Which statement best describes the interaction between lithium and NSAIDs like ibuprofen?

• A. Ibuprofen may increase lithium toxicity
• B. Ibuprofen decreases lithium levels
• C. Ibuprofen has no interaction with lithium
• D. Ibuprofen cures lithium toxicity

Answer: (A)

Lithium is cleared mainly by the kidneys and its excretion is highly sensitive to how the kidneys handle sodium and water. NSAIDs like ibuprofen inhibit prostaglandin production in the kidney, which lowers renal blood flow and the glomerular filtration rate. With reduced GFR, lithium clearance drops. Additionally, the kidney tends to reabsorb more sodium to compensate for any volume or perfusion changes, and lithium follows sodium reabsorption in the proximal tubule, so more lithium is reabsorbed back into the bloodstream. The net effect is higher lithium levels in the blood, increasing the risk of toxicity.

So ibuprofen may increase lithium toxicity, especially in the elderly or when dehydration or other interacting medicines are present. If NSAIDs are needed, monitor lithium levels closely and ensure good hydration, or use an alternative analgesic when possible.