and total peripheral resistance was permanently elevated. 4. Changes in plasma volume, renin and aldosterone were not significantly different in responders and non-responders although non-responders tended to show a greater degree of plasma volume depletion and a more pronounced increase in plasma aldosterone. 5. Thus it is unlikely that the initial decrease in cardiac output is an important determinant of the long-term haemodynamic effect of thiazide diuretics.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=396081&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Correlation of urinary excretion with in vitro dissolution using several dissolution methods for hydrochlorothiazide formulations.

Shah KA, Needham TE.

Four different hydrochlorothiazide formulations were prepared, and cumulative urinary hydrochlorothiazide excretion was determined in a crossover study using six volunteers. A comparison of in vivo results showed that one formulation (Forumulation D) was significantly different from the others at 2, 3, 4, 5, 8, and 14 hr. A dissolution study was conducted on each formulation using the flask, USP basket, and magnetic basket methods at agitation speeds of 50, 100, and 150 rpm. Formulation D was significantly different from other formulations when determined using the USP basket method at 150 rpm and a sampling time of 10 min; the USP basket method at 100 rpm and a sampling time of 100 min; the flask method at 100 rpm and sampling times of 30, 40, 60, and 120 min; and the flask method at 150 rpm and sampling times of 30 and 40 min. Significant in vitro and in vivo correlations were found using a regression analysis and F test. With a correlation coefficient and 95% confidence intervals, it was established that the USP basket method at 150 rpm was the best predictor of urinary hydrochlorothiazide excretion among the dissolution methods tested.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=529036&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Estimating compliance with diuretic therapy: urinary hydrochlorothiazide-creatinine ratios in normal subjects.

Hodge RH Jr, Lynch SS, Davison JP, Knight JG, Sinn JA, Carey RM.

We gave 21 healthy young men 100 mg of hydrochlorothiazide daily to determine whether or not urinary detection of the drug was feasible as a measure of compliance on a standard antihypertensive regimen. All subjects took the drug daily for 6 days, after which they were divided into four groups with differing patterns of medication administration. Urine hydrochlorothiazide and creatinine measurements were obtained to validate the urinary hydrochlorothiazide-creatinine ratio (UHCR) as an accurate quantitative index of compliance. The subjects achieved a constant level of UHCR of 13 +/- 3.0 within 48 hours of hydrochlorothiazide administration. The UHCR levels decreased to 5.0 +/- 0.8 48 hours after discontinuation of the drug (p less than 0.001). UHCR values in the range of 13 +/- 6 indicate that the subject has ingested hydrochlorothiazide 24 hours previously. The UHCR is a potentially useful means of assessing compliance in hypertensive patients taking hydrochlorothiazide.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=541045&dopt=Abstract hydrochlorothiazide Microzide



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

Menon GN, White LB.

Department of Analytical Research, Abbott Laboratories, North Chicago, IL 60064.

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%.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6101161&dopt=Abstract hydrochlorothiazide Microzide