Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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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 -