Major
Enalapril × Lithium
Angiotensin-converting enzyme inhibitors (ACEi)×Psycholeptics. Lithium
Mechanism
Enalapril and other ACE inhibitors reduce renal blood flow and glomerular filtration, decreasing lithium excretion. Lithium plasma concentration rises 25–40% with risk of neurotoxicity and renal injury. Effect is greatest in the elderly and with dehydration.
Symptoms
Tremor, confusion, nausea, diarrhea within 2–4 weeks of enalapril start. Lab: lithium above 1.2 mmol/L.
Management
Check lithium before enalapril, then on days 7 and 14 and at 4 weeks. Reduce lithium by 25–50% if level rises above target. Warn the patient about toxicity signs and the need for adequate water intake.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.