Controlled release drug delivery systems capsules

Hydroxypropyl starch is a modified starch and has been used in combination with carrageenan in the production of soft capsules. " Hydroxypropyl starch has been used experimentally in hydrophilic matrices, where it was shown to be an effective matrix for tablets designed for controlled-release drug delivery systems. It has also been used experimentally in the production of hydrophilic matrices by direct compression. ... 

FIGURE 22.15 Pharmacokinetic parameters for the Spherazole CR tablet, 100 mg, compared with the Sporanc IR capsule. (Note Types A and B differed in levels of rate-controlling excipients.) (Adapted from Jacob, J. Gastroretentive, bioadhesive drug delivery system for controlled release of itraconazole pharmacokinetics of Spherazole CR in healthy human volunteers. Controlled Release Society 34th Annual Meeting and... 

Dissolution rate tests for tablets, capsules, suspensions, suppositories, or other dosage forms. Controlled-release dosage forms or drug delivery systems also should be monitored by appropriate testing methodology. 

Among newly developed colon-specific drug delivery systems, pressure-controlled delivery capsules (PCDCs) [161] can be mentioned. Their mechanism of action is based on the relatively strong peristaltic waves taking place in the colon and leading to an increased luminal pressure. They consist of a capsular-shaped suppositories coated with a water-insoluble polymer (ethyl cellulose). Once taken orally, PCDCs behave like an ethyl cellulose balloon, because the suppository base liquefies at body temperature. In the upper GI tract, PCDCs are not directly subjected to the luminal pressures since sufficient fluid is present in the stomach and small intestine. The reabsorption of water in the colon provokes an increase of the luminal content viscosity. As a result, increased intestinal pressures directly affect the system via colonic peristalsis. Consequently, PCDCs mpture and drug release in the colon take place. 

Novel drug delivery systems evolved over a period of time to improve patient compliance and optimize the dosage regimen without compromising the therapeutic efficacy. The foundations were laid in 1952, with the introduction of the first sustained-release capsule of Dexedrine. " Subsequently, several concepts originated, including prolonged, timed, and extended release and finally matured to controlled-release systems. 

The in-vivo controlled release of norgestrel from PCL capsules implanted in rats was reported by Pitt and Schindler (1980a). This study showed that a constant release rate of 8-10 micrograms/day/cm capsule could be attained over a period of292 days. This paper gives a valuable comprehensive review of the related literature concerning numerous other polymeric drug delivery systems. 

The preparation of cationic lipid nanoparticles containing a lipophilic drug and its encapsulation into an anionic polymer network by ionic interaction for use as an oral drug delivery system are reported. The lipid nanoparticles serve as the core of a capsule, which is produced from a semi-interpenetrating polymer network of sodium alginate and hydroxypropylmethylcellulose. Satisfactory drug release is achieved through control of the composition of the capsule material and environmental pH. 14 refs. 

Capsulation Controlled drug delivery system Sustained drug release... 

Despite the apphcation in drug delivery systems, the contribution of gelatin capsules to the control of soil-borne pests was also investigated." The gelatin capsule (gel cap) formulation of 1,3-dichloropropene (1,3-D) has been a new concept to reduce the environmental release, transport and hazard potential of the use of 1,3-D to control soil-bome diseases and nematodes. The biological efficacy of the 1,3-D gel cap formulation under laboratory and greenhouse trial conditions has been evaluated. Results showed that 1,3-D gel cap application was as effective as 1,3-D liquid injection treatment on tomato and crops. 

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