Flurobuterophenones – Haloperidol MCQs With Answer

Flurobuterophenones – Haloperidol MCQs With Answer

Flurobuterophenones, represented clinically by haloperidol, are an important class of butyrophenone antipsychotics studied extensively in B. Pharm courses. This introduction covers chemistry, structure–activity relationships, pharmacology, pharmacokinetics, clinical uses, side effects (EPS, tardive dyskinesia, NMS), formulation differences including depot preparations, drug interactions and analytical assays. These concise, keyword-rich notes focus on D2 receptor antagonism, fluorinated substituent effects, hepatic metabolism, QT risk and therapeutic monitoring—essential concepts for pharmacy students preparing for exams and clinical practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. What chemical class does haloperidol belong to?

• Phenothiazines
• Thioxanthenes
• Butyrophenones
• Benzodiazepines

Correct Answer: Butyrophenones

Q2. The term “flurobuterophenones” in the context of haloperidol primarily refers to which structural feature?

• A tertiary amine side chain
• A fluorinated phenyl ring attached to a butyrophenone core
• An imidazole ring fused to benzene
• A sulfonamide group

Correct Answer: A fluorinated phenyl ring attached to a butyrophenone core

Q3. What is the primary pharmacological mechanism of haloperidol?

• Selective 5-HT1A agonism
• GABA-A receptor potentiation
• Dopamine D2 receptor antagonism
• NMDA receptor antagonism

Correct Answer: Dopamine D2 receptor antagonism

Q4. Compared with low-potency typical antipsychotics, haloperidol is classified as:

• Low potency with strong anticholinergic effects
• High potency with greater extrapyramidal risk
• Atypical antipsychotic with minimal EPS
• Antidepressant with dopaminergic agonism

Correct Answer: High potency with greater extrapyramidal risk

Q5. Which clinical use is a primary indication for haloperidol?

• Chronic major depressive disorder as first-line
• Acute psychosis and severe agitation
• Primary treatment of generalized anxiety disorder
• First-line therapy for bipolar depression

Correct Answer: Acute psychosis and severe agitation

Q6. Which adverse effect is most strongly associated with haloperidol?

• Severe anticholinergic toxicity
• Extrapyramidal symptoms such as acute dystonia
• Marked hepatic necrosis as the common effect
• Renal tubular acidosis

Correct Answer: Extrapyramidal symptoms such as acute dystonia

Q7. Long-term haloperidol therapy carries the greatest risk for which movement disorder?

• Myasthenia gravis
• Tardive dyskinesia
• Huntington’s chorea
• Essential tremor

Correct Answer: Tardive dyskinesia

Q8. Neuroleptic malignant syndrome (NMS) associated with haloperidol is characterized by:

• Hypothermia and bradycardia
• Hyperthermia, rigidity, autonomic instability and elevated CK
• Persistent cough and bronchospasm
• Petechial rash and thrombocytopenia

Correct Answer: Hyperthermia, rigidity, autonomic instability and elevated CK

Q9. Which laboratory or monitoring test is recommended before and during haloperidol therapy when risk factors exist?

• Serial serum amylase measurements
• Electrocardiogram (ECG) to monitor QT interval
• Frequent urine drug screening only
• Routine liver biopsy

Correct Answer: Electrocardiogram (ECG) to monitor QT interval

Q10. Haloperidol’s fluorine substituent on the phenyl ring primarily affects which property?

• Decreases blood–brain barrier penetration
• Increases D2 receptor affinity and potency
• Eliminates hepatic metabolism
• Converts drug to prodrug form

Correct Answer: Increases D2 receptor affinity and potency

Q11. Which enzyme systems are mainly responsible for haloperidol hepatic metabolism?

• CYP3A4 and CYP2D6
• CYP1A2 only
• Alcohol dehydrogenase
• Monoamine oxidase-B (MAO-B)

Correct Answer: CYP3A4 and CYP2D6

Q12. A clinically important interaction with haloperidol is coadministration with strong CYP3A4 inhibitors. What is the expected result?

• Decreased haloperidol levels and loss of efficacy
• No change in haloperidol pharmacokinetics
• Increased haloperidol plasma levels and heightened toxicity risk
• Conversion of haloperidol to an inactive metabolite

Correct Answer: Increased haloperidol plasma levels and heightened toxicity risk

Q13. Which clinical feature best distinguishes akathisia from other EPS?

