Medical Pharmacology: Chapter 16: Antipsychotic Medications -- Module 2: First-Generation Antipsychotics

Chapter 16: Antipsychotic Medications — Module 2: First-Generation Antipsychotics
Tier: 4 — Extended Clinical Cases

1. [CASE 1 — QUESTION 1] J.R. is a 23-year-old man with no prior psychiatric history who is brought to the emergency department by police after becoming acutely agitated, threatening, and disorganized in a public place. He is combative, has not slept in days according to family, and cannot be safely interviewed or examined. There is no known medical history and no signs of intoxication or head injury. The team decides that pharmacologic management of the acute agitation is required to ensure safety and permit evaluation. Which regimen is best supported for rapid, reliable control of acute agitation in this antipsychotic-naive young man?

A) High-dose chlorpromazine alone given intramuscularly, relying on its sedating profile
B) An intramuscular benzodiazepine alone, since dopamine blockade has no role in acute agitation
C) Intramuscular haloperidol combined with lorazepam, with diphenhydramine added, because haloperidol provides the dopamine D2 blockade, the benzodiazepine adds faster and more reliable sedation than haloperidol alone, and diphenhydramine reduces the risk of acute dystonia that is especially high in an antipsychotic-naive young man
D) Oral risperidone with a plan to reassess in 24 hours

ANSWER: C

Rationale:

The combination of intramuscular haloperidol plus lorazepam, with diphenhydramine added, is a widely used and well-supported protocol for acute agitation because each component contributes a distinct effect: haloperidol supplies the D2 blockade addressing the underlying agitation, the benzodiazepine adds faster and more reliable sedation than haloperidol alone, and diphenhydramine reduces the risk of acute dystonia, which is especially high in an antipsychotic-naive young man.

Option A: Option A is incorrect because high-dose chlorpromazine alone carries heavy anticholinergic and orthostatic burden and provides less reliable, less titratable control than the combination.
Option B: Option B is incorrect because dopamine blockade is central to managing psychotic agitation, so a benzodiazepine alone omits the antipsychotic component.
Option D: Option D is incorrect because an oral agent with reassessment in 24 hours is inadequate for an acutely combative patient who cannot be safely evaluated and needs prompt parenteral control.

2. [CASE 1 — QUESTION 2] Continuing with the same patient. About four hours after receiving intramuscular haloperidol, J.R. develops a sudden, sustained, painful upward deviation of both eyes and twisting of his neck to one side. He is alert and oriented, afebrile, and hemodynamically stable, with no generalized rigidity. Which interpretation best fits this development?

A) This is acute dystonia, the earliest extrapyramidal syndrome, which characteristically emerges within hours to a few days of a first high-potency dose and is most common in young, antipsychotic-naive males
B) This is tardive dyskinesia presenting unusually early after the first dose
C) This is the resting tremor and rigidity of drug-induced parkinsonism
D) This is the motor restlessness of akathisia

ANSWER: A

Rationale:

A young, antipsychotic-naive man developing oculogyric crisis (forced upward eye deviation) and torticollis (neck twisting) within hours of a first high-potency dose has acute dystonia, the earliest of the extrapyramidal syndromes, which typically emerges within hours to about five days of starting or increasing a first-generation agent and is most common in exactly this demographic.

Option B: Option B is incorrect because tardive dyskinesia develops after months to years of exposure and consists of involuntary orofacial movements, not sudden sustained spasm hours after a first dose.
Option C: Option C is incorrect because drug-induced parkinsonism produces bradykinesia, rigidity, and resting tremor over days to weeks, not an acute sustained dystonic posture.
Option D: Option D is incorrect because akathisia is a syndrome of restlessness and an urge to move, not the sustained muscle contraction described here.

3. [CASE 1 — QUESTION 3] Continuing with the same patient. The team wishes to relieve J.R.'s acute dystonic reaction promptly. Which intervention is most appropriate, and what is its mechanistic basis?

A) Intravenous dantrolene, which relieves dystonia by acting on the skeletal muscle ryanodine receptor
B) Intramuscular benztropine or diphenhydramine, which relieves the reaction within about 15 to 30 minutes by countering the relative cholinergic excess that dopamine blockade unmasked in the basal ganglia
C) Oral propranolol, which relieves the reaction by blocking beta-adrenergic receptors
D) An additional dose of haloperidol, which relieves the reaction by deepening dopamine blockade

ANSWER: B

Rationale:

Acute dystonia arises when dopamine blockade unmasks a relative cholinergic excess in the basal ganglia, so an intramuscular anticholinergic such as benztropine, or the antihistamine diphenhydramine which also has anticholinergic action, restores the balance and relieves the spasm rapidly, typically within 15 to 30 minutes.

Option A: Option A is incorrect because dantrolene acts on the ryanodine receptor to reduce rigidity and hyperthermia in neuroleptic malignant syndrome and is not the treatment for an isolated dystonic reaction.
Option C: Option C is incorrect because propranolol is the treatment for akathisia, not acute dystonia, and would not address the cholinergic mechanism.
Option D: Option D is incorrect because additional haloperidol would deepen the dopamine blockade and worsen the dystonia rather than relieve it.

4. [CASE 1 — QUESTION 4] Continuing with the same patient. After the dystonia resolves, the team plans ongoing antipsychotic therapy and asks how to reduce the risk of another acute dystonic reaction in the coming days. Which approach is most appropriate?

