Please check your internet connection and try again.
## 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 through the inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
### Primary Indications
* Short-term management of mild to moderate pain.
* Management of primary dysmenorrhea.
### Adult Dosing
* **Pain/Dysmenorrhea:** 500 mg orally every 6 hours as needed. Do not exceed 1000 mg in the initial dose or 4000 mg per 24-hour period. Treatment duration should not exceed 7 days.
### Pediatric Dosing
Mefenamic acid is generally not recommended for use in children under 14 years of age due to a lack of established safety and efficacy data and concerns regarding potential adverse effects.
### Dose Adjustments
No specific dose adjustments are typically required for renal or hepatic impairment. However, caution is advised, and the lowest effective dose should be used, particularly in patients with pre-existing renal or hepatic disease, given the potential for NSAID-related organ toxicity.
### Contraindications
* Known hypersensitivity to mefenamic acid or other NSAIDs.
* History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs.
* Peri-operative pain in the setting of coronary artery bypass graft (CABG) surgery.
* Inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis).
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
### Adverse Effects
Common adverse effects include gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain, dyspepsia), dizziness, headache, and rash. Serious adverse effects include gastrointestinal bleeding, ulceration, perforation, cardiovascular thrombotic events (MI, stroke), renal toxicity, hepatic toxicity, and hypersensitivity reactions.
### Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding. Monitor INR closely.
* **Corticosteroids:** Increased risk of gastrointestinal ulceration and bleeding.
* **SSRIs/SNRIs:** Increased risk of bleeding, particularly in the gastrointestinal tract.
* **ACE inhibitors/ARBs/Beta-blockers:** May decrease antihypertensive effect and increase risk of renal impairment.
* **Diuretics:** May decrease diuretic effect and increase risk of renal impairment.
* **Lithium:** Increased lithium levels and risk of toxicity. Monitor lithium levels.
* **Methotrexate:** Increased methotrexate levels and risk of toxicity.
### Monitoring
* **GI Bleeding/Ulceration:** Monitor for signs and symptoms (e.g., melena, hematemesis, abdominal pain).
* **Renal Function:** Monitor serum creatinine and BUN, especially in patients with pre-existing renal disease or those at risk for renal toxicity.
* **Hepatic Function:** Monitor LFTs, particularly with long-term use or in patients with hepatic impairment.
* **Cardiovascular Risk:** Patients with risk factors for cardiovascular disease should be monitored for signs and symptoms of MI or stroke.
### Clinical Pearls
* Mefenamic acid should be taken with food or milk to minimize gastrointestinal upset.
* Due to its short duration of action and risk of GI toxicity, it is generally reserved for short-term use.
* Long-term use of mefenamic acid is not recommended and carries significant risks.
* It is not a substitute for aspirin in cardiovascular prophylaxis.
***
*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines for complete and up-to-date details before making any treatment decisions.*
