A Comprehensive Review on Osmotically Controlled Drug Delivery Systems

Conventional immediate-release dosage forms sometimes fail to maintain constant plasma drug concentrations, resulting in inappropriate therapeutic effects. This limitation has driven the evolution various controlled drug release systems for improvement in drug release profiles and patient compliance. Among these, osmotic drug release systems (ODDS) have emerged as a promising platform due to capability to provide controlled and predictable drug release rates. ODDS represent a class of novel drug delivery systems that utilize osmotic pressure as the principal mechanism to regulate the release of active pharmaceutical ingredients. These systems are suitable for both oral and implantable applications and operate by the movement of water through a semi-permeable membrane to facilitate the medicament release. For optimal performance, the drug must possess adequate aqueous solubility to generate the required osmotic gradient. Structurally, these systems consist of a medicament containing core surrounded by a semi-permeable membrane. Upon exposure to a hydrated environment, water penetrates through the membrane, creating osmotic pressure inside the core, which facilitates the controlled release of the drug through an orifice. The rate and extent of drug release from these systems are overblown by multiple factors such as the osmotic pressure, drug solubility, dimensions of the delivery orifice, and the physicochemical properties of the semi-permeable membrane. This review provides a concise overview of the fundamental principles governing osmotic drug delivery systems and discusses the various types and design considerations associated with their development.