Summary

The interaction between lithium and diclofenac is clinically significant and potentially dangerous. Diclofenac can increase lithium blood levels by reducing its kidney elimination, leading to lithium toxicity with symptoms including tremor, confusion, and kidney problems.

Introduction

Lithium is a mood stabilizer primarily used to treat bipolar disorder and prevent manic episodes. It belongs to the class of antimanic agents and requires careful monitoring due to its narrow therapeutic window. Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) commonly prescribed for pain relief, inflammation reduction, and fever management in conditions such as arthritis, muscle pain, and post-operative discomfort.

Mechanism of Interaction

The interaction occurs through diclofenac's effect on kidney function and lithium elimination. Diclofenac inhibits cyclooxygenase enzymes, reducing prostaglandin E2 production in the kidneys. This leads to decreased renal blood flow and reduced glomerular filtration rate, which impairs the kidney's ability to eliminate lithium. Since lithium is primarily excreted unchanged through the kidneys, any reduction in renal clearance can cause lithium accumulation and elevated serum concentrations.

Risks and Symptoms

The primary risk is lithium toxicity, which can be life-threatening. Early signs include nausea, vomiting, diarrhea, tremor, and drowsiness. Severe toxicity may progress to confusion, seizures, coma, irregular heart rhythms, and kidney damage. Studies show that NSAIDs like diclofenac can increase lithium levels by 12-66%, with effects typically occurring within days of starting concurrent therapy. Patients with pre-existing kidney disease, dehydration, or those taking other medications affecting kidney function are at higher risk.

Management and Precautions

Close monitoring is essential when these drugs must be used together. Lithium serum levels should be checked within 4-7 days of starting diclofenac and regularly thereafter. Consider reducing the lithium dose by 25-50% when initiating diclofenac therapy. Monitor for signs of lithium toxicity including tremor, confusion, and gastrointestinal symptoms. Ensure adequate hydration and assess kidney function regularly. Alternative pain management options such as acetaminophen or topical preparations should be considered. If diclofenac is discontinued, lithium levels may decrease, requiring dose adjustments to prevent mood episode relapse.

Lithium interactions with food and lifestyle

Lithium has several important food and lifestyle interactions that require careful monitoring. Sodium intake significantly affects lithium levels - both low sodium diets and sudden increases in sodium intake can alter lithium concentrations and potentially lead to toxicity or reduced effectiveness. Patients should maintain consistent sodium intake and avoid drastic dietary changes. Adequate fluid intake (8-10 glasses of water daily) is essential, as dehydration can increase lithium levels and risk of toxicity. Caffeine intake should be kept consistent, as sudden changes in caffeine consumption can affect lithium levels. Alcohol should be avoided or used with extreme caution, as it can increase the risk of lithium toxicity and may worsen mood symptoms. Patients should also avoid excessive sweating through intense exercise or saunas without proper hydration, as fluid loss can concentrate lithium levels. These interactions are well-documented in major drug databases and clinical guidelines, requiring regular monitoring of lithium blood levels.

Diclofenac interactions with food and lifestyle

Alcohol: Concurrent use of diclofenac with alcohol may increase the risk of gastrointestinal bleeding and ulceration. Patients should limit or avoid alcohol consumption while taking diclofenac. Food: Taking diclofenac with food or milk can help reduce gastrointestinal irritation and improve tolerability. While food may slightly delay absorption, it does not significantly affect the overall effectiveness of the medication.