Colon: a gateway for chronotherapeutic drug delivery systems

Colon-specific delivery systems have attracted considerable attention from the scientific community. One of the distinctions of this site-specific delivery system is its effectiveness in carrying a variety of medicinal agents (required for both localized diseases and systemic therapy). It has been proposed that the biological rhythm of the body may affect the normal physiological as well as biological functions. Diseases such as nocturnal asthma, angina pectoris, inflammation, rheumatoid arthritis, hypertension or cardiac arrhythmia, has been found to follow biological rhythm of the body. For the treatment of these diseases, development of a chronotherapeutic drug delivery system (CrDDS), which delivers a defined dose, at a selected time and chosen rate, and to a targeted site is required. Several CrDDSs have been developed by using various strategies (pH-, time-, microflora-triggered and pressurecontrolled systems) with the aim of achieving colon-specific drug delivery. This Editorial article aims to highlight some of the recent advancements that have emerged in the field of colon-targeted drug delivery systems pertaining to the chronotherapy of certain disease conditions.