A comparative study of modified starches in direct compression of a water soluble drug-chloroquine phosphate

Some in vitro properties of chloroquine phosphate tablets formulated with four modified starches were investigated. The drug was formulated as tablets containing 250 mg of chloroquine phosphate and produced by the direct compression technique. The starches were isolated from maize, zea mays, rice, Oryza sativa, cassava, Manihot esculenta and cocoyam, Zanthosoma sagittifolium. They were modified through physicochemical process, Sta-Rx 1500, a directly compressible starch was used as basis for comparison. The hardness of the chloroquine tablets generally decreased to a minimum with all the modified starches at concentration level of 40% and with maximum hardness obtained when their concentrations were increased to 80%. The least hardness values were obtained with modified cocoa yam starch while the highest hardness values were obtained with modified rice starch. Modified rice and cassava starches produced chloroquine tablets that exhibited higher mechanical properties than those of modified maize starch, cocoayam starch and Sta-Rx 1500. On the basis of dissolution profile of chloroquine phosphate tablets, the modified starch samples were ranked in order of increasing dissolution as modified cocoayam maize Sta-Rx 1500 cassava rice starch sample. The release rate of chloroquine was found to be dependent on the physico-chemical properties of the individual modified starch granules such as particle size and degree of gelatinization.