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# Mefenamic Acid
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) used for the short-term relief of mild to moderate pain and for the treatment of primary dysmenorrhea.
## Primary Indications
* Mild to moderate pain (e.g., dental pain, musculoskeletal pain)
* Primary dysmenorrhea
## Adult Dosing
* **Pain:** 500 mg every 6 hours as needed.
* **Dysmenorrhea:** 500 mg every 6 hours as needed, typically starting with the onset of bleeding and associated symptoms.
* **Maximum:** 1500 mg per day. Dosing beyond 7 days is generally not recommended.
## Pediatric Dosing
* Generally not recommended for children under 14 years of age due to lack of established safety and efficacy data. Some sources may suggest use in older adolescents (14-18 years) at adult doses.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dose reduction may be considered in severe impairment, but specific guidelines are limited.
* **Hepatic Impairment:** Use with caution. Dose reduction may be considered in severe impairment, but specific guidelines are limited.
* **Elderly:** Increased risk of adverse events; consider lower doses and shorter duration of therapy.
## Contraindications
* Hypersensitivity to mefenamic acid, aspirin, 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.
* Active gastrointestinal (GI) bleeding or ulceration.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Diarrhea, nausea, vomiting, abdominal pain, constipation, rash, dizziness, drowsiness.
* **Serious:**
* **GI:** GI bleeding, ulceration, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, heart failure.
* **Renal:** Acute kidney injury, interstitial nephritis.
* **Hepatic:** Hepatotoxicity.
* **Hematologic:** Anemia, thrombocytopenia.
* **Hypersensitivity:** Anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs and Aspirin:** Increased risk of GI toxicity and other adverse effects.
* **Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs):** Increased risk of GI bleeding.
* **Diuretics, ACE inhibitors, ARBs:** May decrease antihypertensive effect and increase risk of renal impairment.
* **Lithium, Methotrexate:** Mefenamic acid can increase serum concentrations.
## Monitoring
* **GI Symptoms:** Monitor for signs and symptoms of GI bleeding (e.g., melena, hematemesis).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those taking concomitant nephrotoxic agents.
* **Hepatic Function:** Monitor liver enzymes, especially in patients with hepatic impairment or those on long-term therapy.
* **Blood Pressure:** Monitor blood pressure, especially in patients with hypertension.
* **Signs of Thrombotic Events:** Educate patients on symptoms of MI and stroke.
## Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize GI upset.
* Due to its potential for GI side effects, it is generally reserved for short-term use.
* Diarrhea is a common and sometimes dose-limiting side effect.
* Avoid concomitant use with other NSAIDs.
* Consider NSAID-associated risks (GI, cardiovascular, renal) when prescribing.
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**Disclaimer:** This information is intended for clinical use and does not replace professional medical advice. Always consult the most current prescribing information or other relevant resources to ensure optimal patient care and safety.