• Sustained muscle contractions causing twisting movements
• Intense subjective sense of inner restlessness and inability to sit still
• Slow, pill-rolling tremor at rest
• Irreversible oral-facial dyskinesia

Correct Answer: Intense subjective sense of inner restlessness and inability to sit still

Q14. For acute haloperidol-induced dystonia, the preferred immediate pharmacologic treatment is:

• Oral risperidone
• Anticholinergic injection such as benztropine or diphenhydramine
• Beta-blocker such as propranolol
• Calcium channel blocker

Correct Answer: Anticholinergic injection such as benztropine or diphenhydramine

Q15. Haloperidol decanoate is formulated as a depot preparation to provide:

• Immediate oral absorption
• Sustained release over weeks following intramuscular injection
• Topical analgesic effect
• Elimination of extrapyramidal side effects

Correct Answer: Sustained release over weeks following intramuscular injection

Q16. Which statement about haloperidol and prolactin is correct?

• Haloperidol decreases serum prolactin by stimulating D2 receptors
• Haloperidol increases serum prolactin due to D2 blockade in the tuberoinfundibular pathway
• Haloperidol has no effect on prolactin levels
• Haloperidol causes prolactin suppression only in males

Correct Answer: Haloperidol increases serum prolactin due to D2 blockade in the tuberoinfundibular pathway

Q17. Which analytical method is most commonly used in laboratories to quantify haloperidol plasma concentrations?

• High-performance liquid chromatography (HPLC)
• Gram staining
• Western blot
• ELISA for antinuclear antibodies

Correct Answer: High-performance liquid chromatography (HPLC)

Q18. Regarding therapeutic drug monitoring of haloperidol, which is true?

• Routine plasma level monitoring is required for all patients
• Monitoring is rarely required but may be used in toxicity or adherence assessment
• Haloperidol levels directly correlate with antipsychotic efficacy in all patients
• Urinary excretion measurement is the standard monitoring tool

Correct Answer: Monitoring is rarely required but may be used in toxicity or adherence assessment

Q19. Which receptor binding profile differentiates typical antipsychotics like haloperidol from many atypical antipsychotics?

• Higher affinity for 5-HT2A than D2 receptors
• Primary blockade of GABA receptors
• High D2 receptor antagonism with relatively lower 5-HT2A antagonism
• Exclusive action on peripheral adrenergic receptors

Correct Answer: High D2 receptor antagonism with relatively lower 5-HT2A antagonism

Q20. Which patient population is particularly at increased risk for tardive dyskinesia from haloperidol?

• Young male adults only
• Elderly patients, especially older women
• Children under 2 years only
• Patients with chronic kidney disease exclusively

Correct Answer: Elderly patients, especially older women

Q21. Which statement about haloperidol’s effect on the cardiovascular system is correct?

• Haloperidol commonly causes severe hypertension as its main adverse effect
• Haloperidol can prolong the QT interval and increase risk of torsades de pointes
• Haloperidol reduces heart rate variability without ECG changes
• Haloperidol has no known cardiac effects

Correct Answer: Haloperidol can prolong the QT interval and increase risk of torsades de pointes

Q22. Which one best describes the blood–brain barrier penetration of haloperidol?

• Poor CNS penetration due to high polarity
• Good CNS penetration reflective of its clinical central effects
• Restricted entry requiring P-glycoprotein inhibition
• Does not cross into the CNS at therapeutic doses

Correct Answer: Good CNS penetration reflective of its clinical central effects

Q23. In overdose of haloperidol, which of the following is NOT a recommended management step?

• Supportive measures including airway and cardiovascular support
• Administration of benzodiazepines for severe agitation or seizures
• Administer intravenous dantrolene as first-line for simple sedation
• Use activated charcoal if presentation is early

Correct Answer: Administer intravenous dantrolene as first-line for simple sedation

Q24. Which structural moiety in haloperidol is responsible for it being classified as a butyrophenone?

• A tertiary alcohol group
• A ketone adjacent to a phenyl ring with a four-carbon (butyro-) chain
• An esterified fatty acid side chain only
• A benzodiazepine core

Correct Answer: A ketone adjacent to a phenyl ring with a four-carbon (butyro-) chain

Q25. Which is a common clinical use of haloperidol outside chronic schizophrenia management?

• Treatment of hyperthyroidism
• Management of severe nausea and vomiting as antiemetic first-line
• Control of acute delirium and severe agitation in hospitalized patients
• Long-term treatment of neuropathic pain

Correct Answer: Control of acute delirium and severe agitation in hospitalized patients

Q26. Which pharmacologic agent is useful to treat haloperidol-induced akathisia?

• Anticholinergics only
• Beta-blockers like propranolol or benzodiazepines
• High-dose antipsychotic augmentation
• ACE inhibitors

Correct Answer: Beta-blockers like propranolol or benzodiazepines

Q27. Which occupational hazard is most relevant when handling haloperidol powder in a compounding pharmacy?

