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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for short-term management of mild to moderate pain. It is also used for primary dysmenorrhea.
## Primary Indications
* Pain (mild to moderate, short-term)
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed. Maximum daily dose is 1500 mg. Treatment duration typically should not exceed 7 days.
* **Primary Dysmenorrhea:** 500 mg every 6 hours as needed, starting at the onset of pain or bleeding, whichever comes first. Treatment duration typically should not exceed 3 days per cycle.
## Pediatric Dosing
* **Pain and Dysmenorrhea:** Generally not recommended for children under 12 years of age. For children 12 years and older, the adult dose of 500 mg every 6 hours can be used. Dosing for younger children is not well-established and should be guided by local protocols and physician discretion.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, but specific guidelines are not well-defined.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, but specific guidelines are not well-defined.
* **Elderly:** Increased risk of adverse effects, particularly gastrointestinal bleeding and renal events. Consider lower doses and shorter duration of therapy.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* 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.
* Active gastrointestinal bleeding or history of recurrent gastrointestinal perforation, ulceration, or bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation, myocardial infarction, stroke, hypertension, renal failure, hepatic failure, hypersensitivity reactions (including anaphylaxis and Stevens-Johnson syndrome), exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Aspirin:** Increased risk of gastrointestinal bleeding. Mefenamic acid can also inhibit the antiplatelet effect of low-dose aspirin.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Diuretics and Antihypertensives:** May reduce the antihypertensive effect and increase the risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Other NSAIDs:** Increased risk of adverse effects.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine).
* Liver function tests (AST, ALT).
* Blood pressure.
* For patients with pre-existing conditions, monitor for exacerbation (e.g., heart failure, renal disease).
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its potential for serious adverse effects, use the lowest effective dose for the shortest duration necessary.
* It is generally not recommended for chronic use.
* Mefenamic acid is not a substitute for aspirin in the prevention of cardiovascular events.
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**Disclaimer:** This information is intended for clinical use and does not replace professional medical advice. Always consult the most current prescribing information and local protocols before administering any medication.
