Subcutaneous Levodopa: A New Engine for the Vintage Molecule.

The management of Parkinson's disease (PD) continues to evolve with advancements in non-oral levodopa-based therapies aiming to provide continuous drug delivery (CDD). Such therapies address the challenges posed by the emergence of motor fluctuations, dyskinesias, and non-motor fluctuations (NMF) associated with oral levodopa administration and contributing to define the advanced stage of PD. The key focus of this review is placed on subcutaneous foslevodopa/foscarbidopa (Foslevodopa/foscarbidopa) infusion, showcasing its recent clinical availability and efficacy in providing continuous levodopa delivery. While providing an overview of the other non-oral levodopa-based CDD systems, such as intrajejunal levodopa-carbidopa infusion and levodopa-entacapone-carbidopa infusion, we highlight the current promising evidence for Foslevodopa/foscarbidopa to improve, for example, "on time" without troublesome dyskinesia and reducing "off time" in people with advanced PD. Additionally, Foslevodopa/foscarbidopa demonstrates potential in managing early morning off periods, sleep quality and other motor and non-motor symptoms. Moreover, other non-oral CDD options such as ND0612 and DIZ102/DIZ101 are discussed, with focus on their pharmacokinetics/pharmacodynamics, efficacy, and safety profiles. While these advancements present new therapeutic avenues, long-term observational studies are warranted to elucidate their impact on existing PD therapies. Overall, this review provides insights into the evolving landscape of non-oral CDD therapies and offers a pragmatic approach for their integration into clinical practice.