Development and Characterization of Paracetamol Complexes with Hydroxypropyl-β-Cyclodextrin

Paracetamol is a sparingly soluble bitter tasting drug. It is widely used as an analgesic and antipyretic. Complexation of drug with different cyclodextrins (α, β and HP-β-CD) was attempted to improve solubility of Paracetamol. During the drug excipient interaction studies, α, β cyclodextrins elicited analytical interference and showed considerable absorbance at λmax (243.5 nm) of Paracetamol while the ones constituting of hydroxypropyl-beta-cyclodextrin (HP-β-CD) did not show any such interference. Therefore, the present study is concentrated on exploring HP-β-CD as complexing agent. Phase solubility studies showed that complexation of Paracetamol/HP-β-CD at molar ratio 1:1 and showed A_L type solubility curve. Complexation was done by various methods like physical mixing, kneading and freeze drying and resulting drug complexes were characterized by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR). The thermograms obtained showed an endothermic peak for Paracetamol, for physical mixture to some extent for kneaded mixture, but was completely eliminated for freeze dried product (Inclusion complex). Similar results were obtained during IR studies. Therefore, solid inclusion complex of paracetamol prepared by freeze drying method was found to be an ideal complex. The solubility of paracetamol, was significantly increased (six folds of normal solubility) by complexation with HP-β-CD.