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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term management of mild to moderate pain. It is also indicated for primary dysmenorrhea.
## Primary Indications
* Pain (mild to moderate)
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Primary dysmenorrhea:** 500 mg orally every 6 hours as needed, starting at the onset of pain or bleeding, whichever comes first.
* **Maximum Daily Dose:** 1500 mg. Treatment duration should not exceed 7 days.
## Pediatric Dosing
Mefenamic acid is generally not recommended for children under 14 years of age due to limited data and potential for adverse effects. For specific situations, dosing may be guided by weight, but this is not standard practice.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Data on dose adjustment is limited; however, the lowest effective dose for the shortest duration is recommended due to potential for renal toxicity.
* **Hepatic Impairment:** Use with caution. No specific dose adjustments are established, but monitoring for hepatic adverse effects is advised.
## 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.
* Severe renal impairment.
* Severe hepatic impairment.
* Active gastrointestinal bleeding or ulceration.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, constipation, dyspepsia, headache, dizziness, rash.
* **Serious:**
* **Cardiovascular:** Myocardial infarction, stroke, hypertension, heart failure.
* **Gastrointestinal:** Ulceration, bleeding, perforation; colitis.
* **Renal:** Acute kidney injury, interstitial nephritis, papillary necrosis.
* **Hepatic:** Hepatitis, jaundice.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Dermatologic:** Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis.
* **Hypersensitivity:** Anaphylaxis, angioedema, bronchospasm.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Lithium:** Increased serum lithium levels; potential for lithium toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
* **Diuretics and Antihypertensives:** May decrease their efficacy and increase risk of renal toxicity.
* **Other NSAIDs and Salicylates:** Increased risk of gastrointestinal adverse effects and other toxicities.
## Monitoring
* Monitor for signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Monitor renal function (serum creatinine, BUN) especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* Monitor liver function (ALT, AST) especially in patients with hepatic impairment or those on long-term therapy.
* Monitor blood pressure.
* Assess for signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its short half-life, it is typically dosed every 6 hours.
* It is generally indicated for short-term use only (maximum 7 days).
* Consider the risks of cardiovascular events, gastrointestinal bleeding, and renal toxicity associated with NSAID use.
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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 guidelines before administering any medication. Local protocols and patient-specific factors may necessitate adjustments to the recommendations provided.*
