Background: Both biodegradable and non-biodegradable peptide-loaded implants are
already developed for the long-term treatment of patients, thereby reducing the frequency of drug
administration. To further improve peptide formulation, extending the scope of implant-based drug
delivery systems towards other polymers and processing techniques is highly interesting.
Objective: In this study, as a proof-of-principle, the feasibility of hot-melt processing of a peptide
active pharmaceutical ingredient was assessed by developing a non-biodegradable poly(ethylenevinyl
acetate) (33% VA) implant loaded with 20% (w/w) buserelin acetate.
Methods: Cross-sectional implant characterization was performed by Raman microscopy. The
stability of buserelin acetate in the polymeric matrix was evaluated for 3 months under ICH
stability conditions and the quantity as well as the degradation products analyzed using LC-UV
methods. An in vitro dissolution study was performed as well and buserelin acetate and its
degradants analyzed using the same chromatographic methods.
Results: No significant quantities of buserelin acetate-related degradation products were formed
during the hot-melt preparation as well as during the stability study. Together with the consistent
buserelin acetate assay values over time, chemical peptide stability was thus demonstrated. The in
vitro buserelin acetate release from the implant was found to be diffusion-controlled after an initial
burst release, with stable release profiles in the stability study, demonstrating the functional
stability of the peptide implant.
Conclusion: These results indicate the feasibility of preparing non-biodegradable peptide-loaded
implants using the hot-melt production method and may act as a proof of principle concept for
further innovation in peptide medicinal formulations.