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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term symptomatic treatment of mild to moderate pain. It works by inhibiting prostaglandin synthesis.
## Primary Indications
* Pain, including dysmenorrhea, headache, dental pain, and musculoskeletal pain.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours as needed, starting at the onset of pain and bleeding.
* **Maximum Dose:** Not to exceed 1500 mg in a 24-hour period.
* **Duration of Therapy:** Generally limited to 7 days.
## Pediatric Dosing
* Mefenamic acid is **not recommended** for use in children under 14 years of age due to lack of established efficacy and safety data.
## Dose Adjustments
* **Renal Impairment:** Use with caution; dose reduction may be necessary. Data is limited.
* **Hepatic Impairment:** Use with caution; dose reduction may be necessary. Data is limited.
* **Geriatric Patients:** Increased risk of adverse effects; consider lower doses and closer monitoring.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, allergic rhinitis, or urticaria triggered by aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
* Active gastrointestinal bleeding or history of recurrence.
* Inflammatory bowel disease.
* Pregnancy (third trimester).
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, dyspepsia, constipation, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic dysfunction; cardiovascular thrombotic events (MI, stroke); hypersensitivity reactions; bronchospasm; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of GI bleeding.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly GI.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Renal function:** Baseline and periodically, especially in patients with pre-existing renal disease.
* **Hepatic function:** Baseline and periodically.
* **Signs and symptoms of GI bleeding:** Especially with prolonged use.
* **Blood pressure:** NSAIDs can cause hypertension.
## Clinical Pearls
* Mefenamic acid is intended for short-term use only.
* Administer with food or milk to reduce gastrointestinal upset.
* Discontinue if diarrhea is severe.
* Avoid concomitant use with other NSAIDs.
* Consider the risks of GI bleeding, renal impairment, and cardiovascular events with NSAID use, especially in elderly patients or those with risk factors.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and local protocols before making clinical decisions.
