Racial differences in response to acute dosing with hydrochlorothiazide

Area of Science:

• Pharmacology
• Nephrology
• Hypertension Research

Background:

• Black individuals exhibit a higher response rate to diuretic therapy for hypertension compared to white individuals.
• Understanding the pharmacokinetic (PK), pharmacodynamic, and neurohumoral effects of antihypertensive medications is crucial for optimizing treatment strategies.

Purpose of the Study:

• To investigate the PK, pharmacodynamic, and neurohumoral responses to hydrochlorothiazide (HCTZ) in black and white hypertensive patients.
• To identify potential racial differences in the excretion of electrolytes and hormones following HCTZ administration.

Main Methods:

• A matched group of 9 black and 9 white hypertensive patients participated in the study.
• Subjects received a single 25 mg dose of HCTZ after a washout period and control diet.
• Serial blood and urine collections were performed for 36 hours to analyze PK and electrolyte/hormone excretion.

Main Results:

• Sodium excretion increased comparably in both black and white patients post-HCTZ.
• Potassium excretion was significantly higher in white patients following HCTZ, particularly within the first 12 hours.
• Aldosterone excretion showed a normal circadian pattern in whites but not in blacks, with generally lower post-dosing levels in blacks.

Conclusions:

• Single-dose pharmacokinetic and natriuretic responses to HCTZ were not racially distinct.
• Differences in potassium and aldosterone excretion patterns between black and white patients were observed.
• Altered aldosterone excretion patterns in black patients may contribute to their distinct potassium excretion response to HCTZ.