• Risk of radiation exposure
• Dermal absorption and inhalation, requiring protective measures
• Immediate flammability at room temperature
• Spontaneous polymerization risk

Correct Answer: Dermal absorption and inhalation, requiring protective measures

Q28. Which statement about haloperidol’s oral bioavailability is accurate?

• It has complete (100%) oral bioavailability
• Oral bioavailability is variable due to first-pass metabolism
• It cannot be administered orally
• Oral route leads to immediate depot formation

Correct Answer: Oral bioavailability is variable due to first-pass metabolism

Q29. Which adverse endocrine effect is commonly seen with haloperidol therapy?

• Hypothyroidism
• Hyperprolactinemia leading to galactorrhea and menstrual disturbances
• Adrenal insufficiency
• Hypoglycemia as the main endocrine effect

Correct Answer: Hyperprolactinemia leading to galactorrhea and menstrual disturbances

Q30. Which statement best describes structure–activity relationship (SAR) in haloperidol-like compounds?

• Removal of the fluorine atom typically increases D2 potency
• Butyrophenone core with appropriate para-substitution on phenyl rings is critical for D2 antagonism
• Replacing the ketone with an alcohol increases antipsychotic potency
• Large polar substituents invariably improve CNS penetration

Correct Answer: Butyrophenone core with appropriate para-substitution on phenyl rings is critical for D2 antagonism

Q31. Which adverse effect would prompt immediate discontinuation of haloperidol and emergent treatment?

• Mild sedation that improves after dose reduction
• Development of neuroleptic malignant syndrome (NMS)
• Transient dry mouth
• Constipation manageable with laxatives

Correct Answer: Development of neuroleptic malignant syndrome (NMS)

Q32. In patients with hepatic impairment, haloperidol dosing should be approached how?

• No adjustment is ever needed
• Cautiously with dose reduction and close monitoring due to hepatic metabolism
• Only intravenous dosing is safe
• Hepatic impairment enhances renal clearance so dose should be increased

Correct Answer: Cautiously with dose reduction and close monitoring due to hepatic metabolism

Q33. Which statement about haloperidol’s affinity for serotonin 5-HT2A receptors is true relative to many atypical antipsychotics?

• Haloperidol has a higher 5-HT2A/D2 ratio than atypicals
• Haloperidol has relatively lower 5-HT2A antagonism compared with many atypicals
• Haloperidol is a potent 5-HT2A agonist
• Haloperidol exclusively blocks serotonin receptors

Correct Answer: Haloperidol has relatively lower 5-HT2A antagonism compared with many atypicals

Q34. Which formulation change converts haloperidol into a long-acting injectable depot?

• Formation of haloperidol sulfate salt for oral solution
• Esterification to haloperidol decanoate and oil-based intramuscular injection
• Conversion into an immediate-release oral syrup only
• Mixing with water to form a subcutaneous gel

Correct Answer: Esterification to haloperidol decanoate and oil-based intramuscular injection

Q35. Which of the following best explains why butyrophenone antipsychotics cause EPS?

• Excessive serotonergic stimulation in motor pathways
• D2 receptor blockade in nigrostriatal pathways leading to dopamine deficiency
• Inhibition of peripheral muscarinic receptors exclusively
• Direct myotoxic effects on skeletal muscle fibers

Correct Answer: D2 receptor blockade in nigrostriatal pathways leading to dopamine deficiency

Q36. Which drug interaction increases extrapyramidal symptoms when coadministered with haloperidol?

• Anticholinergics like benztropine
• Other dopamine antagonists such as metoclopramide
• Selective serotonin reuptake inhibitors that reduce EPS
• Vitamin supplements that block D2 receptors

Correct Answer: Other dopamine antagonists such as metoclopramide

Q37. Which monitoring parameter is most important in a patient on long-term haloperidol therapy to detect tardive dyskinesia early?

• Monthly liver function tests only
• Regular clinical assessment using the Abnormal Involuntary Movement Scale (AIMS)
• Weekly brain MRI scans
• Urinalysis for ketones

Correct Answer: Regular clinical assessment using the Abnormal Involuntary Movement Scale (AIMS)

Q38. Which of the following best characterizes haloperidol’s therapeutic onset in acute agitation when given intramuscularly?

• Rapid onset within minutes to an hour
• Onset delayed for several days
• Onset only after two weeks of continuous dosing
• No clinical effect when given intramuscularly

Correct Answer: Rapid onset within minutes to an hour

Q39. Which adverse metabolic effect is less commonly associated with haloperidol compared with many atypical antipsychotics?

