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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term relief of mild to moderate pain. It works by inhibiting prostaglandin synthesis.
## Primary Indications
* Pain associated with osteoarthritis and rheumatoid arthritis
* Primary dysmenorrhea
* Mild to moderate pain (e.g., dental pain, musculoskeletal pain)
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg initially, followed by 250 mg every 6 hours as needed for up to 6 days, starting with the onset of bleeding.
* **Rheumatoid Arthritis/Osteoarthritis:** Doses typically range from 250 mg to 500 mg three times daily.
* **Maximum Dose:** Not to exceed 1500 mg per day for longer than 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to limited safety and efficacy data. Specific pediatric dosing is not well-established.
## Dose Adjustments
No specific dose adjustments are required for renal or hepatic impairment, but caution is advised due to potential for NSAID-induced organ damage.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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.
* Inflammatory bowel disease (active or history of).
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, drowsiness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity; cardiovascular thrombotic events; hypersensitivity reactions; hepatic dysfunction; blood dyscrasias.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and potential for toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., black, tarry stools, hematemesis).
* Renal function (e.g., BUN, creatinine), especially in patients with pre-existing renal disease or those at risk.
* Liver function tests, particularly with prolonged use or in patients with hepatic impairment.
* Blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest possible duration to minimize risks.
* Avoid concurrent use with other NSAIDs or aspirin.
* Consider alternatives in patients with cardiovascular disease risk factors or a history of gastrointestinal issues.
* Duration of use should generally be limited to 7 days for pain relief.
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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 any treatment decisions.
