I am treating a 55-year-old man with a history of hypertension, which is controlled with amlodipine (Norvasc) 5 mg. Over the past 18 months, urinalysis and ultrasound of kidneys have been normal, but blood work shows slightly abnormal creatinine levels. Should he switch to an angiotensin-converting enzyme (ACE) inhibitor or angiotensin II receptor blocker (ARB)?—HANH NGUYEN, PA-C, Beaumont, Tex.
Dihydropyridine calcium channel blockers (CCBs), such as amlodipine, preferentially dilate the afferent arteriole and impair renal autoregulation. Therefore, if systemic BP is not lowered sufficiently, glomerular hypertension may develop. ACE inhibitors work by dilating efferent renal arterioles, which theoretically carries a much lower risk of causing glomerular hypertension. (ARBs are recommended if a patient cannot tolerate an ACE inhibitor.) A large, three-year, randomized study of hypertensive patients with nondiabetic nephropathy evaluated the effects of amlodipine vs. enalapril on renal function and found no statistically significant difference in true glomerular filtration rate decline even in patients with proteinuria (Clin Ther. 2008;30:482-498). So the verdict remains undecided. My first recommendation is to be sure the hypertension is well controlled and monitor for proteinuria. If proteinuria is suspected, ARB or ACE inhibitor therapy may be more renoprotective than a CCB-based therapy.—Claire Babcock O’Connell, MPH, PA-C (139-7)