Use of nonionic block copolymers in vaccines and therapeutics.

Nonionic block copolymers synthesized from ethylene oxide and propylene oxide were developed specifically for use as surfactants. Because the sizes and relative positions of the hydrophobic polyoxypropylene (POP) and hydrophilic polyoxyethylene (POE) blocks can be altered during synthesis, copolymers with significantly different surfactant characteristics can be produced. Copolymers of this type are currently used as excipients in a wide variety of pharmaceutical products where they act as emulsifying, wetting, thickening, stabilizing, and dispersing agents. Copolymers with unique physicochemical properties have recently been developed through the use of new manufacturing and purification techniques, and these copolymers are being used as drug-active and drug-delivery components. In this review, we summarize the current status of these new copolymers in terms of research and product development. This includes the use of new, high molecular weight copolymers as vaccine adjuvants and as vaccine-delivery vehicles. The use of purified, pharmaceutical-grade copolymers as anti-infectives and as antibiotic-delivery systems for the treatment of established bacterial and viral infections is also reviewed. These novel uses for copolymers are significantly different from the excipient uses common to this type of product and demonstrate the widespread utility of synthetic surfactant polymers.