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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties, primarily through inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, usually initiated at the onset of pain and bleeding.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to safety concerns and lack of established dosing guidelines. If used, it should be under strict medical supervision. Some sources suggest a dose of 6.5 mg/kg every 6 hours for children aged 6 months to 14 years for fever, but this is off-label and requires careful consideration.
## 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.
* **Elderly:** Increased risk of adverse effects; use lowest effective dose.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, urticaria, or allergic-type reactions after aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active peptic ulceration or gastrointestinal bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events; renal failure; hepatic failure; hypersensitivity reactions (including anaphylaxis); bronchospasm; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Aspirin:** May decrease the antiplatelet effect of aspirin; increased risk of GI adverse effects.
* **Corticosteroids:** Increased risk of GI bleeding.
* **Diuretics and antihypertensives:** May reduce their efficacy and increase risk of renal impairment.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
* **Other NSAIDs:** Increased risk of adverse effects.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine).
* Liver function tests (ALT, AST).
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only. Duration of use should not exceed 7 days for pain or 3 days for fever.
* Administer with food or milk to minimize gastrointestinal upset.
* Consider gastroprotective agents (e.g., PPIs) in patients with increased risk of GI complications.
* Discontinue if signs of serious adverse events (e.g., GI bleeding, renal impairment, skin rash) occur.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before prescribing or administering any medication. Local protocols and patient-specific factors may influence dosing and management.
