Comparative Analysis of Reconstitution and Solubility of Two Poly-L-Lactic Acid Fillers for Medical Applications.

OBJECTIVE

This study aimed to evaluate the reconstitution and solubility characteristics of two injectable poly L-lactic acid (PLLA) formulations, the next-generation injectable PLLA-LASYNPRO™ and a previous-generation PLLA (PLLA-SCA), through in vitro analysis.

METHODS

The study, conducted from 20 November to 11 December 2024, involved reconstituting PLLA-LASYNPRO™ in 5 mL saline solution and PLLA-SCA in 8 mL sterile water or saline (as specified in the instructions for use). Reconstitution processes were recorded using a 4K camera, and microscopic and sieve-based analyses were performed at various time points (1-120 min). The study used standardized methods for reconstitution, observation, and sample collection, including a light microscope and micrometric sieves.

RESULTS

PLLA-LASYNPRO™ exhibited rapid, uniform reconstitution, resulting in a homogeneous milky-white solution with no foam formation. In contrast, PLLA-SCA showed a two-phase mixture with foam formation, requiring more vigorous shaking. Over time, PLLA-LASYNPRO™ displayed gradual sedimentation, with no foam, while PLLA-SCA showed a progressive increase in foam volume and sedimentation. Microscopic analysis revealed consistent particle morphology, with PLLA-LASYNPRO™ particles being smaller and homogeneous, and PLLA-SCA exhibiting larger, irregular particles prone to aggregation. Sieve analysis showed that PLLA-LASYNPRO™ produced minimal sediment, whereas PLLA-SCA consistently produced sediment on both 71 µm and 200 µm sieves.

CONCLUSIONS

PLLA-LASYNPRO™ and PLLA-SCA display distinct reconstitution behaviors, with PLLA-LASYNPRO™ showing more consistent characteristics and fewer issues with foam and sedimentation. These differences may impact clinical applications and require consideration in treatment planning.