A) Routinely give a standing anticholinergic to every patient on an antipsychotic indefinitely, since the benefit always outweighs the burden
B) Increase the haloperidol dose, since higher doses reduce the risk of recurrent dystonia
C) Switch immediately to thioridazine, which carries no extrapyramidal risk
D) Consider short-term oral anticholinergic prophylaxis over roughly the first two weeks because this patient is high-risk (young, antipsychotic-naive, on a high-potency agent), while avoiding indefinite routine prophylaxis in all patients given the cognitive and anticholinergic burden

ANSWER: D

Rationale:

Short-term oral anticholinergic prophylaxis during roughly the first two weeks of therapy is appropriate for high-risk patients — young males, high-potency agents, higher doses — which describes this patient, while routine indefinite prophylaxis in all patients is not recommended because of the cognitive and peripheral anticholinergic burden. Option D correctly targets prophylaxis to the high-risk early window without committing the patient to long-term anticholinergic exposure.

Option A: Option A is incorrect because indefinite routine prophylaxis for everyone is explicitly not recommended owing to that burden.
Option B: Option B is incorrect because higher doses increase, not decrease, extrapyramidal risk.
Option C: Option C is incorrect because thioridazine does carry extrapyramidal risk and, more importantly, has the worst cardiac profile in the class, so it is not an appropriate reflexive substitute.

5. [CASE 2 — QUESTION 1] M.K. is a 44-year-old man with chronic schizophrenia who has relapsed twice in the past year, each time after stopping his oral medication. He has no prominent negative symptoms and no notable cognitive deficits, and his care is delivered in a setting where cost is a genuine constraint and second-generation long-acting injectables are not affordable. A large effectiveness trial found that the first-generation agent perphenazine performed comparably to several second-generation agents on all-cause treatment discontinuation. Considering that finding together with his clinical picture, which reasoning best supports drug-class selection for M.K.?

A) A second-generation agent must be chosen regardless of cost, because second-generation drugs are categorically superior for all patients
B) The comparable-effectiveness finding makes a first-generation agent a defensible, pharmacoeconomically reasonable choice for a patient without a specific indication for a second-generation drug
C) Only an agent with strong anticholinergic activity should be chosen, to guarantee sedation
D) Drug-class selection is irrelevant because all antipsychotics are interchangeable in efficacy and adverse effects

ANSWER: B

Rationale:

The finding that perphenazine performed comparably to several second-generation agents on all-cause discontinuation challenged the assumption of categorical second-generation superiority and supports a first-generation agent as a defensible, cost-conscious choice in a patient without a specific indication for a second-generation drug, which fits M.K.

Option A: Option A is incorrect because second-generation superiority is not categorical and the effectiveness data are directly relevant to this decision.
Option C: Option C is incorrect because strong anticholinergic activity is a liability rather than a selection goal and does not follow from the trial finding.
Option D: Option D is incorrect because antipsychotics differ meaningfully in receptor profile, adverse effects, and formulation, so class selection is not irrelevant.

6. [CASE 2 — QUESTION 2] Continuing with the same patient. Given that M.K.'s relapses have followed his stopping oral medication, the team wants an approach that directly addresses adherence. Which option best matches the problem to the appropriate first-generation tool?

A) Use an established, inexpensive first-generation long-acting injectable such as haloperidol decanoate or fluphenazine decanoate, because non-adherence is among the strongest predictors of relapse in schizophrenia and a depot converts a daily-dosing requirement into a periodic clinical contact
B) Continue oral therapy unchanged and rely on more frequent verbal reminders, since formulation has no effect on adherence outcomes
C) Lower the dose of an oral agent, because reducing the dose reliably solves non-adherence
D) Prescribe two different oral antipsychotics together to increase the chance that at least one is taken

ANSWER: A

Rationale:

Non-adherence to oral medication is among the strongest predictors of relapse in schizophrenia, and a long-acting injectable directly addresses it by replacing the daily-dosing requirement with a fixed pharmacokinetic profile established at each injection; established, inexpensive first-generation depots such as haloperidol decanoate and fluphenazine decanoate are well suited to a cost-constrained setting.

Option B: Option B is incorrect because formulation strongly affects adherence outcomes and reminders alone have already failed to prevent relapse.
Option C: Option C is incorrect because lowering an oral dose does not solve non-adherence.
Option D: Option D is incorrect because combining two oral agents adds adverse-effect burden and complexity without addressing the underlying adherence barrier.

7. [CASE 2 — QUESTION 3] Continuing with the same patient. The team selects haloperidol decanoate and plans the transition. Which statement about depot pharmacokinetics and safe initiation is most accurate?

A) The depot alters the receptor-binding profile of haloperidol, so prior oral tolerability is irrelevant to depot planning
B) The depot reaches steady state within 48 hours, so the dose can be finalized at the first visit
C) It is sound practice to establish tolerability of oral haloperidol at a dose roughly equivalent to the planned depot dose first, because the depot changes only delivery kinetics rather than the receptor profile, reaches steady state only after about three to four months of monthly injections, and has a long washout that makes dose-related adverse effects slow to resolve
D) The decanoate ester is water-soluble and rapidly absorbed, producing peak levels within minutes

ANSWER: C

Rationale:

A depot formulation changes only the delivery kinetics, not the receptor-binding profile, so establishing tolerability of the oral form at a roughly equivalent dose first is sound practice; haloperidol decanoate reaches steady-state plasma concentrations only after about three to four months of monthly injections and has a long washout, which makes any dose-related adverse effect slow to resolve once it appears.

