ABSTRACT

Many polymer based in situ forming implants are currently under development (1,2). The majority of these systems are based on combinations of polymers with hydrophobic or hydrophilic solvents. These solvents either stay associated with or leave the system after injection depending on the aqueous solubility of the solvent. Polylactic acid (PLA) Depot (PLAD) is a novel biodegradable sustained release system based on the combination of PLA with both hydrophilic and hydrophobic solvents. A unique characteristic of the system is its ability to solvate protein powders resulting in a low-viscosity solution that upon injection forms a soft depot that slowly releases the dissolved protein. The presence of hydrophilic solvents facilitates protein dissolution while the hydrophobic solvent solvate the nonwater soluble PLA. The main advantages of the PLAD system are ease of preparation and the ability to administer high drug doses in a volume less than 1mL.