Drug release leakage

Serum-stable formulations with minimal leakage at physiological pH and rapid drug release at pH 5.0-5.5 can be easily prepared by inserting a hydrophobicaUy modified iV isopropylacrylamide/ methacrylic acid copolymer (poly(NIPAM-co-MAA)) in the Hpid bilayer of sterically stabilized liposomes. The present chapter describes polymer synthesis, as well as the preparation, and characterization of large unilamelar pH-sensitive vesicles. 

Particle size change, crystalline form change, viscosity, loss of consistency and flow characteristics (caking, coalescence, bleeding), drug release rate change In-vitro release rate leakage peel and adhesive forces... 

Liposomes The pH-sensitive liposomes so developed were able 56 to overcome the three main problems associated with liposomes, i.e., low stability, slow drug release and accumulation In liver/spleen. The ECM targeting liposome could prevent protein adsorption and drug leakage from liposome due to the biotin 2-PEG cross-linker located on interface of liposome. The uptake within the cancer cell is improved and could actively target tumor in tumor ECM to increase tumor accumulation. Also the drug release was enhanced at low pH, thus the potential bioavailability and drug resistance problem are also avoided. 

Electrically controlled drug release, including that of insulin, has also been investigated for polymer gels of DMAPAA [93]. When the electric field is applied to the PDMAPAA gel, insulin leaks from the gel at a constant rate, whereas the leakage ceases by stopping the applied field. 

Liposomes that remain impermeable to their contents cannot release these compounds without interaction with cells. This cellular interaction occurs by three different mechanisms (Fig. 11) [57], Of these, fusion and adsorption usually involve drug leakage, whereas effective drug delivery results from en-docytosis. 

Damage to connective caused by leakage of elastases leads to damage associated with inflammatory diseases, such as pulmonary emphysema, adult respiratory distress syndrome, septic shock, cystic fibrosis, carcinogenesis, chronic bronchitis, and rheumatoid arthritis. Compounds that directly inhibit elastase or its release from human neutrophils are of enormous pharmaceutical and cosmetological interest in the development of new anti-inflammatory drugs. A possible source for elastase inhibitors are the medicinal Asteraceae and Droseraceae, particularly those used as traditional medicine in Asia. 

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