comprehensive overview of schizophrenia and its treatment and modern researches targeting schizophrenia therapy.

1. Antipsychotic Drugs
Faraza Javed
Mphil Pharmacology

2. PSYCHOSIS
Psychosis (from the Greek , psyche, "mind/soul", and -osis,
"abnormal condition or derangement") refers to an
abnormal condition of the mind.
A syndrome of chronic disordered thinking and
disturbed behavior (schizophrenia, mania,
depression)
The most important types of psychosis are:
Schizophrenia
Affective disorders (e.g. depression, mania)
Organic psychoses (mental disturbances caused by head
injury, alcoholism, or other kinds of organic disease).

3. Schizophrenia
A chronic mental disorder involving
a breakdown in the relation
between thought, emotion, and
behaviour, leading to faulty
perception, inappropriate actions
and feelings, withdrawal from
reality and personal relationships
into fantasy and delusion, and a
sense of mental fragmentation.
The disorder is characterized by a
divorcement from reality in the
mind of the person (psychosis).

4. Schizophrenia

5. Etiology
DOPAMENERGIC SYSTEM:
There are four major pathways for the
dopamenergic system in brain :
I. The Nigro-Striatal Pathway.
II. The Mesolimbic Pathway.
III. The Mesocortical Pathway.
IV. The Tuberoinfundibular Pathway.

7. The Dopamine Hypothesis
Schizophrenia results from excess activity of dopamine
neurotransmission in Mesolimbic and Mesocortical
Pathways because:
 All antipsychotic drugs block dopamine receptors.
Higher levels of dopamine receptors measured in
brains of schizophrenics by PET.
 Stimulant drugs which act through dopamine can
produce schizophrenic-like behaviors
(eg.amphetamines).

8. SYMPTOMS
POSITIVE
SYMPTOMS:
 Delusions
 Hallucinations
 Combativeness
 Insomnia

9. SYMPTOMS
NEGATIVE SYMPTOMS:
 Affective Flattening
(blunt)
 Alogia
 Avolition
 Amotivation
 Apathy
 Asocial Behavior

10. SYMPTOMS
DISORGANIZED
SYMPTOMS:
 Disorganized
thought, speech,
behavior.
 Poor Attention.

11. Antipsychotic Agents
Antipsychotic drugs are able to reduce psychotic
symptoms in a wide variety of conditions,
including schizophrenia, bipolar disorder,
psychotic depression and drug induced
psychosis.
They have also been termed neuroleptics, because
they suppress motor activity and emotionality.
** These drugs are not a cure **
Psychotic diseases are life long and it is preferable
to prevent the psychotic episodes than to treat
them.

12. Classification of Antipsychotic
Drugs
Typical antipsychotics
Phenothiazines (Chlorpromazine, Perphenazine,
Fluphenazine, Thioridazine)
Thioxanthenes (Flupenthixol, Clopenthixol)
Butyrophenones (Haloperidol, Droperidol)
Atypical antipsychotics
(Clozapine, Risperidone, Sulpiride, Olanzapine,
Aripiprazole)

13. Distinction between ‘typical’ and ‘atypical’
groups is not clearly defined, but rests on:
Incidence of extrapyramidal side-effects
(less in ‘atypical’ group)
Efficacy in treatment-resistant group of
patients
Efficacy against negative symptoms.

14. Drug Targets
Dopamine receptors: D1, D2, D3, D4, D5
Serotonin receptors: 5-HT-1A, 2A, 3, 6, 7
Norepinephrine: Alpha-1 & Alpha-2
Muscarinic Acetylcholine: M1 & M4
Dopamine, Norepinephrine & Serotonin
transporters
NMDA-glutamate receptor

15. Typical
Antipsychotics

16. MECHANISM OF ACTION
 There are many type of DA-receptors.
 The antipsychotic drugs probably owe their
therapeutic effects mainly to blockade of D2
receptors.
 The main groups, phenothiazines, thioxanthines and
butyrophenones, show preference for D2 over D1
receptors; whereas clozapine is relatively non-selective
between D1 and D2, but has high affinity for
D4.

17. Therapeutic Uses
 Treatment of psychotic disorders:
schizophrenia, mania, paranoid states.
 Treatment of nausea and vomiting of certain
causes.
 Anesthesia in hypothermia and artificial
hibernation (used with pethidine and
promethazine).