Option A: Option A is incorrect because the depot does not alter the receptor profile, so prior oral tolerability is directly relevant.
Option B: Option B is incorrect because steady state takes months, not 48 hours, which is precisely why dosing must be planned carefully rather than finalized at the first visit.
Option D: Option D is incorrect because the decanoate ester is lipophilic and slowly absorbed from the oil depot, not water-soluble with peak levels in minutes.

8. [CASE 2 — QUESTION 4] Continuing with the same patient. M.K. smokes heavily, and during a later admission for an unrelated illness he is placed on a smoke-free unit and stops smoking abruptly. He is also taking oral chlorpromazine for breakthrough symptoms. Cigarette smoke induces the liver enzyme CYP1A2 that clears chlorpromazine. What should the team anticipate?

A) Chlorpromazine levels will fall on the unit, so the dose should be increased to prevent relapse
B) Smoking status has no effect on chlorpromazine, so no change is expected
C) The change will speed renal elimination of chlorpromazine, lowering its level
D) Loss of the smoking-related induction of CYP1A2 will slow chlorpromazine metabolism and raise its plasma level over the following days, so the team should monitor for new sedation and anticholinergic toxicity and consider a proactive dose reduction

ANSWER: D

Rationale:

Heavy smoking induces CYP1A2, keeping chlorpromazine levels relatively low; when M.K. stops smoking on a smoke-free unit, that induction is lost over several days, metabolism slows, and chlorpromazine levels rise, so the team should anticipate new sedation and anticholinergic toxicity and consider a proactive dose reduction.

Option A: Option A is incorrect because stopping the inducer raises rather than lowers levels, so increasing the dose would compound toxicity.
Option B: Option B is incorrect because chlorpromazine is a CYP1A2 substrate and is directly affected by the change in smoking status.
Option C: Option C is incorrect because the interaction operates through hepatic enzyme induction, not renal elimination, and levels rise rather than fall.

9. [CASE 3 — QUESTION 1] L.D. is a 57-year-old woman with long-standing psychosis that has failed multiple antipsychotics and is currently maintained on thioridazine, which she has tolerated for several years. Her clinician notes that thioridazine occupies an unusual position among the first-generation agents because of a specific dose-limiting toxicity. Which property best explains why thioridazine is generally restricted to patients who have failed other antipsychotics?

A) It causes irreversible kidney failure through direct renal tubular toxicity
B) It is a potent blocker of the cardiac hERG potassium channel, producing dose-dependent QTc prolongation that can progress to torsades de pointes, which led regulators to restrict it to an agent of last resort
C) It produces immediate severe liver necrosis in most patients within hours of the first dose
D) It causes profound immunosuppression requiring weekly blood-count monitoring

ANSWER: B

Rationale:

Thioridazine is a potent blocker of the cardiac hERG potassium channel, which controls cardiac repolarization, and this produces dose-dependent QTc prolongation that can progress to polymorphic ventricular tachycardia including torsades de pointes; this cardiac toxicity is the reason regulatory agencies restricted thioridazine to patients who have failed other antipsychotics.

Option A: Option A is incorrect because the dose-limiting toxicity is cardiac, not renal tubular injury.
Option C: Option C is incorrect because severe acute hepatic necrosis is not thioridazine's characteristic dose-limiting toxicity; cholestatic effects are more associated with chlorpromazine and are not the basis for restriction.
Option D: Option D is incorrect because mandatory blood-count monitoring for marrow suppression is the hallmark of clozapine, not thioridazine.

10. [CASE 3 — QUESTION 2] Continuing with the same patient. L.D. develops pneumonia, and the admitting team plans moxifloxacin, a fluoroquinolone that also prolongs the QTc interval. Her baseline electrocardiogram shows a high-normal QTc and her serum potassium is 3.1 millimoles per liter. What is the safest management approach?

A) Continue thioridazine and start moxifloxacin without monitoring, since QTc effects from different drug classes do not combine
B) Continue thioridazine and start moxifloxacin, relying on the low potassium to shorten the QTc and offset the risk
C) Recognize that thioridazine, the fluoroquinolone, and the hypokalemia together compound the risk of torsades de pointes; switch to a different antipsychotic for the duration of the antibiotic course and correct the potassium, with electrolyte and electrocardiographic monitoring
D) Double the thioridazine dose during the acute illness and proceed with the antibiotic

ANSWER: C

Rationale:

Thioridazine's hERG-channel blockade is additive with other QTc-prolonging agents such as fluoroquinolones, and hypokalemia independently lowers the threshold for torsades de pointes, so the three factors here compound the arrhythmia risk; the safest approach is to switch to a different antipsychotic for the duration of the QTc-prolonging antibiotic and to correct the potassium, with monitoring.

Option A: Option A is incorrect because QTc-prolonging effects from different drugs are additive, not independent.
Option B: Option B is incorrect because hypokalemia worsens, not offsets, the torsades risk.
Option D: Option D is incorrect because doubling thioridazine would further prolong the QTc and increase the danger.

11. [CASE 3 — QUESTION 3] Continuing with the same patient. The team reviews thioridazine's other distinctive toxicity that depends on dose. Which adverse effect is most characteristically associated with thioridazine at high doses, and how does it differ from the signature dermatologic effect of chlorpromazine?

