Major
Lithium × Losartan
Psycholeptics. Lithium×Angiotensin II receptor blockers (sartans)
Mechanism
The ARB (losartan) reduces glomerular filtration rate and renal lithium clearance by 25–40%. Serum lithium rises with toxicity risk.
Symptoms
Tremor, muscle twitching, nausea, diarrhoea, confusion, ataxia. Symptoms emerge when serum lithium exceeds 1.2 mmol/L.
Management
Reduce lithium dose by 25% when starting losartan; check serum lithium at 1 and 4 weeks. Alternative antihypertensives in bipolar patients: a beta-blocker or calcium channel blocker (amlodipine).