Synthetic cholinergic blocking agents – Procyclidine hydrochloride MCQs With Answer

Synthetic cholinergic blocking agents – Procyclidine hydrochloride MCQs With Answer

Procyclidine hydrochloride is a centrally acting synthetic cholinergic blocking agent widely used in pharmacotherapy of Parkinsonism and drug-induced extrapyramidal symptoms. This antimuscarinic (anticholinergic) drug crosses the blood-brain barrier to restore dopaminergic–cholinergic balance, reducing tremor and dystonia. B. Pharm students should understand its mechanism of action, clinical uses, pharmacokinetics, adverse effects (dry mouth, blurred vision, urinary retention, confusion), contraindications (angle‑closure glaucoma, prostatic hypertrophy), drug interactions, and overdose management. Clear knowledge of dosing, monitoring and patient counselling is essential. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which pharmacological class does procyclidine hydrochloride belong to?

• Beta-adrenergic blocker
• Synthetic cholinergic blocking agent (antimuscarinic)
• Monoamine oxidase inhibitor
• Cholinesterase inhibitor

Correct Answer: Synthetic cholinergic blocking agent (antimuscarinic)

Q2. What is the primary therapeutic indication for procyclidine?

• Essential hypertension
• Parkinsonism and drug-induced extrapyramidal symptoms
• Type 2 diabetes mellitus
• Hypothyroidism

Correct Answer: Parkinsonism and drug-induced extrapyramidal symptoms

Q3. The main mechanism of action of procyclidine is:

• Enhancement of dopamine synthesis in substantia nigra
• Inhibition of acetylcholinesterase enzyme
• Competitive antagonism of muscarinic acetylcholine receptors in central nervous system
• Stimulation of nicotinic receptors at neuromuscular junction

Correct Answer: Competitive antagonism of muscarinic acetylcholine receptors in central nervous system

Q4. Procyclidine is more effective for which Parkinsonian symptom?

• Bradykinesia
• Tremor
• Postural instability
• Freezing of gait

Correct Answer: Tremor

Q5. Why does procyclidine produce central effects?

• It is a quaternary ammonium compound that binds peripheral receptors
• It is a tertiary amine that crosses the blood–brain barrier
• It acts only on peripheral M3 receptors
• It is highly protein-bound in plasma preventing CNS entry

Correct Answer: It is a tertiary amine that crosses the blood–brain barrier

Q6. Which adverse effect is most characteristically associated with procyclidine?

• Hypersalivation
• Diarrhoea
• Dry mouth
• Bradycardia

Correct Answer: Dry mouth

Q7. In acute dystonic reactions caused by antipsychotics, procyclidine is used because it:

• Increases serotonin levels
• Enhances GABAergic transmission
• Antagonizes central muscarinic receptors to reduce cholinergic overactivity
• Directly stimulates dopamine D2 receptors

Correct Answer: Antagonizes central muscarinic receptors to reduce cholinergic overactivity

Q8. Which of the following is a contraindication to procyclidine use?

• Angle-closure glaucoma
• Iron deficiency anemia
• Allergic rhinitis
• Hyperlipidemia

Correct Answer: Angle-closure glaucoma

Q9. Which drug can be used as an antidote for severe anticholinergic toxicity from procyclidine overdose?

• Neostigmine
• Physostigmine
• Atropine
• Propranolol

Correct Answer: Physostigmine

Q10. Compared with trihexyphenidyl and benztropine, procyclidine is best described as:

• A peripheral cholinergic agonist
• Another centrally acting antimuscarinic with similar clinical uses
• A selective dopamine agonist
• An acetylcholinesterase inhibitor

Correct Answer: Another centrally acting antimuscarinic with similar clinical uses

Q11. The most important precaution when prescribing procyclidine for an elderly patient is monitoring for:

• Hypoglycaemia
• Excessive sedation and confusion
• Rash and photosensitivity
• Hearing loss

Correct Answer: Excessive sedation and confusion

Q12. Common urinary adverse effect due to procyclidine is:

• Increased urinary frequency
• Urinary incontinence
• Urinary retention
• Hematuria

Correct Answer: Urinary retention

Q13. Which receptor subtype in the CNS is primarily involved in the anticholinergic therapeutic effect for Parkinsonian symptoms?

