An isothermal heat conduction microcalorimeter has been used to study the stability of diclofenac sodium both alone and its inclusion complex with β-cyclodextrin in aqueous solution. The rates of heat evolved during degradation of diclofenac sodium have been measured by a highly
sensitive microcalorimetric technique as function of concentration, pH and temperature. The calorimetric accessible data have been incorporated in the equations for determination of rate constants, change in enthalpy and order of reaction. The decomposition of diclofenac sodium both alone
and its inclusion complex with β-cyclodextrin in solution corresponds to a pseudo-first order reaction. The values of rate constants, k's at 338.15 K, (calculated from the variation of heat evolution with the time) for the degradation of diclofenac sodium at pH 5, 6, 7, 8 and its
inclusion complex with β-cyclodextrin at pH 7 are found to be 4.71 × 10–4, 5.69 × 10–4, 6.12 × 10–4, 6.57 × 10–4 and 4.26 × 10–4 h–1 respectively. There
is good agreement between calorimetric determined t0.5 and literature values. It has been found that β-cyclodextrin retards the degradation of diclofenac sodium. The kinetic parameters have been calculated for the reaction. The negative entropy of activation suggests the formation
of an ordered transition state.
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Document Type: Research Article
Pharmaceutical Chemistry Division, University Institute of Pharmaceutical Sciences, Chandigarh, 160014, India, Email: [email protected]
Pharmaceutical Chemistry Division, University Institute of Pharmaceutical Sciences, Chandigarh, India
Department of Chemistry, Panjab University, Chandigarh, India
Publication date: September 1, 2003
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Pharmazie is a leading journal in the field of pharmaceutical sciences. As a peer-reviewed scientific journal, Pharmazie is regularly indexed in the relevant databases like Web of science, Journal Citation Reports and many others. The journal is open for submissions from the whole spectrum of pharnaceutical sciences including Pharmaceutical Chemistry, Experimental and Clinical Pharmacology, Drug Analysis, Pharmaceutics, Pharmaceutical Biology, Clinical Pharmacy etc.
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