PREPARATION AND EVALUATION OF RESPERPIN – CYCLODEXTRINS INCLUSION COMPLEXES
*Nikunjana A. Patel and Rakesh P. Patel
ABSTRACT
The focus of this investigation was to confirm the potential of chemically modified cyclodextrins (hydroxypropyl-
β-cyclodextrin (HP-β-CD/Kleptose® HPB) and sulfobutylether-β-cyclodextrin (SBE-β-CD/Captisol®)) to
improve the dissolution rate of Reserpine in oral delivery. Native and modified cyclodextrins were screened via
phase solubility studies in order to select the most efficient cyclodextrin in formation of stable inclusion
complexes. AP –type phase solubilization resulted from phase solubility diagrams of all cyclodextrin indicated
formation of 2:1 stoichiometric inclusion complexes between CDs and Reserpine. Gibbs free energy (Gtr)
values were all negative, indicating the spontaneous nature of Reserpine solubilization, and they decreased with
increase in the cyclodextrins concentration, demonstrating that the reaction conditions became more favorable as
the concentration of cyclodextrins increased. The inclusion complexes of Reserpine and both cyclodextrins were
prepared in 2:1 molar ratio by various methods such as physical mixing, kneading, spray drying and
lyophilization. The complexes characterized by Fourier-transform infrared (FTIR) spectroscopy differential
scanning calorimetry (DSC) and Scanning electron microscopy (SEM) studies delineates amorphousness as well
as the successful inclusion of the Reserpine molecule into the cyclodextrin cavity. The complexation exhibited
marked improvement in the solubility and wettability of Reserpine. These complexes exhibited substantially
higher and faster rates of dissolution compared to that of Reserpine and physical mixture. Physical mixture also
showed significant improvement in the dissolution rate compared to pure Reserpine. Mean dissolution time
(MDT) of Reserpine decreased significantly after preparation of complexes and physical mixture. Similarity factor
(f2) indicated significant difference between the release profiles of Reserpine from complexes, physical mixture
and from pure Reserpine.
Keywords: Reserpine, hydroxypropyl-?-cyclodextrin, sulfobutyl-?-cyclodextrin, inclusion complexation, invitro dissolution studies.
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