Microzide
Clinical efficacy and cost comparison of an amiloride-hydrochlorothiazide combination versus hydrochlorothiazide and wax-matrix potassium supplement in the treatment of essential hypertension.

Vardan S, Rapacke J, Mookherjee S.

To compare the clinical efficacy and cost of therapy with an amiloride-hydrochlorothiazide combination versus hydrochlorothiazide and a wax-matrix potassium supplement, we reviewed the medical records of 20 hypertensive men who had received both treatments. The review period included 5.9 +/- 0.9 (mean +/- SE) months on hydrochlorothiazide and wax-matrix potassium and 5.3 +/- 0.7 months after changeover to the amiloride-hydrochlorothiazide combination. Control of blood pressure, maintenance of serum potassium levels, and number of outpatient visits were similar before and after the change in therapy. The monthly cost of medication, based on the lowest listed price in the Drug Topics Red Book and also in the Red Book Update, was approximately 12% higher for the hydrochlorothiazide and wax-matrix potassium regimen than for the amiloride-hydrochlorothiazide combination, whereas the federal agency contract price for the latter was significantly higher. The change to the amiloride-hydrochlorothiazide combination reduced the mean number of tablets taken daily from 5.3 +/- 0.6 to 1.25 +/- 0.1, suggesting a more convenient therapeutic regimen.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3731211&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Absorption and disposition of two combination formulations of hydrochlorothiazide and triamterene: influence of age and renal function.

Williams RL, Thornhill MD, Upton RA, Blume C, Clark TS, Lin E, Benet LZ.

In this study we compared the absorption and disposition of two commonly used combination formulations of hydrochlorothiazide and triamterene (Dyazide and Maxzide) in 48 patients with essential hypertension after dosing with each formulation to steady state. Interdose AUC and urinary recovery of hydrochlorothiazide, triamterene, and the major metabolite of triamterene, hydroxytriamterene sulfate (adjusted for dose), documented marked impairment in the absorption of hydrochlorothiazide (approximately two third as bioavailable) and triamterene (about half as bioavailable) from Dyazide in comparison to Maxzide. The study also demonstrated a reduction in the clearance of triamterene, hydrochlorothiazide, and hydroxytriamterene sulfate with increasing age. Linear correlation analyses suggested that this effect was a result of the reduction in renal function that occurs with increasing age.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3731685&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Diuretic therapy for hypertension in the elderly.

Myers MG.

Recent studies have confirmed the benefits of treating hypertension in the elderly. Thiazide diuretics appear to be effective in achieving goal blood pressure in a majority of patients above the age of 60 years. Increasing concern regarding the biochemical abnormalities associated with diuretic therapy has led to the more widespread use of lower doses of these agents. Preliminary results from a study of hydrochlorothiazide +/- amiloride treatment in 99 hypertensive patients aged 65 to 80 years indicate that hydrochlorothiazide 25 to 50 mg/day will lower diastolic blood pressure to less than 90 mmHg in about 90% of elderly patients with mild to moderate elevations in blood pressure. These lower dosages of hydrochlorothiazide were only occasionally associated with mild hypokalaemia. However, the addition of amiloride to the treatment regimen resulted in the maintenance of normal serum potassium concentrations. Thus, relatively low doses of thiazide diuretics may effectively lower blood pressure in elderly hypertensive patients while causing fewer biochemical abnormalities than previously associated with the use of these drugs.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3732095&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Hypercalciuria associated with long-term administration of calcitriol (1,25-dihydroxyvitamin D3). Action of hydrochlorothiazide.

Santos F, Smith MJ, Chan JC.

Urine calcium excretion was evaluated in 19 patients before and after calcitriol (1,25-dihydroxyvitamin D3) treatment that was followed up for a five- to seven-year period. The effects of increases of calcitriol dosage and modifications of calciuria with hydrochlorothiazide were systematically examined. The urine calcium excretion before calcitriol therapy was 2.3 +/- 0.8 mg/kg/day (mean- +/- SEM) and the urine calcium-creatinine concentration ratio was 0.12 +/- 0.04. With the dose of calcitriol at 23 ng/kg/day, these values increased to 3.2 +/- 0.8 mg/kg/day and 0.19 +/- 0.04, respectively. Following double dose of calcitriol (44 ng/kg/day), increments in calciuria and urinary calcium/creatinine concentration of 1.4 +/- 0.6 mg/kg/day and 0.10 +/- 0.03, respectively, were observed. With concomitant administration of hydrochlorothiazide (1 to 2 mg/kg/day) therapy at maintenance dose and calcitriol (31 ng/kg/day), the urine calcium excretion effectively decreased by 1.3 +/- 0.6 mg/kg/day and the urine calcium-creatinine concentration ratio by 0.05 +/- 0.02. The results suggest that children with calcium-phosphate disorders who require long-term treatment with calcitriol must be carefully monitored in terms of urine calcium excretion, especially when the dosages are increased to achieve maximal therapeutic efficacy. Calciuria induced by calcitriol administration is effectively reversed by addition of hydrochlorothiazide to the treatment regimen.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3753816&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Pharmacodynamics and pharmacokinetics of furosemide combinations with potassium-retaining and thiazide-like diuretics: clearance and micropuncture studies.

Hropot M, Sorgel F, Mutschler E.

The interaction between furosemide on the one hand and hydrochlorothiazide, tizolemide, amiloride and triamterene on the other was studied by clearance and micropuncture techniques in rats. Simultaneous administration of furosemide with hydrochlorothiazide and tizolemide distinctly increased the natriuresis compared to that induced by furosemide alone, whereas the potassium excretion diminished. In contrast, amiloride and triamterene primarily decreased furosemide-induced fractional potassium excretion by about 30%, whereas sodium excretion increased only slightly compared to that produced by furosemide alone. Hydrochlorothiazide and triamterene significantly decreased furosemide secretion and changed its pharmacokinetics. Furosemide plasma concentration increased, thus possibly prolonging the salidiuretic effect. Amiloride and tizolemide did not influence the secretion of furosemide at all.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3774022&dopt=Abstract hydrochlorothiazide Microzide