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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term relief of mild to moderate pain. It is a fenamate derivative.
## Primary Indications
* Pain associated with gynecological conditions (e.g., dysmenorrhea)
* Mild to moderate pain of other origins (e.g., dental pain, headache)
## Adult Dosing
* **Initial dose:** 500 mg orally every 6 hours as needed.
* **Maintenance dose:** 250 mg orally every 6 hours as needed.
* **Maximum daily dose:** 1500 mg (in divided doses).
* **Duration of therapy:** Generally limited to 7 days.
## Pediatric Dosing
* Mefenamic acid is generally not recommended for use in children under 14 years of age due to insufficient data and potential safety concerns.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosage reduction may be necessary. Data is limited.
* **Hepatic Impairment:** Use with caution. Dosage reduction may be necessary. Data is limited.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal (GI) ulceration or bleeding.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache.
* **Serious:**
* **GI:** Bleeding, ulceration, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and related death.
* **Renal:** Renal papillary necrosis, interstitial nephritis, glomerulonephritis, renal failure.
* **Hepatic:** Elevated liver enzymes, hepatitis, jaundice.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Hypersensitivity:** Rash, pruritus, bronchospasm, anaphylaxis.
* **Dermatologic:** Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of GI toxicity and additive pharmacologic effects.
* **Diuretics, ACE inhibitors, ARBs:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and risk of toxicity. Monitor lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **GI symptoms:** Monitor for signs and symptoms of GI bleeding or ulceration.
* **Renal function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease.
* **Hepatic function:** Monitor liver function tests periodically.
* **Blood pressure:** Monitor blood pressure, especially in patients with hypertension.
* **Signs of hypersensitivity or allergic reaction.**
## Clinical Pearls
* Mefenamic acid is typically used for short-term pain relief. Prolonged use increases the risk of serious adverse effects.
* Administer with food or milk to minimize GI upset.
* Diarrhea is a common and sometimes dose-limiting side effect.
* Due to its potential for serious GI adverse effects, consider alternative analgesics if the patient has risk factors for GI complications.
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**Disclaimer:** This information is intended for clinical use and does not replace the official prescribing information. Always consult the most current drug labeling and local protocols for complete and up-to-date guidance.
