Ponstan - Mefenamic acid

Pink Bismuth bismuth Ponstan mefenamic acid... 

Based on the fact that mefenamic acid reacts quantitatively with tV-bromosuccinimide (NBS) in an acidic medium, Hassib et al. [8] reported the titrimetric determination of mefenamic acid. A solution of mefenamic acid in acetic acid (0.02% m/V) was prepared. A volume of this solution containing 1.5-3.5 mg of mefenamic acid was allowed to react with 40 mL of 0.05 M NBS solution for 10 min in the dark (temperature of 25 2°C). Potassium iodide solution (10 mL) was added, and the solution was titrated with 0.01 N sodium thiosulfate to the starch end-point. A blank determination was carried out. For the determination of mefenamic acid in the capsules, the contents of 20 Ponstan capsules were mixed thoroughly and an accurately weighed portion of the mixed powder (nominally containing 25 mg of mefenamic acid) was extracted with diethyl ether (3 x 10 mL). The residue remaining after evaporation of diethyl ether was dissolved in acetic acid, and the procedure was continued as described for the determination of mefenamic acid. 

Hassib et al. [29] determined mefenamic acid by ferric hydroxamate complex formation and measurement of the absorbance of the colored complex at 530 nm. The method is applicable to mefenamic acid amounts varying from 0.5 to 74.5 mg/25 mL, and Ponstan capsules were successfully determined using this method. 

Mansour et al. [46] developed a simple, rapid efficient quantitative proton magnetic resonance method for the determination of mefenamic acid in Ponstan capsules. The method is based on a comparison between the sum integrals of the two methyl singlets of mefenamic acid and that integral of the sharp singlet of / -methoxybenzylidenemalononitrile (internal standard). The method gave accurate and reproducible results. 

If mefenamic acid tablets are too big for Miss SM to swallow then a branded capsule formulation (Ponstan) is available. The GP would need to be contacted to agree the change for Drug Tariff reimbursement purposes. 

Mefenamic acid (Ponstel, Ponstan [United Kingdom], Dysman [United Kingdom]) and meclofenamate sodium [Meclomen] have been used mostly in the short-term treatment of pain in soft-tissue injuries, dysmenorrhea, and in rheumatoid and osteoarthritis. These drugs are not recommended for use in children or pregnant women. 

JV-substituted anthranilic acids, mefenamic acid (iV-2,3-xylylanthranilic acid, Ponstan, XXXVII, R = 2,3-xylyl) , flufenamic acid (iV-( ,a,a-trifluoro-m-tolyl)anthranilic acid, XXXVII, R = 3-trifluoromethylphenyl) and GI-583 XXXVII, R = 2,6-dichloro-3-methylphenyl) have been described. 

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