Antipsychotic agents Flashcards
ANTIPSYCHOTIC AGENTS
Should not be used to treat dementia in the older adult
First-generation antipsychotics (FGAs) or conventional antipsychotics
– Block receptors for dopamine in the central nervous system (CNS) – Cause serious movement disorders known as extrapyramidal
symptoms (EPS)
Second-generation antipsychotics (SGAs) or atypical
antipsychotics
– Produce only the moderate blockade of dopamine receptors; stronger blockade for serotonin
– Fewer EPS
FIRST-GENERATION ANTIPSYCHOTIC AGENTS
Classification by potency
– Low potency: Chlorpromazine – Medium potency
– High potency: Haloperidol
• Chemical classification
– Five major chemical categories
– Phenothiazines and butyrophenones
– Drugs in all groups equivalent with respect to antipsychotic actions
ADVERSE EFFECTS
Extrapyramidal symptoms (EPS) – Acute dystonia-spasms
– Oculogyric crisis
– Opisthotonus
– Joint dislocation
– Impaired respiration
– Anticholinergic medication (e.g., benztropine and diphenhydramine) – Some manifestations of EPS are IRREVERSIBLE
– It is crucial to monitor patients treated with antipsychotics for EPS
Parkinsonism: Bradykinesia, mask-like facies, drooling, tremor, rigidity,
shuffling gait, cogwheeling, and stooped posture
– Akathisia: Pacing and squirming brought on by an uncontrollable need to be in motion
– Tardive dyskinesia: Choreoathetoid movements of the tongue and face; lip-smacking movements; tongue flicks out in a “fly-catching” motion; slow, worm-like movement of the tongue; and involuntary movements of the limbs, toes, fingers, and trunk
Other adverse effects
Neuroleptic malignant syndrome
• Rare but serious reaction
• Risk of death without treatment
• “Lead pipe” rigidity, sudden high fever, sweating, autonomic instability, dysrhythmias, fluctuations in blood pressure, altered level of consciousness, and seizures or coma may develop
• Death can result from respiratory failure, cardiovascular collapse, dysrhythmias, and other causes
Anticholinergic effects
• Dry mouth, blurred vision, photophobia, urinary hesitancy, constipation, and tachycardia
Agranulocytosis
PHYSICAL AND PSYCHOLOGIC DEPENDENCE
Development of physical and psychologic dependence is rare
• Abrupt withdrawal of antipsychotics can precipitate a mild abstinence syndrome
DRUG INTERACTIONS
Anticholinergic drugs
– Intensify the anticholinergic effect
• CNS depressants
– Can intensify the depressant effect
• Levodopa and direct dopamine receptor agonists
– May counteract the antipsychotic effects of neuroleptics
TOXICITY
Treatment
– Intravenous fluids, alpha-adrenergic agonists, and gastric lavage – Emetics not effective: Neuroleptics block the antiemetic action
Haloperidol (Haldol)
– Butyrophenone family
– Principal indications: Schizophrenia and acute psychosis – Preferred agent for Tourette syndrome
– Adverse effects
• Extrapyramidal reactions
• Neuroendocrine effects
• Can prolong the QT interval and cause dysrhythmias
Fluphenazine
Piperazine subclass of phenothiazines
– Principal indications: Schizophrenia and other psychiatric disorders
– Adverse effects
• Early EPS
• Acute dystonia
• Parkinsonism
• Akathisia
• Sedation, orthostatic hypotension, anticholinergic effects, gynecomastia,
galactorrhea, and menstrual irregularities
LOW-POTENCY AGENTS
Chlorpromazine
Therapeutic uses: Schizophrenia, schizoaffective disorder, and the manic
phase of bipolar disorder
– Other uses: Suppression of emesis, relief of intractable hiccups, and control of severe behavioral problems in children
– Adverse effects: Sedation, orthostatic hypotension, and anticholinergic effects (e.g., dry mouth, blurred vision, urinary retention, photophobia, constipation, and tachycardia)
Drug interactions: Intensifies responses to CNS depressants (e.g., antihistamines, benzodiazepines, and barbiturates) and anticholinergic drugs (e.g., antihistamines, tricyclic antidepressants, and atropine-like drugs)
Low potency
Thioridazine
– Prolongs the QT interval and can cause fatal cardiac dysrhythmias
– Reserved for treating schizophrenia in patients who have not responded to safer agents
– Most common adverse effects: Sedation, orthostatic hypotension, anticholinergic effects, and weight gain
ATYPICAL ANTIPSYCHOTIC AGENTS
CLOZAPINE
metabolized in the liver.
• Mechanism of action
– Blocks dopamine and serotonin
• Therapeuticuse – Schizophrenia
– Levodopa-induced psychosis • Pharmacokinetics
• Adverse effects and interactions – Agranulocytosis – Seizures – Extrapyramidal symptoms – Diabetes – Dyslipidemia – Weight gain – Myocarditis – Effects in older adult patients with dementia • About double the mortality rate – Drug interactions • Preparations, dosage, and administration
OTHER ATYPICAL ANTIPSYCHOTICS
Risperidone [Risperdal]
– Mechanism of action • Binds to multiple receptors – Pharmacokinetics – Therapeutic effects – Adverse effects • Generally infrequent and mild – Preparations,dosage,andadministration • Schizophrenia, oral therapy • Schizophrenia, intramuscular therapy • Bipolar disorder
