Antipsychotics - AMBOSS PDF
Antipsychotics - AMBOSS PDF
Antipsychotics - AMBOSS PDF
Antipsychotics
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Summary
Antipsychotics are a heterogeneous group of substances used primarily to treat schizophrenia, psychosis, mania, delusions,
and states of agitation. The term neuroleptics was formerly used interchangeably with antipsychotics because early
antipsychotic drugs induced apathy, quiescence, and reduced psychomotor activity, but newer antipsychotic drugs no longer
have these effects. The antipsychotic effect of first-generation (typical) antipsychotics (e.g., haloperidol) is based on D2
antagonism, while second-generation (atypical) antipsychotics interact with several receptors (e.g., D2, D3, D4, 5-HT).
Extrapyramidal symptoms, which include acute dystonia, akathisia, and tardive dyskinesia, are the most common side
effects of first-generation antipsychotics. Metabolic side effects (e.g., weight gain, insulin resistance), on the other hand, are
more typical of second-generation antipsychotics. A potentially life-threatening side effect of both first-generation and
second-generation antipsychotics is neuroleptic malignant syndrome, which manifests with fever, muscle rigidity,
autonomic instability, and mental status changes.
Overview
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Adverse effects
First-generation Second-generation
Details antipsychotics antipsychotics
Extrapyramidal See EPS below for details. High-potency FGAs Significantly fewer
symptoms (EPS) have the highest motor side effects
incidence of EPS. (EPS) due to
Low-potency FGAs reduced D2
have a rate of EPS receptor
similar to that of antagonism;
SGA. greater affinity for
5HT2A receptors
and interaction
with other
receptors
Hyperprolactinemia Elevated prolactin levels: Dopamine All FGAs cause Smaller increase
inhibits the release of prolactin via elevated prolactin in prolactin levels
the D2 receptor in the levels. compared to
tuberoinfundibular pathway. Annual monitoring of typical
Therefore, dopamine antagonists symptoms is antipsychotics
increase the effects of prolactin. recommended. Most common in
In men: gynecomastia, risperidone,
galactorrhea, hypogonadotropic amisulpride,
hypogonadism (erectile dysfunction, and paliperidone
reduced libido, infertility)
In women: galactorrhea,
hypogonadotropic hypogonadism
(amenorrhea, reduced libido,
infertility)
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First-generation Second-generation
Details antipsychotics antipsychotics
Metabolic effects Usually weight gain, hyperglycemia, More common in low- Prominent in most
dyslipidemia potency FGAs SGA
Occasionally loss of appetite and Clozapine,
weight loss olanzapine,
quetiapine carry
the highest risk of
metabolic
syndrome
(hyperglycemia,
dyslipidemia,
weight gain).
Olanzapine also
causes an
asymptomatic
increase of liver
enzymes.
Sympatholytic Orthostatic hypotension (due to α1- More common in low- Common during
effect adrenergic blockade) potency FGAs treatment initiation
Rare in high-potency and dose
FGAs adjustments
Particularly
olanzapine
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First-generation Second-generation
Details antipsychotics antipsychotics
Ocular effects Lenticular and corneal deposits Associated with low- Not reported
Cataracts potency FGAs
Epithelial keratopathy Chlorpromazine
Retinitis pigmentosa Thioridazine
carries the
highest risk of
retinitis
pigmentosa.
Definition: a collection of movement disorders that are typically due to disruption of dopaminergic pathways in the
basal ganglia, resulting in bradykinesia, rigidity, dystonia, athetosis, chorea, ballismus, akathisia, tics, and tremors
Etiology: All antipsychotics that interact with the D2 receptor may cause EPS, but the probability of this side effect is
significantly higher with high-potency antipsychotics.
Metoclopramide, although not an antipsychotic, may also cause extrapyramidal symptoms.
Pathophysiology: Inhibition of the nigrostriatal dopaminergic pathways results in EPS.
First-generation high-potency antipsychotics: D2 antagonism → EPS
Second-generation antipsychotics: weaker D2 antagonism → fewer EPS
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)
See differential diagnosis of drug-induced hyperthermia.
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Treatment
Discontinuation of the antipsychotic drug!
Supportive measures (e.g., ICU care)
Pharmacotherapy
Dantrolene (ryanodine receptor antagonist): prevents the release of calcium from the sarcoplasmic
reticulum of striated muscle → reduced muscle rigidity and hyperthermia
Alternatives: bromocriptine, apomorphine, or amantadine
Benzodiazepines can be administered to treat psychomotor agitation.
To remember the different symptoms of neuroleptic malignant syndrome, think "FALTER": Fever, Autonomic
instability, Leukocytosis, Tremor, Elevated enzymes (creatine kinase, transaminases), Rigor
References:[6][7][8][9][10][11][12][13][14][15][5][4]
We list the most important adverse effects. The selection is not exhaustive.
Indications
All antipsychotics, with the exception of clozapine (used for treatment-resistant schizophrenia), have similar clinical
effectiveness.
The choice of drug depends on the side effect profile of the antipsychotic drugs and the patient's clinical status.
SGAs are preferred in many cases because they carry a lower risk of EPS; however, in some patients (e.g., those with
significant metabolic risk factors), FGAs may be more suitable.
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To reduce/avoid anticholinergic side effects in patients of advanced age, high-potency substances (e.g., haloperidol,
risperidone) or melperone are preferred!
References
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