MODERN STATE OF CREATION, PRODUCTION AND RESEARCH OF DRUGS. Notice 25. Osmotic drug release and delivery systems: the characteristics and application of implantable mini osmotic pump, oral and special types of osmotic release and delivery systems of drugs

• Main Authors: M. B. Demchuk, M. B. Chubka, L. V. Vronska, T. A. Hroshovyi
• Format: Article
• Language: English
• Published: Ukrmedknyha Publishing House 2017-02-01
• Series: Фармацевтичний часопис
• Subjects: осмотичні системи; осмотичні речовини; лікарські речовини.
• Online Access: https://ojs.tdmu.edu.ua/index.php/pharm-chas/article/view/7128
• ISSN: 2312-0967; 2414-9926

Introduction The implantable mini osmotic pump is most advanced version in the category of implantable pumps developed by Alza corporation. It is composed of three concentric layers – the drug reservoir, the osmotic sleeve and the rate controlling semi permeable membrane. The addition component called flow moderator is inserted into the body of the osmotic pump after filling. These pump are available with variety of delivery rates between 0.25 to 10 ml per hour and delivery duration between 1 day and 4 weeks. There are single and multi osmotic systems among the oral osmotic systems. Type I: Single compartment. In this design, the drug and the osmotic agent are located in the same compartment and are surrounded by the semi permeable membrane. Both the core components are dissolved by water, which enters the core via osmosis. Elementary osmotic pump was introduced to delivery drugs at zero order rates for prolonged periods. The tablet consists of an osmotic core containing the drug surrounded by a semi permeable membrane laser drilled with delivery office. Following ingestion, water in absorbed into system dissolving the drug, and the resulting drug solution is delivered at the same rate as the water entering the tablet. Type II: Multiple compartments. In this design, drug is separated from the osmotic compartment by an optional flexible film, which is displaced by the increased pressure in the surrounding osmotic compartment, which, in turn, displaces the drug solution or suspension. Push pull osmotic pump is a modified type of elementary osmotic pump. This system resembles a standard belayed coated tablet. One layer contains drug in a formulation of polymeric, osmotic agent and other tablet excipients. This polymeric osmotic agent has the ability to form a suspension of drug in situ. When this tablet later imbibes water, the other layer contains osmotic and colorings agents, polymer and tablet excipients. This layer are formed and bonded together by tablet compression to form a single belayed core. The tablet core is then coated with semi permeable membrane. After the coating has been applied, a small hole is drilled through the membrane by a laser or mechanical drill on the drug layer side of the tablet. There are special types of osmotic release and delivery systems of drugs. When Controlled porosity osmotic pump is placed in aqueous environment the water soluble component of coating dissolves and forms micropores in membrane and water diffuses inside the core through microporous membrane, setting up an osmotic gradient and there by controlling the release of drug. The rate of release from controlled porosity osmotic pump is dependent on level of soluble component in coating, coating thickness, osmotic pressure across the membrane, solubility of drug in tablet core. Liquid OROS are designed to deliver drugs as liquid formulations and combine the benefits of extended release with high bioavailability. They are of three types: L OROS hard cap, L OROS soft cap, delayed liquid bolus delivery system. Delayed Delivery osmotic system consists of two chambers, the first contains the drug and an exit port, and the second contains an osmotic engine. A layer of wax like material separates the two section. To assemble the delivery device, the desired active agent is placed into one of the sections by manual or automated fill mechanism. OROS-CT (colon targeting) is used as a once or twice a day formulation for targeted delivery of drugs to the colon. After coming in contact with the gastric fluids, gelatin capsule dissolved and the enteric coating prevents entry of fluids from stomach to the system as the system enters into the small intestine the enteric coating dissolves and water is imbibed into the core thereby causing the push compartment to swell. At the same time flowable gel is formed in the drug compartment, which is pushed out of the orifice at a rate, which is precisely controlled, by the rate of water transport across the semi permeable membrane. Sandwiched oral therapeutic system is composed of polymeric push layer sandwiched between two drug layers with two delivery orifices. When placed in the aqueous environment the middle push layer containing the swelling agent’s swells and the drug is released from the two orifices situated on opposite sides of the tablet. Osmotic pump for insoluble drugs concerns an osmotic agent for dispensing beneficial active agent that has poor solubility in water. The core of the system comprises a beneficial amount of a substantially water- insoluble active agent, which is lipid soluble or lipid- wettable; a sufficient amount of water insoluble lipid carrier, which is liquid at the temperature of use to dissolve or suspend the drug and agent to ensure the release of the lipid carrier of the drug from the pump. Monolithic osmotic system constitutes a simple dispersion of water-soluble agent in polymer matrix. When the system comes in contact in with the aqueous environment water imbibition by the active agents takes place rupturing the polymer matrix capsule surrounding the drug. Thus liberating it to the outside environment. Initially this process occurs at the outer environment of the polymeric matrix, but gradually proceeds towards the interior of then matrix in a serial fashion. Osmat is a novel osmotically driven matrix system, which utilizes the hydrophilic polymers to swell, and gel in aqueous medium forming a semipermeable membrane in-situ releases from such a matrix system containing an osmogen could, therefore be modulated by the osmotic phenomenon. Conclusions The characteristics and opportunities of application of implantable mini osmotic pump, oral and special types of osmotic release and delivery systems of drugs was conducted, examples of such drugs registered on the world market were represented.