Formulation of solid dispersion and surface solid dispersion of nifedipine: A comparative study

In this study, an attempt was taken to enhance the solubility and dissolution characteristics of nifedipine, a poorly water soluble calcium channel blocking agent, by preparing solid dispersions (SD) with water soluble carriers; Poloxamer 407, HPMC 5 cPs, polyethylene glycol (PEG) 4000 and 6000 and surface solid dispersions (SSD) with insoluble carriers; sodium starch glycolate (SSG) and croscarmellose sodium (CCS). In vitro dissolution study showed that all the preparations were effective to improve the dissolution of nifedipine to several folds when compared with the drug and physical mixtures (PMs). Drug loading in SDs and SSDs was found uniform and they produced satisfactory results on drug content analysis (95 to 102%), compatibility and thermal analysis. PEG 6000, Poloxamer 407 and SSG were found to be the most effective carriers to enhance the dissolution behavior of nifedipine. SDs with water soluble carriers were found more effective in improving solubility of nifedipine than SSDs and PMs. Tablets were prepared using SDs and SSDs, and compared to marketed preparations and to a simple compressed tablet of nifedipine. Tablets prepared from SDs with PEG 6000 and Poloxamer 407 showed better release profile than all the marketed products.   Key words: Bioavailability, hydrophilic carrier, hydrophobic agents, interactions, solid matrix and compatibility.