Drugs for Parkinson’s disease MCQs With Answer is a focused study resource designed for B. Pharm students to master antiparkinsonian pharmacology. This introduction covers core topics: Parkinson’s disease pathophysiology, levodopa therapy, peripheral decarboxylase inhibitors (carbidopa), COMT inhibitors (entacapone, tolcapone), MAO-B inhibitors (selegiline, rasagiline), dopamine agonists, anticholinergics, amantadine, side effects, drug interactions, and motor complications such as wearing-off and dyskinesia. Emphasis on mechanisms, kinetics, adverse effects, and clinical decision-making prepares you for exams and practice. Keywords: Parkinson’s disease, levodopa, dopamine agonists, MAO-B inhibitors, COMT inhibitors, anticholinergics, pharmacology, B. Pharm, MCQs. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. What is the primary mechanism of action of levodopa in Parkinson’s disease?
- Direct stimulation of dopamine receptors
- Conversion to dopamine by aromatic L-amino acid decarboxylase (AADC) in the brain
- Inhibition of monoamine oxidase B
- Blocking dopamine reuptake
Correct Answer: Conversion to dopamine by aromatic L-amino acid decarboxylase (AADC) in the brain
Q2. Why is carbidopa co-administered with levodopa?
- To inhibit COMT in the brain
- To block central dopamine receptors
- To inhibit peripheral decarboxylation of levodopa and reduce peripheral side effects
- To enhance gastric absorption of levodopa
Correct Answer: To inhibit peripheral decarboxylation of levodopa and reduce peripheral side effects
Q3. Which statement best explains the “wearing-off” phenomenon in patients on levodopa?
- Development of tolerance in dopamine receptors only
- Short plasma half-life of levodopa and progressive loss of nigrostriatal neurons leading to motor fluctuations
- Excessive central dopamine storage
- Immune-mediated neutralization of levodopa
Correct Answer: Short plasma half-life of levodopa and progressive loss of nigrostriatal neurons leading to motor fluctuations
Q4. Which drug is associated with potentially fatal hepatotoxicity and requires liver function monitoring when used for Parkinson’s disease?
- Entacapone
- Tolcapone
- Selegiline
- Pramipexole
Correct Answer: Tolcapone
Q5. What is the main pharmacological action of MAO-B inhibitors like selegiline and rasagiline in Parkinson’s treatment?
- Enhance peripheral levodopa decarboxylation
- Inhibit dopamine breakdown in the brain by selectively blocking monoamine oxidase B
- Directly activate D1 receptors only
- Block central glutamate receptors
Correct Answer: Inhibit dopamine breakdown in the brain by selectively blocking monoamine oxidase B
Q6. Combining MAO-B inhibitors with which class of drugs increases risk of serotonin syndrome?
- SSRIs (selective serotonin reuptake inhibitors)
- Anticholinergics
- COMT inhibitors
- Beta-blockers
Correct Answer: SSRIs (selective serotonin reuptake inhibitors)
Q7. Which dopamine agonist has high affinity for D3 receptors and is primarily renally excreted?
- Ropinirole
- Pramipexole
- Bromocriptine
- Apomorphine
Correct Answer: Pramipexole
Q8. Which antiparkinsonian drug has antiviral origins and may cause livedo reticularis and ankle edema?
- Amantadine
- Trihexyphenidyl
- Entacapone
- Selegiline
Correct Answer: Amantadine
Q9. Which class of drugs is most useful for predominant tremor in young Parkinson’s patients?
- Anticholinergics (e.g., trihexyphenidyl)
- COMT inhibitors
- MAO-B inhibitors
- Peripheral decarboxylase inhibitors alone
Correct Answer: Anticholinergics (e.g., trihexyphenidyl)
Q10. COMT inhibitors like entacapone primarily act by:
- Increasing MAO-B activity
- Inhibiting catechol-O-methyltransferase to prolong levodopa plasma half-life
- Blocking dopamine receptors peripherally
- Enhancing renal excretion of levodopa
Correct Answer: Inhibiting catechol-O-methyltransferase to prolong levodopa plasma half-life
Q11. Which strategy helps reduce levodopa-induced motor fluctuations by providing continuous dopaminergic stimulation?
- Intermittent high oral doses of levodopa
- Levodopa–carbidopa intestinal gel infusion or continuous subcutaneous apomorphine infusion
- Adding high-dose vitamin B6
- Using only anticholinergics
Correct Answer: Levodopa–carbidopa intestinal gel infusion or continuous subcutaneous apomorphine infusion
Q12. Impulse control disorders (gambling, hypersexuality) are most commonly associated with which PD drug class?
- COMT inhibitors
- Anticholinergics
- Dopamine agonists (e.g., pramipexole, ropinirole)
- MAO-B inhibitors
Correct Answer: Dopamine agonists (e.g., pramipexole, ropinirole)
Q13. Which combination is contraindicated due to risk of hypertensive crisis?
- Levodopa plus peripheral decarboxylase inhibitor
- Levodopa with nonselective MAO inhibitors (nonselective MAOIs)
- Selegiline with rasagiline
- Entacapone with tolcapone
Correct Answer: Levodopa with nonselective MAO inhibitors (nonselective MAOIs)
Q14. Inhibition of COMT decreases formation of which metabolite of levodopa?
