Major
Established
Description
Naproxen, like all NSAIDs, reduces renal prostaglandin synthesis, impairing lithium excretion and causing lithium toxicity.
Mécanisme
Naproxen inhibits COX-1 and COX-2, reducing prostaglandin E2-mediated vasodilation of renal afferent arterioles, decreasing GFR and lithium clearance with 25–50% elevation in serum lithium.
Signification clinique
Even short courses of naproxen can precipitate lithium toxicity; the interaction is well-documented across all NSAIDs.
Prise en charge
Avoid NSAIDs; use acetaminophen for analgesia in patients on lithium; if NSAID is essential, monitor lithium levels within days.