Metolazone, a diuretic agent

Dosing of antihypertensive medications in patients with renal insufficiency

The use of antihypertensive agents in patients with renal insufficiency necessitates careful consideration of dosages, titration, and monitoring. Renal function must be estimated to appropriately make dosage adjustments for antihypertensives that exhibit extensive renal elimination. Thiazide diuretics are useful in mild degrees of renal insufficiency but loop diuretics become necessary as renal function deteriorates further. With either class, low dosages should be used to prevent hypovolemia, hyponatremia, and hypokalemia which may worsen renal blood flow. Angiotensin-converting enzyme (ACE) inhibitors have become popular because they may have unique renal protective properties. All ACE inhibitors except fosinopril require reduced dosages and/or less frequent administration in patients with renal insufficiency. It is often necessary to use a diuretic with an ACE inhibitor and special dosing considerations are important. Due to demographic and physiologic characteristics of patients with renal insufficiency, beta blockers are often reserved for patients with other indications for beta blockers such as ischemic heart disease. Several beta blockers are eliminated primarily by the kidney and dosage reductions are necessary for these agents. Calcium antagonists may also have renal protective effects. Because calcium antagonists are metabolized extensively, significant dosage adjustments are not necessary. Data suggest that antihypertensives may slow the decline in renal insufficiency. The pharmacokinetics of several antihypertensives change with renal impairment because of reduced elimination. Therefore, dosage adjustments, slower titration, and less frequent administration are often necessary.