Raman and IR spectroscopic studies of fenamates – Conformational differences in polymorphs of flufenamic acid, mefenamic acid and tolfenamic acid

Jabeen, Saima; Dines, Trevor J.; Leharne, Stephen A.; Chowdhry, Babur Z.

doi:10.1016/j.saa.2012.07.129

Cited by 61 publications

(45 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In pure crystalline form, TA shows N-H stretching vibrations at around 3,342-3,340 cm −1 while one of its other polymorphic forms is reported to give the similar stretching vibrations at 3,324-3,315 cm −1 . Therefore, the spectral features for the change in the crystalline forms of TA can be studied within the spectral range of 3,350-3,300 cm −1 (13,42,43). Our findings are also in agreement with other workers as N-H stretching band for TA either alone or in combination with CT after freeze-drying is observed at 3,340 cm −1 (Fig.…”

Section: Ftir Studiessupporting

confidence: 92%

Studies on Tolfenamic Acid–Chitosan Intermolecular Interactions: Effect of pH, Polymer Concentration and Molecular Weight

2013

View full text Add to dashboard Cite

Solid-state properties of tolfenamic acid (TA) and its complexes with chitosan (CT) have been studied. Effect of medium pH, molecular weight of polymer and its different concentrations on these TA-CT complexes were studied in detail. Low and medium molecular weight CT have been used in different ratios at pH ranging from 4 to 6 and freeze-drying technique has been employed to modify the appearance of crystalline TA. Physical properties of the formed complexes have been studied by employing X-ray diffraction, differential scanning calorimetry and scanning electron microscopy; chemical structure has been studied using Fourier transform infrared spectroscopy. The results showed that both forms of the polymer exhibited complete conversion in 1:8 ratio at pH 4, 1:4 at pH 5 and 1:1 at pH 6 indicating a marked effect of pH on drug-polymer complexation. The percent crystallinity calculations indicated low molecular weight CT slightly more effective than the other form. No changes in the complexes have been observed during the 12 week storage under controlled conditions. Both forms of CT at different pH values indicated retardation of recrystallization in TA during cooling of the melt from 1:1 ratios exhibiting formation of strong intermolecular hydrogen bonding between the drug and the polymer.

show abstract

Section: Ftir Studiessupporting

confidence: 92%

Studies on Tolfenamic Acid–Chitosan Intermolecular Interactions: Effect of pH, Polymer Concentration and Molecular Weight

2013

View full text Add to dashboard Cite

show abstract

“…Bands in the region 1440–1400 cm −1 indicated symmetrical stretching of a methyl group, whereas 1267 and 749 cm −1 showed C–H and C–N deformation, respectively (Figure 2). [ 4,5,31–33 ] Results from both techniques therefore confirmed that TA was of the highest purity and could be used for development of an analytical method and for its validation studies.…”

Section: Resultsmentioning

confidence: 75%

“…TA is known to exhibit polymorphism under different conditions and its yellow form is the most common among others. [ 5,26,27,32–35 ] The yellow polymorphic form of TA exhibits unique N–H vibrational bands in the region around 3324–3315 cm −1 and 1521 cm −1 that differentiate it from the white form. [ 5,27,35 ] In the present study, the yellow polymorphic form of TA was prepared to study the effect of polymorphism on the fluorescence intensity of the molecule.…”

Section: Resultsmentioning

confidence: 99%

Development and validation of a spectrofluorimetric method for the analysis of tolfenamic acid in pure and tablet dosage form

et al. 2020

View full text Add to dashboard Cite

Tolfenamic acid (TA) is commonly used in humans and animals because of its anti-inflammatory, antipyretic, and analgesic effects. So far, no study has been carried out to develop a validated spectrofluorimetric method for determination of TA. Therefore, the present study aimed to develop and validate a simple, accurate, rapid, economical, and precise spectrofluorimetric method to assay TA in its pure and dosage forms, and also in degraded solutions. The fluorimetric method had higher sensitivity compared with the spectrophotometric and highperformance liquid chromatography methods and could determine the drug at the microgram level. Optimum pH of TA for maximum fluorescence intensity was 3, and its two pK a values were calculated as 1.95 and 4.05. The proposed method was validated according to the guidelines of the International Council for Harmonisation, and parameters such as linearity, range, accuracy, precision, sensitivity, robustness, specificity, and solution stability were tested. Stress-induced degradation studies on TA did not affect the accuracy and precision of the proposed method. The results obtained indicated that the method was linear over the concentration range 0.2-0.9 × 10 −3 M with good accuracy, precision, and robustness for assay of TA in its pure and its tablet dosage forms and was comparable statistically with the British Pharmacopoeia method.

show abstract

“…However, still the appearance of small shoulder in the same peak in 1 : 2 ratios (Figures 4(c) and 4(e)) can be observed which eventually disappeared in 1 : 5 ratios (Figures 4(d) and 4(f)). The sharp peak at 749 cm −1 (Figure 4(a)) corresponds to the C–N deformation [41, 42] which has also reduced in the films (Figures 4(c)–4(f)) thus further confirming modification in the solid state properties of TA due to strong complexation and intermolecular hydrogen bonding between TA and PU.…”

Section: Resultsmentioning

confidence: 83%

Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

Istanbullu

Ahmed

Sheraz

et al. 2013

BioMed Research International

View full text Add to dashboard Cite

The present study deals with the preparation of polyurethane (PU) films impregnated with a nonsteroidal anti-inflammatory drug, tolfenamic acid (TA). Solvent evaporation technique has been employed for the preparation of TA-PU films in two different ratios of 1 : 2 and 1 : 5 in Tetrahydrofuran (THF) or THF-ethanol mixtures. The prepared films were characterized using X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and release studies. The results indicate transformation of crystalline TA to its amorphous form. The degree of crystallinity changes both by increasing the polymer concentration and solvent used for the film preparations. The release profiles of TA were also found to be affected, showing a decrease from approximately 50% to 25% from 1 : 2 to 1 : 5 ratios, respectively.

show abstract

Raman and IR spectroscopic studies of fenamates – Conformational differences in polymorphs of flufenamic acid, mefenamic acid and tolfenamic acid

Cited by 61 publications

References 31 publications

Studies on Tolfenamic Acid–Chitosan Intermolecular Interactions: Effect of pH, Polymer Concentration and Molecular Weight

Studies on Tolfenamic Acid–Chitosan Intermolecular Interactions: Effect of pH, Polymer Concentration and Molecular Weight

Development and validation of a spectrofluorimetric method for the analysis of tolfenamic acid in pure and tablet dosage form

Development and Characterization of Novel Polyurethane Films Impregnated with Tolfenamic Acid for Therapeutic Applications

Contact Info

Product

Resources

About