• M3 muscarinic receptor
• M2 muscarinic receptor
• M1 muscarinic receptor
• Nicotinic receptor

Correct Answer: M1 muscarinic receptor

Q14. Procyclidine hydrochloride is commonly administered by which routes?

• Oral and parenteral (intramuscular/intravenous)
• Topical and inhalational
• Sublingual and transdermal only
• Rectal suppository exclusively

Correct Answer: Oral and parenteral (intramuscular/intravenous)

Q15. A patient on procyclidine reports blurred vision and photophobia. This is due to which pharmacological action?

• Stimulation of corneal receptors
• Mydriasis and cycloplegia from antimuscarinic effect
• Increased aqueous humor production
• Allergic conjunctivitis

Correct Answer: Mydriasis and cycloplegia from antimuscarinic effect

Q16. Which of the following conditions may be worsened by procyclidine due to its anticholinergic effects?

• Benign prostatic hyperplasia
• Iron overload
• Hypothyroidism
• Vitamin B12 deficiency

Correct Answer: Benign prostatic hyperplasia

Q17. The most appropriate counseling advice for a patient starting procyclidine would include:

• Expect increased sweating and improved heat tolerance
• Avoid driving until you know how the drug affects you
• Double the dose if symptoms are severe
• Stop other antiparkinsonian drugs immediately

Correct Answer: Avoid driving until you know how the drug affects you

Q18. The pharmacokinetic property that explains central effects of procyclidine is:

• High renal excretion of unchanged drug
• High polarity preventing CNS entry
• Lipophilicity allowing blood–brain barrier penetration
• Extensive first-pass elimination preventing systemic exposure

Correct Answer: Lipophilicity allowing blood–brain barrier penetration

Q19. Which combination increases risk of additive anticholinergic side effects when taken with procyclidine?

• Beta-blockers such as metoprolol
• Antihistamines with anticholinergic activity
• Thyroid hormones
• PPI medications like omeprazole

Correct Answer: Antihistamines with anticholinergic activity

Q20. In the pathophysiology of drug-induced parkinsonism, anticholinergics like procyclidine work by:

• Increasing dopamine receptor density
• Reducing excessive cholinergic neurotransmission due to dopamine blockade
• Blocking serotonin receptors in basal ganglia
• Enhancing acetylcholine release

Correct Answer: Reducing excessive cholinergic neurotransmission due to dopamine blockade

Q21. Which of the following is a serious CNS adverse effect that may occur with procyclidine, especially in high doses or elderly patients?

• Peripheral neuropathy
• Confusion and hallucinations
• Sensorineural hearing loss
• Severe hyponatraemia

Correct Answer: Confusion and hallucinations

Q22. The salt form ‘hydrochloride’ in procyclidine hydrochloride mainly affects which property of the drug?

• It converts the drug into a peptide
• Enhances water solubility and stability for formulations
• Adds pharmacodynamic effects on receptors
• Inactivates the drug until metabolized

Correct Answer: Enhances water solubility and stability for formulations

Q23. Which test or monitoring is most relevant when starting procyclidine in a patient with glaucoma risk?

• Serum creatinine
• Intraocular pressure assessment
• Liver function tests weekly
• ECG for QT prolongation

Correct Answer: Intraocular pressure assessment

Q24. Procyclidine’s effect on sweating can predispose patients to:

• Hypothermia
• Hyperthermia due to impaired heat dissipation
• Increased sweating at night
• Enhanced skin hydration

Correct Answer: Hyperthermia due to impaired heat dissipation

Q25. A patient who develops severe anticholinergic delirium after procyclidine ingestion should NOT be treated with which drug?

• Physostigmine
• Benzodiazepines for agitation
• Activated charcoal if within ingestion window
• High-dose atropine

Correct Answer: High-dose atropine

Q26. Procyclidine is metabolized primarily by which organ system?

