Mefenamic acid

Mefenamic acid

Clinical data
Pregnancy category	C (Au, U.S.)
Routes of administration	Oral
ATC code	M01AG01 (WHO)
Legal status
Legal status	℞-only (U.S.)
Pharmacokinetic data
Bioavailability	90%
Protein binding	90%
Metabolism	Hepatic (CYP2C9)
Elimination half-life	2 hours
Excretion	Renal and fecal
Identifiers
IUPAC name 2-(2,3-dimethylphenyl)aminobenzoic acid
CAS Number	61-68-7
PubChem CID	4044
DrugBank	APRD0073
E number	{{#property:P628}}
ECHA InfoCard	{{#property:P2566}}
Chemical and physical data
Formula	C15H15NO2
Molar mass	241.285 g/mol

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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.

Sources

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