Clinical Studies Using Intranasal Therapies for Parkinson's Disease: A Review

Intranasal delivery is a method of administering medications through the nasal cavity. It offers several advantages, such as rapid absorption, bypassing first-pass metabolism, direct nose-to-brain transport and localized effects. These benefits make it a promising approach for drug delivery in Parkinson's disease, a progressive neurological disorder characterized by the degeneration of nerve cells in the brain. This review evaluates the efficacy and safety of intranasal delivery for Parkinson's disease treatment. Several studies on intranasal apomorphine reported rapid clinical response, improved UPDRS motor scores, tapping scores, and median Webster's scores, suggesting its effectiveness as a rescue therapy during "off" states. Intranasal recombinant erythropoietin was well tolerated and showed cognitive benefits. intranasal glutathione was safe and showed better bioavailability. Intranasal insulin improved cognitive performance without hypoglycemia, indicating a localized effect. Intranasal cholecystokinin and ipratropium bromide did not show significant benefits. Intranasal desmopressin is a safe and effective medication for nocturnal polyuria in Parkinson disease. Intranasal transplantation of neural stem cells is safe and is associated with functional improvement. Finally, Rivastigmine nasal spray offered better bioavailability and fewer side effects compared with conventional forms. The most common adverse effect was mild transient nasal or throat irritation. This review highlights the potential applications, efficacy, and side effects of various intranasal medications for Parkinson's disease and proposes using new interventions for future studies. The general benefits of nasal administration for Parkinson's disease treatment include localized effects, fewer side effects, faster onset of action, improved bioavailability, and enhanced therapeutic effectiveness.