A protocol for assay of poly(lactide-co-glycolide) in clinical products

Poly(lactide-co-glycolide) (PLGA) is the key component of long acting drug products responsible for providing sustained release in a controlled manner. The objective of the current study was to develop and validate an analytical protocol to determine key properties of PLGA used in commercial long-acting drug products. Procedures to isolate PLGA from commercial products have been established and the key properties of PLGA, such as polymer molecular weight, lactide:glycolide (L:G) ratio, and nature of polymer end-cap, have been determined. Identification of the polymer end-cap was confirmed by using two PLGA polymers with acid and ester end-caps. Trelstar(®) and Risperdal Consta(®) were chosen as model products. The calculated L:G ratios of PLGA used in Trelstar(®) and Risperdal(®) are 52:48 and 78:22, respectively. PLGAs from both Trelstar(®) and Risperdal Consta(®) possess ester end-caps. Since the properties of specific PLGA in clinically used formulations are not readily available, this protocol will be useful in developing PLGA-based long acting drug products.