Drug interactions
Mefenamic acid + Pemetrexed
Severity: Major
Mefenamic acid and Pemetrexed: major interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
NSAIDs can reduce renal clearance of pemetrexed, raising its exposure and the risk of myelosuppression, renal toxicity and gastrointestinal toxicity. The risk is greatest in patients with mild to moderate renal impairment.
What this interaction means in plain words
Mefenamic acid and Pemetrexed can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Mefenamic acid belongs to Musculoskeletal; Pemetrexed belongs to Oncology.
Why it happens
NSAID-induced reduction in renal blood flow and competition for tubular secretion decrease pemetrexed elimination.
What to do
Mefenamic acid has a short half-life, so withhold it for about two days before, on the day of, and for two days after pemetrexed per labeling for short half-life NSAIDs. If it cannot be stopped, monitor blood counts and renal function closely.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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Other interactions of Mefenamic acid
- Ketorolac intranasal + Mefenamic acid Contraindicated
- Ketorolac + Mefenamic acid Contraindicated
- Aceclofenac + Mefenamic acid Major
- Acemetacin + Mefenamic acid Major
- Acetylsalicylic acid + Mefenamic acid Major
- Alteplase + Mefenamic acid Major
Other interactions of Pemetrexed
Frequently asked questions
Can I take Mefenamic acid with Pemetrexed?
MediHelp rates the interaction as major. Mefenamic acid and Pemetrexed can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. NSAIDs can reduce renal clearance of pemetrexed, raising its exposure and the risk of myelosuppression, renal toxicity and gastrointestinal toxicity. The risk is greatest in patients with mild to moderate renal impairment.
How serious is the interaction between Mefenamic acid and Pemetrexed?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Mefenamic acid has a short half-life, so withhold it for about two days before, on the day of, and for two days after pemetrexed per labeling for short half-life NSAIDs. If it cannot be stopped, monitor blood counts and renal function closely.
What other medicines interact with Mefenamic acid?
MediHelp also lists interactions of Mefenamic acid with, for example, Ketorolac intranasal, Ketorolac, Aceclofenac. The full list is on the Mefenamic acid page.
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