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# Mefenamic acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term relief of mild to moderate pain. It acts by inhibiting prostaglandin synthesis.
## Primary Indications
* Pain associated with menstruation (dysmenorrhea)
* Mild to moderate pain
## Adult Dosing
* **Initial dose:** 500 mg
* **Subsequent doses:** 250 mg every 6 hours as needed.
* **Maximum duration:** Typically no longer than 7 days for pain management.
## Pediatric Dosing
* **Children 6 months to 12 years:** Dosing is typically based on weight. A common regimen is 6.5 mg/kg every 6-8 hours. For example, a 20 kg child would receive approximately 130 mg every 6-8 hours.
* **Maximum pediatric dose:** Not to exceed adult doses.
* **Note:** Use in children younger than 6 months is generally not recommended due to potential safety concerns.
## Dose Adjustments
* **Renal impairment:** Use with caution. Dose reduction may be necessary, especially in severe impairment.
* **Hepatic impairment:** Use with caution. Dose reduction may be necessary.
* **Elderly:** Increased risk of adverse effects; consider a lower starting dose and monitor closely.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal, hepatic, or cardiac impairment.
* Active peptic ulceration or gastrointestinal bleeding.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions; Stevens-Johnson syndrome; toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of gastrointestinal adverse effects and potential for reduced cardioprotective effects of aspirin.
* **ACE inhibitors, ARBs, Diuretics:** May reduce antihypertensive efficacy and increase risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum levels and risk of toxicity.
## Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease, elderly patients, or those on concomitant nephrotoxic agents.
* **Hepatic function:** Particularly with long-term use or in patients with liver disease.
* **Signs and symptoms of gastrointestinal bleeding:** Black, tarry stools; hematemesis.
* **Blood pressure:** NSAIDs can increase blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Should be used at the lowest effective dose for the shortest duration necessary.
* Consider risk factors for cardiovascular and gastrointestinal events when prescribing.
* Not typically used for chronic pain due to risk of serious adverse effects.
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**Disclaimer:** This information is intended for healthcare professionals and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant guidelines before making any clinical decisions.
