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(HIV antiviral, CAS No. 154598-52-4), mefenamic acid (nonsteroidal anti-inflammatory, CAS No. 61-68-7), and atovaquone (antifungal and anti-parasite, CAS No. 95233-18-4) + proguanil HCl (antimalarial, CAS No. 637-32-1). In addition, two previously

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A simple, rapid, and reliable HPTLC method has been established for determination of ethamsylate and mefenamic acid in tablets. Identification and quantification were performed on silica gel 60 F 254 HPTLC plates, prewashed with methanol, with chloroform-methanol-acetic acid, 10 + 8 + 0.2 ( v/v ), as mobile phase. Calibration plots were established showing the dependence of response (peak area) on the amount chromatographed. The validated calibration ranges were 500–2500 ng spot −1 ( r = 0.998) and 500–2500 ng spot −1 ( r = 0.997) for ethamsylate and mefenamic acid, respectively. The spots were scanned at λ = 300 nm. The suitability of this HPTLC method for quantitative determination of the compounds was proved by validation in accordance with the requirements of the ICH guidelines (Q2B). The method was used for determination of the compounds in commercial pharmaceutical dosage forms. The method is simple, reproducible, and accurate and can be used as a more economical alternative to other chromatographic techniques for routine quality control.

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A simple, sensitive, and precise high-performance thin-layer chromatographic method has been developed for the estimation of paracetamol, dicyclomine hydrochloride, and mefenamic acid in combined dosage form. The method employed high-performance thin-layer chromatography (HPTLC) aluminum plates precoated with silica gel 60 F254 as the stationary phase, while the solvent system was toluene-ethyl acetate-methanol (6:3:1, v/v). The R F values were observed to be 0.27 ± 0.02, 0.41 ± 0.03, and 0.61 ± 0.02 for paracetamol, dicyclomine hydrochloride, and mefenamic acid, respectively. The separated spots were densitometrically analyzed in absorbance mode at 290 nm. The method was linear in the range of 300-1800 ng band−1 for paracetamol, 400–2400 ng band−1 for dicyclomine hydrochloride, and of 150–1500 ng band−1 for mefenamic acid. The method was validated with respect to accuracy, precision, specificity, sensitivity, and robustness. The limits of detection for paracetamol, dicyclomine hydrochloride, and mefenamic acid were found to be 35, 109, and 42 ng band−1, respectively. The limits of quantification for paracetamol, dicyclomine and mefenamic acid were found to be 116, 360, and 140 ng band−1, respectively. The method was successfully applied to the estimation of all three drugs in combined tablet dosage form.

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Journal of Thermal Analysis and Calorimetry
Authors: Y. A. Ribeiro, J. D. S. de Oliveira, M. I. G. Leles, S. A. Juiz, and M. Ionashiro

Thermogravimetry, derivative thermogravimetry (TG, DTG) and differential scanning calorimetry (DSC), were used to study the thermal behaviour of mefenamic acid, ibuprofen, acetaminophen, sodium diclofenac, phenylbutazone, dipyrone and salicylamide. The results led to thermal stability data and also to the interpretation concerning the thermal decomposition.

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Abstract  

Differential scanning calorimetry (DSC), supported by hot stage microscopy, IR spectroscopy and X-ray powder diffractometry, was used to investigate the characteristics of the solid phases of mefenamic, niflumic, and flufenamic acids and of paracetamol, before and after equilibration with saturated solutions in different solvents. Mixtures of Lewis base (dioxane and ethyl acetate) and amphiprotic solvents (ethanol and water) were prepared for evaluating the influence of both nature and polarity of the solvents. Solid-state analysis performed on the original samples (commercial products) made it possible to establish that paracetamol, mefenamic acid and flufenamic acid were in their respective Form I. No polymorphic modifications are known for niflumic acid. Paracetamol, niflumic and mefenamic acids did not show any change after equilibration with the various solvents or solvent mixtures, regardless of their different chemical nature. In contrast, DSC, IR and X-ray analyses revealed the partial recrystallization of flufenamic acid into its polymorphic Form III in solid phases at equilibrium with ethanol, ethyl acetate and their blends, as well as in dioxane-water mixtures containing 30 to 100% dioxane and in ethanol-water mixtures with a water content less than 50%.

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with acetylsalicylic acid, acetaminophen, diflunisal, dimenhydrinate, ketoconazole, and mefenamic acid. Experimental Chemicals Acetyl salicylic acid, acetaminophen, diflunisal, dimenhydrinate, ketoconazole

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The chromatographic separation of fenbufen, ibuprofen, ketoprofen, diclofenac sodium, mefenamic acid, and tiaprofenic acid has been investigated. Normal-phase chromatography on silica gel by the ascending and horizontal techniques, and reversed-phase chromatography on octadecyl-bonded silica gel (RP-18) in horizontal chambers, were performed with suitable mobile phases. The substances were identified by UV illumination at λ = 254 nm and by use of dyeing reagents. Reversed phase chromatography with phosphate buffer, pH 5.73–10% CTMA-Br in methanol, 3.5 + 6.5 ( v/v ), as mobile phase enabled better separation of the six drugs than normal-phase mode. A simple videodensitometric TLC method on silica gel RP-18 was developed and validated for quantitative determination of fenbufen in tablets. The limits of detection and quantification were determined by videodensitometry at λ = 254 nm. A calibration plot was constructed in the range 2.0–12.0 μg/5-μL spot and was linear with a good correlation coefficient (0.9926). RSD for quantitation of fenbufen were from 2.44 to 3.10%. The method was applied satisfactorily to pharmaceutical preparations.

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