How Do ARB-HCTZ Combos Work?

Angiotensin II receptor blocker/hydrochlorothiazide (ARB/HCTZ) combination drugs are used to treat hypertension (high blood pressure). Hypertension is one of the major risk factors for cardiovascular disease, kidney disease, and stroke.

ARBs or angiotensin II receptor antagonists work by reducing the activity of angiotensin II (a hormone that narrows your blood vessels and contributes to salt and water retention in the body). They block the receptors that the hormone acts on, particularly AT1 receptors, which are found in the heart, blood vessels and kidneys. Blocking the activity of angiotensin II helps to lower blood pressure.

Diuretics also known as water pills are drugs that cause diuresis (increase in the production of urine by the kidneys). Thiazide diuretics cause both natriuresis (removal of sodium in urine) and diuresis. They work by blocking sodium and chloride (Na/Cl) channels in the distal convoluted tubule of the nephron and inhibit the reabsorption of sodium and water. This also causes a loss of potassium and calcium ions. Elimination of excess sodium and water from the body results in the reduction of blood pressure.

• ARB/HCTZ combos are given orally to treat hypertension (high blood pressure)

Side effects associated with ARB/HCTZ combos include:

• Orthostatic hypotension (a form of low blood pressure that happens when standing up from sitting or lying down)
• Dizziness
• Headache
• Flu-like symptoms
• Upper respiratory tract infections
• Tiredness
• Muscle weakness
• Back pain
• Abdominal pain
• Diarrhea
• Confusion
• Photosensitivity (oversensitivity and formation of skin rash after long exposure to ultraviolet rays present in sunlight)
• Peripheral edema (accumulation of fluid beneath the skin)
• Rash
• Non-melanoma skin cancer
• Angioedema (abrupt and short-lived swelling of the skin and mucous membranes)
• Gastroenteritis (inflammation of stomach and intestines)
• Albuminuria (loss of albumin in urine)
• Anaphylaxis (life-threatening allergic reaction caused when exposed to a particular food or drug)
• Hyperuricemia (increased urine production)
• Hypokalemia (decreased potassium levels in the blood)
• Hypomagnesemia (decreased magnesium levels in the blood)
• Increased creatinine phosphokinase enzyme levels
• Increased liver enzymes

Rare but serious side effects of ARB/HCTZ combos may include:

• Thrombocytopenia (decreased platelet count)
• Exfoliative dermatitis (severe inflammation of the skin)
• Toxic epidermal necrolysis (a life-threatening skin condition characterized by widespread redness and death of skin tissue)
• Erythema multiforme (autoimmune skin reaction caused by medicine)
• Steve-Johnson syndrome (severe skin reaction where the skin and mucous membrane are damaged)

The information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Generic and brand names of ARB/HCTZ combos drugs include:

• Candesartan/hydrochlorothiazide (Atacand HCT)
• Eprosartan/hydrochlorothiazide (Teveten HCT, Teveten Plus)
• Irbesartan/hydrochlorothiazide (Avalide)
• Losartan/hydrochlorothiazide (Hyzaar)
• Olmesartan/hydrochlorothiazide (Benicar HCT)
• Telmisartan/hydrochlorothiazide (Micardis HCT, MicardisPlus)
• Valsartan/hydrochlorothiazide (Diovan HCT)