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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term treatment of mild to moderate pain. It functions by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain, mild to moderate
* Dysmenorrhea
## Adult Dosing
* **Initial dose:** 500 mg orally every 8 hours.
* **Maximum daily dose:** 1500 mg.
* **Duration:** Typically for short-term use, not exceeding 7 days.
## Pediatric Dosing
* Mefenamic acid is generally **not recommended for children under 14 years of age** due to insufficient safety and efficacy data.
## Dose Adjustments
* No specific dose adjustments are routinely recommended for renal or hepatic impairment, but caution is advised. Mefenamic acid should be used cautiously in patients with pre-existing renal or hepatic disease.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (active or history of).
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal impairment; hepatic impairment; cardiovascular thrombotic events; hypersensitivity reactions; exacerbation of asthma; anemia.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of bleeding, particularly gastrointestinal.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
* **Diuretics, ACE inhibitors, Angiotensin II Receptor Blockers (ARBs):** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* **Renal function:** Especially in elderly patients or those with pre-existing renal disease.
* **Hepatic function:** If signs or symptoms of liver dysfunction develop.
* **Signs of gastrointestinal bleeding:** Such as melena or hematemesis.
* **Blood pressure:** NSAIDs can increase blood pressure.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Be aware of the potential for bronchospasm in patients with asthma, particularly those with aspirin sensitivity.
* Discontinue if any signs of serious adverse events (e.g., severe rash, GI bleeding) occur.
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**Disclaimer:** This information is intended for clinical pharmacists and should not replace professional medical advice. Always consult the most current prescribing information and patient-specific factors before making clinical decisions.