• Significant weight gain and marked dyslipidemia
• EPS such as parkinsonism
• Acute dystonia
• Hyperprolactinemia

Correct Answer: Significant weight gain and marked dyslipidemia

Q40. Which recommendation is appropriate when initiating haloperidol in a patient with known prolonged QT interval?

• Proceed with high-dose haloperidol without ECG monitoring
• Avoid haloperidol or use extreme caution with ECG monitoring and consider alternatives
• Haloperidol corrects QT prolongation so it is preferred
• No adjustment; prescribe any QT-prolonging co-medication freely

Correct Answer: Avoid haloperidol or use extreme caution with ECG monitoring and consider alternatives

Q41. Which pharmacokinetic property explains why haloperidol decanoate can be injected monthly?

• Rapid renal clearance
• Slow hydrolysis of the long-chain decanoate ester providing sustained release
• Immediate conversion to water-soluble metabolites
• Complete evasion of plasma proteins

Correct Answer: Slow hydrolysis of the long-chain decanoate ester providing sustained release

Q42. Which adverse effect is a medical emergency and requires immediate discontinuation and treatment when seen with haloperidol?

• Mild akathisia
• Neuroleptic malignant syndrome
• Transient dizziness on standing
• Intermittent dry mouth

Correct Answer: Neuroleptic malignant syndrome

Q43. Which biochemical parameter is typically elevated in neuroleptic malignant syndrome caused by haloperidol?

• Serum creatine kinase (CK)
• Serum amylase only
• Urinary glucose exclusively
• Serum sodium decreased markedly

Correct Answer: Serum creatine kinase (CK)

Q44. Which of the following is the most appropriate strategy to reduce the risk of extrapyramidal side effects when starting haloperidol?

• Start at high doses immediately
• Use the lowest effective dose and titrate slowly; consider anticholinergic prophylaxis in selected patients
• Combine immediately with another dopamine antagonist
• Abruptly switch from an atypical to high-dose haloperidol

Correct Answer: Use the lowest effective dose and titrate slowly; consider anticholinergic prophylaxis in selected patients

Q45. Which receptor interaction is primarily responsible for haloperidol’s antipsychotic effects in the mesolimbic pathway?

• Mu-opioid receptor agonism
• Dopamine D2 receptor blockade
• Histamine H1 blockade only
• α2-adrenergic agonism

Correct Answer: Dopamine D2 receptor blockade

Q46. Which statement regarding haloperidol and pregnancy is the most cautious pharmacists’ advice?

• Haloperidol is absolutely contraindicated in all pregnancies
• Use only when benefits justify potential risks; monitor and consult specialists for perinatal management
• Haloperidol prevents all fetal malformations and is preferred
• There are no data; give without counseling

Correct Answer: Use only when benefits justify potential risks; monitor and consult specialists for perinatal management

Q47. Which adverse effect differentiates drug-induced parkinsonism from Parkinson’s disease in haloperidol-treated patients?

• Drug-induced parkinsonism often has a rapid onset after starting or increasing dose of antipsychotic
• Drug-induced parkinsonism is always irreversible
• Parkinson’s disease never causes bradykinesia
• Only Parkinson’s disease responds to anticholinergics

Correct Answer: Drug-induced parkinsonism often has a rapid onset after starting or increasing dose of antipsychotic

Q48. Which laboratory test is most useful to assess haloperidol-induced hepatic dysfunction?

• Serum transaminases (ALT, AST)
• CBC differential only
• Serum amylase specifically for hepatic injury
• Serum troponin as primary liver marker

Correct Answer: Serum transaminases (ALT, AST)

Q49. Which strategy can improve adherence in patients with schizophrenia who have difficulty taking daily haloperidol tablets?

• Switching to a long-acting injectable such as haloperidol decanoate
• Stopping antipsychotic therapy entirely
• Prescribing multiple daily short-acting sedatives instead
• Encouraging irregular dosing

Correct Answer: Switching to a long-acting injectable such as haloperidol decanoate

Q50. From a pharmaceutical chemistry perspective, which analytical property is most relevant when designing HPLC methods for haloperidol quantification?

• Its strong protein-binding prevents chromatographic separation
• Its UV absorbance and chemical stability allow reliable HPLC-UV detection after appropriate extraction
• Haloperidol cannot be detected by HPLC methods
• Its radioactivity requires specialized detectors only

Correct Answer: Its UV absorbance and chemical stability allow reliable HPLC-UV detection after appropriate extraction

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