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Mefenamic acid

Mefenamic acid
Systematic (IUPAC) name
2-(2,3-dimethylphenyl)aminobenzoic acid
CAS number 61-68-7
ATC code M01AG01
PubChem 4044
DrugBank APRD0073
Chemical data
Formula C15H15NO2 
Mol. mass 241.285 g/mol
Pharmacokinetic data
Bioavailability 90%
Protein binding 90%
Metabolism Hepatic (CYP2C9)
Half life 2 hours
Excretion Renal and fecal
Therapeutic considerations
Pregnancy cat.

C (Au, U.S.)

Legal status

℞-only (U.S.)

Routes Oral

Mefenamic acid is a non-steroidal anti-inflammatory drug used to treat pain, including menstrual pain. It is commercially available in the US as Ponstel® and internationally by Pfizer as Ponstan®. It is also prescribed as an antipyretic drug. It is typically prescribed for oral administration.

Mefenamic acid decreases inflammation (swelling) and uterine contractions by a still unknown mechanism. However it is thought to be related to the inhibition of prostaglandin synthesis.

Since hepatic metabolism plays a significant role in mefenamic acid elimination, patients with known liver deficiency may be prescribed lower doses. Kidney deficiency may also cause accumulation of the drug and its metabolites in the excretory system. Therefore patients suffering from renal conditions should not be prescribed mefenamic acid.

Side effects

Mefenamic acid is known to cause an upset stomach, therefore it is recommended to take prescribed doses together with food or milk. Instances of drowsiness may also occur. As such, it is recommended to avoid driving or consuming alcohol while taking this medication.

Other known mild side effects of mefenamic acid include headaches, nervousness and vomiting. Serious side effects may include diarrhoea, bloody vomit, blurred vision, skin rash, itching and swelling, sore throat and fever. It is advised to consult a doctor immediately if these symptoms appear while taking this medication.


  • MedlinePlus Drug Information: Mefenamic Acid. Last accessed September 28, 2005.
  • Ponstel Pharmacology, Pharmacokinetics, Studies, Metabolism - Mefenamic Acid - RxList Monographs. Last accessed September 28, 2005.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Mefenamic_acid". A list of authors is available in Wikipedia.
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