Sustained release composition

Alderman DA. Sustained release compositions comprising Hydroxypropyl cellulose ethers. United States Patent No. 4,704,285 1987. 

Sivaramakrishnan, K. N., 1991, Sustained release composition for macromolecular proteins, W091/05548 (Pitman-Moore, Inc., assignee). 

A. (1990b). Effect of lipid composition on the in vivo integrity of doxorubicin-containing liposomes. Two pathways for sustained release of doxorubicin. Submitted. 

Factors known to influence the clearance of drugs from interstitial sites, following extravasation or parenteral interstitial or transepithelial administration, include size and surface characteristics of particles, formulation medium, the composition and pH of the interstitial fluid, and disease within the interstitium. Studies indicate that soluble macromolecules smaller than 30 nm can enter the lymphatic system, whereas particulate materials larger than 50 nm are retained in the interstitial sites and serve as a sustained-release depot. The use of lipids or an oil in a formulation and the presence of a negative surface charge all appear to... 

The incorporation of fatty acids into a polyanhydride chain was investigated using two fatty acids lithocholic acid and ricinoleic acid. Lithocholic acid containing polyanhydrides (Figure 2) were prepared by two step synthesis. Polyanhydrides reached molecular weights of 21000-115000 Da, depending on the polymer composition. Release of model drugs from these polymers showed sustained release of 5FU for almost 3 weeks and triamcinolone for 4 weeks (22). 

Fathy M, Safwat SM, El-Shanawany SM, Tons SS, Otagiri M. Preparation and evaluation of beads made of different calcium alginate compositions for oral sustained release of tiaramide. Pharm Dev Tech 1998 3(3) 355-364. 

Membrane permeability is a function of thickness, porosity, tortuosity, and composition. Therefore, film formation is a substantial determinant of drug release rate through a sustained release film coat. Drug release through an insoluble polymeric membrane produced from a latex dispersion will decrease with the evolution of film... 

Hydrogels formed by PEO block copolymers have previously been proposed as sustained release matrix [85,86], The a-CD-PEO hydrogel delivery system differs in that the gelation relies on the formation of a polymer inclusion complex induced by the PEO-threaded CDs. The properties of the supramolecular hydrogel can be fine-tuned with the composition, molecular weight and chemical structure of the polymer or copolymers. 

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