Drug delivery systems have evolved from the first generation to the fifth generation dosage forms. The new approaches to drug delivery are based on the realization that optimum biological response occurs when the spatial placement and the temporal delivery of bioactive agents are optimized.
Parallel to the advances in drug delivery systems are the developments in the materials of formulation, especially polymers because their properties can be manipulated easily and the diffusion rates of drug molecules through polymers are very much less than the diffusion rates of the same molecules through water. The advent of biodegradable and biocompatible polymers has increased the versatility of polymers. Polymers have been used in various macromolecular architectures for the design of drug delivery systems, especially nanoparticles for targetable, modulated and self-regulated (fourth generation) and gene (fifth generation) delivery systems.
We have developed stealth hydrolyzable cross-linked PEG-MMA nanospheres capable of sustaining the release of naltrexone and anticancer drugs. Transmission electron micrograph showed a cross-linked core with polyethyleneglycol shell. Further, drug-loaded stealth PAMAM dendrimers have been investigated: a series of PEG conjugated PAMAM dendrimers with varying degrees of substitution of the dendrimer surface functional group by PEG were synthesized, characterized and used for encapsulation of an anticancer drug. IR spectra showed that many of the encapsulated drug molecules were located within the cavity of the dendrimer.
Acknowledgements: Supports from NIAAA/NIH: # 5 R21 AA13407-02, HU and W.M. Keck Foundation are gratefully acknowledged. This investigation was conducted in a facility supported by NCRR/NIH: #1 C06 RR14469-01
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