MRCPsych Pharmacology Fundamentals 3

Question 1

Which antipsychotic is most associated with QTc prolongation and carries the highest risk of torsades de pointes?

Accepted Answer

Thioridazine

Answer

Thioridazine has the greatest QTc-prolonging effect among antipsychotics and has been withdrawn in many countries due to fatal arrhythmia risk.

Question 2

The Maudsley Prescribing Guidelines recommend plasma level monitoring for which drug primarily to assess adherence and toxicity?

Accepted Answer

Clozapine

Answer

Clozapine plasma level monitoring (target 0.35–0.60 mg/L) is recommended to confirm adherence and reduce toxicity risk.

Question 3

A patient develops rigidity, hyperthermia, autonomic instability, and elevated CK after starting haloperidol. What is the most likely diagnosis?

Accepted Answer

Neuroleptic malignant syndrome

Answer

Neuroleptic malignant syndrome (NMS) presents with the tetrad of hyperthermia, rigidity, autonomic instability, and altered consciousness after antipsychotic exposure.

Question 4

Which of the following best describes the concept of 'receptor occupancy' in antipsychotic prescribing?

Accepted Answer

The percentage of target receptors bound by a drug at a given plasma level

Answer

Receptor occupancy describes the fraction of receptors occupied by a drug, with D2 occupancy of 60–80% associated with antipsychotic efficacy and <80% minimising EPS.

Question 5

Which SSRI is considered safest in overdose due to its relatively flat dose-response curve and low cardiac toxicity?

Accepted Answer

Fluoxetine

Answer

Fluoxetine has a very wide therapeutic index; in overdose it rarely causes serious cardiac effects, unlike citalopram which prolongs QTc in high doses.

(MRCPsych) Member of the Royal College of Psychiatrists Practice Test

(MRCPsych) Member of the Royal College of Psychiatrists Practice Test

MRCPsych Pharmacology Fundamentals 3