Table 6 Some common drugs used in PD therapy, their mode of actions and effects and disadvantages

L-DOPA

Dopamine agonist

Increases dopamine concentrations

Nausea, vomiting, low blood pressure, restlessness, drowsiness.

[324, 325]

Selegiline

MAO-B inhibitor

Maintains L-DOPA levels

Dizziness, dry mouth, insomnia, muscle pain, rash, nausea, constipation, severe headache, tachycardia, arrhythmia, hallucinations, chorea, or difficulty in breathing.

[326]

Creatine

Boosts mitochondrial function

Antioxidant, prevents MPTP-induced neuronal damage

Nausea, stomach pain, diarrhea, muscle cramps; difficult breathing; swelling of face, lips, tongue, or throat, and weight gain.

[327]

Bromocriptine, Apomorphine, Pramipexole, Rropinirole

Dopamine agonist

Increases dopamine levels

Drowsiness, nausea, vomiting, dry mouth, dizziness, leg swelling, and feeling faint upon standing, drop in blood pressure, confusion, hallucinations, or psychosis.

[328]

Entacapone and tolcapone

preventing the breakdown of dopamine

prolongs the effects of L-DOPA

Hepatotoxic, nausea, diarrhea, orthostatic hypotension, urine discoloration and dizziness, mitochondrial dysfunction,

[329]

Amantidine

Activate dopamine synthesis

Increases dopamine levels

Blurred vision, confusion, difficult urination, dizziness, fainting seeing, and hearing, swelling of the hands, feet, or lower legs.

[330]

Rofecoxib

Inhibit COX-2

Prevents inflammation

Back pain, diarrhea, dizziness, headache, heartburn, and loss of energy or weakness, nausea, stuffy or runny nose, swelling of legs and feet, blurred vision, constipation.

[331]

ACP-103

(Pimavanserin)

Blocks serotonin receptors

Decrease levodopa-associated complications

Hyperprolactinemia, menstrual and sexual dysfunction, akathisia, distressful motor disturbance, restlessness

[332]

GM1 gangliosides

Dimerization of tyrosine kinase A and increases neurotropic factors

Increases dopamine

Not known

[333]

Quetiapine

Blocking of the dopamine type 2 (D2) and serotonin type 2 (5-HT2) receptors

Reduce psychosis and/or agitation

Agitation, dizziness, tremor, anxiety, hypertonia, abnormal dreams, dyskinesia, involuntary movements, confusion, amnesia, hyperkinesia, increased libido, abnormal gait, myoclonus, apathy, ataxia, hemiplegia, aphasia, buccoglossal syndrome

[334]

Ubiquinone or coenzyme Q10

Improves mitochondrial function

Antioxidant, slows disease progression in early-stages

Lower blood pressure, hemorrhage, skin itching, nausea, vomiting, headache or migraines, abnormal breathing, back pain, bronchitis, changes in attention, chest pain, constipation, coughing, diarrhea, dizziness, fainting, falling, fatigue, hearing loss, heart attack, indigestion, insomnia, irritability, loss of appetite, low energy, muscle pain, night sweats, respiratory tract infection, sore throat, urinary infection etc.

[335, 336]

S-Adenosyl-methionine (SAM)

Methylates phospholipid and increase nerve-cell communication

Improves dopamine transmission, decreases depression

Gastrointestinal disorders, dyspepsia, and anxiety.

[337]

Entacapone, tolcapone

COMT inhibitors

Inhibit DA breakdown

Diarrhea, nausea, sleeps disturbances, dizziness, urine discoloration, abdominal pain, low blood pressure, hallucinations.

[338]