A) Pigmentary retinopathy occurring at doses above roughly 800 milligrams per day, caused by melanin binding in the retinal pigment epithelium and potentially leading to irreversible visual impairment, which differs from chlorpromazine's characteristic blue-grey discoloration of sun-exposed skin with corneal and lenticular deposits
B) Blue-grey discoloration of sun-exposed skin with corneal deposits, which is thioridazine's signature effect and not seen with chlorpromazine
C) Permanent sensorineural hearing loss from cochlear toxicity
D) Diffuse hair loss that is unique to thioridazine among the phenothiazines

ANSWER: A

Rationale:

Thioridazine is characteristically associated with pigmentary retinopathy at doses above roughly 800 milligrams per day, caused by melanin binding in the retinal pigment epithelium and potentially leading to irreversible visual impairment; this is distinct from chlorpromazine's signature blue-grey discoloration of sun-exposed skin with corneal and lenticular deposits.

Option B: Option B is incorrect because the blue-grey skin discoloration with corneal-lenticular deposits is the signature of chlorpromazine, not thioridazine.
Option C: Option C is incorrect because sensorineural hearing loss is not a characteristic thioridazine toxicity.
Option D: Option D is incorrect because diffuse hair loss is not the distinctive dose-related toxicity of thioridazine described here.

12. [CASE 3 — QUESTION 4] Continuing with the same patient. After the pneumonia resolves, the team intends to resume thioridazine because L.D. has failed other agents. Which monitoring approach is most appropriate for continued thioridazine use?

A) No specific cardiac monitoring is needed because she has tolerated the drug for years
B) Routine monitoring should focus on weekly complete blood counts to detect agranulocytosis
C) Monitoring should center on regular liver function testing as the principal safety measure
D) Obtain a baseline electrocardiogram and monitor the QTc and electrolytes, given the dose-dependent QTc prolongation, and document informed consent regarding the cardiac and ophthalmologic risks, with periodic eye examination in view of the pigmentary retinopathy risk at high doses

ANSWER: D

Rationale:

Because thioridazine produces dose-dependent QTc prolongation through hERG-channel blockade, appropriate monitoring centers on a baseline electrocardiogram with QTc and electrolyte surveillance and documented informed consent regarding cardiac and ophthalmologic risks, with periodic eye examination given the pigmentary retinopathy risk at high doses.

Option A: Option A is incorrect because prior tolerance does not eliminate the cardiac risk, which is dose- and interaction-dependent and warrants ongoing monitoring.
Option B: Option B is incorrect because weekly complete blood counts are the monitoring requirement for clozapine, not thioridazine.
Option C: Option C is incorrect because liver function testing is not the principal safety measure for thioridazine, whose dominant risks are cardiac and ophthalmologic.

13. [CASE 4 — QUESTION 1] T.B. is a 39-year-old man hospitalized for acute psychosis whose haloperidol was rapidly escalated over two days. He now has a temperature of 40 degrees Celsius, generalized lead-pipe rigidity, blood pressure and heart rate that fluctuate widely, and a fluctuating level of consciousness. His creatine kinase, a muscle enzyme released by muscle injury, is markedly elevated at 18,000 units per liter. Which condition does this presentation represent, and what is its underlying mechanism?

A) Neuroleptic malignant syndrome, an idiosyncratic reaction thought to result from rapid, extensive dopamine D2 blockade in the nigrostriatal pathway and hypothalamus, producing rigidity, impaired heat dissipation, and disrupted thermoregulation, with the muscle injury reflected in the markedly elevated creatine kinase
B) A simple febrile infection unrelated to the antipsychotic, requiring only antibiotics
C) Acute dystonia, caused by a localized cholinergic excess in the basal ganglia
D) Tardive dyskinesia, caused by chronic dopamine receptor supersensitivity

ANSWER: A

Rationale:

The combination of high fever, lead-pipe rigidity, autonomic instability, fluctuating consciousness, and a markedly elevated creatine kinase after rapid dose escalation is the defining tetrad of neuroleptic malignant syndrome, an idiosyncratic reaction thought to result from rapid, extensive D2 blockade in the nigrostriatal pathway and hypothalamus, which produces rigidity and impaired heat dissipation along with disrupted thermoregulation; the muscle injury from sustained rigidity accounts for the elevated creatine kinase.

Option B: Option B is incorrect because the rigidity, autonomic instability, and very high creatine kinase point to a drug-induced syndrome rather than a simple infection.
Option C: Option C is incorrect because acute dystonia is an isolated sustained spasm without fever, autonomic instability, or markedly elevated creatine kinase.
Option D: Option D is incorrect because tardive dyskinesia produces involuntary orofacial movements after months to years, not an acute febrile rigid emergency.

14. [CASE 4 — QUESTION 2] Continuing with the same patient. A consultant asks the team to distinguish this presentation from serotonin syndrome before finalizing management. Which set of features most reliably identifies neuroleptic malignant syndrome rather than serotonin syndrome?

A) Hyperreflexia and clonus with onset within hours of a precipitating drug
B) Prominent gastrointestinal hyperactivity with diarrhea and minimal rigidity
C) Dilated pupils and early seizures without any change in body temperature
D) Lead-pipe rigidity with reduced reflexes, onset over roughly 24 to 72 hours, and a markedly elevated creatine kinase, in contrast to the hyperreflexia, clonus, and more rapid onset of serotonin syndrome

ANSWER: D

Rationale:

Neuroleptic malignant syndrome is characterized by lead-pipe rigidity with reduced reflexes, onset over roughly 24 to 72 hours, and markedly elevated creatine kinase, which distinguishes it from serotonin syndrome, where hyperreflexia, clonus, and a more rapid onset predominate.