- 3-O-methyldopa (3-OMD)
- Dopamine
- Homovanillic acid (HVA)
- Noradrenaline
Correct Answer: 3-O-methyldopa (3-OMD)
Q15. Which drug is preferred for acute drug-induced parkinsonism caused by antipsychotics?
- Levodopa
- Trihexyphenidyl (anticholinergic)
- Selegiline
- Entacapone
Correct Answer: Trihexyphenidyl (anticholinergic)
Q16. Which dopamine agonist is an ergot derivative with risk of fibrotic valvular heart disease?
- Pramipexole
- Ropinirole
- Bromocriptine
- Rotigotine
Correct Answer: Bromocriptine
Q17. The “on–off” phenomenon in advanced Parkinson’s disease is primarily related to:
- Anticholinergic overdose
- Rapid and unpredictable swings in central dopaminergic stimulation due to levodopa pharmacokinetics and disease progression
- Excessive COMT inhibition
- Peripheral neuropathy
Correct Answer: Rapid and unpredictable swings in central dopaminergic stimulation due to levodopa pharmacokinetics and disease progression
Q18. High-protein meals reduce the clinical response to levodopa mainly because:
- Protein enhances peripheral decarboxylation of levodopa
- Amino acids compete with levodopa for transport across the gut and BBB
- Proteins increase levodopa renal clearance
- Protein induces hepatic enzymes that metabolize levodopa
Correct Answer: Amino acids compete with levodopa for transport across the gut and BBB
Q19. Which imaging modality helps differentiate Parkinson’s disease from essential tremor by assessing presynaptic dopaminergic terminals?
- MRI
- DaTscan (dopamine transporter SPECT)
- CT scan
- Plain X-ray
Correct Answer: DaTscan (dopamine transporter SPECT)
Q20. Orthostatic hypotension as an adverse effect is most commonly seen with which antiparkinsonian agents?
- MAO-B inhibitors only
- Dopamine agonists and levodopa
- Anticholinergics alone
- COMT inhibitors exclusively
Correct Answer: Dopamine agonists and levodopa
Q21. Which COMT inhibitor acts only peripherally and does not significantly cross the blood–brain barrier?
- Tolcapone
- Entacapone
- Selegiline
- Rasagiline
Correct Answer: Entacapone
Q22. Selegiline differs from rasagiline in that selegiline is metabolized to:
- Inactive metabolites only
- Amphetamine and methamphetamine derivatives
- Serotonin analogs
- COMT substrates
Correct Answer: Amphetamine and methamphetamine derivatives
Q23. Which antiparkinsonian drug is contraindicated in patients with narrow-angle glaucoma due to anticholinergic effects?
- Levodopa
- Trihexyphenidyl
- Selegiline
- Entacapone
Correct Answer: Trihexyphenidyl
Q24. Which antiparkinsonian medication requires periodic monitoring of liver enzymes because of potential severe hepatic injury?
- Entacapone
- Selegiline
- Tolcapone
- Pramipexole
Correct Answer: Tolcapone
Q25. Which agent is commonly used as a rapid rescue therapy (subcutaneous) for sudden “off” episodes?
- Oral levodopa only
- Subcutaneous apomorphine
- Intravenous selegiline
- Oral entacapone single dose
Correct Answer: Subcutaneous apomorphine
Q26. Long-term levodopa therapy most characteristically leads to which motor complication?
- Peripheral neuropathy only
- Dyskinesias (involuntary movements)
- Improved tremor without side effects
- Permanent cure of Parkinson’s disease
Correct Answer: Dyskinesias (involuntary movements)
Q27. Which enzyme is responsible for peripheral conversion of levodopa to dopamine and is inhibited by carbidopa?
- Monoamine oxidase B (MAO-B)
- Catechol-O-methyltransferase (COMT)
- Aromatic L-amino acid decarboxylase (AADC / DOPA decarboxylase)
- Dopamine beta-hydroxylase
Correct Answer: Aromatic L-amino acid decarboxylase (AADC / DOPA decarboxylase)
Q28. For younger Parkinson’s patients (<65 years), initial therapy to delay levodopa-induced dyskinesia commonly involves:
- Immediate high-dose levodopa/carbidopa
- Dopamine agonists (e.g., pramipexole, ropinirole)
- High-dose entacapone monotherapy
- Only dietary modification
Correct Answer: Dopamine agonists (e.g., pramipexole, ropinirole)
Q29. Which adverse effect is specifically reported with entacapone therapy?
- Brownish-orange discoloration of urine
- Severe hyperglycemia
- Marked bradycardia
- Pulmonary fibrosis
Correct Answer: Brownish-orange discoloration of urine
Q30. Which clinical feature suggests a poorer response to levodopa and may indicate atypical parkinsonism rather than idiopathic Parkinson’s disease?
- Marked initial improvement with levodopa
- Rapid progression, early falls, prominent autonomic failure, and poor levodopa response
- Typical resting tremor and gradual improvement
- Asymmetric onset with sustained levodopa responsiveness
Correct Answer: Rapid progression, early falls, prominent autonomic failure, and poor levodopa response
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com