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Medical Pharmacology Chapter 16: Pharmacology of Antipsychotics Drugs
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First Generation Antipsychotics Practice Questions
Multiple Choice Questions
1. A 35-year-old man with chronic schizophrenia develops a resting tremor, cogwheel rigidity, and slowed movements two weeks after his haloperidol dose was increased. Which of the following is the MOST appropriate next step?
A. Increase the haloperidol dose to control the newly emerging psychosis.
B. Add benztropine
C. Switch immediately to clozapine.
D. Discontinue haloperidol and initiate no antipsychotic therapy
Answer: B Add benztropine
The clinical picture describes drug-induced parkinsonism (DIP), an extrapyramidal side effect resulting from haloperidol's D2 blockade in the nigrostriatal pathway. Anticholinergic agents such as benztropine are first-line treatment for DIP.
Option A is incorrect, the patient's symptoms are adverse effects, not psychosis.
Option C (clozapine) may be appropriate eventually if EPS persists, but is not the immediate first step.
Option D is inappropriate given the patient's established psychiatric condition requiring maintenance therapy.
2. Which of the following receptor binding properties BEST explains why low-potency FGAs (e.g., chlorpromazine) cause more orthostatic hypotension than high-potency agents (e.g., haloperidol)?
A. Greater affinity for D2 receptors.
B. Greater affinity for α-1 adrenergic receptors
C. Greater affinity for histamine H2 receptors
D. Lesser affinity for muscarinic M1 receptors
Answer: B, Greater affinity for α-1 adrenergic receptors.
Orthostatic hypotension is mediated by α-1 adrenergic receptor blockade, which impairs vasoconstriction and leads to pooling of blood in peripheral vasculature upon standing.
Low potency FGAs, such as chlorpromazine and thioridazine, have substantially higher affinity for α1 receptors than high-potency agents such as haloperidol.
D2 affinity (A) determines antipsychotic potency and EPS risk, not cardiovascular effects.
H2 (C) is incorrect; H1 blockade causes sedation.
Muscarinic binding (D) causes anticholinergic effects.
3. A 67-year-old woman on haloperidol 5 mg daily for the past 15 years develops repetitive lip-smacking and tongue protrusion that her family reports worsening over the past year. AIMS examination confirms moderate orofacial dyskinesias. Which of the following is MOST accurate regarding her condition?
A. Stopping haloperidol immediately will completely resolve the movements in most patients.
B. Adding benztropine will reliably suppress the dyskinesias.
C. Annual incidence of this condition increases substantially with age. D.
D. This condition is most commonly caused by the tuberoinfundibular dopamine pathway.
Answer: C — Annual incidence increases substantially with age.
The clinical description is consistent with tardive dyskinesia (TD). Kane and colleagues' 1988 epidemiological review established that annual incidence rates of TD rise from approximately 5% in younger adults to 25–30% per year in elderly patients.
Option A is incorrect as TD persists after antipsychotic discontinuation in 50–75% of cases.
Option B is incorrect and potentially harmful given that anticholinergics can worsen or unmask TD (the movements may have been suppressed by any anticholinergic effect of another medication).
Option D is incorrect sinceTD arises from nigrostriatal pathway blockade, not the tuberoinfundibular pathway (which governs prolactin secretion).
4. The CATIE trial is significant because it demonstrated which of the following regarding the FGA perphenazine?
A. Perphenazine was significantly less effective than all SGAs tested.
B. Perphenazine caused more metabolic side effects than olanzapine.
C. Perphenazine's time to treatment discontinuation was comparable to most SGAs.
D. Perphenazine should no longer be used in clinical practice.
Answer: C — Perphenazine's time to discontinuation was comparable to most SGAs
The CATIE trial (Lieberman et al., 2005) found that perphenazine did not significantly differ from quetiapine, risperidone, or ziprasidone in time to discontinuation, the primary effectiveness outcome.
Olanzapine outperformed perphenazine on this measure but caused significantly more weight gain and metabolic adverse effects.
A is incorrect.
Option B is incorrect as perphenazine caused fewer metabolic side effects than olanzapine.
Option D reflects an overcorrection; CATIE actually supported perphenazine as a clinically reasonable option, particularly when metabolic comorbidities are a priority concern.
5. A 29-year-old man with schizophrenia is brought to the ED after three days of worsening agitation following abrupt discontinuation of his antipsychotic. On examination he has a temperature of 40.1°C, diffuse rigidity, diaphoresis, and confusion. His creatine kinase is 12,400 U/L. What is the MOST appropriate immediate management?
A. Administer haloperidol IV to control agitation.
B. Initiate cooling measures, IV hydration, and discontinue any remaining antipsychotics.
C. Administer benztropine for suspected acute dystonia.
D. Restart his antipsychotic immediately to reverse the syndrome.
Answer: B; Initiate cooling measures, IV hydration, and discontinue antipsychotics.
The clinical picture, high fever, severe rigidity, altered consciousness, autonomic instability, and markedly elevated CK, is classic for Neuroleptic Malignant Syndrome (NMS).
This is a medical emergency requiring immediate supportive care: discontinuation of the offending agent, aggressive cooling, IV fluid resuscitation to protect against renal failure from rhabdomyolysis, and consideration of dantrolene or bromocriptine.
Option A is absolutely contraindicated since haloperidol is an antipsychotic and would worsen NMS.
Option C (benztropine) is appropriate for acute dystonia, not NMS noting that the two are pathophysiologically and clinically distinct.
Option D is also contraindicated; reintroduction of the antipsychotic before full resolution is dangerous
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