Option A: Option A is incorrect because hyperreflexia and clonus with onset within hours are hallmarks of serotonin syndrome, not neuroleptic malignant syndrome.
Option B: Option B is incorrect because prominent gastrointestinal hyperactivity points toward serotonin syndrome rather than the rigidity-dominant neuroleptic malignant syndrome.
Option C: Option C is incorrect because dilated pupils and seizures without temperature change do not capture the defining fever, rigidity, and altered consciousness of neuroleptic malignant syndrome.

15. [CASE 4 — QUESTION 3] Continuing with the same patient. The diagnosis of neuroleptic malignant syndrome is established. Which management plan best matches the treatments to the underlying pathophysiology?

A) Continue haloperidol and add a second antipsychotic to control the agitation driving the fever
B) Give high-dose antihistamines as the mainstay, since the syndrome is an allergic reaction
C) Immediately discontinue the antipsychotic and provide supportive care including intravenous hydration and external cooling with monitoring for rhabdomyolysis and acute kidney injury, use dantrolene to reduce the rigidity and hyperthermia, and use a dopamine agonist such as bromocriptine or amantadine to restore central dopaminergic tone
D) Administer a serotonin antagonist as the definitive and sufficient treatment

ANSWER: C

Rationale:

Management of neuroleptic malignant syndrome maps onto its mechanism: immediately discontinue the antipsychotic and provide aggressive supportive care with intravenous hydration and external cooling while monitoring for rhabdomyolysis and acute kidney injury, give dantrolene to reduce rigidity and hyperthermia, and use a dopamine agonist such as bromocriptine or amantadine to restore the central dopaminergic tone removed by the blockade.

Option A: Option A is incorrect because continuing or adding antipsychotic blockade would worsen a syndrome caused by excessive D2 blockade.
Option B: Option B is incorrect because the syndrome is not an allergic reaction and antihistamines are not the mainstay.
Option D: Option D is incorrect because, although a serotonergic contribution and overlap with serotonin syndrome may exist, a serotonin antagonist is not the definitive treatment for neuroleptic malignant syndrome.

16. [CASE 4 — QUESTION 4] Continuing with the same patient. T.B. recovers fully from the neuroleptic malignant syndrome, but he still requires antipsychotic treatment for his underlying psychosis. Which approach to reintroducing an antipsychotic is most appropriate?

A) Restart the same dose of haloperidol immediately, since the episode has resolved
B) Wait at least two weeks after complete resolution before reintroducing an antipsychotic, and when reintroduction is necessary, choose a lower-potency agent at a lower dose with gradual titration and close monitoring for recurrence
C) Permanently withhold all antipsychotic therapy, since any antipsychotic is absolutely contraindicated after neuroleptic malignant syndrome
D) Reintroduce treatment with a long-acting injectable immediately to guarantee adherence during recovery

ANSWER: B

Rationale:

After complete resolution of neuroleptic malignant syndrome, the antipsychotic should not be restarted for at least two weeks, and when reintroduction is necessary a lower-potency agent at a lower dose with gradual titration and close monitoring for recurrence is preferred.

Option A: Option A is incorrect because immediately restarting the same agent at the same dose risks recurrence of a life-threatening syndrome.
Option C: Option C is incorrect because prior neuroleptic malignant syndrome is not an absolute permanent contraindication to all antipsychotic therapy; cautious, well-monitored reintroduction is possible when treatment is needed.
Option D: Option D is incorrect because a long-acting injectable with its long washout is a poor choice in the immediate post-episode period, when slow-to-resolve drug exposure would be especially hazardous if the syndrome recurred.

17. [CASE 5 — QUESTION 1] R.S. is a 62-year-old woman with a long history of a mood disorder and chronic psychosis who has been maintained on haloperidol for several years. At a routine visit she is noted to have involuntary lip-smacking, tongue protrusion, and chewing movements. Which condition does this most likely represent, and which of her features are recognized risk factors for it?

A) Acute dystonia, with risk driven by young age and male sex
B) Tardive dyskinesia, with recognized risk factors including older age, female sex, a history of affective (mood) disorder, and longer, higher cumulative exposure to a high-potency first-generation agent
C) Drug-induced parkinsonism, with risk driven mainly by recent dose reduction
D) Akathisia, with risk driven by rapid dose escalation in the preceding days

ANSWER: B

Rationale:

Involuntary orolingual movements — lip-smacking, tongue protrusion, and chewing — after years of antipsychotic exposure are characteristic of tardive dyskinesia, and recognized risk factors include older age, female sex, a history of affective disorder, the presence of early extrapyramidal symptoms, and longer, higher cumulative exposure to a high-potency first-generation agent, several of which this patient has.

Option A: Option A is incorrect because acute dystonia is an early sustained spasm whose risk is highest in young males, not a chronic orolingual movement disorder in an older woman.
Option C: Option C is incorrect because drug-induced parkinsonism produces bradykinesia, rigidity, and tremor rather than orolingual dyskinesia.
Option D: Option D is incorrect because akathisia is restlessness with an urge to move, not involuntary orofacial movements.

18. [CASE 5 — QUESTION 2] Continuing with the same patient. Hoping to help, her clinician lowers the haloperidol dose, but over the following weeks the orofacial movements become more pronounced. How is this change best explained?

