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# Mefenamic Acid (meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term relief of mild to moderate pain, including menstrual pain.
## Primary Indications
* Pain relief (mild to moderate)
* Primary dysmenorrhea
## Adult Dosing
* **Initial dose:** 500 mg orally every 4 to 6 hours as needed.
* **Maximum daily dose:** 1500 mg per day. Treatment duration typically should not exceed 7 days.
## Pediatric Dosing
* **Children 14 years and younger:** Data for efficacy and safety in pediatric patients is limited. Use is generally not recommended.
* **Children 14 years and older:** Dosing may be similar to adults, but caution and careful monitoring are advised.
## Dose Adjustments
* **Renal impairment:** Use with caution. Dose adjustments may be necessary based on renal function.
* **Hepatic impairment:** Use with caution. Monitor liver function closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* History of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (may exacerbate).
* Severe heart failure, renal impairment, or hepatic impairment.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal toxicity; hepatic toxicity; hypersensitivity reactions; 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 and Aspirin:** Increased risk of GI toxicity, bleeding, and renal impairment.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect; increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
## Monitoring
* **Renal function:** Baseline and periodically during therapy, especially in patients with risk factors for renal impairment.
* **Liver function:** Baseline and periodically during therapy.
* **Signs and symptoms of GI bleeding/ulceration:** Advise patients to report any black, tarry stools, or persistent abdominal pain.
* **Blood pressure:** NSAIDs can increase blood pressure.
## Clinical Pearls
* Mefenamic acid is generally intended for short-term use only.
* Administer with food or milk to minimize gastrointestinal upset.
* Risk of serious cardiovascular thrombotic events increases with duration of use and in patients with existing cardiovascular disease.
* Use the lowest effective dose for the shortest duration necessary.
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*Disclaimer: This information is intended for healthcare professionals and does not substitute for comprehensive prescribing information. Always consult the official drug monograph and local institutional protocols for the most current and complete guidance.*
