Antipsychotics Flashcards

1
Q

Atypical (Second-generation) Antipsychotics drug list

A
Aripiprazole 
Brexpiprazole 
Cariprazine 
Iloperidone 
Lurasidone 
Quetiapine 
Risperidone 
Ziprasidone
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2
Q

Special Use Atypical Antipsychotics

drug list

A

Clozapine

Olanzapine

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3
Q

Typical (First-generation) Low-Potency Agents drug list

A

Chlorpromazine

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4
Q

Typical (First-generation) High-Potency Agents drug list

A

Haloperidol

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5
Q

Things that fall under psychosis

A

Positive symptoms:
hallucinations
delusions
disorganized thinking or speech

Negative symptoms:
declining self care
flattened affect
anhedonia

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6
Q

Biological basis of schizophrenia

A

glutamate, serotonin, dopamine

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7
Q

Major Dopamine Pathways

A

Mesolimbic-mesocortical pathways

  • Behavior and cognitive function
  • Excess mesolimbic DA likely causes positive symptoms
  • DA loss likely mediates negative symptoms
  • DA blockade mediates antipsychotic action

Nigrostriatal pathway

  • Coordination of voluntary movement
  • Dopamine imbalance leads to EPS

Tuberoinfundibular system
- Dopamine inhibits prolactin secretion

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8
Q

Therapeutic Potency of Typical Antipsychotics

A

What you need to know:

Efficacy Correlates with D2, but not D1 (top), receptor binding affinity

Measured by displacing selective antagonists

D2 affinity also correlates with extrapyramidal toxicity

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9
Q

Dopaminergic Sites of Antipsychotic Action

A

on preynaptic membrane– shuts off release

on post-synaptic membrane

Regulation of receptor expression as an adaptive response

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10
Q

Summary: Mechanism of Action- typical drugs

A

Block dopamine receptors

  • Especially D2
  • Clinical efficacy correlates with this action

Messy pharmacology; side effects result from action at muscarinic, histamine, and adrenergic receptors

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11
Q

Summary: Mechanism of Action- atypical drugs

A

Exhibit higher affinity for 5-HT2A receptors than D2 receptors

Also block DA receptors, including D2
- Clinical efficacy is not necessarily correlated with D2 blockade

Newer agents are partial agonists at 5-HT1A and D2 receptors and antagonists at 5-HT2A receptors

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12
Q

Drug Choice: Compare and Contrast

A

Typical (1st Gen):
Relatively high risk of EPS and tardive dyskinesia
Highly effective against positive symptoms
Overall efficacy may be equivalent
Intermediate risk of weight gain
Lower cost

Atypical (2nd Gen)

Less prone to cause EPS and tardive dyskinesia
Efficacious for positive and negative symptoms
Overall efficacy may be equivalent
Variable risk of weight gain
Higher cost

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13
Q

General Adverse Effects

A
More Common:
Extrapyramidal Symptoms (EPS)
- Akathisia
- Parkinsonism
- Dystonias
Tardive dyskinesia
Metabolic dysfunction
Prolactin elevation
Anticholinergic effects
Sedation
Rare:
Seizures
Orthostatic hypotension
Neuroleptic malignant syndrome
QT prolongation
Sudden death
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14
Q

Adverse effects - manifestations and mechanisms- Autonomic nervous system

A

Loss of accommodation, dry mouth, difficulty urinating, constipation– Muscarinic cholinoceptor blockade

Orthostatic hypotension, dizziness, sedation, failure to ejaculate, impotence–α-Adrenoceptor blockade

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15
Q

Adverse effects - manifestations and mechanisms- Central nervous system

A

EPS: Parkinson’s syndrome, akathisia, dystonias- Dopamine-receptor blockade

Tardive dyskinesia- Supersensitivity of dopamine receptors

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16
Q

Adverse effects - manifestations and mechanisms- Endocrine system

A

Amenorrhea-galactorrhea, infertility, impotence

– DA-receptor blockade; hyperprolactinemia

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17
Q

Adverse effects - manifestations and mechanisms- other

A

Weight gain - Possibly combined H1 and 5-HT2 blockade

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18
Q

Adverse Motor System Effects- acute onset

A

Extrapyramidal symptoms
Usually occurs within days of treatment initiation
Direct result of D2 blockade in basal ganglia
Treatable

