Mefenamic acid

Mefenamic acid

File:Mefenamic acid Structural Formulae V.1.svg
Systematic (IUPAC) name
2-(2,3-dimethylphenyl)aminobenzoic acid
Clinical data
Pregnancy category	C (Au, U.S.)
Routes of administration	Oral
Legal status
Legal status	℞-only (U.S.), POM in UK
Pharmacokinetic data
Bioavailability	90%
Protein binding	90%
Metabolism	Hepatic (CYP2C9)
Biological half-life	2 hours
Excretion	Renal and fecal
Identifiers
CAS Number	61-68-7
ATC code	M01AG01 (WHO)
PubChem	CID 4044
DrugBank	APRD0073
ChemSpider	3904
Chemical 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 typically prescribed for oral administration. Mefenamic acid is marketed in the USA as Ponstel.

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. There is also 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.

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.

Brand Names
Ponstel, Ponstan, Ponstal, Parkemed, Mafepain, Mephadolor, Meftal, Dyfenamic, Potarlon, Dolfenal, Meyerdonal, Alfoxan.

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 diarrhea, bloody vomit, haematuria (blood in urine), 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.

Non-steroidal anti-inflammatory drugs (NSAIDs) may worsen hypertension. Persons with hypertension, left ventricular dysfunction, and heart failure may wish to avoid NSAIDs.

Overdose

Overdose can lead to a range of symptoms including convulsions, nausea, vomiting, vomiting blood, shallow breathing, coma. Onset of symptoms is usually between 30 minutes and 4 hours, but signs of renal failure may appear several days after an overdose. Seek medical attention immediately in the case of overdose. The lethal dose can be as low as 2.5g.

Synthesis

Analogous to fenamic acid, this compound may be synthesized from 2-chlorobenzoic acid and 2,3-dimethylaniline.

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.
• Consumption of NSAIDs and the Development of Congestive Heart Failure in Elderly Patients
• NSAIDs May Increase Risk for Worsening Heart Failure

ar:حمض ميفيناميك