Mefenamic acid is a member of the anthranilic acid derivatives (or fenamate) class of NSAID drugs, and is used to treat mild to moderate pain, including menstrual pain, and is sometimes used to prevent migraines associated with menstruation. It is not widely used in the United States due to its side effects and high cost compared to other NSAID drugs.:334
|Trade names||Ponstel, Ponstan, others|
|Elimination half-life||2 hours|
|Excretion||Urine (66%), faeces (20-25%)|
|CompTox Dashboard (EPA)|
|ECHA InfoCard||100.000.467 |
|Chemical and physical data|
|Molar mass||241.285 g/mol g·mol−1|
|3D model (JSmol)|
Its name derives from its systematic name, dimethylphenylaminobenzoic acid. It was discovered and brought to market by Parke-Davis in the 1960s. It became generic in the 1980s and is available worldwide under many brand names like Meftal-Spas. As of 2015 the cost for a typical course of medication in the United States is more than $200.
Mefenamic acid is used to treat moderate pain and menstrual pain.
There is evidence that supports the use of mefenamic acid for perimenstrual migraine headache prophylaxis, with treatment starting 2 days prior to the onset of flow or 1 day prior to the expected onset of the headache and continuing for the duration of menstruation.
Known mild side effects of mefenamic acid include headaches, nervousness, and vomiting. Serious side effects may include diarrhea, hematemesis (vomiting blood), hematuria (blood in urine), blurred vision, skin rash, itching and swelling, sore throat and fever.:334 It has been associated with acute liver damage.
In 2008 the US label was updated with a warning concerning a risk of premature closure of the ductus arteriosus in pregnancy.
Mechanism of action
Scientists led by Claude Winder from Parke-Davis invented mefenamic acid in 1961, along with fellow members of the class of anthranilic acid derivatives, flufenamic acid in 1963 and meclofenamate sodium in 1964.:718 U.S. Patent 3,138,636 on the drug was issued in 1964.:918–919
Society and culture
Availability and pricing
In the US, wholesale price of a week's supply of generic mefenamic acid has been quoted as $426.90 in 2014. Brand-name Ponstel is $571.70. In contrast, in the UK, a weeks supply is £1.66, or £8.17 for branded Ponstan. In the Philippines, 1 tablet of 500 mg generic mefenamic acid cost PHP25.00 (or the equivalent of US$0.50) as of September 2, 2019.
While studies have been conducted to see if mefenamic acid can improve behavior in transgenic mouse models of Alzheimer's disease there is no good evidence that mefenamic acid or other NSAIDs can treat or prevent Alzheimer's in humans; clinical trials of NSAIDs other than mefenamic acid for treatment of Alzheimer's have found more harm than benefit.
- FDA Ponstel Label Updated February 19, 2008
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- Consumption of NSAIDs and the Development of Congestive Heart Failure in Elderly Patients
- NSAIDs May Increase Risk for Worsening Heart Failure