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19
Q

Adverse Motor System -
Late-Onset
Effects

A

Tardive dyskinesia
Occurs after years of antipsychotic use
Imbalance of cholinergic (relative deficiency) and dopaminergic (relative supersensitivity) activity
May be irreversible

20
Q

Extrapyramidal Symptoms (EPS)

A

More commonly associated with haloperidol, fluphenazine, thiothixene, and trifluoperazine
Uncommon with most of the atypical agents

Akathisia: inability to sit still, restlessness

  • Consider dose reduction, if feasible
  • Lorazepam, propranolol, or benztropine

Parkinsonian syndrome: resting tremor, difficulty initiating movement

  • Benztropine
  • Amantadine

Dystonia: involuntary muscle contractions, abnormal postures

  • Switch to a different antipsychotic
  • Benztropine or diphenhydramine (prophylactic with IM haloperidol)
21
Q

Tardive Dyskinesia

A

Motor dysfunction - stereotypical, repetitive, involuntary movements
- Lateral jaw movements, lip smacking or sucking, twisting and protrusion of the tongue, purposeless movements of the extremities

Causes
- Imbalance of neurotransmitters in the basal ganglia: ACh deficiency and supersensitivity of DA receptors

Treatment

  • Decrease the dose of the antipsychotic
  • – Initially the dyskinesia will get worse
  • – Over the next several weeks it may improve
  • Consider switching to quetiapine or clozapine
22
Q

Receptor Occupancy and Clinical Response

A

D2 receptor occupancy > 60% provides antipsychotic effects

D2 receptor occupancy > 80% causes EPS

Atypical agents combine weak D2 antagonism with 5-HT2A antagonism/inverse agonism, permitting therapeutic efficacy at doses below the D2 receptor occupancy threshold for EPS

23
Q

Metabolic Effects: Weight Gain

A

Very common

Requires monitoring food intake, BMI, and fasting blood sugar and lipids

Hyperglycemia may develop, can be serious, and complicates pre-existing diabetes

Hyperlipidemia and hypertension

Possibly associated with combined H1 and 5-HT2 blockade

Relative Risk:
Highest risk: Clozapine, Olanzapine
Intermediate risk: Iloperidone, Paliperidone, Quetiapine, Risperidone (and most typical agents)
Low risk: Asenapine
Lowest risk: Aripiprazole, Lurasidone, Ziprasidone

24
Q

Endocrine Effects: Hyperprolactinemia

A

Increased secretion of prolactin caused by block of dopamine receptors in the pituitary
Most pronounced with older typical antipsychotics as well as risperidone and paliperidone
Galactorrhea, amenorrhea, and infertility in females
Gynecomastia, infertility, loss of libido, and impotence in males
Atypical antipsychotics with reduced D2 antagonism, such as aripiprazole, clozapine, iloperidone, olanzapine, and quetiapine cause no or minimal increases in prolactin

