Non-Oral Drug Delivery in Parkinson's Disease: Current Applications and Future

Parkinson's disease (PD) is a type of movement disorder that affects the ability to perform daily activities. It is considered that 1 million people in the U.S. and more than 10 million people worldwide live with PD. It is a chronic and progressive disease, so symptoms worsen over the time. Patients experience motor symptoms such as tremors, stiffness and slow motion, and non-motor symptoms such as sleep problems, constipation, anxiety, depression and fatigue. Dopaminergic drugs are critical for treating motor symptoms in PD. Levodopa (L-DOPA) is the "gold standard" medication for the control of motor symptoms. Because of the progression of the disease, the effectiveness of oral L-DOPA decreases over time and motor fluctuations such as "delayed ON", "no ON" and unpredictable "ON-OFF" periods appear. These motor fluctuations affect the quality of life of the patient at a high rate and the patient has problems in fulfilling his daily morning routines. Gastrointestinal (GI) problems, as the common non-motor symptom, are the most important cause of motor fluctuations that occur because of inadequate oral treatment with the progression of PD. When oral treatments are not sufficient, non-oral treatments that are not affected by GI problems are required. In this review, the treatment strategies, developed and approved non-oral drug delivery systems in the early and advanced stages of PD are emphasized.