ANTIPSYCHOTIC DRUGS
 Used in Schizophrenia (chronic psychosis) & other Psychoses
 Psychosis is when people lose some contact with reality. This
might involve seeing or hearing things that other people
cannot see or hear (hallucinations) and believing things that
are not actually true (delusions)
 Other symptoms of psychosis include rapid & constant speech,
sudden loss in train of thoughts, patients are unaware that
their behavior is strange, the person may stop speaking, and
their body may be fixed in a single position for a very long time
(catatonia).
 Positive symptoms: refer to added thoughts or actions that
aren’t based in reality, include hallucinations & delusions
 Negative symptoms: refer to absence of normal behaviors in
people with schizophrenia, include reduced emotional
expression (flat affect), inability to feel pleasure (anhedonia).
Dr.Sadia Ghousia Baig
12-May-23
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Schizophrenia is a severe, chronic mental disorder characterized by disturbances in
thought, perception and behavior . Dopamine transmission disorder is a primary
factor
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A person is diagnosed with schizophrenia if they have at least two of
these symptoms for at least 6 months:
Delusions
Hallucinations
Disorganized speech
Disorganized or catatonic behavior
Negative symptoms
One of the symptoms has to be
Delusions
Hallucinations
Disorganized speech
During the 6 months, the person must have a month of active
symptoms. (It can be less with successful treatment.) Symptoms should
negatively affect them socially or at work, and can’t be caused by any
other condition.
Dr.Sadia Ghousia Baig
12-May-23
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Classification of Antipsychotics
 First generation include Phenothiazines ( chlorpromazine,
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Thioridazine, Fluphenazine), Thioxanthenes ( Thiothixene) &
Butyrophenones ( Haloperidol).
High potency antipsychotics have more affinity for D2 receptor &
include Haloperidol, Fluphenazine,
Thiothixene,Pimozide,Loxapine.
Low potency include chlorpromazine & Thioridazine
First generation high potency drugs cause movement disorders (
Extrapyramidal symptoms EPS) Egs: Dystonia( sustained
contraction of muscles, distorted postures, occur in few hrs);
Parkinson like symptoms ( bradykinesia, tremors , rigidity occur
in weeks to months), akathisia (motor restlessness, occur in a day
to weeks ); tardive dyskinesia ( involuntary movements of
tongue,lips, neck, trunk ,limbs, occur after months or years of
treatment)
Second generation ( atypical) drugs have varied heterocyclic
structures and include clozapine, loxapine, olanzapine,
risperidone, quetiapine,ziprasidone, and aripiprazole
Dr.Sadia Ghousia Baig
12-May-23
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P/K & P/D
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The antipsychotic drugs are well absorbed when given orally, lipid soluble,
readily enter CNS & other body tissues.
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Many are bound extensively to plasma proteins. These drugs require
metabolism by liver enzymes before elimination & have long plasma
halflives, drugs that inhibit CYP enzymes can prolong the halflives of
antipsychotic agents.
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Parenteral forms of some agents (eg, fluphenazine, haloperidol,
ziprasidone, olanzapine, and aripiprazole) are available
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Dopamine receptor blockade correlates with therapeutic benefit for first
generation antipsychotic drugs. Dopaminergic tracts in the brain include the
mesocortical mesolimbic pathways (regulating mood), nigrostriatal tract
(extrapyramidal function), tuberoinfundibular pathways (control of prolactin
release), and chemoreceptor trigger zone (emesis).
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Mesocortical mesolimbic dopamine receptor blockade presumably underlies
antipsychotic effects & a similar action on the chemoreceptor trigger zone
(CTZ) leads to the useful antiemetic properties
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almost all antipsychotic agents block both α1 and histamine H1 receptors to
Dr.Sadia Ghousia Baig 12-May-23
some extent
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USES OF ANTIPSYCHOTIC DRUGS
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Schizophrenia ( coventional antipsychotics reduce positive symptoms like
hallucinations, work less on negative symptoms. Clozapine is used in treatment
resistant cases ( use is limited due to S/E of agranulocytosis)
Prevention & Treatment of acute mania (aripiprazole, olanzapine)
Management of schizoaffective disorders
Toxic psychoses( caused by over dose of CNS stimulants)
Tourette syndrome ( to control tics, sudden repetitive movements or sounds for
example blinking)
Psychotic symptoms management in PD & AD
Antiemetic ( Prochlorperazine)
ADR: Sedation (chlorpromazine) , conduction defects & visual impairments by
retinal deposits ( thioridazine), QT interval prolongation ( quetiapine,
ziprasidone), seizures & agranulocytosis ( clozapine) , wt gain, hyperglycemia
(clozapine. Olanzapine), hyperprolactinemia ( risperidone), amenorrhea,
gynecomastia , postural hypotension, EPS
NMS ( neuroleptic malignat syndrome) : reaction to antipsychotic drugs
characterized by muscle rigidity, hyperpyrexia, bp changes. treated by
dantrolene , diazepam, dopamine agonist drugs. Most common by haloperidol,
chlorpromazine.
Dr.Sadia Ghousia Baig
12-May-23
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