Pharmacotherapeutic Approaches of Parkinson's Disease

Parkinson disease is a very common neurodegenerative disease. Most of the drug classes discussed in this review generally acts on the dopaminergic system. Therefore, researchers are attempting to develop drugs which act on non-dopaminergic pathways downstream in the basal ganglia, which are generally involved in the pathophysiology of PD. Compounds that act on noradrenergic, serotinergic, glutamatergic, adenosine, opioid and cannabinoid pathways have been developed so far. Hence, the most preferential symptomatic treatment for PD is levodopa. Due to long-term use, levodopa causes motor complications including involuntary movements and response fluctuations leading to more preferential and cautious prescribing of levodopa. Dopamine agonists can be used as an alternative initial therapy to delay the onset of motor complications but this leads to more dopaminergic adverse events, poorer control of motor symptoms and increased cost. Once motor complications have been developed, adjuvant therapy with dopamine agonists can decrease off time and levodopa dose. Severe fluctuations which are not controlled by oral combination therapy can be controlled with subcutaneous apomorphine injections or infusions.