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# Mefenamic Acid (Meftal Spas)
## Overview
Mefenamic acid is a nonsteroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid derivative class. It possesses analgesic, anti-inflammatory, and antipyretic properties.
## Primary Indications
* Short-term relief of mild to moderate pain, including:
* Primary dysmenorrhea
* Headache
* Dental pain
* Musculoskeletal pain
* (In combination product like Meftal Spas, with an antispasmodic, for pain associated with smooth muscle spasm.)
## Adult Dosing
* **Pain:** 500 mg orally every 6 hours as needed.
* **Dysmenorrhea:** 500 mg orally every 6 hours, starting at the onset of pain and bleeding, and continuing for the duration of symptoms.
* **Maximum Dose:** 1500 mg per day. Treatment should not exceed 7 days.
## Pediatric Dosing
* **Under 6 months:** Safety and efficacy have not been established.
* **6 months to 12 years:** Dosing is typically based on weight, often around 6.5 mg/kg orally every 6 hours. However, specific pediatric dosing for mefenamic acid is not widely established or consistently recommended by major guidelines. Consult specific pediatric protocols or specialized resources.
## Dose Adjustments
* **Renal Impairment:** Use with caution. May require dose reduction or discontinuation in severe impairment.
* **Hepatic Impairment:** Use with caution. May require dose reduction.
* **Elderly:** Increased risk of adverse effects, particularly gastrointestinal bleeding and renal events. Consider lower doses and shorter duration of treatment.
## 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.
* Active gastrointestinal bleeding or ulceration.
* Severe renal or hepatic impairment.
* Third trimester of pregnancy.
## Adverse Effects
* **Common:** Nausea, vomiting, diarrhea, abdominal pain, dyspepsia, constipation, headache, dizziness, drowsiness, rash.
* **Serious:**
* **Gastrointestinal:** Gastrointestinal bleeding, ulceration, perforation.
* **Cardiovascular:** Increased risk of myocardial infarction, stroke, and heart failure.
* **Renal:** Renal impairment, interstitial nephritis, papillary necrosis.
* **Hepatic:** Hepatotoxicity, elevated liver enzymes.
* **Hematologic:** Anemia, leukopenia, thrombocytopenia.
* **Dermatologic:** Severe skin reactions (e.g., Stevens-Johnson syndrome, toxic epidermal necrolysis).
* **Hypersensitivity:** Anaphylaxis, angioedema, bronchospasm.
## 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.
* **Lithium:** Mefenamic acid can decrease lithium clearance, leading to increased lithium levels.
* **Methotrexate:** Mefenamic acid can decrease methotrexate clearance, leading to increased methotrexate toxicity.
* **Other NSAIDs / Aspirin:** Increased risk of gastrointestinal adverse effects and potentially other toxicities.
* **Diuretics and Antihypertensives:** NSAIDs can reduce the efficacy of these drugs and increase the risk of renal toxicity.
## Monitoring
* **Gastrointestinal:** Assess for signs and symptoms of bleeding (melena, hematemesis, abdominal pain).
* **Renal Function:** Monitor BUN, creatinine, and urine output, especially in those with pre-existing renal disease or receiving concomitant nephrotoxic agents.
* **Hepatic Function:** Monitor liver enzymes, especially with prolonged use or in patients with hepatic impairment.
* **Blood Pressure:** Monitor for potential increases.
* **Signs of Hypersensitivity:** Educate patients on symptoms and advise to discontinue medication if they occur.
## Clinical Pearls
* Administer with food or milk to minimize gastrointestinal upset.
* Use the lowest effective dose for the shortest duration necessary to minimize risks.
* Consider gastroprotective agents (e.g., PPIs) in patients at high risk for GI complications.
* Discontinue at the first sign of rash, skin reaction, or any adverse reaction.
* In the context of combination products with antispasmodics, consider the specific indications and contraindications of both agents.
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*Disclaimer: This information is intended for clinical use and is not a substitute for professional medical advice. Always consult the most current prescribing information and relevant clinical guidelines before making treatment decisions.*
