Мефенамовая кислота

Химические свойства

white or light yellow crystalline powder, odorless, insoluble in water, slightly soluble in ethanol, chloroform, slightly soluble in ether. Melting point 230-231°C, mefenamic acid is an anti-inflammatory analgesic with antipyretic, analgesic and anti-inflammatory effects.

Использование

Mefenamic acid is used for the same indications as flufenamic acid. Synonyms for this drug are parkemed, ponstan, ponstel, and others.

Показания

Mefenamic acid (Ponstel) is indicated only for analgesia and primary dysmenorrhea when therapy will not exceed 1 week.

Определение

ChEBI: An aminobenzoic acid that is anthranilic acid in which one of the hydrogens attached to the nitrogen is replaced by a 2,3-dimethylphenyl group. Although classed as a non-steroidal anti-inflammatory drug, its anti-inflammatory properties are considered to b minor. It is used to relieve mild to moderate pain, including headaches, dental pain, osteoarthritis and rheumatoid arthritis.

Общее описание

Mefenamic acid (Ponstel, Ponstan) is one of the oldestNSAIDs, introduced into the market in 1967 for mild tomoderate pain and for primary dysmenorrhea. It is rapidly absorbed with peak plasma levels occurring 2 to 4 hoursafter oral administration. It undergoes hepatic benzylic hydroxylationof its 3'methyl group regioselectively into twoinactive metabolites, 3'-hydroxymethylmefenamic acid andthe 3'carboxylate metabolite (via further oxidation of thebenzylic alcohol group). The parent drugs and these metabolitesare conjugated with glucuronic acid and excreted primarilyin the urine. Thus, although patients with knownliver deficiency may be given lower doses, it is contraindicatedin patients with preexisting renal dysfunction.
Common side effects associated with its use include diarrhea,drowsiness, and headache. The possibility of blood disordershas also prompted limitation of its administration to 7days. It is not recommended for children or during pregnancy.

Клиническое использование

Mefenamic acid is synthesized from o-chlorobenzoic acid and 2,3-dimethylaniline under catalytic conditions. Mefenamic acid is the only fenamic acid derivative that produces analgesia centrally and peripherally. Mefenamic acid is indicated for the short-term relief of moderate pain and for primary dysmenorrhea.

Метаболизм

Mefenamic acid is absorbed rapidly following oral administration, with peak plasma levels being attained within 2 to 4 hours. It is highly bound to plasma proteins (78.5%) and has a plasma half-life of 2 to 4 hours. Metabolism occurs through regioselective oxidation of the 3′-methyl group and glucuronidation of mefenamic acid and its metabolites. Urinary excretion accounts for approximately 50 to 55% of an administered dose, with unchanged drug accounting for 6%, the 3′-hydroxymethyl metabolite (primarily as the glucuronide) accounting for 25%, and the remaining 20% as the dicarboxylic acid (of which 30% is the glucuronide conjugate). These metabolites are essentially inactive.