25
Galactorrhea, amenorrhea, and infertility in females Gynecomastia, infertility, loss of libido, and impotence in males Atypical antipsychotics with reduced D2 antagonism, such as aripiprazole, clozapine, iloperidone, olanzapine, and quetiapine cause no or minimal increases in prolactin
Rare (0.5-1.0%) but life-threatening (10-20% mortality) Tetrad of clinical features: - Fever - Muscle rigidity - Mental status changes - Autonomic instability Treatment - Cardiovascular support - Stop antipsychotics and anticholinergics - Antipyretics for symptoms - Dopamine agonist (e.g., bromocriptine) can be used, evidence for efficacy is limited - Muscle relaxants (e.g., diazepam or dantrolene)
26
Pharmacological Promiscuity of Antipsychotics
Neuroleptic drugs- antagonists at : cholinergic, alpha adrenergic, dopamine, serotonin, H1 histamine receptor
27
Haloperidol
High affinity D2 antagonist with relatively lower affinity for other receptors: D2 > D4 > α1 > 5-HT2A > D1 > H1 Highly effective against positive symptoms; some effect on negative symptoms Greater potential for extrapyramidal side effects than some typical (and all atypical) antipsychotics
28
Chlorpromazine
Relatively promiscuous with high affinity for several receptors: α1 > H1 ≈ D2 = 5-HT2A > D4 > D1 Low potency as an antipsychotic; useful for other indications (e.g., antiemetic) Greater potential for antimuscarinic and anti-alpha-adrenergic side effects
29
Atypical Antipsychotics
Called “atypical” because they dissociate clinical efficacy and EPS Now considered first-line treatment (except clozapine and olanzapine) for schizophrenia and other psychotic disorders
30
Clozapine (Clozaril)
Original atypical antipsychotic (discovered 1959, FDA approval 1989) Antagonist at 5-HT2A, M1, α1, and H1 receptors with high affinity, modest affinity for D2 receptors More efficacious than other antipsychotics, but most dangerous (life-threatening agranulocytosis) Can also cause myocarditis and de novo seizures Causes severe weight gain and hyperglycemia Significant sedation, orthostatic hypotension, and antimuscarinic side effects Essentially devoid of extrapyramidal motor side-effects Most useful for treatment-resistant schizophrenia or suicidal ideation
31
Olanzapine (Zyprexa)
Antagonist at 5-HT2A, 5-HT2C, D1-4, α1, and H1 receptors with high affinity, modest affinity for M1-5 receptors Weight gain is severe and profound Eli Lilly has paid over $1bn in settlements to people who claimed they developed Type II diabetes Also illegally marketed for off-label use in Alzheimer patients (caused increased risk of death) Recently subject to Risk Evaluation and Mitigation Strategy restrictions due to two unexplained deaths in June 2013 Not recommended for patients with diabetes Combination with SSRI fluoxetine makes it especially useful in bipolar depression
32
Risperidone (Risperdal)
Antagonist with high affinity for 5-HT2A, D2, and a1 receptors, little affinity for muscarinic receptors Highest potential for EPS and hyperprolactinemia relative to other atypical agents (dose-dependent) Sedation and weight gain also common Risk for intraoperative floppy iris syndrome should be considered before cataract surgery Approved for use in children Available as oral, long-acting microspheres, and intramuscular formulations Paliperidone is the major active metabolite of risperidone
33
Aripiprazole
is a partial agonist Partial D2 agonist that can achieve only 75% functional blockade; also partial agonist at 5-HT1A Antagonist at 5-HT2A receptors Relatively lower affinity for other receptors Often used in bipolar depression Efficacious against positive and negative symptoms of schizophrenia as well as depression Very low incidence of more common side-effects, including less weight gain and hyperglycemia Minimal hyperprolactinemia and sedation Minimal EPS, except akathisia Approved for use in children Notable side effects: dizziness, hypotension, nausea, vomiting
34
Quetiapine
Antagonist with relatively low affinity for both D2 and 5-HT2A receptors, yet has antipsychotic activity Higher affinity for H1 and α1 receptors leads to sedation and orthostatic hypotension Weight gain and hyperglycemia/hyperlipidemia are also common Minimal EPS and no prolactin elevation Somnolence is significant and has lead to inappropriate, wide-spread, off-label use as a sleep aid QT interval prolongation potential makes it a poor choice for those with cardiac conditions or family history of sudden cardiac death
35
Ziprasidone
Antagonist at D2, 5-HT2A, and 5-HT1D receptors Agonist at 5-HT1A receptors Also moderately blocks 5-HT and NE reuptake transporters Has antipsychotic activity against positive and negative symptoms Minimal EPS and prolactin elevation Minimal weight gain and hyperglycemia (advantage) Minimal risk of sedation and antimuscarinic effects QT interval prolongation; contraindicated in patients with recent MI, arrhythmia, uncompensated HF, or in the presence of other drugs that prolong the QT interval