A) Lowering the dose unmasked dopamine receptor supersensitivity that ongoing blockade had been partly concealing, a withdrawal-emergent pattern in which the dyskinesia was already present but suppressed, so the worsening reflects unmasking rather than a newly caused disorder
B) The dose reduction created an entirely new acute dystonic reaction
C) The worsening proves the movements were never tardive dyskinesia and are unrelated to the antipsychotic
D) The dose reduction accelerated drug metabolism, lowering the level and directly generating the movements as a toxic effect

ANSWER: A

Rationale:

Tardive dyskinesia arises from dopamine receptor supersensitivity that develops during chronic D2 blockade, and lowering the dose can make the movements more pronounced because the reduced blockade unmasks that supersensitivity which had been partly concealed — the withdrawal-emergent or unmasking pattern, in which the dyskinesia was already present but suppressed.

Option B: Option B is incorrect because acute dystonia is a sudden sustained spasm seen early in treatment, not a gradual worsening of orofacial movements over weeks.
Option C: Option C is incorrect because worsening on dose reduction is in fact characteristic of tardive dyskinesia and does not exclude it.
Option D: Option D is incorrect because the mechanism is unmasking of receptor supersensitivity, not a toxic effect generated by accelerated metabolism.

19. [CASE 5 — QUESTION 3] Continuing with the same patient. The team confirms tardive dyskinesia and plans treatment. Which management approach is most appropriate?

A) Start a standing anticholinergic such as benztropine to suppress the movements
B) Permanently increase the haloperidol dose to mask the dyskinesia
C) Begin propranolol, the first-line agent for this movement disorder
D) Minimize the antipsychotic dose where feasible, consider a vesicular monoamine transporter 2 (VMAT2) inhibitor such as valbenazine or deutetrabenazine that reduces excessive dopamine signaling by depleting presynaptic dopamine stores, avoid anticholinergics because they can worsen tardive dyskinesia, and monitor severity with the Abnormal Involuntary Movement Scale (AIMS)

ANSWER: D

Rationale:

Management of tardive dyskinesia includes minimizing the antipsychotic dose where feasible, considering a VMAT2 inhibitor such as valbenazine or deutetrabenazine — which reduce excessive dopaminergic signaling by depleting presynaptic dopamine stores — avoiding anticholinergics because they can worsen the condition, and monitoring severity with the AIMS.

Option A: Option A is incorrect because anticholinergics do not help tardive dyskinesia and can aggravate it.
Option B: Option B is incorrect because permanently raising the dose to mask the dyskinesia is the wrong strategy and does not address the underlying supersensitivity.
Option C: Option C is incorrect because propranolol is the first-line treatment for akathisia, not tardive dyskinesia.

20. [CASE 5 — QUESTION 4] Continuing with the same patient. R.S. and her family ask what can be done to keep the tardive dyskinesia from worsening over time. Which statement best reflects sound long-term management principles?

A) Once tardive dyskinesia appears, complete resolution is guaranteed simply by stopping the antipsychotic, so no ongoing strategy is needed
B) The most effective approach is to escalate the antipsychotic dose steadily, since higher doses prevent progression
C) Because established tardive dyskinesia often persists even after drug discontinuation, the most effective strategy is prevention and minimization: use the lowest effective dose, reassess the ongoing need for antipsychotic therapy at regular intervals, and consider transition to an agent with lower tardive-dyskinesia liability whenever the clinical context permits
D) No preventive strategy is possible, because tardive-dyskinesia risk is entirely random and unrelated to dose or duration

ANSWER: C

Rationale:

Because established tardive dyskinesia often persists even after drug discontinuation, the most effective strategy is prevention and minimization: using the lowest effective dose, reassessing the ongoing need for antipsychotic therapy at regular intervals, and considering transition to an agent with lower tardive-dyskinesia liability when the clinical context permits.

Option A: Option A is incorrect because complete resolution after discontinuation is uncommon, so an ongoing strategy is genuinely needed.
Option B: Option B is incorrect because higher cumulative dose increases, not decreases, tardive-dyskinesia risk.
Option D: Option D is incorrect because the risk is related to cumulative dose and duration and is therefore at least partly modifiable, not entirely random.

21. [CASE 6 — QUESTION 1] E.W. is a 76-year-old woman started on haloperidol three weeks ago for late-onset psychosis. She now has bradykinesia, limb rigidity, and a mild resting tremor that are bilateral and roughly symmetric from the outset, with reduced facial expression. She had no movement disorder before starting the drug. Which interpretation best fits this presentation, and how is it distinguished from idiopathic Parkinson disease?

A) Acute dystonia, distinguished by its sudden sustained spasms within hours of dosing
B) Tardive dyskinesia, distinguished by involuntary orofacial movements after years of exposure
C) Drug-induced parkinsonism, distinguished from idiopathic Parkinson disease by its bilateral, roughly symmetric onset and its clear temporal link to the drug, whereas idiopathic Parkinson disease characteristically begins asymmetrically; drug-induced parkinsonism also tends to improve within weeks to months of dose reduction or discontinuation
D) Neuroleptic malignant syndrome, distinguished by high fever and markedly elevated creatine kinase

ANSWER: C

Rationale:

Drug-induced parkinsonism produces bradykinesia, rigidity, and resting tremor over days to weeks and is typically bilateral and symmetric from the outset with a clear temporal link to the drug, in contrast to the characteristically asymmetric onset of idiopathic Parkinson disease; it also tends to improve within weeks to months of dose reduction or discontinuation, and the elderly are at higher risk because of reduced nigrostriatal reserve.

