ANTI – PSYCHOTICS
How ar e anti-psychotics classifi ed?
Classified based on the period when they
were developed & their mechanism of
Schizophr en ia
action.
Definition: A mental illness characterized
Classified into typical ( First generation) by dopamine dysregulation.
& atypical ( second-generation)
Presentation: Schizophrenia exhibits a
combination of positive & negative
SGAs are preferred as first line due to symptoms due to dysregulation in
their low risk of extra-pyramidal different dopamine pathways in the
symptoms & tardive dyskinesia brain.
compared to FGAs.
Extra-pyramidal symptoms are a group Positive sym ptom s are linked to
of acute & subacute movement disorders dopamine hyperactivity in the
caused by dopamine inhibition in the mesolimbic pathway. This over activity
basal ganglia. They include: dystonia, leads to hallucinations, delusions,
akathisia, Parkinsonism etc. disorganized thinking.
Tardive dyskinesia is a late-onset, Negative sym ptom s are associated
irreversible movement disorder caused with dopamine hypoactivity in the
by prolonged dopamine receptor mesocortical pathway resulting in social
blockade leading to dopaminergic withdrawal, lack of motivation etc.
receptor hypersensitivity.
The pathophysiology is complex &
multifactorial. It is not solely a
dopamine disorder but also involves
abnormalities in other neurotransmitters
e.g glutamate & serotonin.
Neuroinflammatory processes,
oxidative stress & genetic predisposition
may disrupt multiple brain networks
silmuntaneously leading to a mix of
positive & negative symptoms.
, Acute phase – positive symptoms are Normally, dopamine normally inhibits
more prominent. prolactin release. Inhibition of dopamine
Chr onic phase – negative symptoms & leads to hyperprolactinaemia causing
cognitive deficits are more pronounced. galactorrhoea, amenorrhoea &
gynecomastia.
Pathw ays of Dopam ine dysr egulation.
These pathways contribute to both symptoms of
schizophrenia & effects of antipsychotic
treatments.
Mesolimbic pathway
Involved in motivation & emotions.
Hyperactivity by of dopamine in this
pathway leads to Positive symptoms e.g
hallucinations
Mesocortical pathway
Responsible for cognition, decision
making & emotional regulation.
Hypoactivity of dopamine in this
pathway contributes to negative
symptoms e.g. apathy, anhedonia &
cognitive deficits e.g. impaired memory &
attention.
Nigrostriatal pathway *
Involved in movement regulation.
Dopamine blockade by typical
antipsychotics here will cause extra-
pyramidal symptoms.
Tuberoinfandibular pathway *
Regulates the secretion of pituitary
hormones especially prolactin.
How ar e anti-psychotics classifi ed?
Classified based on the period when they
were developed & their mechanism of
Schizophr en ia
action.
Definition: A mental illness characterized
Classified into typical ( First generation) by dopamine dysregulation.
& atypical ( second-generation)
Presentation: Schizophrenia exhibits a
combination of positive & negative
SGAs are preferred as first line due to symptoms due to dysregulation in
their low risk of extra-pyramidal different dopamine pathways in the
symptoms & tardive dyskinesia brain.
compared to FGAs.
Extra-pyramidal symptoms are a group Positive sym ptom s are linked to
of acute & subacute movement disorders dopamine hyperactivity in the
caused by dopamine inhibition in the mesolimbic pathway. This over activity
basal ganglia. They include: dystonia, leads to hallucinations, delusions,
akathisia, Parkinsonism etc. disorganized thinking.
Tardive dyskinesia is a late-onset, Negative sym ptom s are associated
irreversible movement disorder caused with dopamine hypoactivity in the
by prolonged dopamine receptor mesocortical pathway resulting in social
blockade leading to dopaminergic withdrawal, lack of motivation etc.
receptor hypersensitivity.
The pathophysiology is complex &
multifactorial. It is not solely a
dopamine disorder but also involves
abnormalities in other neurotransmitters
e.g glutamate & serotonin.
Neuroinflammatory processes,
oxidative stress & genetic predisposition
may disrupt multiple brain networks
silmuntaneously leading to a mix of
positive & negative symptoms.
, Acute phase – positive symptoms are Normally, dopamine normally inhibits
more prominent. prolactin release. Inhibition of dopamine
Chr onic phase – negative symptoms & leads to hyperprolactinaemia causing
cognitive deficits are more pronounced. galactorrhoea, amenorrhoea &
gynecomastia.
Pathw ays of Dopam ine dysr egulation.
These pathways contribute to both symptoms of
schizophrenia & effects of antipsychotic
treatments.
Mesolimbic pathway
Involved in motivation & emotions.
Hyperactivity by of dopamine in this
pathway leads to Positive symptoms e.g
hallucinations
Mesocortical pathway
Responsible for cognition, decision
making & emotional regulation.
Hypoactivity of dopamine in this
pathway contributes to negative
symptoms e.g. apathy, anhedonia &
cognitive deficits e.g. impaired memory &
attention.
Nigrostriatal pathway *
Involved in movement regulation.
Dopamine blockade by typical
antipsychotics here will cause extra-
pyramidal symptoms.
Tuberoinfandibular pathway *
Regulates the secretion of pituitary
hormones especially prolactin.