• Renal tubular secretion without metabolism
• Hepatic metabolism
• Pulmonary metabolism
• Gastrointestinal bacterial metabolism only

Correct Answer: Hepatic metabolism

Q27. When treating acute dystonic reaction in an emergency, procyclidine is chosen because it:

• Has very slow onset when given parenterally
• Provides rapid relief of dystonia when given intramuscularly or intravenously
• Is ineffective for dystonic reactions
• Causes long-term neuroprotection against antipsychotics

Correct Answer: Provides rapid relief of dystonia when given intramuscularly or intravenously

Q28. Which patient history should prompt extra caution before prescribing procyclidine?

• History of seasonal allergies
• History of urinary retention or enlarged prostate
• Recent vaccination for influenza
• Mild eczema on hands

Correct Answer: History of urinary retention or enlarged prostate

Q29. Which of the following is a distinguishing pharmacological difference between tertiary and quaternary anticholinergics?

• Tertiary anticholinergics do not affect the CNS
• Quaternary anticholinergics cross the BBB readily
• Tertiary anticholinergics (like procyclidine) cross the BBB, quaternary do not
• There is no difference in blood–brain barrier penetration

Correct Answer: Tertiary anticholinergics (like procyclidine) cross the BBB, quaternary do not

Q30. If a patient on procyclidine develops severe constipation, the best immediate step is:

• Increase the dose of procyclidine
• Advise laxatives and review anticholinergic drug burden
• Start antidiarrheal medication
• Ignore, as constipation is unrelated

Correct Answer: Advise laxatives and review anticholinergic drug burden

Q31. Combining procyclidine with which drug class could reduce its therapeutic effectiveness by opposing its mechanism?

• Muscarinic agonists or cholinesterase inhibitors
• Catechol-O-methyltransferase inhibitors
• Dopamine precursors like levodopa
• Antidepressants without anticholinergic effects

Correct Answer: Muscarinic agonists or cholinesterase inhibitors

Q32. Which of the following clinical situations is procyclidine most likely to be prescribed for as an adjunct?

• Monotherapy for advanced bradykinesia
• Adjunct to dopaminergic therapy for tremor predominant Parkinson’s disease
• Primary treatment of Alzheimer’s disease
• First-line therapy for essential tremor

Correct Answer: Adjunct to dopaminergic therapy for tremor predominant Parkinson’s disease

Q33. Which lab or physiologic parameter should be monitored in long-term procyclidine therapy in elderly patients?

• Bone mineral density annually
• Cognitive function and signs of confusion or delirium
• Daily fasting glucose
• Monthly lipid profile

Correct Answer: Cognitive function and signs of confusion or delirium

Q34. Which of the following best describes the effect of procyclidine on heart rate?

• It commonly causes bradycardia
• It may cause tachycardia due to antimuscarinic blockade
• It has no cardiovascular effects
• It causes hypotension by alpha blockade

Correct Answer: It may cause tachycardia due to antimuscarinic blockade

Q35. In pregnancy, procyclidine should be used:

• Without restriction as it is proven safe
• Only if potential benefit justifies potential risk to the fetus
• As a first-line therapy for pregnancy-induced nausea
• To treat gestational diabetes

Correct Answer: Only if potential benefit justifies potential risk to the fetus

Q36. Which sign is NOT typical of anticholinergic syndrome caused by procyclidine overdose?

• Dry mucous membranes
• Hyperreflexia due to cholinergic excess
• Flushed skin and hyperthermia
• Delirium and hallucinations

Correct Answer: Hyperreflexia due to cholinergic excess

Q37. Which of the following patient counselling points is important regarding concomitant alcohol use?

• Alcohol reduces anticholinergic side effects
• Avoid alcohol as it may increase sedation and cognitive impairment
• Alcohol enhances drug absorption making it safer
• Alcohol cures dry mouth caused by procyclidine

Correct Answer: Avoid alcohol as it may increase sedation and cognitive impairment

Q38. A desirable pharmacodynamic property of procyclidine in treating antipsychotic-induced acute dystonia is:

• Long half-life causing cumulative sedation
• Rapid central antimuscarinic action when given parenterally
• Ineffectiveness for dystonic symptoms
• Peripheral antimuscarinic activity only

Correct Answer: Rapid central antimuscarinic action when given parenterally

Q39. Which of the following is a potential interaction of clinical significance with procyclidine?

