Microzide
Efficacy of low dose captopril once daily in diuretic resistant hypertension.

Baumgart P, Tenschert W, Vetter H.

In 12 essential hypertensive patients insufficiently controlled by treatment with 50 mg hydrochlorothiazide, the blood pressure lowering effect of the addition of 25 mg captopril once daily was examined. Twenty four hour ambulatory blood pressure monitoring was performed using portable automatic recording devices before treatment, after 4 weeks of treatment with hydrochlorothiazide alone, and again after 4 weeks of combined treatment with captopril. The combined treatment yielded a marked additional blood pressure reduction in comparison with the previous medication of the diuretic alone. The additional antihypertensive effect of captopril lasted 24 hours. During the daytime between 08.00 h and 20.00 h the mean blood pressure was 158 +/- 13/100 +/- 8 mmHg before treatment. After treatment with hydrochlorothiazide alone it was 151 +/- 11/93 +/- 8 mmHg and after hydrochlorothiazide and captopril it was 140 +/- 13/88 +/- 9 mmHg. Our results indicate that the addition of only 25 mg captopril once a day to a diuretic may result in a marked additional blood pressure reduction or normalization in cases of insufficient control by the diuretic alone.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3534846&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Potassium-sparing effect of trilostane in hydrochlorothiazide-treated rats and dogs.

DeFelice AF, Brousseau AC, O'Connor B.

Trilostane, which inhibits three beta-hydroxysteroid dehydrogenase and aldosterone synthesis in rats and monkeys, significantly attenuated the oral potassium-wasting effect of hydrochlorothiazide (HCTZ) in rats and dogs when coadministered with the diuretic. The steroid reduced the kaliuretic and enhanced the natriuretic (and hyperreninemic) activity of HCTZ in rats, thereby promoting the urinary sodium/potassium ratio. Trilostane completely prevented HCTZ-induced hypokalemia in dogs and tended to reduce the degree of secondary aldosteronism. The combination also promoted hematocrit of dogs by 8% and decreased serum Na+ concentration by 7 meq/liter. When administered alone, trilostane increased canine serum potassium levels slightly and promoted rat urinary Na+/K+ ratio. Results confirm previous reports of antikaliuretic activity of trilostane in diuretic-treated rats. Further, the data indicate that frank hypokalemia induced in dogs by hydrochlorothiazide can be prevented by adjunctive trilostane therapy without eliciting hyperkalemia.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3540974&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Serum magnesium and potassium levels in hypertensive patients after a therapeutic switch from hydrochlorothiazide plus a potassium supplement to maxzide.

Davidov ME, Becker FE, Hollifield JW.

Determinations of serum magnesium and potassium levels and blood pressure were made in 40 hypertensive patients in whom daily therapy with 50 mg of hydrochlorothiazide plus potassium supplements was switched to a once-daily regimen of 50 mg of hydrochlorothiazide plus 75 mg of triamterene (Maxzide). Patients showed no clinically significant changes in blood pressure or in serum magnesium or serum potassium values following the switch. It is concluded that therapy in patients receiving hydrochlorothiazide and up to 60 meq of potassium can be safely switched to Maxzide without adversely affecting serum magnesium levels, serum potassium levels, or blood pressure control.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3565425&dopt=Abstract hydrochlorothiazide Microzide



Microzide
A comparative study of the pharmacokinetics and pharmacodynamics of atenolol, hydrochlorothiazide and amiloride in normal young and elderly subjects and elderly hypertensive patients.

Sabanathan K, Castleden CM, Adam HK, Ryan J, Fitzsimons TJ.

Six normal young and six normal elderly volunteers and six elderly hypertensive patients took part in an acute and chronic dose study of a combination capsule containing atenolol (50 mg), hydrochlorothiazide (25 mg) and amiloride (2.5 mg) designed for the treatment of hypertension. No difference in any of the drug pharmacokinetic parameters could be detected between the hypertensives and the normal elderly subjects. The bio-availability and the 24-h blood concentrations of all three drugs, half-life of atenolol and amiloride and the peak concentration of hydrochlorothiazide was significantly greater in the elderly. The 24-h blood concentrations of atenolol and hydrochlorothiazide did not alter with chronic dosing, but amiloride concentrations were significantly higher at this time in all groups. A significant fall in the blood pressure was observed in the hypertensive group. Heart rate fell more in the normal and hypertensive elderly subjects than in the young. The combination has shown to be an effective and well tolerated antihypertensive in the elderly patient with a 24-h duration of action.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3582468&dopt=Abstract hydrochlorothiazide Microzide



Microzide
Eventual attenuation of hypocalciuric response to hydrochlorothiazide in absorptive hypercalciuria.

Preminger GM, Pak CY.

The effect of long-term hydrochlorothiazide therapy on renal calcium excretion was measured in 12 well defined cases of absorptive hypercalciuria and 10 of renal hypercalciuria. Patients were studied during a control phase, at 3 to 6 months of therapy and after long-term treatment with hydrochlorothiazide (mean 61 months for absorptive hypercalciuria and 71 months for renal hypercalciuria). Evaluation comprised measurement of urinary calcium and fractional (intestinal) calcium absorption while patients were maintained on a constant metabolic diet (400 mg. calcium per day) for 3 days. In patients with absorptive hypercalciuria urinary calcium decreased significantly at 3 months of treatment (from 266 to 137 mg. per day, p less than 0.001). However, with continued treatment urinary calcium rebounded to 197 mg. per day. Of the patients with absorptive hypercalciuria 50 per cent were hypercalciuric (greater than 200 mg. per day) on long-term treatment, whereas none was hypercalciuric at 3 months. In contrast, urinary calcium in the patients with renal hypercalciuria decreased from 299 to 104 mg. per day (p less than 0.001) at 3 months of treatment and remained reduced (116 mg. per day) during long-term treatment. Intestinal calcium absorption was increased initially and remained unchanged throughout treatment in the patients with absorptive hypercalciuria. In patients with renal hypercalciuria intestinal calcium absorption decreased significantly after short-term treatment with hydrochlorothiazide and remained so after long-term therapy. The results suggest that, unlike patients with renal hypercalciuria, some with absorptive hypercalciuria lose the hypocalciuric effect of hydrochlorothiazide during long-term treatment.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3586136&dopt=Abstract hydrochlorothiazide Microzide