Option A: Option A is incorrect because acute dystonia is a sudden sustained spasm within hours to days, not evolving bradykinesia and rigidity.
Option B: Option B is incorrect because tardive dyskinesia involves orofacial movements after months to years, not subacute parkinsonism.
Option D: Option D is incorrect because there is no fever, autonomic instability, or markedly elevated creatine kinase to indicate neuroleptic malignant syndrome.

22. [CASE 6 — QUESTION 2] Continuing with the same patient. The team wants to relieve E.W.'s parkinsonism while minimizing additional risk in an elderly patient. Which management approach is most appropriate?

A) Add a standing anticholinergic such as trihexyphenidyl as the first-line treatment, accepting its cognitive effects
B) Favor reducing the haloperidol dose or switching to a lower-extrapyramidal-risk agent, and if a pharmacologic agent is needed, prefer amantadine over an anticholinergic in this elderly patient because amantadine has a more favorable cognitive profile
C) Increase the haloperidol dose to push through the parkinsonism
D) Start levodopa while continuing full-dose haloperidol

ANSWER: B

Rationale:

Management of drug-induced parkinsonism favors dose reduction or switching to a lower-extrapyramidal-risk agent, and when a pharmacologic agent is needed, amantadine is preferred over an anticholinergic in an elderly patient because anticholinergics carry significant cognitive and peripheral burden and are particularly hazardous in the elderly, whereas amantadine has a more favorable cognitive profile.

Option A: Option A is incorrect because anticholinergics are not the preferred first-line choice in an elderly patient given their cognitive risk.
Option C: Option C is incorrect because increasing the dose worsens the parkinsonism.
Option D: Option D is incorrect because adding levodopa while continuing full-dose haloperidol pits a dopamine precursor against ongoing D2 blockade and does not address the drug-induced cause.

23. [CASE 6 — QUESTION 3] Continuing with the same patient. Even after a modest dose reduction, E.W.'s extrapyramidal symptoms remain unexpectedly severe for her dose. Genotyping shows she is a poor metabolizer at the liver enzyme CYP2D6, which clears haloperidol. What is the expected pharmacokinetic consequence?

A) Poor CYP2D6 metabolism slows clearance of haloperidol, so plasma concentrations run roughly two to three times higher than in extensive metabolizers at the same dose, pushing D2 occupancy above the therapeutic window and producing disproportionate extrapyramidal effects
B) Poor CYP2D6 metabolism speeds clearance, so levels run far below expected and her symptoms must be unrelated to drug level
C) CYP2D6 does not metabolize haloperidol, so the genotype is irrelevant to her presentation
D) The genotype converts haloperidol entirely to an inactive metabolite, eliminating its effect

ANSWER: A

Rationale:

Poor metabolizers at CYP2D6 clear haloperidol and perphenazine slowly, so at a given dose they reach plasma concentrations roughly two to three times higher than extensive metabolizers, pushing D2 occupancy above the therapeutic 65 to 80 percent window and producing disproportionate extrapyramidal effects, which explains her unexpectedly severe symptoms.

Option B: Option B is incorrect because poor metabolism slows rather than speeds clearance, raising levels rather than lowering them.
Option C: Option C is incorrect because CYP2D6 is specifically relevant to haloperidol metabolism.
Option D: Option D is incorrect because impaired CYP2D6 activity reduces metabolism rather than converting the drug entirely to an inactive metabolite.

24. [CASE 6 — QUESTION 4] Continuing with the same patient. Integrating E.W.'s poor-metabolizer status with the relationship between D2 occupancy and extrapyramidal effects, what is the most appropriate management conclusion, and when is genotyping clinically useful?

A) Increase the dose, since the persistent symptoms indicate insufficient receptor occupancy
B) Maintain the current dose indefinitely, since genotype cannot affect clinical decisions
C) Switch to thioridazine, which is unaffected by metabolizer status and carries no comparable risk
D) Further reduce the dose or switch to a lower-extrapyramidal-risk agent, because the toxicity is concentration-driven from reduced clearance pushing occupancy past the therapeutic window; CYP2D6 genotyping is not routine but should be considered in patients with unexpectedly high adverse-effect burden at standard doses of haloperidol or perphenazine

ANSWER: D

Rationale:

Because the toxicity is concentration-driven — reduced CYP2D6 clearance raising levels and pushing D2 occupancy above the therapeutic window — the correct conclusion is to further reduce the dose or switch to a lower-extrapyramidal-risk agent, not to escalate; CYP2D6 genotyping is not performed routinely but should be considered in patients who show an unexpectedly high adverse-effect burden at standard doses of haloperidol or perphenazine.

Option A: Option A is incorrect because the symptoms reflect excessive, not insufficient, occupancy, so increasing the dose would worsen them.
Option B: Option B is incorrect because the genotype directly informs the decision to lower the dose.
Option C: Option C is incorrect because thioridazine carries the worst cardiac risk in the class and is not an appropriate reflexive substitute for an elderly patient with drug-induced parkinsonism.

25. [CASE 7 — QUESTION 1] G.P. is a 69-year-old man recovering from major surgery in the intensive care unit who develops hyperactive delirium with agitation that threatens his lines and airway. Reversible contributors have been addressed, and the team judges that pharmacologic treatment is warranted. Among the first-generation antipsychotics, which agent is best supported for this setting, and why?

