Question 26

Question:

A 22-year-old man is admitted to inpatient psychiatry after an attempt to strangle a stranger on the street in order to “squeeze the demons out” at the command of a voice in his head. He was put on a standing dose of haloperidol. Which of the following long-term adverse effects can be attributed to haloperidol?

Correct Answer: A.  Tardive dyskinesia

Haloperidol is a high-potency typical antipsychotic. Unlike low potency antipsychotics such as chlorpromazine, haloperidol has a much stronger adverse effect profile due to its high affinity for D2 receptors. Tardive dyskinesia is due to the strong dopamine receptor blockade. The blockade leads to long-term up-regulation of D2 receptors and the resultant hyperkinesis.
B is incorrect: Excess salivation would be due to stimulation of cholinergic receptors.
C, D, and E are incorrect: Antihistamine effects, in fact, include anti-nausea (antiemetic) and decreased itching (pruritus). Hypotension would be expected with alpha-1 blockade.