Hallucinogens MCQs With Answer

Hallucinogens MCQs With Answer provides B. Pharm students a focused review of pharmacology, mechanisms, therapeutic potential, adverse effects, and clinical considerations related to hallucinogenic drugs. This set emphasizes key topics such as 5-HT2A receptor agonism, NMDA receptor antagonism, prominent agents (LSD, psilocybin, mescaline, ketamine, PCP, MDMA), pharmacokinetics, metabolic pathways, drug interactions, toxicity management, and regulatory status. Questions target receptor pharmacodynamics, metabolism (psilocin formation, CYP2D6), tolerance, dependence profiles, diagnostic testing, and current therapeutic research. Designed to deepen conceptual understanding and aid exam preparation, the MCQs blend basic science with clinical relevance. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which receptor subtype is most directly associated with the psychedelic effects of classic hallucinogens like LSD and psilocybin?

• Activation of dopamine D2 receptors
• Activation of 5-HT2A serotonin receptors
• Blockade of GABA-A receptors
• Activation of nicotinic acetylcholine receptors

Correct Answer: Activation of 5-HT2A serotonin receptors

Q2. Lysergic acid diethylamide (LSD) is chemically derived from which natural source?

• Psilocybe mushrooms
• Mescaline from peyote cactus
• Ergot alkaloids (ergotamine/lysergic acid)
• Opium poppy

Correct Answer: Ergot alkaloids (ergotamine/lysergic acid)

Q3. Which hallucinogen primarily produces its effects through noncompetitive antagonism of the NMDA receptor?

• Psilocybin
• Ketamine
• Mescaline
• LSD

Correct Answer: Ketamine

Q4. Which naturally occurring hallucinogen is a tryptamine that is dephosphorylated to its active form, psilocin, after ingestion?

• Mescaline
• Psilocybin
• LSD
• MDMA

Correct Answer: Psilocybin

Q5. Mescaline belongs to which chemical class of hallucinogens?

• Tryptamines
• Phenethylamines
• Ergoline derivatives
• Arylcyclohexylamines

Correct Answer: Phenethylamines

Q6. Which of the following is NOT a common characteristic of classic serotonergic hallucinogens?

• Acute perceptual distortions and visual hallucinations
• Rapid development of severe physical dependence with dramatic withdrawal
• Tachycardia and pupillary dilation
• Tolerance with repeated daily use

Correct Answer: Rapid development of severe physical dependence with dramatic withdrawal

Q7. Tolerance to repeated doses of classic psychedelics is primarily mediated by which mechanism?

• Upregulation of dopamine D2 receptors
• Downregulation/desensitization of cortical 5-HT2A receptors
• Increased hepatic clearance via CYP3A4 induction
• Permanent neuronal loss in the visual cortex

Correct Answer: Downregulation/desensitization of cortical 5-HT2A receptors

Q8. Which agent has well-documented rapid antidepressant effects in treatment-resistant depression and is studied clinically for this purpose?

• Mescaline
• Ketamine
• LSD
• Psilocybin

Correct Answer: Ketamine

Q9. What is the primary metabolic activation step for oral psilocybin converting it to the psychoactive compound?

• N-demethylation to psilocin
• Oxidation by CYP2D6
• Dephosphorylation to psilocin
• Conjugation with glucuronic acid

Correct Answer: Dephosphorylation to psilocin

Q10. Which analytical method is considered the gold standard confirmatory test for detecting many hallucinogens in biological samples?

• Urine dipstick immunoassay
• Thin layer chromatography (TLC)
• Gas chromatography–mass spectrometry (GC-MS)
• Rapid saliva colorimetric test

Correct Answer: Gas chromatography–mass spectrometry (GC-MS)

Q11. Co-administration of MDMA with an SSRI most significantly increases the risk of which serious condition?

• Hepatotoxicity leading to acute liver failure
• Serotonin syndrome
• Severe respiratory depression
• Anticholinergic crisis

Correct Answer: Serotonin syndrome

Q12. What is the primary mechanism by which MDMA produces its psychoactive effects?

• Direct agonism at 5-HT2A receptors exclusively
• Reversal of monoamine transporters causing serotonin and dopamine release
• Noncompetitive blockade of NMDA receptors
• Potentiation of GABAergic transmission

Correct Answer: Reversal of monoamine transporters causing serotonin and dopamine release

Q13. Which drug is classified as a dissociative anesthetic and can produce hallucinations, dissociation, and analgesia?

• LSD
• Mescaline
• Phencyclidine (PCP)
• Psilocybin

Correct Answer: Phencyclidine (PCP)

Q14. Under United States federal scheduling (Controlled Substances Act), LSD is historically placed in which schedule indicating high abuse potential and limited accepted medical use?

• Schedule II
• Schedule III
• Schedule I
• Schedule IV

Correct Answer: Schedule I

Q15. In acute severe agitation or psychosis from hallucinogen intoxication, the first-line pharmacologic management is usually which of the following?

