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Saturday, July 10, 2010

Diuretics potentiate the blood pressure–lowering effects of ACE inhibitors and β-blockers

A 60-year-old man with type 2 diabetes mellitus, hypertension, and coronary artery disease is evaluated during a routine office visit. Medications are metformin, a β-blocker, an angiotensin-converting enzyme inhibitor, aspirin, and a statin.

On physical examination, blood pressure is repeatedly 160/90 mm Hg. There is evidence of early diabetic retinopathy.

Laboratory Studies
Blood urea nitrogen 15 mg/dL
Creatinine 1.1 mg/dL
Potassium 5.4 meq/L
Spot urine albumin–creatinine ratio 175 mg/g

Addition of which of the following agents is indicated to treat this patient's hypertension?
A An angiotensin receptor blocker
B An α-blocker
C A potassium-sparing diuretic
D A thiazide diuretic

Answer and Critique (Correct Answer = D)

Key Point
Diuretics potentiate the blood pressure–lowering effects of angiotensin-converting enzyme inhibitors and β-blockers.

Therapy with a thiazide diuretic is indicated for this patient. This patient has type 2 diabetes mellitus, coronary artery disease, possible early diabetic nephropathy, and inadequate blood pressure control. His current regimen of a β-blocker and angiotensin-converting enzyme inhibitor is appropriate for cardiovascular disease and target organ protection. The addition of a thiazide diuretic is likely to improve blood pressure control, which is indicated to prevent further progression of target organ damage.

The addition of an angiotensin receptor blocker or potassium-sparing diuretic may provide renal protection and additional blood pressure control but would likely further exacerbate his hyperkalemia. Therapy with α-blockers has not been shown to have particular advantages compared with use of the other agents listed and may not lower blood pressure sufficiently.

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