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# Mefenamic Acid (Meftal-P)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It exhibits analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term management of mild to moderate pain.
* Primary dysmenorrhea.
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Primary Dysmenorrhea:** 500 mg every 6 hours as needed, typically starting with the onset of pain or bleeding.
* **Maximum Duration:** Generally recommended for use for no more than 7 days.
## Pediatric Dosing
* Dosing in children is not well-established and generally not recommended due to potential risks, especially concerning febrile seizures. Use in pediatric populations requires careful consideration and may be guided by institutional protocols. Some sources suggest doses around 6.5 mg/kg/dose every 6-8 hours for pain or fever, with a maximum of 50 mg/kg/day. **Caution is strongly advised.**
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe renal impairment. Data is limited.
* **Hepatic Impairment:** Use with caution. Dose reduction may be necessary. Data is limited.
* **Elderly:** No specific dose adjustment is typically recommended, but elderly patients may be at higher risk for adverse effects and should be monitored closely.
## Contraindications
* Known 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.
* Inflammatory bowel disease (active or history).
* Severe heart failure.
* Severe renal impairment.
* Severe hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain), headache, dizziness.
* **Serious:** Gastrointestinal bleeding, ulceration, perforation; cardiovascular thrombotic events (MI, stroke); renal failure; hepatic failure; hypersensitivity reactions (including anaphylaxis); exacerbation of asthma; Stevens-Johnson syndrome/toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Diuretics:** Reduced diuretic effect; increased risk of renal impairment.
* **Lithium:** Increased serum lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Other NSAIDs/Aspirin:** Increased risk of adverse effects, particularly gastrointestinal.
## Monitoring
* **Signs and symptoms of GI bleeding or ulceration:** Especially with prolonged use or in patients with risk factors.
* **Renal function:** Monitor serum creatinine and BUN, particularly in patients with pre-existing renal disease or those concurrently taking nephrotoxic agents.
* **Hepatic function:** Monitor LFTs, especially in patients with hepatic impairment or those on long-term therapy.
* **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 effective period due to the risk of gastrointestinal and cardiovascular adverse events.
* This drug is generally not an alternative to aspirin for cardiovascular protection.
* Due to the risk of serious adverse effects, particularly in children, other antipyretics/analgesics (e.g., acetaminophen, ibuprofen) are often preferred, especially in younger populations.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines before making clinical decisions. Local formularies and protocols may dictate specific usage.
