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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) from the anthranilic acid derivative class. It is used for the short-term management of mild to moderate pain.
## Primary Indications
* Dysmenorrhea
* Mild to moderate pain (e.g., dental pain, musculoskeletal pain)
## Adult Dosing
* **Pain:** 500 mg orally every 4 to 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 4 to 6 hours as needed, not to exceed 1250 mg in a 24-hour period.
* Maximum daily dose for pain: 1250 mg.
* Duration of use should be limited to 7 days or less for pain.
## Pediatric Dosing
* **Pain and Dysmenorrhea:** 6 months and older: 6.5 mg/kg orally every 4 to 6 hours as needed.
* Maximum dose per administration: 250 mg.
* Maximum daily dose: 50 mg/kg/day, not to exceed 1250 mg/day.
* Duration of use should be limited to 7 days or less.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose adjustment may be necessary in severe impairment, although specific guidelines are not well-established.
* **Hepatic Impairment:** Use with caution. Dose adjustment may be necessary in severe impairment.
## 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.
* Inflammatory bowel disease (Crohn's disease, ulcerative colitis).
* History of gastrointestinal (GI) bleeding or perforation related to previous NSAID use.
* Active peptic ulceration or bleeding.
* Severe renal or hepatic impairment.
* Severe heart failure.
* Pregnancy (third trimester).
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, and perforation; cardiovascular thrombotic events (myocardial infarction, stroke); renal toxicity (including interstitial nephritis, papillary necrosis, renal failure); hepatic toxicity (including hepatitis, jaundice); hypersensitivity reactions; exacerbation of asthma; fluid retention and edema.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs (including aspirin):** Increased risk of adverse effects, particularly GI toxicity.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics and Antihypertensives:** NSAIDs can reduce the efficacy of these drugs and increase the risk of renal impairment.
* **Lithium:** Increased serum lithium levels and risk of toxicity. Monitor lithium levels.
* **Methotrexate:** Increased risk of methotrexate toxicity.
* **Ciclosporin and Tacrolimus:** Increased risk of nephrotoxicity.
## Monitoring
* **Renal function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those on concurrent nephrotoxic agents.
* **Hepatic function:** Monitor liver enzymes, particularly with prolonged use or in patients with hepatic impairment.
* **Gastrointestinal symptoms:** Assess for signs of bleeding or ulceration.
* **Blood pressure:** Monitor for potential increases.
* **Signs of hypersensitivity or allergic reaction.**
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use due to the risk of GI toxicity.
* Administer with food or milk to reduce gastric irritation.
* Hydration is important to minimize the risk of renal adverse effects.
* Consider gastroprotective agents (e.g., proton pump inhibitors) for patients at high risk of GI bleeding.
* Discontinue if signs of serious adverse effects (e.g., GI bleeding, rash, edema, vision changes) occur.
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*Disclaimer: This information is intended for clinical use and does not substitute for professional medical advice. Always consult the most current prescribing information and relevant literature for complete details and to verify dosages and recommendations before use.*
