Lithium intoxication in patients using angiotensin II receptor antagonists and hydrochlorothiazide: two case reports

Objectives.
Lithium has a relatively narrow therapeutic index, necessitating careful consideration of drug interactions. Commonly used drugs that increase lithium levels include angiotensin-converting enzyme inhibitors, angiotensin II receptor antagonists, thiazide diuretics, and non-steroidal anti-inflammatory drugs.

Case report.
This article describes two cases of lithium intoxication: a 72-year-old female treated with telmisartan and hydrochlorothiazide, and a 69-year-old female receiving olmesartan and hydrochlorothiazide. Both patients had been using antihypertensive drugs for an extended period without dose adjustments.

Conclusions.
Patients with bipolar disorder often suffer from comorbidities such as hypertension and metabolic syndrome. Medications used for these indications may interact with lithium, increasing its concentration in the blood. Few cases of lithium intoxication associated with the use of sartans have been reported to date; this article presents two patients taking an angiotensin receptor II blocker in combination with hydrochlorothiazide.