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Studies on tolfenamic acid-chitosan intermolecular interactions: Effect of pH, polymer concentration and molecular weight

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Studies on tolfenamic acid-chitosan intermolecular interactions : Effect of pH, polymer concentration and molecular weight. / Ahmed, S.; Sheraz, M.A.; Rehman, I.U.

In: AAPS PharmSciTech, Vol. 14, No. 2, 2013, p. 870-879.

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@article{dac0e002f6c2402dae29d79eb206b07e,
title = "Studies on tolfenamic acid-chitosan intermolecular interactions: Effect of pH, polymer concentration and molecular weight",
abstract = "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. {\textcopyright} 2013 American Association of Pharmaceutical Scientists.",
keywords = "amorphous, chitosan, effect of pH and molecular weight, freeze-drying, recrystallization, tolfenamic acid, polymer, article, complex formation, concentration (parameters), cooling, crystallization, differential scanning calorimetry, drug storage, drug structure, freeze drying, hydrogen bond, infrared spectroscopy, molecular interaction, molecular weight, pH, physical chemistry, priority journal, scanning electron microscopy, structure analysis, X ray diffraction, Calorimetry, Differential Scanning, Chemistry, Pharmaceutical, Chitosan, Crystallization, Crystallography, X-Ray, Cyclooxygenase Inhibitors, Desiccation, Drug Carriers, Freezing, Hydrogen Bonding, Hydrogen-Ion Concentration, Microscopy, Electron, Scanning, Molecular Weight, ortho-Aminobenzoates, Spectroscopy, Fourier Transform Infrared, Technology, Pharmaceutical",
author = "S. Ahmed and M.A. Sheraz and I.U. Rehman",
year = "2013",
doi = "10.1208/s12249-013-9974-9",
language = "English",
volume = "14",
pages = "870--879",
journal = "AAPS PharmSciTech",
issn = "1530-9932",
publisher = "American Association of Pharmaceutical Scientists",
number = "2",

}

RIS

TY - JOUR

T1 - Studies on tolfenamic acid-chitosan intermolecular interactions

T2 - Effect of pH, polymer concentration and molecular weight

AU - Ahmed, S.

AU - Sheraz, M.A.

AU - Rehman, I.U.

PY - 2013

Y1 - 2013

N2 - 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. © 2013 American Association of Pharmaceutical Scientists.

AB - 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. © 2013 American Association of Pharmaceutical Scientists.

KW - amorphous

KW - chitosan

KW - effect of pH and molecular weight

KW - freeze-drying

KW - recrystallization

KW - tolfenamic acid

KW - polymer

KW - article

KW - complex formation

KW - concentration (parameters)

KW - cooling

KW - crystallization

KW - differential scanning calorimetry

KW - drug storage

KW - drug structure

KW - freeze drying

KW - hydrogen bond

KW - infrared spectroscopy

KW - molecular interaction

KW - molecular weight

KW - pH

KW - physical chemistry

KW - priority journal

KW - scanning electron microscopy

KW - structure analysis

KW - X ray diffraction

KW - Calorimetry, Differential Scanning

KW - Chemistry, Pharmaceutical

KW - Chitosan

KW - Crystallization

KW - Crystallography, X-Ray

KW - Cyclooxygenase Inhibitors

KW - Desiccation

KW - Drug Carriers

KW - Freezing

KW - Hydrogen Bonding

KW - Hydrogen-Ion Concentration

KW - Microscopy, Electron, Scanning

KW - Molecular Weight

KW - ortho-Aminobenzoates

KW - Spectroscopy, Fourier Transform Infrared

KW - Technology, Pharmaceutical

U2 - 10.1208/s12249-013-9974-9

DO - 10.1208/s12249-013-9974-9

M3 - Journal article

VL - 14

SP - 870

EP - 879

JO - AAPS PharmSciTech

JF - AAPS PharmSciTech

SN - 1530-9932

IS - 2

ER -