Table 1.

Current treatments of Parkinson’s disease.

Group of treatment	Name of medicine	Pharmaceutical names	Mechanism of action	Drawbacks	Ref.
increase or substitute for dopamine	Carbidopa-levodopaa.	Lodosyn-levodopa	Levodopa converted to dopamine, carbidopa protect levodopa breakdown	Lightheadedness, nausea, dyskinesia	(Kell et al., 2017; Haddad et al., 2018; Lau et al., 2018)
	Duopa therapya.	Duopa	Delivers the medicine in the gel, reduces motion fluctuations and movement disorders	The tube fall out, and infections, blockage in the tube	(Chaudhuri et al., 2016; LeWitt, 2016)
	Dopamine agonistsa.	Requip, Mirapex, Neupro	Similar effects as dopamine	Hallucinations, sleepiness, and compulsive behaviors	(Pahwa and Lyons, 2009; Kulisevsky and Pagonabarraga, 2010; Yu and Fernandez, 2017)
		Apomorphine	Intermittent subcutaneous injections treat the motor symptoms of PD	Hallucinations, sleepiness, and compulsive behaviors	(Patel et al, 2017; Antonini and Nitu, 2018)
	MAO B inhibitorsa.	rasagiline, safinamide, selegiline,	Prevent the breakdown of brain dopamine	Nausea, insomnia,	(Dezsi and Vecsei, 2017; Binde et al., 2018; Szökő et al., 2018)
	COMT inhibitorsb	Comtan, Tasmar	Block the enzyme that breaks down dopamine;	Risk of serious liver damage, diarrhea, dyskinesia	(Schlesinger and Korczyn, 2016; Katsaiti and Nixon, 2018; Silva et al., 2020)
	Anticholinergb	Cogentin, trihexyphenid-yl	Used as monotherapy or combination regimen, they work better on tremors	Impaired memory, hallucinations, dry mouth, and impaired urination.	(Nishtala et al., 2016; Mishima et al., 2018; Morrow et al., 2018; Hong et al., 2019)
	Amantadineb	Amantadine	short-term relief of mild symptoms, control involuntary movements	Ankle swelling, skin purple mottling, or hallucinations	(Wolf et al., 2010; Kim et al., 2018)
	Creatineb	Creatine	Energy compound that exerts neuroprotective effects	Weight gain, impairment of renal function	(Xiao et al., 2014; Duarte-Silva et al., 2018; Marques and Wyse, 2019)
Surgical procedures	Deep brain stimulationb	DBS	Send electrical pulses to the patient’s brain and reduces the symptoms of PD	Infection, brain hemorrhage or stroke.	(Follett et al., 2010; Lee et al., 2018)
Gene therapyc	Gene therapy	GAD, GABA	Alter local neurotransmitters or neurotrophic factors in the basal	Clinical results have been less encouraging	(Bartus et al., 2014)
Immunotherapyc	Immunotherapy	α-syn immunotherapies	Using antibodies against misfolded α-synuclein	Induction of Th17 cell-mediated inflammatory autoimmunity,	(George and Brundin, 2015)
Cell transplantationc	Embryonic stem cells	Fetal mesencephalic tissue, stem cell	Introducing new dopamine cells into the brain of PD	Unacceptable graft-induced dyskinesia	(Normile, 2018)

^aStandard therapeutic agents.

^bAlternative therapeutic agents.

^cTherapeutical agents under investigation.