Mefenamic Acid

A classic NSAID widely used for menstrual pain and acute inflammatory conditions.

What is Mefenamic Acid?

Mefenamic acid is a non-steroidal anti-inflammatory drug (NSAID) belonging to the anthranilic acid (fenamate) class. It is mainly prescribed for short-term relief of pain, especially menstrual pain (dysmenorrhea).

Due to its strong prostaglandin-inhibiting action, it is effective in conditions where pain is linked with uterine contractions and inflammation.

History & Development

Mefenamic acid was developed in the 1960s as part of the fenamate group of NSAIDs. It became popular for gynecological use because of its effectiveness in menstrual pain compared to many older analgesics.

Chemical Structure & Properties

• IUPAC name: 2-[(2,3-dimethylphenyl)amino]benzoic acid
• Molecular formula: C₁₅H₁₅NO₂
• Molar mass: 241.29 g/mol
• Functional groups: Carboxylic acid, aromatic rings, amine

The anthranilic acid backbone allows strong interaction with COX enzymes, leading to effective suppression of prostaglandin synthesis.

Mechanism of Action

Mefenamic acid inhibits cyclooxygenase (COX-1 and COX-2) enzymes, reducing prostaglandin production. This leads to:

• Reduced uterine contractions
• Lowered inflammation
• Relief from pain and fever

It also has mild effects on prostaglandin receptors, contributing to its effectiveness in menstrual pain.

Pharmacokinetics

• Absorption: Rapid after oral intake
• Peak plasma time: 2–4 hours
• Protein binding: ~90%
• Metabolism: Liver
• Excretion: Urine and bile

Medical Uses

• Menstrual pain (primary dysmenorrhea)
• Mild to moderate musculoskeletal pain
• Dental pain
• Post-operative pain
• Fever

Dosage Guidelines

Adults: 500 mg initially, then 250 mg every 6 hours

Maximum duration: Usually not more than 7 days

⚠️ Intended for short-term use only.

Side Effects

• Diarrhea
• Abdominal pain
• Nausea
• Headache

Serious Risks & Warnings

• Gastric ulcers and bleeding
• Kidney impairment (long-term or high dose)
• Hemolytic anemia (rare)

Drug Interactions

• Other NSAIDs
• Blood thinners
• Antihypertensive drugs
• Alcohol

Mefenamic Acid vs Naproxen

Mefenamic acid is better for short-term menstrual pain, while naproxen is preferred for long-term inflammatory conditions.

Frequently Asked Questions

Is mefenamic acid safe? – Yes, when used short-term as prescribed.

Can it stop periods? – No, it only reduces pain.

Is it an antibiotic? – No.

Can it be taken daily? – Only for a few days, not long-term.

⚠️ Educational content only. Not a substitute for professional medical advice.