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Dose response to hydrochlorothiazide in hypertensives receiving a calcium channel blocker
M G Ziegler1, E Lernhardt, V Solt-Buzsaki
1Department of Medicine, UCSD Medical Center, San Diego, CA 92103.
Insights
Adding hydrochlorothiazide (HCTZ) to nicardipine showed minimal blood pressure reduction but increased metabolic side effects. Higher HCTZ doses amplified these effects, suggesting caution when combining these hypertension medications.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
- Nephrology
Background:
- Dihydropyridine calcium channel blockers like nicardipine are common antihypertensives.
- Hydrochlorothiazide (HCTZ) is a frequently used diuretic for hypertension.
- The combined effects and metabolic impacts of nicardipine and HCTZ require investigation.
Purpose of the Study:
- To evaluate the efficacy and safety of combining nicardipine with varying doses of HCTZ.
- To assess the dose-dependent effects of HCTZ on blood pressure and metabolic parameters in patients on nicardipine.
Main Methods:
- A randomized crossover study involving seven hypertensive patients.
- Patients received nicardipine plus placebo, 6.25, 12.5, 25, or 50 mg of HCTZ.
- Measurements included blood pressure, serum potassium, glucose, and uric acid levels.
Main Results:
- Blood pressure decreased by approximately 7/3 mmHg, irrespective of HCTZ dose.
- Potassium, glucose, and uric acid levels increased in a dose-dependent manner with HCTZ.
- The 50 mg HCTZ dose resulted in significant hypokalemia and hyperglycemia, exceeding typical responses.
Conclusions:
- Low-dose HCTZ offers a modest antihypertensive effect when combined with nicardipine.
- Higher doses (25 and 50 mg) of HCTZ did not improve blood pressure control.
- Combining higher HCTZ doses with nicardipine led to substantial metabolic side effects, indicating potential risks.
Abstract:
Seven hypertensive patients receiving the dihydropyridine calcium channel blocking agent nicardipine were given placebo, 6.25, 12.5, 25 and 50 mg hydrochlorothiazide (HCTZ) in a randomized crossover design. Blood pressure (BP) decreased by about 7/3 mmHg irregardless of dose. In contrast, potassium, glucose and uric acid increased in a dose-dependent fashion. The hypokalemic and hyperglycemic responses at 50 mg were larger than usually seen with HCTZ. Low doses of HCTZ provided a modest antihypertensive effect, but 25 and 50 mg of HCTZ were no more effective in lowering BP and gave unusually large metabolic side effects when combined with a calcium channel blocker.