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# Mefenamic Acid
## 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, particularly in conditions like dysmenorrhea, headache, and dental pain.
* Relief of pain and inflammation associated with rheumatoid arthritis and osteoarthritis.
## Adult Dosing
* **Pain:** 500 mg every 6 to 8 hours as needed. Do not exceed 1500 mg per day.
* **Rheumatoid Arthritis/Osteoarthritis:** 750 mg three times daily. Milder cases may respond to 500 mg three times daily. Do not exceed 1500 mg per day.
* Treatment should generally be limited to 7 days.
## Pediatric Dosing
The use of mefenamic acid is not generally recommended in children under 14 years of age due to lack of established safety and efficacy data. For specific indications in children, alternative NSAIDs with established pediatric dosing are preferred.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be necessary in severe impairment. Mefenamic acid is primarily renally excreted.
* **Hepatic Impairment:** Use with caution. Consider dose reduction in patients with significant hepatic impairment.
## Contraindications
* Known hypersensitivity to mefenamic acid, aspirin, other NSAIDs, or any component of the formulation.
* 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 history of gastrointestinal bleeding/perforation related to prior NSAID use.
* Severe heart failure, renal impairment, or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, dizziness, headache, rash.
* **Serious:** Gastrointestinal bleeding, ulceration, and perforation; renal failure; hepatic dysfunction; cardiovascular thrombotic events (myocardial infarction, stroke); hypersensitivity reactions; exacerbation of asthma.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) / Serotonin Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of gastrointestinal bleeding.
* **Diuretics, ACE Inhibitors, Angiotensin II Receptor Blockers (ARBs):** May decrease antihypertensive effect and increase risk of renal impairment.
* **Lithium:** May increase serum lithium levels.
* **Methotrexate:** May increase methotrexate toxicity.
## Monitoring
* **Gastrointestinal:** Monitor for signs and symptoms of bleeding or ulceration (e.g., melena, hematemesis).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk.
* **Hepatic Function:** Monitor liver enzymes, especially in patients with pre-existing liver disease or those receiving long-term therapy.
* **Blood Pressure:** NSAIDs can cause or worsen hypertension.
## Clinical Pearls
* Mefenamic acid is typically reserved for short-term use due to a higher incidence of gastrointestinal adverse effects compared to some other NSAIDs.
* Onset of action for pain relief is usually within 1 hour.
* Administer with food or milk to minimize gastrointestinal upset.
* Avoid concomitant use with other NSAIDs, including aspirin.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before initiating therapy.*
