Synthesis of monomethoxypolyethyleneglycol-cholesteryl ester and effect of its incorporation in liposomes.

The objective of the present study was to synthesize monomethoxypolyethyleneglycol-5000 cholesteryl ester [PEG-CH] as a cost-effective substitute for polyethyleneglycol-phosphatidylethanolamine and to evaluate the influence of its incorporation in liposomal bilayers for surface modification. PEG-CH was synthesized and characterized by infrared (IR), proton nuclear magnetic resonance spectroscopy ((1)H NMR), and differential scanning calorimetry (DSC) studies. Influence of incorporation of PEG-CH in liposomes was evaluated on various parameters such as zeta potential, DSC, and encapsulation efficiency of a hydrophilic drug pentoxyfylline.

Block copolymer micelles: preparation, characterization and application in drug delivery.

Block copolymer micelles are generally formed by the self-assembly of either amphiphilic or oppositely charged copolymers in aqueous medium. The hydrophilic and hydrophobic blocks form the corona and the core of the micelles, respectively. The presence of a nonionic water-soluble shell as well as the scale (10-100 nm) of polymeric micelles are expected to restrict their uptake by the mononuclear phagocyte system and allow for passive targeting of cancerous or inflamed tissues through the enhanced permeation and retention effect.

Enhancement of oral bioavailability of poorly water-soluble drugs by poly(ethylene glycol)-block-poly(alkyl acrylate-co-methacrylic acid) self-assemblies.

The purpose of the present study was to determine whether pH-sensitive polymeric micelles could improve the oral bioavailability of a poorly water-soluble drug. Poly(ethylene glycol)-block-poly(alkyl acrylate-co-methacrylic acid)s were synthesized by atom transfer radical polymerization and the composition of the ionizable polymer block was varied to maximize drug loading and pH-dependent release. Poorly water-soluble model drugs viz.

Novel pH-sensitive supramolecular assemblies for oral delivery of poorly water soluble drugs: preparation and characterization.

The objective of the present study was to synthesize novel pH-sensitive block copolymers forming supramolecular assemblies and to explore their potential as poorly water-soluble drug carriers for oral delivery. Diblock copolymers of polyethylene glycol and t-butyl methacrylate (tBMA), ethyl acrylate (EA) or n-butyl acrylate (nBA) were synthesized by atom transfer radical polymerization (ATRP). The pH-sensitive polymers obtained by hydrolysis of t-butyl groups were characterized for aggregation behaviour.

Sterically stabilized etoposide liposomes: evaluation of antimetastatic activity and its potentiation by combination with sterically stabilized pentoxifylline liposomes in mice.

Cytotoxic activity of chemotherapeutic agents can be enhanced by site-specific delivery or by combination with other less toxic agents. In the present study, enhancement in the antimetastatic activity of etoposide (ETP) by encapsulation in sterically stabilized liposomes was evaluated in the murine experimental B16F10 melanoma model. Further, potentiation of its antimetastatic activity by combination with pentoxifylline (PTX) solution or sterically stabilized PTX liposomes was evaluated in the same animal model.