Lithium Intoxication After Administration of AT¹ Blockers

Letter to the Editor

Sir: Candesartan is one of the new antihypertensive agents targeting the AT_¹ subtype of the angiotensin II receptor. Apart from candesartan, the AT_¹ receptor agents available in the United States are losartan, telmisartan, irbesartan, and valsartan. Candesartan exerts its antihypertensive effect by a selective blockade of the angiotensin II receptor, whereas angiotensin- converting enzyme (ACE) inhibitors, another class of antihypertensive agents, act through decreasing the production of angiotensin II and aldosterone by inhibiting the conversion of angiotensin I to angiotensin II. Whereas to our knowledge no interaction between the AT¹ blocker candesartan and lithium has been reported to date, cases of lithium intoxication have been observed during concomitant therapy of lithium with ACE inhibitors and with the angiotensin II receptor blockers losartan and valsartan. It has been shown that simultaneous administration of ACE inhibitors and lithium can elevate lithium levels from 1.7- to 5-fold.