Weekly Injectable Treatment May Transform Parkinson’s Disease Management: Study

In a recent study published in Drug Delivery and Translational Research, Professor Sanjay Garg from the Centre for Pharmaceutical Innovation, University of South Australia, and his team explored the development of an in-situ forming implant system designed to provide sustained delivery of levodopa and carbidopa—two standard drugs used to treat Parkinson’s disease symptoms. The primary objective was to alleviate the burden of frequent oral dosing and improve medication adherence among patients.

The study led to the following findings:

• The formulation uses biocompatible polymers—poly-lactic-co-glycolic acid (PLGA 50:50) and Eudragit L-100—to create a biodegradable implant after injection.
• The optimized composition contains 26% PLGA and 6% Eudragit L-100, enabling sustained drug release over seven days.
• Laboratory studies showed an initial release of approximately 34% of levodopa and 37% of carbidopa in the first 24 hours.
• By the end of seven days, cumulative release reached 92% for levodopa and 81% for carbidopa.
• The formulation exhibited low viscosity, facilitating easy injection through a standard 22-gauge needle.
• Syringeability tests showed that the required injection force was within acceptable limits, supporting ease of administration.
• In-vitro and ex-vivo release profiles showed a strong correlation, with coefficients of 0.91 for levodopa and 0.90 for carbidopa.
• Degradation studies indicated that about 82% of the implants disintegrated within seven days.
• Complete degradation of the implant occurred within 13 days, demonstrating temporary in-body presence.
• Pharmacokinetic modeling predicted an AUC₀–∞ of 26,505.5 ng/ml.
• The peak plasma concentration (Cmax) was estimated at 399.3 ng/ml, occurring 24 hours after injection.
• The drug concentrations remained within therapeutic levels throughout the one-week period.

The researchers highlighted that this in-situ forming implant system offers a simple, cost-effective, and scalable approach to long-acting drug delivery for Parkinson’s disease. By reducing the dosing frequency, the new formulation has the potential to significantly improve medication adherence and alleviate the treatment burden on elderly patients.

The researchers concluded, "If further validated in clinical trials, this weekly injectable therapy could mark a significant step forward in Parkinson’s disease management, offering patients a more convenient and consistent treatment option."

Reference:

Nakmode, D.D., Abdella, S., Song, Y. et al. Development of an in-situ forming implant system for levodopa and carbidopa for the treatment of parkinson’s disease. Drug Deliv. and Transl. Res. (2025). https://doi.org/10.1007/s13346-025-01892-y