• Concurrent use with cholinesterase inhibitors used in Alzheimer’s disease
• Concurrent use with vitamin C supplements
• Concurrent use with topical emollients
• Concurrent use with insulin injections

Correct Answer: Concurrent use with cholinesterase inhibitors used in Alzheimer’s disease

Q40. When switching from another antimuscarinic to procyclidine, what is an important consideration?

• No need to assess prior anticholinergic burden
• Evaluate cumulative anticholinergic load to avoid excessive side effects
• Immediate withdrawal of all other drugs is mandatory
• Double the dose for the first week for effect

Correct Answer: Evaluate cumulative anticholinergic load to avoid excessive side effects

Q41. Procyclidine may worsen symptoms of which neuromuscular disorder?

• Myasthenia gravis
• Multiple sclerosis
• Charcot-Marie-Tooth disease
• Peripheral vascular disease

Correct Answer: Myasthenia gravis

Q42. What is the rationale for gradual withdrawal of procyclidine rather than abrupt cessation?

• Abrupt stopping causes permanent receptor damage
• To avoid sudden return or worsening of Parkinsonian symptoms and potential rebound effects
• Because the drug accumulates and cannot be stopped quickly
• Withdrawal produces life-threatening hypoglycaemia

Correct Answer: To avoid sudden return or worsening of Parkinsonian symptoms and potential rebound effects

Q43. For a patient with severe benign prostatic hyperplasia experiencing urinary retention on procyclidine, the best action is:

• Increase dose to overcome retention
• Discontinue procyclidine and consider alternative therapy
• Add another antimuscarinic agent
• Ignore since urinary retention is harmless

Correct Answer: Discontinue procyclidine and consider alternative therapy

Q44. Which symptom improvement would suggest procyclidine is effective in a Parkinson’s patient?

• Marked improvement in rigidity with no change in tremor
• Reduction in resting tremor and drooling
• Complete resolution of bradykinesia
• Increased rigidity and stiffness

Correct Answer: Reduction in resting tremor and drooling

Q45. Which preparation of procyclidine is suitable for emergency management of acute dystonia?

• Topical gel
• Intramuscular or intravenous injection
• Transdermal patch
• Inhalation aerosol

Correct Answer: Intramuscular or intravenous injection

Q46. In a patient on multiple medications, the pharmacist should flag procyclidine use if the patient is also prescribed which of the following?

• Anticholinergic antidepressant such as amitriptyline
• Levothyroxine for hypothyroidism
• Low-dose aspirin for cardioprotection
• Topical antifungal cream for athlete’s foot

Correct Answer: Anticholinergic antidepressant such as amitriptyline

Q47. Which adverse ocular effect requires immediate medical review in a patient taking procyclidine?

• Mild dryness of eyes
• Soreness from contact lens use
• Sudden eye pain with blurred vision suggesting acute angle-closure glaucoma
• Intermittent tearing while crying

Correct Answer: Sudden eye pain with blurred vision suggesting acute angle-closure glaucoma

Q48. The typical role of procyclidine in Parkinson’s disease management is best described as:

• First-line monotherapy for all stages
• Adjunctive therapy to dopamine-based treatment for tremor and dystonia
• Primary treatment for gait freezing
• Replacement for levodopa in advanced disease

Correct Answer: Adjunctive therapy to dopamine-based treatment for tremor and dystonia

Q49. Which of the following statements about procyclidine and driving is correct?

• It enhances alertness and improves driving ability
• Patients should be cautioned not to drive until they understand its effect on their alertness
• There are no driving warnings for this drug
• It is safe to drive at higher doses

Correct Answer: Patients should be cautioned not to drive until they understand its effect on their alertness

Q50. Which of the following statements is true regarding routine laboratory monitoring for procyclidine therapy?

• Frequent serum drug level monitoring is mandatory
• There are no specific routine laboratory tests required; monitor clinically for anticholinergic adverse effects
• Weekly liver enzyme monitoring is required for all patients
• Daily complete blood counts are necessary

Correct Answer: There are no specific routine laboratory tests required; monitor clinically for anticholinergic adverse effects

G S Sachin

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