A) Chlorpromazine, chosen specifically for its strong anticholinergic activity, which is advantageous in delirium
B) Thioridazine, chosen for its favorable cardiac profile in monitored settings
C) Haloperidol, which has the best-established evidence base among first-generation agents for delirium in the critically ill and whose limited anticholinergic activity is an advantage over low-potency agents, since anticholinergic burden can itself worsen delirium
D) A low-potency agent at high dose, to maximize sedation regardless of receptor profile

ANSWER: C

Rationale:

Haloperidol has the best-established evidence base among first-generation agents for delirium in the medically ill and critically ill, and its limited anticholinergic activity is an advantage over low-potency agents because anticholinergic burden can itself worsen delirium and confusion.

Option A: Option A is incorrect because chlorpromazine's strong anticholinergic activity is a liability in delirium, not an advantage.
Option B: Option B is incorrect because thioridazine has the worst cardiac profile in the class, not a favorable one.
Option D: Option D is incorrect because a high-dose low-potency agent maximizes anticholinergic and orthostatic burden, which is precisely what should be avoided in a delirious elderly patient.

26. [CASE 7 — QUESTION 2] Continuing with the same patient. The team considers giving haloperidol intravenously for rapid effect in the monitored intensive care setting. Which precaution is most important with this route?

A) Intravenous haloperidol has no greater cardiac risk than oral or intramuscular dosing, so no special monitoring is required
B) The intravenous route abolishes the risk of extrapyramidal symptoms, so movement monitoring can be discontinued
C) The intravenous route eliminates any QTc concern because first-pass metabolism is bypassed
D) Intravenous haloperidol carries a higher risk of QTc prolongation than the oral or intramuscular routes, so it should be used with cardiac monitoring, which is feasible in this intensive care setting

ANSWER: D

Rationale:

Intravenous haloperidol carries a higher risk of QTc prolongation than the oral or intramuscular routes, so it should be used with cardiac monitoring; the intensive care setting makes such monitoring feasible.

Option A: Option A is incorrect because the intravenous route does carry greater QTc risk and does warrant monitoring.
Option B: Option B is incorrect because the route of administration does not abolish extrapyramidal risk, which arises from D2 blockade regardless of route.
Option C: Option C is incorrect because bypassing first-pass metabolism does not eliminate QTc concern; the intravenous route is in fact associated with greater QTc risk.

27. [CASE 7 — QUESTION 3] Continuing with the same patient. A colleague suggests switching to chlorpromazine instead, reasoning that its strong sedative effect would calm the patient more reliably. Why is a low-potency agent such as chlorpromazine a poor choice in this delirious elderly patient?

A) Its strong muscarinic (anticholinergic) blockade can worsen delirium and confusion, and its alpha-1 blockade causes orthostatic hypotension while its histamine blockade adds heavy sedation, so its broad low-potency receptor profile is exactly what should be avoided in a delirious elderly patient
B) It has no sedative effect at all, so it would fail to calm the patient
C) It is a high-potency, highly D2-selective agent that would cause excessive extrapyramidal symptoms but no other problems
D) It cannot be given to hospitalized patients under any circumstances

ANSWER: A

Rationale:

Chlorpromazine is a low-potency agent whose large required doses produce substantial muscarinic (anticholinergic) blockade that can worsen delirium and confusion, alpha-1 blockade that causes orthostatic hypotension, and histamine blockade that adds heavy sedation; this broad receptor profile is precisely what should be avoided in a delirious elderly patient, which is why a high-potency agent with limited anticholinergic activity is preferred.

Option B: Option B is incorrect because chlorpromazine is in fact strongly sedating; the problem is its accompanying anticholinergic and orthostatic burden, not a lack of sedation.
Option C: Option C is incorrect because chlorpromazine is low-potency with a broad receptor profile, not a high-potency D2-selective agent, and its problems extend well beyond extrapyramidal symptoms.
Option D: Option D is incorrect because chlorpromazine can be used in hospitalized patients; it is simply a poor choice in this specific delirium context.

28. [CASE 7 — QUESTION 4] Continuing with the same patient. Another team member proposes giving haloperidol decanoate, the long-acting injectable form, to provide steady control over the coming weeks. Integrating depot pharmacokinetics with the clinical course of delirium, why is this inappropriate?

A) The depot would reach therapeutic levels too quickly, causing immediate toxicity within minutes
B) Delirium is typically acute and often reversible and requires flexible, rapidly titratable dosing, whereas the depot reaches steady state only after months and has a long washout that makes dose-related adverse effects slow to resolve, so a long-acting formulation is poorly matched to a short-term, evolving condition
C) The depot changes the receptor-binding profile of haloperidol, so it would no longer be effective against delirium
D) Long-acting injectables are contraindicated in all patients over the age of 65 without exception

ANSWER: B

Rationale:

Delirium is typically acute and often reversible and calls for flexible, rapidly titratable dosing that can be reduced or stopped as the underlying causes resolve; haloperidol decanoate reaches steady state only after about three to four months and has a long washout, so dose-related adverse effects resolve slowly, making a long-acting depot poorly matched to a short-term, evolving condition.

Option A: Option A is incorrect because the depot is slowly, not rapidly, absorbed and does not reach therapeutic levels within minutes.
Option C: Option C is incorrect because the depot changes only delivery kinetics, not the receptor-binding profile, so this is not the reason it is inappropriate.
Option D: Option D is incorrect because long-acting injectables are not categorically contraindicated in all patients over 65; the issue here is the mismatch between depot kinetics and an acute, reversible condition.