Pharmaceutical Studies on certain Drugs indifferent sustainecd release dosage

In this investigation different types of Eudragits, namelyEudragit S,L,R1,RS and RSPM, and methylmethacrylate of low molecular weight were employed for sustaining the availability of ephedrine HG1 and chloroquine in different pharmaceutical dosage forma, using three different techni¬ques. i.e, molecular dispersion of drug in polymer matrix, granulation and film coating techniques. Most of the obtained pharmaceutical preparations were found to exhibit timed release of the drug. In vitro dissolution pattern of drug-polymer made into compressed tablets are reported. The tablets were made employing a single force of compression and beiging approximately of the same weight and hardness. The rate of ephedrine HC1 and chloroquine phosphate was evaluated in both acid and alkaline media. The Higuchi’s. model for drug release from inert matrices could describe . the release pattern only for few hours for most of the tab¬lets when variables other than the amount of drug and time. were esseutially constant. Greater deviation in the latter stage can. be attributed to geometric effects. Accordingly the mechansim of release from all the formulations tasted is proposed as combination of diffusion, leaching and erosions from surface changed tablets. Also, in vivo availability study of sustained release matrix of ephedrine HQ1 which was suggested to give a most predictable prolong¬ation in vitro test was tried and compared with conventional dose .