Review Question - QID 103787

The patient in this vignette requires analgesic therapy but is on lithium. Any drug that decreases his glomerular filtration rate could potentially cause lithium toxicity (tremor, ataxia, dysarthria, nystagmus, renal impairment, confusion, and convulsions) and should be avoided if possible, leaving acetaminophen as the only safe choice.

Because lithium has a small therapeutic range, it is essential to monitor serum lithium levels when starting or changing doses. Patients should be counseled about the early signs of toxicity, which include tremors, sedation, acne, polyuria, and edema, among others. Additionally, any drug that changes renal filtration should be avoided, including calcium channel blockers, ACE inhibitors, and others.

Herschberg et al. present a case in which a patient on lithium became delirious when administered indomethacin which led to potentially fatal lithium toxicity.

Phelan et al. found that serum lithium concentration could increase between 99% and 448% with concomitant COX-2 inhibitor use.. They also report that increased lithium concentrations have been shown in association with aspirin and sulindac, two thought to have the least effect on GFR, as well as 14 other NSAIDs.

Illustration A shows common medications that result in altered lithium levels.

Incorrect Answers:
Answers 1, 3-5: These are all examples of NSAIDs which may affect renal function and should be avoided in this patient.