The N-Arylanthranilic Acids

The structural analogues of N-arylanthranilic acid opened an altogether new horizon of antipyretic, analgesic and anti-inflammatoiy compounds which have recently gained recognition in the therapeutic armamentarium. A few compounds belonging to this category are discussed here. 

3-Xylyl) anthranilic acid Benzoic acid, 2-[(2,3-dimethylphenyl) amino]- B.P., Ponstef (Parke-Davis). 

It may be prepared by the condensation of o-chlorobenzoic acid with 2, 3-xylidine in the presence of potassium carbonate to give the potassium salt of mefenamic acid, which on treatment with hydrochloric acid yields the official compound. 

It is an analgesic drug usually indicated for the treatment of primary dysmenorrhea, mild pain and for pain due to dental extractions. 

Dose Usual, adults, children over 14 years of age, oral, 500 mg, followed by 250 mg 4 times 

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N-Arylanthranilie Acids (2). In equations 21 and 22 it can be seen tnat the N-arylanthranilic acids are similar to phenols (eq 12, 13) in the effect of pKa on activity. The more acidic the anthranilic acid, the more potent it will be as an uncoupler for any given log P. In contrast, binding to bovine serum albumin for some of the same compounds is satisfied by an equation in log D alone (eq 23). The pKa terms in eq 21 and 22 may not be significant enough to make anything of the difference in magnitude of the pKj, coefficients between heart and liver mitochondria, but this is a potential tool for this type of compar-i son. 

The pKa values of the N-arylanthranilic acids (4.0-4.2) resemble those of the arylalkanoic acids thus, it is not surprising that they are strongly bound to plasma proteins and that interactions with other highly protein bound drugs are very probable. The most common interactions reported are those of mefenamic acid and meclofenamic acid with oral anticoagulants. Concurrent administration of aspirin results in a reduction of plasma levels of meclofenamic acid. 

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