|PLGA Microspheres-1 μm
|PLGA Microspheres-2 μm
|PLGA Microspheres-5 μm
|PLGA Microspheres-10 μm
|PLGA Microspheres-20 μm
|PLGA Microspheres-25 μm
|PLGA Microspheres-30 μm
|PLGA Microspheres-40 μm
Poly(lactic-co-glycolicacid) (PLGA), which consists of two monomers - lactic acid and hydroxyacetic acid - randomly polymerized, is a degradable functional polymeric organic compound with good biocompatibility, non-toxicity, good capsule- and film-forming properties. Since its degradation degree varies with the monomer ratio, it is widely used in slow and controlled release formulations, i.e., by changing the ratio of lactic acid to glycolic acid, the release rate of drug molecules in PLGA microspheres formulations can be changed. Among them, PLGA microspheres can be used as carriers for protein and enzyme drugs.
The two main mechanisms driving the drug release from PLGA microspheres are diffusion and degradation/erosion. For PLGA microspheres, drug release is divided into two phases. In the first phase, the molecular weight decreases rapidly with minimal mass loss, while in the second phase, the opposite is true. This suggests that PLGA particle degradation involves a multiphase mechanism and that drug release is mainly supported by diffusion rather than polymer degradation.
PLGA is a typically bulky and aggressive biopolymer, and therefore water can easily penetrate the polymer matrix to form pores and thus degradation occurs throughout the microspheres.
Drugs, including many small molecules, are soluble in polymer solutions and can be encapsulated by simply co-solubilizing with the polymer, which is the most common method.
For water-soluble salts of small molecule drugs, encapsulation efficiency can be improved by converting them to hydrophobic forms, for example by complexation with ionic surfactants or conversion to the corresponding free acid or free base forms. Alternative methods include suspension of solid particles in polymer solutions; or relatively high drug loading and reproducible sustained release profiles can be achieved by using oil-in-water (W/O/W) solvent evaporation (double emulsion) methods with controlled smaller internal aqueous phase volumes, lower preparation temperatures and suitable pH values for the external phase.