Mefenamic acid formulations

In this case, the solubility is extremely poor, even at pH 7, which is considerably above the pKa of troglitazone and corresponds to pH values commonly found in the mid section of the small intestine. Other well-known compounds with analogous behavior are mefenamic acid, glyburide, and phe-nytoin. For troglitazone, the presence of bile salts improves the solubility quite dramatically and lipophilic constituents in the dissolution medium (e.g., in full-fat milk) lead to better dissolution, and in turn better absorption when troglitazone is administered in the fed than the fasted state, as reported by Nicolaides (13). Use of biorelevant dissolution testing permitted these authors not only to qualitatively predict the food effect, but also to predict relative bioavailability of three test formulations. 

Issa et al. [9] used various metal ions for the volumetric determination of mefenamic acid. Mefenamic acid was precipitated from its neutral alcoholic solution by a standard solution of either silver nitrate, mercurous acetate, or potassium aluminum sulfate. In the argentimetric procedure, residual Ag(I) was titrated with standard NH4SCN. With Hg(OAc)2 or potash alum, the residual metal was determined by adding EDTA and conducting back titration of excess of EDTA with standard Pb(N03)2 using xylenol orange indicator. The applied methods were used for the determination in bulk drug substance, and in its formulations. 

Gangwal and Sharma [16] described a simultaneous spectrophotometric method for the determination of mefenamic acid and paracetamol in their combined dosage forms based on the native UV absorbance maxima of mefenamic acid and paracetamol in 0.02 M NaOH. Mefenamic acid exhibits two absorption maxima at 285 nm and 333 nm, while paracetamol has one absorbance maxima at 257 nm. In a separate study, the same group [17] also reported a spectrophotometric procedure for mefenamic acid and paracetamol in two component tablet formulations. The method is based on the two-wavelength method of calculation. The difference in absorbances at 217 nm and 285 nm was used for determination of mefenamic acid, and the difference in absorbances at 257 nm and 308.8 nm was used for the determination of paracetamol. Beer s law is obeyed by both the drugs within the concentration ranges employed for analysis. The method has been statistically validated, and was found to be satisfactory. 

Deveaux et al. [21] reported that mefenamic acid, being an N-aryl derivative of anthranilic acid, can be characterized by two color reactions. The color reactions, negative with N-aryl derivatives of aminonicotinic acid, are associated with the diphenylamine structure. For the first color reaction, add to a test tube approximately 0.5 g of oxalic acid dihydrate and at least 1 mg of the test material. Place the tube into an oil bath at 180-200°C for 4-5 min. After cooling, dissolve the residue in 10 mL of 95% ethanol to obtain a stable, intense blue solution (absorption maximum at 586-590 nm). To use the reaction for capsule formulations, extract the active ingredient with acetone and filter prior to the assay. For the second color reaction, add mefenamic acid (100-800 pg) in 1 mL of H0Ac-H2S04 (98 2, v/v), 5 mL of HOAc-HCl (50 50, v/v) and 1 mL of 0.10% (w/w) aqueous levulose. Heat the mixture for 25 min at 100°C, and after cooling, measure the absorbance at 597 nm. 

Khalil et al. [51] described the microquantitative determination of mefenamic acid based on the reaction of mefenamic acid with a silver nitrate solution in a neutral alcoholic medium. The formed precipitation is quantitatively determined directly or indirectly through the silver content of the precipitation formed or the residual unreacted silver ions in the filtrate by atomic absorption spectrophotometry. The results obtained in both the procedures either in their pure form or in their pharmaceutical formulations are accurate and precise. The stoichiometric relationship of the reaction was studied using lob s continuous variation method, and it was found to be (1 1) drug Ag+ for the mefenamic acid. 

What other formulations of mefenamic acid are there ... 

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. 

Ethyl acetate has also been shown to increase the solubility of chlortalidone and to modify the polymorphic crystal forms obtained for piroxicam pivalate and mefenamic acid, and has been used in the formulation of microspheres.Its use as a chemical enhancer for the transdermal iontophoresis of insulin has been investigated. 

KhullarR, Kumar D, SethN, SainiS. Formulation and evaluation of mefenamic acid emulgel for topical delivery. Saudi Pharmaceutical Journal. 2012 20(l) 63-67. 

Many patients who respond to aspirin with asthma, rhinitis and urticaria are also sensitive to other analgesic anti-inflammatory drugs. Cross-sensitivity has been demonstrated with indomethacin, mefenamic acid, flufenamic acid, phenylbutazone, paracetamol, fenoprofen and ibuprofen (37, 39, 40C, 44C 4gc 55C 566 57R) Furthermore, cross-sensitivity may also occur with widely used food additives and colourings such as benzoic acid and the acidic yellow dye tartrazine (46 ", 47, 57, 58 ). In Holland tartrazine is used in the colouring of at least 79 pharmaceutical formulations including antibiotics and even preparations... 

The use of second-derivative synchronous fluorescence spectrometry was reported by Ruiz et al. [42] to develop a simple, rapid and sensitive fluorimetric method for the determination of binary mixtures of the nonsteroidal antiinflammatory drugs flufenamic (FFA), meclofenamic (MCFA) and mefenamic (MFA) acids in serum and in pharmaceutical formulations. The method is based on the intrinsic fluorescence of these compounds in chloroform. A differential wavelength of 105 nm was used for the resolution of FFA-MFA and MFA-MCFA mixtures, whereas the FFA-MCFA mixture was determined at a differential wavelength of 40 nm. Serum samples were treated with trichloroacetic acid to remove the proteins, and the analytes were extracted in chloroform prior to determination. Pharmaceutical preparations were analyzed without prior separation steps. 

Alpdogan and Sungur [50] developed an indirect atomic absorption spectroscopy method for the determination of mefenamic and flufenamic acids, and diclofenac sodium, based on the complexation with copper (II) amine sulfate. The complex was extracted into chloroform, and the concentrations of substances were determined indirectly by AAS measurement of copper after re-extraction into 0.3 N nitric acid solution. The developed method was applied to the assay of the substances in commercial tablet formulations. The results were statistically compared with those obtained by HPLC method by t- and F tests at 95% confidence level. Calculated t and F values were both lower than the table values. 

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