Table 1: Drugs used in PD and ADHD and their side effects.

Drugs for PD [7]MechanismSide effects

L-DOPA and CarbidopaA precursor to dopamine, combined with carbidopa, which blocks aromatic amino acid decarboxylaseNausea, vomiting, insomnia, psychosis, hallucinations, hypotension, arrhythmia, somnolence, nightmares
Selegiline, Rasagiline, SafinamideMonoamine oxidase B inhibitors (MAO-B); increase the synaptic availability of dopamine; safinamide also inhibits glutamate releaseAbnormal movements, dizziness, nausea, vomiting, dry mouth, persistent diarrhoea, constipation, weight loss
Entacapone and TolcaponeCatechol-O-methyltransferase inhibitors (COMT); Increase CNS L-DOPA bioavailability by decreasing peripheral L-DOPA metabolismDyskinesia, nausea, sleep disturbances, arterial hypotension, liver toxicity, vomiting, dizziness
Pramipexole,
Ropinirole,
Rotigotine,
Apomorphine
Dopamine agonists; stimulate the action of dopamine at postsynaptic receptorsNausea, dyskinesia, hallucinations, sleepiness, sleep attacks, confusion, ankle oedema, orthostatic hypotension, constipation
Trihexyphenidyl and
Benztropine
Anticholinergics; block acetylcholine in the striatumDry mouth, urine retention, hallucinations, dry eyes, constipation, blurred vision, loss of memory, and confusion, somnolence, dizziness
AmantadineIs an antagonist of the NMDA type glutamate receptor and also stimulates dopamine releaseOedema, hallucinations, insomnia, confusion

Drugs For ADHD [8]MechanismSide effects

MethylphenidateInhibits reuptake of dopamine and norepinephrineAnxiety, agitation, insomnia, decrease appetite, weight loss, irritability, hypertension, headache, stomach pain, numbness
AmphetaminesInhibit reuptake of dopamine and norepinephrineDecrease appetite, weight loss, irritability, hypertension, anxiety, agitation, nervousness, depression
AtomoxetineSelective norepinephrine reuptake inhibitorDry mouth, sedation, fatigue, increased sweating, hypertension, decrease appetite, dizziness, drowsiness, insomnia, itching, impotence, unusually fast or irregular heartbeat, increased suicidality
Imipramine, Nortriptyline, Amitriptyline, DesipramineTricyclic antidepressants; Inhibit reuptake of dopamine and norepinephrineDry mouth, sweating abnormalities, drowsiness/sedation, increased suicidality
Clonidine and GuanfacineAgonists of the -2 and -2A adrenergic receptors in the prefrontal cortexDry mouth, fatigue, dizziness, profound withdrawal effects