• High-dose antipsychotics like haloperidol as first choice
• Benzodiazepines for sedation and anxiolysis
• Intravenous naloxone
• Immediate administration of anticholinesterase agents

Correct Answer: Benzodiazepines for sedation and anxiolysis

Q16. Which receptor is directly blocked by arylcyclohexylamines (e.g., PCP, ketamine) leading to dissociative and psychotomimetic effects?

• GABA-B receptor
• Nicotinic acetylcholine receptor
• N-methyl-D-aspartate (NMDA) receptor
• 5-HT3 receptor

Correct Answer: N-methyl-D-aspartate (NMDA) receptor

Q17. MDMA is chemically classified as which of the following?

• A substituted amphetamine (phenethylamine derivative)
• An ergoline alkaloid
• An arylcyclohexylamine
• A classical indole tryptamine

Correct Answer: A substituted amphetamine (phenethylamine derivative)

Q18. Typical subjective effects of a single oral dose of LSD last approximately how long in most individuals?

• 1–3 hours
• 3–5 hours
• 8–12 hours
• 24–48 hours

Correct Answer: 8–12 hours

Q19. Which hepatic enzyme is principally involved in the metabolism of MDMA and contributes to interindividual variability and drug interactions?

• CYP3A4
• CYP2C19
• CYP2D6
• Monoamine oxidase A (MAO-A)

Correct Answer: CYP2D6

Q20. Persistent, distressing visual disturbances that continue after acute hallucinogen intoxication are referred to as what clinical syndrome?

• Neuroleptic malignant syndrome
• Hallucinogen persisting perception disorder (HPPD)
• Delirium tremens
• Chronic serotonergic toxicosis

Correct Answer: Hallucinogen persisting perception disorder (HPPD)

Q21. The active psychotropic molecule produced after oral ingestion of psilocybin is:

• Psilocin
• Bufotenine
• Mescaline
• Lysergic acid

Correct Answer: Psilocin

Q22. Which dissociative anesthetic is commonly used in research to model schizophrenia-like symptoms due to transient psychotomimetic effects?

• Mescaline
• Ketamine
• Psilocybin
• MDMA

Correct Answer: Ketamine

Q23. LSD shows high affinity for multiple serotonin receptor subtypes. Which statement best describes its receptor profile?

• Selective 5-HT3 receptor antagonist only
• High affinity agonist/partial agonist at several 5-HT receptors including 5-HT2A and 5-HT1A
• Exclusive dopamine D1 receptor agonist
• GABA-A receptor positive allosteric modulator

Correct Answer: High affinity agonist/partial agonist at several 5-HT receptors including 5-HT2A and 5-HT1A

Q24. Cross-tolerance between LSD, psilocybin, and mescaline indicates which pharmacological principle?

• They share identical chemical structures
• They have overlapping mechanisms at common receptor targets (e.g., 5-HT2A)
• They are all metabolized exclusively by the same CYP enzyme
• They produce permanent receptor upregulation

Correct Answer: They have overlapping mechanisms at common receptor targets (e.g., 5-HT2A)

Q25. In cases of severe serotonin syndrome due to MDMA or SSRI interactions, which drug, an antihistamine with 5-HT2 antagonism, is used as a specific serotonin antagonist?

• Flumazenil
• Cyproheptadine
• Naloxone
• Propranolol

Correct Answer: Cyproheptadine

Q26. Which laboratory technique is commonly used to characterize binding affinity of hallucinogens at cloned 5-HT2A receptors in drug development studies?

• Radioligand binding assays
• Enzyme-linked immunosorbent assay (ELISA) for antibodies
• Complete blood count (CBC)
• Luminescence ATP assay

Correct Answer: Radioligand binding assays

Q27. Mescaline is the principal psychoactive constituent of which traditional plant used in indigenous rituals?

• Amanita muscaria mushroom
• Peyote cactus (Lophophora williamsii)
• Ayahuasca vine (Banisteriopsis caapi)
• Salvia divinorum

Correct Answer: Peyote cactus (Lophophora williamsii)

Q28. Acute MDMA toxicity can lead to hyponatremia. What is a primary mechanism contributing to this electrolyte disturbance?

• Direct renal tubular damage causing salt wasting
• Inappropriate antidiuretic hormone (ADH) release combined with excessive fluid intake
• Massive GI sodium loss from vomiting
• Decreased dietary sodium intake only

Correct Answer: Inappropriate antidiuretic hormone (ADH) release combined with excessive fluid intake

Q29. Which classic hallucinogen is active at microgram doses and is therefore noted for extreme potency?

• Mescaline
• LSD
• Psilocybin
• MDMA

Correct Answer: LSD

Q30. Which of the following is NOT a typical pharmacologic risk of classic serotonergic hallucinogens at commonly encountered doses?

• Visual distortions and altered perception
• Marked respiratory depression leading to hypoventilation
• Autonomic stimulation such as tachycardia and hypertension
• Anxiety, panic, or transient psychosis in susceptible individuals

Correct Answer: Marked respiratory depression leading to hypoventilation

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