Losartan Disease Interactions

The coadministration of some angiotensin II receptor blocker agents with aliskiren is contraindicated in patients with diabetes.

The use of these agents is contraindicated in patients with a history of angioedema related to previous angiotensin-converting enzyme (ACE) inhibitor or angiotensin II receptor blocker (ARB) therapy or in patients with hereditary angioedema. Patients with a history of angioedema unrelated to these agents may be at increased risk of angioedema while receiving angiotensin II receptor (AR) antagonists. Patients should be advised to immediately report any signs or symptoms suggestive of angioedema (swelling of face, extremities, eyes, lips, or tongue, or difficulty swallowing or breathing) and to stop taking the medication until otherwise directed by their physician. Emergency therapy and/or measures to prevent airway obstruction are required for angioedema involving the tongue, glottis, or larynx. Treatment with angiotensin II receptor (AR) antagonists should be discontinued permanently if angioedema develops in association with therapy.

Angiotensin II receptor (AR) antagonists can cause symptomatic hypotension in patients with an activated renin-angiotensin system, such as volume- and/or sodium-depleted patients. Therapy with AR antagonists should be administered cautiously in such patients and in those predisposed to hypovolemic or hyponatremic states (e.g., patients on diuretic therapy, especially if high doses were used or if recently instituted; those on dietary salt restriction; renal dialysis patients). Volume and/or sodium depletion should be corrected prior to initiating therapy with AR antagonists, and the patient should be hemodynamically stable. Ideally, patients at risk for excessive hypotension should initiate AR antagonist therapy under close medical supervision, preferably with a lower dose, and followed closely for the first 2 weeks of treatment and whenever the dosage of AR antagonist or diuretic is increased.

Angiotensin II receptor (AR) antagonists can cause renal impairment in patients whose renal function depends on the activity of the renin-angiotensin-aldosterone system. In addition, symptomatic hypotension can occur in susceptible individuals, which may compromise renal and myocardial perfusion. In patients with severe congestive heart failure (CHF), treatment with AR antagonists has been associated with oliguria and/or progressive azotemia and, rarely, renal failure, myocardial ischemia, and death. Therapy with AR antagonists should be initiated cautiously in patients with severe CHF, especially when accompanied by volume and/or sodium depletion. In patients who experience a decline in renal function, discontinuation of AR antagonist therapy is usually not required provided there is symptomatic improvement of the heart failure and renal deterioration is well-tolerated. Transient hypotension is also not a contraindication to further treatment with AR antagonists, since therapy can usually be reinstated without difficulty after blood pressure stabilizes.

Drugs that inhibit the renin-angiotensin, such as angiotensin II receptor antagonist system can cause hyperkalemia. Concomitant use of these agents with drugs that increase potassium levels may increase the risk of hyperkalemia. Use caution when using these agents together and monitor serum potassium periodically.

Changes in renal function including acute renal failure can be caused by drugs that inhibit the renin-angiotensin system and by diuretics. Patients whose renal function may depend in part on the activity of the renin-angiotensin system (e.g., patients with renal artery stenosis, chronic kidney disease, severe congestive heart failure, or volume depletion) may be at particular risk of developing acute renal failure with these agents. Monitor renal function periodically in these patients. Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function with these agents.

Losartan is converted in the liver to an active carboxylic acid metabolite and several inactive metabolites, and both parent drug and metabolites are eliminated by the kidney (35%) as well as by biliary excretion (60%). Dosage adjustments are not necessary in patients with renal impairment unless they are also volume-depleted, in which case therapy should be initiated under medical supervision. In patients with cirrhosis, however, significantly increased plasma concentrations of parent drug and active metabolite have been reported. Therapy with losartan should be initiated cautiously at a reduced dosage (50%) in patients with impaired liver function.