Designing an extended release waxy matrix tablet containing nicardipine–hydroxy propyl β cyclodextrin complex

Aim: The current study aimed to prepare a sustained release tablet for a drug which has poor solubility in alkaline medium using complexation with cyclodextrin. Nicardipine hydrochlo- ride (NC) a weak basic drug was chosen as a model drug for this study. Method: Firstly the most suitable binary system NC-HPbCD was selected in order to improve drug solubility in the intestinal media and then embedding the complexed drug into a plastic matrix, by fusion method, consists of glycerol monostearate (GMS) as an inert waxy substance and polyeth- ylene glycol 4000 (PEG4000) as a channeling agent, after that the final solid dispersion [(NC:HPβCD):GMS:PEG4000] which was prepared at different ratios was mixed with other excip- ients, avicel PH101, lactose, and talc, to get a tablet owning dissolution profile complying with the FDA and USP requirements for the extended release solid dosage forms. Results: Infrared spectroscopy (IR), differential scanning colorimetry (DSC), polarized microscopy and X-ray diffractometry proved that the coevaporation technique was effective in preparing amor- phous cyclodextrin complexes with NC and trapping of NC within the HPbCD cavity by dissolving both in ethanol and evaporate the solvent using a rotavapor at 65 °C. Dissolution profile of NC enhanced significantly in pH 6.8 from NC:HPβCD inclusion complex prepared by the rotavapor (t-test Student p 0.05). The release of NC from tablet containing [(NC:HPβCD):GMS:PEG4000] [(1):0.75:0.5] (w/w/w) solid dispersion (F8) was complying with the FDA dissolution requirements for extended release dosage forms, and studying the kinetics of the release showed that the diffu- sional contribution is the major factor controlling the drug release from that formula. Conclusion: The prepared waxy matrix tablet containing NC complexes with CD shows promising results as extended release tablets.