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# Mefenamic Acid (Meftal spas)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the fenamate class. It possesses analgesic, anti-inflammatory, and antipyretic properties. Its mechanism of action involves the inhibition of cyclooxygenase (COX) enzymes, thereby reducing prostaglandin synthesis.
## Primary Indications
* Pain, including menstrual pain (dysmenorrhea).
* Mild to moderate pain associated with inflammatory conditions.
## Adult Dosing
* **For pain:** 500 mg every 6 hours as needed.
* **Maximum dose:** 1500 mg per day.
* **Duration:** Generally not recommended for use longer than 7 days.
## Pediatric Dosing
* Established pediatric dosing is **not readily available** for mefenamic acid. Use in children should be based on specific clinical assessment and guidance, with caution.
## Dose Adjustments
* **Renal Impairment:** Use with caution; dose reduction may be necessary. Specific guidelines vary and should be consulted.
* **Hepatic Impairment:** Use with caution; dose reduction may be necessary. Specific guidelines vary and should be consulted.
## 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.
* Severe renal impairment.
* Severe hepatic impairment.
* Severe heart failure.
## Adverse Effects
* **Gastrointestinal:** Dyspepsia, nausea, vomiting, abdominal pain, diarrhea, constipation, and potentially serious GI bleeding, ulceration, or perforation.
* **Renal:** Renal insufficiency, interstitial nephritis, papillary necrosis.
* **Cardiovascular:** Fluid retention, edema, hypertension, and increased risk of serious cardiovascular thrombotic events (MI, stroke).
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Dermatologic:** Rash, pruritus.
* **Other:** Dizziness, headache, tinnitus, bronchospasm.
## Key Drug Interactions
* **Anticoagulants (e.g., warfarin):** Increased risk of bleeding.
* **Corticosteroids:** Increased risk of GI ulceration and bleeding.
* **Other NSAIDs or Salicylates:** Increased risk of adverse effects, including GI toxicity.
* **ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Diuretics:** May diminish antihypertensive effect and increase risk of renal impairment.
* **Lithium:** NSAIDs can increase serum lithium levels.
* **Methotrexate:** NSAIDs can increase methotrexate toxicity.
## 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 periodically.
* **Gastrointestinal symptoms:** Assess for signs of bleeding or ulceration.
* **Blood pressure:** Monitor for new onset or worsening hypertension.
* **Signs of fluid retention/edema.**
## Clinical Pearls
* Mefenamic acid is generally recommended for short-term use only due to the risk of GI and cardiovascular adverse events.
* It is often used for dysmenorrhea and is particularly effective when initiated at the onset of pain.
* Administer with food or milk to minimize GI upset.
* Consider lowest effective dose for shortest duration necessary.
**Disclaimer:** This information is intended for clinical pharmacists and healthcare professionals. It is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before administering or recommending any medication. Dosing and safety information can vary based on local protocols and individual patient factors.
