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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 used for dysmenorrhea.
## Primary Indications
* Mild to moderate pain (e.g., dental pain, post-operative pain, musculoskeletal pain).
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed. Maximum daily dose is 1500 mg.
* **Dysmenorrhea:** 500 mg orally every 6 hours, starting at the onset of pain and bleeding and continuing for up to 3 days.
## Pediatric Dosing
* Mefenamic acid is **not recommended** for use in children under 12 years of age for pain relief due to lack of established efficacy and safety data.
* For dysmenorrhea, it is generally considered for adolescents. Dosing would typically follow adult recommendations (500 mg every 6 hours), but specific pediatric guidelines are not robust. Always consult pediatric-specific resources or local protocols.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment, but specific guidelines are not well-defined. Avoid if severe.
* **Hepatic Impairment:** Use with caution. Avoid in severe hepatic impairment.
* **Elderly:** Consider reduced doses and increased monitoring due to potential for increased adverse effects.
## Contraindications
* Hypersensitivity to mefenamic acid or other NSAIDs.
* History of bronchospasm, asthma, allergic rhinitis, or urticaria triggered by aspirin or other NSAIDs.
* Perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Active gastrointestinal bleeding or a history of recurrent gastrointestinal bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Third trimester of pregnancy.
## Adverse Effects
Common: Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache, rash.
Serious: Gastrointestinal bleeding and perforation, renal failure, hepatic failure, cardiovascular thrombotic events (myocardial infarction, stroke), Stevens-Johnson syndrome, toxic epidermal necrolysis, anaphylaxis, exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of gastrointestinal toxicity and reduced cardioprotective effects of aspirin.
* **Diuretics, ACE inhibitors, ARBs:** Reduced antihypertensive effect and increased risk of renal impairment.
* **Lithium:** Increased lithium levels and toxicity.
* **Methotrexate:** Increased methotrexate toxicity.
## Monitoring
* Signs and symptoms of gastrointestinal bleeding (e.g., melena, hematemesis).
* Renal function (BUN, creatinine) especially in patients with pre-existing renal disease or those at risk.
* Liver function tests (LFTs) especially in patients with pre-existing hepatic disease or those at risk.
* Blood pressure.
* Signs of hypersensitivity reactions.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Duration of use should be as short as possible, generally not exceeding 7 days for pain.
* Due to the risk of diarrhea, which can be severe and dose-limiting, patients should be advised to discontinue the medication and contact their healthcare provider if severe diarrhea occurs.
* Mefenamic acid is often prescribed for dysmenorrhea, with doses typically started at the onset of menstrual pain and bleeding.
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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 making clinical decisions.
