What it Is
Hydrochlorothiazide, often abbreviated HCTZ, is the most frequently prescribed diuretic, or "water pill" in the United States. According to the National Institutes of Health, it's considered first-line therapy in the treatment of hypertension, or high blood pressure. This means it's usually the first drug physicians prescribe to lower their patients' blood pressure. Hydrochlorothiazide comes in tablet and capsule form. Its dosage ranges from 12.5mg to 50mg once daily.
About Blood Pressure
Blood pressure is a measurement of the force the blood puts on blood vessels as blood pumps through your system. When blood pressure is high, your heart has to work harder to pump blood through your body. This puts added strain on the heart and the rest of your circulatory system. It also can lead to arteriosclerosis, the hardening and thickening of the walls of the arteries. High blood pressure increases your risk for heart attack and stroke.
Hydrochlorothiazide and Blood Pressure
Hydrochlorothiazide increases the amount of sodium secreted by the kidneys. Because sodium pulls water out with it, this decreases the fluid volume of the blood. When blood volume decreases, it puts less strain on the blood vessels and reduces the work the heart must put forth to pump the blood.
Hydrochlorothiazide in the Kidneys
As blood flows through the kidneys, it passes through small sections of the kidneys called nephrons. The nephrons filter fluid, wastes and electrolytes out of the blood. As the blood continues to flow through the nephrons, necessary fluid and electrolytes are returned to the blood while waste and extra fluid are collected to form urine. Hydrochlorothiazide prevents the last section of the nephron from reabsorbing sodium. This portion of the nephron normally reabsorbs about 5 percent of the filtered sodium, so hydrochlorothiazide is considered a weak diuretic.
References
- National Institutes of Health: The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure
- U.S. Pharmacist: Diuretics in the Treatment of Heart Failure
- Basic and Clinical Pharmacology; Bertram Katzung; 2007
