The effect of pH and triethanolamine on sulfisoxazole complexation with hydroxypropyl--cyclodextrin

The effect of pH and triethanolamine on sulfisoxazole complexation with hydroxypropyl--cyclodextrin
November 2003
Received 9 September 2002; revised 10 June 2003; accepted 15 July 2003. ; Available online 6 September 2003.
Granero Gladys, Garnero Claudia and Longhi Marcela
European Journal of Pharmaceutical Sciences
Volume 20, Issue 3
ScienceDirect
Abstract
A novel complexation of sulfisoxazole with hydroxypropyl--cyclodextrin (HP--CD) was studied. Two systems were used: binary complexes prepared with HP--CD and multicomponent system (HP--CD and the basic compound triethanolamine (TEA)). Inclusion complex formation in aqueous solutions and in solid state were investigated by the solubility method, thermal analysis (differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)), Fourier-transform infrared spectroscopy (FT-IR) and dissolution studies. The solid complexes of sulfisoxazole were prepared by freeze-drying the homogeneous concentrated aqueous solutions in molar ratios of sulfisoxazole:HP--CD 1:1 and 1:2, and sulfisoxazole:TEA:HP--CD 1:1:2. FT-IR and thermal analysis showed differences among sulfisoxazole:HP--CD and sulfisoxazole:TEA:HP--CD and their corresponding physical mixtures and individual components. The HP--CD solubilization of sulfisoxazole could be improved by ionization of the drug molecule through pH adjustments. However, larger improvements of the HP--CD solubilization are obtained when multicomponent systems are used, allowing to reduce the amount of CD necessary to prepare the target formulation.
Author Keywords: Multicomponent complex formation; Inclusion complex; Sulfisoxazole; Solubility; Thermal analysis; Hydroxypropyl--cyclodextrin (HP--CD)
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