Nitin Saigal, Sanjula Baboota, Alka Ahuja and Javed Ali Pages 64 - 70 ( 7 )
Oral dosage forms are known to provide a zero order or first order release in which the drug is released at a substantially steady rate of release per unit of time. However, there are instances where maintaining a constant blood level of a drug is not desirable. In such cases a pulsatile drug delivery may be more advantageous. Pulsatile drug delivery systems can be classified into site-specific systems in which the drug is released at the desired site within the intestinal tract (e.g., the colon), or time-controlled devices in which the drug is released after a well-defined time period. Environmental factors like pH or enzymes present in the intestinal tract control the release of a site-controlled system whereas the drug release from time-controlled systems is controlled primarily by the delivery system and not by the environment. The delayed liberation of orally administered drugs has been achieved through a range of formulation approaches, including single or multiple unit systems provided with release-controlling coatings, capsular devices and osmotic pumps. Our aim in this review is to outline the rational and prominent design strategies behind site-specific oral pulsatile delivery. The present article provides a good patent review regarding the Site Specific Chronotherapeutic Drug Delivery Systems.
Pulsatile release, colon specific systems, lag time, burst release, enteric coating, methylmethaacrylate copolymers
Department of Pharmaceutics, Faculty of Pharmacy, Jamia Hamdard, Hamdard Nagar, New Delhi - 110 062, India.