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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.
## Primary Indications
* Mild to moderate pain, including menstrual pain (dysmenorrhea) and pain associated with dental procedures.
* Inflammation.
## Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg every 6 hours as needed. Dosing should not exceed 7 days.
## Pediatric Dosing
* Mefenamic acid is **not generally recommended** for use in pediatric patients due to limited data and potential for adverse effects. The use of other NSAIDs or analgesics is typically preferred.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data for dose adjustment in renal impairment is limited. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. Data for dose adjustment in hepatic impairment is limited. Monitor liver function closely.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* Patients with a history of bronchospasm, asthma, rhinitis, or urticaria induced by aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) bleeding or history of recurrent GI ulceration or bleeding.
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, dizziness, drowsiness.
* **Serious:**
* **GI:** Gastric ulceration, perforation, bleeding.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and new-onset or worsening hypertension.
* **Renal:** Renal papillary necrosis, interstitial nephritis, acute renal failure.
* **Hepatic:** Hepatotoxicity, elevated liver enzymes.
* **Hematologic:** Anemia, thrombocytopenia, leukopenia.
* **Dermatologic:** Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Hypersensitivity:** Anaphylaxis, angioedema, bronchospasm.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs and SNRIs:** Increased risk of GI bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly GI bleeding.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Renal function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Monitor liver enzymes (AST, ALT), especially in patients with pre-existing liver disease or those at risk.
* **GI symptoms:** Advise patients to report any signs of GI bleeding (e.g., black, tarry stools, hematemesis).
* **Cardiovascular risk factors:** Assess and manage risk factors for cardiovascular disease.
* **Blood pressure:** Monitor blood pressure regularly.
## Clinical Pearls
* Mefenamic acid has a short duration of action; it is typically dosed every 6 hours.
* Due to potential GI toxicity, it should be used at the lowest effective dose for the shortest duration necessary.
* Concomitant use with alcohol may increase the risk of GI bleeding.
* Avoid in patients with a history of NSAID-induced asthma.
* Use with caution in elderly patients due to increased risk of 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 clinical guidelines before making therapeutic decisions.
