FORMULATION AND IN-VITRO EVALUATION OF HALOPERIDOL SOLID DISPERSION INCORPORATED INTO RECTAL SUPPOSITORIES

The potential of solid dispersion (SD) technique to improve the dissolution of haloperidol (Hal) and to develop Hal rectal suppository was investigated. Hal solid dispersions with hydrophilic carriers, namely, polyethylene glycol 6000 (PEG 6000) or sodium starch glycolate (SSG) in different mixing ratios were prepared by kneading technique. Dissolution studies in phosphate buffer pH 7.4 using USP paddle method were performed for Hal and its physical mixtures and solid dispersions. Fourier- transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray powder diffraction (XRD) analysis were performed to identify the physicochemical interactions between the drug and carrier, hence its effect on dissolution. Hal suppositories were prepared using water soluble base, polyethylene glycol (PEG 6000, 40% w/w and PEG 400, 60% w/w) and oleaginous base (Witepsol H15) utilizing molding technique. The prepared suppositories were tested for hardness, melting time, weight variation and drug content. All these properties were found to be satisfactory for practical use. The dissolution of Hal was improved significantly from its kneaded products with both carriers. Highest dissolution rate of the drug was obtained from Hal solid dispersions at the mixing ratio of 1:7 drug: carriers ratios. SSG was superior in dissolution enhancement of Hal from its solid dispersion. FTIR spectra suggested the presence of hydrogen bonds between the carriers hydroxyl groups and the drug. Powder-XRD technique in combination with differential scanning calorimetry revealed that Hal existed in crystalline form in PEG and SSG polymers. Drug release from the water soluble suppository base was greater than that from oleaginous base. Maximum drug release was obtained from suppositories containing water soluble base incorporated with Hal solid dispersion.