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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis. It is indicated for the short-term relief of mild to moderate pain.
## Primary Indications
* Pain associated with dysmenorrhea
* Mild to moderate pain (e.g., headache, dental pain, musculoskeletal pain)
## Adult Dosing
* **Initial dose:** 500 mg orally.
* **Subsequent doses:** 250 mg orally every 6 hours as needed.
* **Maximum daily dose:** 1500 mg orally.
* **Duration of therapy:** Not recommended for use for more than 7 days.
## Pediatric Dosing
* Mefenamic acid is **not recommended** for use in children under 14 years of age.
## Dose Adjustments
* **Renal impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment.
* **Hepatic impairment:** Use with caution. Dose reduction may be necessary in severe hepatic impairment.
## 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) bleeding or ulceration.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation.
* **Serious:**
* **GI:** Ulceration, bleeding, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction and stroke.
* **Renal:** Renal papillary necrosis, interstitial nephritis, renal failure.
* **Hepatic:** Elevated liver enzymes, hepatitis.
* **Hematologic:** Anemia, thrombocytopenia.
* **Dermatologic:** Stevens-Johnson syndrome, toxic epidermal necrolysis.
* **Hypersensitivity:** Anaphylaxis, angioedema.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs or salicylates:** Increased risk of GI adverse effects and reduced efficacy.
* **ACE inhibitors and ARBs:** May increase the risk of renal impairment.
* **Diuretics:** May reduce diuretic efficacy and increase the risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Baseline and periodic:** Renal function (BUN, creatinine), liver function tests (AST, ALT).
* **Assess for:** Signs and symptoms of GI bleeding, cardiovascular events, and hypersensitivity reactions.
## Clinical Pearls
* Administer with food or milk to minimize GI upset.
* Due to the potential for GI toxicity, use the lowest effective dose for the shortest duration necessary.
* Patients with pre-existing renal or hepatic disease, heart failure, or hypertension should be monitored closely.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols for definitive guidance.*
