Preformulation and Formulation Studies of Novel pH Independent Controlled Release Drug Delivery System of Quetiapine Fumarate

Advent of pharmacology, combinatorial chemistry and High Through Put Screening offered large number of synthetic drugs as a therapeutic substances. These molecules are potent to elucidate their pharmacological activity. However, pharmacokinetic properties of such molecules are rate limiting factors for its safety as well as efficacy. Most of the synthetic drug available so far in market are either weakly acidic or basic in nature, such molecules are possess narrow range of absorption profile, when administered orally for systemic therapies. The erratic and poor absorption of these molecules are closely related with different physiological pH of gastrointestinal tract. There is a continuous need for improving bioavailability of such molecules. pH independent matrix drug delivery system is one such approach that can not only improve the dissolution and absorption of weakly basic or weakly acidic drug but also release the drug for prolonged period of time. Quetiapine fumerate was selected as a model drug for our present investigation. Quetiapine shows pH dependent solubility i.e. it is soluble in acidic aqueous media but solubility of drug decreases with increase in pH of media, which can result in pH dependent release of drug from drug delivery system. Eudragit L30 D55 an enteric polymer was selected to control the release in acidic medium and facilitate the release in basic medium by providing acidic microenvironment to release the drug independent of pH. Sodium alginate and HPMC was used as retarding and matrix forming agent, respectively. The prepared granules and tablets were characterized for its pharmaceutical properties, drug release studies and release kinetics. The ratio of HPMC and sodium alginate was studied and found suitable in ratio of 1:1, 1: 1.5, and 1.5: 1 when used with 10 % acidifying and granulating agent to achieve not only desired release profile but also for better pharmaceutical standards. The present pre-formulation and formulation studies of pH independent matrix tablet had shown promising potential for delivery of pH dependent drugs that can improve the bioavailability and clinical success of dosage form.