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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) with analgesic properties. It works by inhibiting cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Mild to moderate pain, particularly associated with menstruation (dysmenorrhea).
* Pain and inflammation from other causes, such as musculoskeletal disorders.
## Adult Dosing
* **Dosage:** 500 mg every 6 hours as needed.
* **Maximum Dose:** Typically not to exceed 1500 mg per day, though some sources may suggest up to 2000 mg in specific, short-term situations under strict medical supervision. It is generally recommended to use the lowest effective dose for the shortest duration.
## Pediatric Dosing
* **Age:** Generally not recommended for children under 14 years of age due to safety concerns and lack of established dosing guidelines. Data for efficacy and safety in younger pediatric populations is limited.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in patients with severe renal impairment, though specific guidelines are not well-established. Monitor renal function closely.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary in patients with severe hepatic impairment. Monitor liver function closely.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, or other NSAIDs.
* History of bronchospasm, asthma, rhinitis, or urticaria induced by aspirin or other NSAIDs.
* Active gastrointestinal bleeding or ulceration.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; renal toxicity (including interstitial nephritis, papillary necrosis); hepatic toxicity; cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions; worsening of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly gastrointestinal.
* **ACE inhibitors, ARBs, Beta-blockers:** May reduce antihypertensive effect and increase risk of renal impairment.
* **Diuretics:** May reduce diuretic effect and increase risk of renal impairment.
* **Lithium, Methotrexate:** Increased serum concentrations and risk of toxicity.
## Monitoring
* **Renal function:** Especially in patients with pre-existing renal disease or those at risk.
* **Hepatic function:** Particularly with prolonged use or in patients with liver disease.
* **Gastrointestinal symptoms:** Monitor for signs of bleeding or ulceration.
* **Blood pressure:** NSAIDs can cause or worsen hypertension.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Limit duration of use to the shortest period necessary for symptom control, as the risk of serious adverse events increases with duration of use.
* Not typically considered first-line therapy for chronic pain due to potential for adverse effects.
* If used for dysmenorrhea, it is often initiated at the onset of bleeding or pain and continued for 1-3 days.
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**Disclaimer:** This information is intended for clinical professionals. It is essential to consult the most current prescribing information and relevant guidelines for definitive patient care decisions. Dosing and safety recommendations can vary.
