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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. It exhibits analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, initiated at the onset of pain or bleeding, whichever comes first.
* **Maximum Duration:** Typically recommended for a maximum of 7 days for pain.
## Pediatric Dosing
* **Age 12 years and older:** Dosing is the same as adults: 500 mg every 6 hours as needed.
* **Under 12 years:** Mefenamic acid is generally not recommended due to insufficient data and potential for toxicity. Specific dosing for younger children is not well-established and should be approached with extreme caution, if at all, under specialist guidance.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria triggered by aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Gastrointestinal bleeding or perforation.
* Severe renal or hepatic impairment.
* Pregnancy (especially in the third trimester).
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, and perforation; renal toxicity (including interstitial nephritis, papillary necrosis, and renal failure); hepatic toxicity (including hepatitis and jaundice); cardiovascular thrombotic events; hypersensitivity reactions; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal adverse effects.
* **Other NSAIDs and Salicylates:** Increased risk of gastrointestinal toxicity and other adverse effects.
* **ACE Inhibitors and ARBs:** May decrease antihypertensive efficacy and increase risk of renal impairment.
* **Diuretics:** May decrease diuretic efficacy and increase risk of renal impairment.
* **Lithium:** May increase serum lithium levels.
* **Methotrexate:** May increase methotrexate levels and toxicity.
## Monitoring
* **Renal Function:** Particularly in patients with pre-existing renal disease, dehydration, or those taking concomitant nephrotoxic agents.
* **Hepatic Function:** Monitor for signs and symptoms of liver dysfunction.
* **Gastrointestinal Symptoms:** Assess for signs of bleeding or ulceration.
* **Blood Pressure:** NSAIDs can elevate blood pressure.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use only.
* Advise patients to take with food or milk to minimize gastrointestinal upset.
* Discontinue use immediately if signs of hypersensitivity, severe GI distress, or bleeding occur.
* The risk of serious cardiovascular events, myocardial infarction, and stroke may increase with NSAID use.
* Diarrhea is a particularly common and sometimes dose-limiting side effect.
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*Disclaimer: This information is intended for clinical decision-making support only and does not replace professional clinical judgment. Always refer to the most current prescribing information and relevant guidelines for definitive patient care decisions.*