36
Lurasidone
Newer agent approved for treatment of schizophrenia and bipolar depression (recent marketing) Antagonist at D2 and 5-HT2A receptors with high affinity Partial agonist at 5-HT1A receptors No significant affinity for muscarinic M1 and histamine H1 receptors Similar side effect profile to ziprasidone, except more sedation and no QT prolongation
37
New 2nd Generation Antipsychotics
Brexpiprazole (Rixulti) and cariprazine (Vraylar) FDA approval July and September 2015, respectively Brexpiprazole approved for SZ and as adjunctive therapy for major depressive disorder Cariprazine approved for SZ and bipolar disorder Partial agonist activity for 5-HT1A and D2 receptors and antagonist activity for 5-HT2A receptors
38
Psychiatric Indications for 2nd generation antipsychotics
Primarily used acute control and maintenance of schizophrenia Also useful in management of: Acute mania Bipolar disorder, schizoaffective disorders Behavioral disturbances in dementias Behavioral disturbances in children and adolescents Disorders associated with problems of impulse control Psychotic depression, treatment-resistant depression Tourette’s syndrome Drug-induced psychoses
39
Non-Psychiatric Indications
Antiemesis - Due to dopamine receptor blockade in the medulla and stomach - Prochlorperazine (Compazine), Promethazine (Phenergan) - Metoclopramide (Reglan), Ondansetron (Zofran) Neuroleptanesthesia (analgesia & amnesia) - Droperidol (a butyrophenone D2 blocker) + fentanyl + nitrous oxide
40
A 42-year-old woman develops akathisias, parkinsonian-like dyskinesias, galactorrhea, and amenorrhea as a consequence of psychotropic drug therapy. What drug-receptor-based mechanism, occurring in the central nervous system, most likely caused these responses? ``` Blockade of dopamine receptors Blockade of muscarinic receptors Blockade of serotonin receptors Stimulation of glutamate receptors Stimulation of nicotinic receptors ```
Blockade of dopamine receptors
41
A 33-year-old female patient who has been treated with haloperidol presents at the ED. Her husband reports that she has complained of rapidly worsening fever and muscle stiffness, and she has “the shakes” (tremor). Her level of consciousness is diminishing. Her temperature is 104ºF, and her blood creatine kinase level is elevated. What is the most likely explanation for these findings? ``` Allergic response to her medication Neuroleptic malignant syndrome Overdose Parkinsonism Tardive dyskinesia ```
Neuroleptic malignant syndrome
42
Chlorpromazine and haloperidol can be considered prototypes of two relatively old but still-used antipsychotic drug classes: the phenothiazines and the butyrophenones, respectively. While many of the actions and side effects of these drugs are qualitatively similar, they are different quantitatively: that is, in terms of incidence and severity. Which effect or side effect typically occurs more frequently, is usually more severe, and has a relatively rapid onset, with haloperidol? ``` Extrapyramidal symptoms Intense atropine-like side effects Lethal blood dyscrasias Orthostatic hypotension Urinary retention ```
Extrapyramidal symptoms haloperidol much more potent at those D2 receptors
43
We perform a meta-analysis on the ability of various antipsychotic drugs to cause constipation, urinary retention, blurred vision, and dry mouth—all of which reflect significant blockade of muscarinic receptors in the peripheral nervous system. Which of the following drugs most likely caused these unwanted effects? ``` Chlorpromazine Fluphenazine Haloperidol Olanzapine Sertraline ```
Chlorpromazine it is more potent at muscarinic and other receptor subtypes than at D2
44
Clozapine, as an example of the “atypical” antipsychotics, seldom is used as first-line therapy of schizophrenia. Compared with the older antipsychotics, it is associated with a much higher risk of a serious adverse response. What is that greater risk? ``` Agranulocytosis Extrapyramidal side effects Hypoglycemia Hypotension, severe Ventilatory depression or arrest ```
agranulocytosis
45
Chlorpromazine has been prescribed for a patient with SZ, and the patient has been taking the drug, at usually effective doses, for about 6 months. Today he comes to the hospital with other medical conditions that require surgery and the administration of other drugs, and we decide it is unwise to stop the chlorpromazine and risk psychotic behavior while we perform other interventions. What other signs/symptoms that the patient may also have or acquire as a result of surgery and drug therapy are most likely to be affected beneficially by the continued use of chlorpromazine? ``` Epilepsy and the risk of seizures Hypotension Nausea and vomiting Urinary retention caused by abdominal surgery Dry mouth caused by antimuscarinics ```
Nausea and vomiting