TABLE 2.

List of repurposed drugs for PD.

Drug name	Earlier indication	Repurposed	References
Amantadine	Anti influenza	As a mild glutamate receptor antagonist, it is used to treat Parkinson’s disease (PD), boosting dopamine and preventing its reuptake	Lee and Kim, (2016)
Nilotinib	Tyrosine kinase Abl inhibitors, used to treat chronic myeloid leukaemia	It was found that α-synuclein build-up and increased α-synuclein expression are both signs of Abl activation in neurodegeneration. Nilotinib accelerates α-synuclein breakdown by preventing Abl phosphorylation	Pagan et al. (2016)
Zonisamide	Antiepileptic drug	Increased dosages revealed a reduction in intracellular dopamine. Both motor and non-motor symptoms have responded well to this medication, but its exact mode of action is yet unknown	Fox et al. (2018)
Methylphenidate	Central nervous system stimulant used to treat attention-deficit hyperactivity disorder	This medication has been found in numerous studies to be beneficial in lowering PD-related gait problems and non-motor symptoms	Devos et al. (2013)
Exenatide	Glucagon-like peptide-1 (used for type 2 diabetes)	It has proven to be capable of neuroprotection and beneficial neuroplastic change, which can stop or reduce the progression of the disease. It can cross the blood-brain barrier and offers neuroprotection by turning on GLP-1 receptors	Jankovic, (2017)