Self-regulated release

Modulated/self-regulated release the system delivers the necessary amount of dmg under the control of the patient. 

The regulations also address the need to ensure that drug information provided by pharmaceutical firms is truthful, balanced, and accurately communicated. As such, it must be consistent with the indications for use and the established performance and limitations. In Europe, the directives do not impose a specific requirement to review advertising or promotional material before it is released. Acceptable standards may be achieved via voluntary codes of practice and self-regulation. However, national authorities must monitor such material and should have the power to act where the need arises. In the U S, the F DA must vet advertising and promotional material before it is released. 

G Albin, TA Horbett, BD Ratner. Glucose-sensitive membranes for controlled release of insulin. In J Kost, ed. Pulsed and Self-Regulated Drug Delivery. Boca Raton, FL CRC Press, 1990, pp 159-185. 

With the advance of pharmaceutical science, it has been recognized that constant release is not the only way to maximize drug effectiveness and minimize side effects and that the assumptions used for constant release rate sometimes fail due to physiological conditions. From this perspective, zero-order dmg release is not acceptable in all cases and externally modulated or self-regulating dmg delivery systems have been developed as novel approaches to deliver dmgs as required. To realize such dmg delivery systems, it is important to constmct a system where the dmg itself senses environmental stimuli and responds appropriately to control the dmg release. For this purpose, the phase transition polymers have been intensively exploited as a candidate material during last decade [21]. 

Makino K, Mack EJ, Okano T, Kim SW. A microcapsule self-regulating delivery system for insulin. J Controlled Release 1990 12 235-239. 

Figure 16.8 Self-regulated insulin release membrane made of poly(N,N -diethylaminoethyl methacrylate) hydrogel membrane. As glucose enters the membrane, glucose oxidase entrapped inside the membrane transforms glucose into gluconic acid, which in turn reduces the pH of the hydrogel membrane. This causes swelling of the membrane followed by more release of insulin through the membrane...

Further development of the self-regulating insulin delivery system has utilized the complex of glycosylated insulin-concanavalin A, which is encapsulated inside a polymer membrane. As glucose penetrates into the system, it activates the release of glycosylated insulin from the complex for a controlled release from the system (Fig. 28). The amount of insulin released is thus self-regulated by the concentration of glucose that has penetrated into the insulin delivery system. 

Self-regulated insulin device. Because replacement of insulin in diabetic patients by simple injection is not able to prevent the serious consequences of the disease [37], considerable effort is currently being devoted to the development of devices that can release insulin in response to external glucose concentration. 

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