18. Adverse Effects
Extrapyramidal motor disturbances:
 Parkinson-like symptoms
 Neuroleptic Malignant Syndrome
 Tardive dyskinesia (involuntary movements
of face, tongue and limbs , appearing after
months or years of antipsychotic treatment).
 Acute dystonias.
Seizures
Cardiac toxicity Produce hypotension
(primarily postural) by α-adrenergic blocked.

19. Endocrine effects: Increase prolactin : which
may result in gynecomastia. They reduce
gonadotropin secretion but infertility occur
only occasionally.
ACTH release in response to stress is diminish.
Decreased release of ADH may result in an
increase in urine volume.
Urticarial skin reactions are common but
usually mild. Excessive sensitivity to ultraviolet
light may also occur.

20. Other side-effects (dry mouth, constipation,
blurred vision, hypotension, etc.) are due to
block of other receptors, particularly α–
adrenoceptors and muscarinic ACh receptors.
 Contact dermatitis, blood dyscrasias,
obstructive jaundice sometimes occurs with
phenothiazines.

21. Limitations Of
Conventional/Typical
Antipsychotics
Approximately one-third of patients with
schizophrenia fail to respond
Limited efficacy against Negative symptoms
High proportion of patients relapse
Side effects and compliance issues
Atypical/New generation Antipsychotics are
preffered for the treatment of various
psychotic disorders.

22. Atypical
Antipsychotics

23. Clozapine
Effective in treating some patients with
psychosis unresponsive to standard neuroleptic
drug.
Blocks D4 receptor and have low affinity for D1
and D2 dopamine receptors.
Relative high selectivity for D4 and 5-HT2
receptors
Lacks extrapyramidal side effects.
Must monitor the granulocyte counts due to
higher incidence of agranulocytosis and other
blood dyscrasias.

24. Risperidone
Combination of D2 + 5-HT2 receptor blockade.
In addition it has high affinity for α1, α2 and H1
receptors; blockade of these may contribute to
efficacy as well as side effects like postural
hypotension.
Risperidone is more potent D2 blocker than
clozapine; extrapyramidal side effects are less.
Prolactin levels rise during risperidone therapy,
but it is less epileptogenic than typical agents.
Caution: increased risk of stroke in the elderly.

25. Olanzapine
Broader spectrum of efficacy covering schizo-affective
disorders.
Resembles clozapine in blocking multiple
monoaminergic (D2, 5- HT2, α1, α2) as well as
muscarinic and H1 receptors.
Both positive and negative symptoms of
schizophrenia appear to be benefited.
Monotherapy with olanzapine may be as effective
as a combination of lithium/valproate +
benzodiazepines.
Incidence of stroke may be increased in the elderly.
Agranulocytosis has not been reported with
olanzapine.

26. Therapeutic uses
Treatment of schizophrenia
Prevention of severe nausea and vomiting
Other uses: Treatment of mania, organic brain
syndromes, anxiety.
Chlorpromazine is used to treat intractable
hiccups. Risperidone and haloperidol are also
commonly prescribed for this tic disorder.

27. Adverse events
Parkinson-like symptoms of bradykinesia,
rigidity, and tremor usually occur within weeks
to months of initiating treatment.
Tardive dyskinesia
Hypersensitivity reaction: Cholestatic jaundice,
myocarditis, agranulocytosis.
Miscellaneous: Weight gain (not with
haloperidol), blood sugar and lipids may tend
to rise. Risk of worsening of diabetes and blue
pigmentation on skin and retinal degeneration
may increases.

28. Clinical Efficacy of
Antipsychotic Drugs
Antipsychotic drugs are effective in controlling
symptoms of acute schizophrenia, when large
doses may be needed.
Long-term antipsychotic treatment is often
effective in preventing recurrence of
schizophrenic attacks, and is a major factor in
allowing schizophrenic patients to lead
normal lives.

29. Depot preparations are often used for
maintenance therapy.
Antipsychotic drugs are not generally
effective in improving negative schizophrenic
symptoms.
Approximately 40% of chronic schizophrenic
patients are poorly controlled by
antipsychotic drugs; clozapine may be
effective in some of these ‘antipsychotic-resistant’
cases.

30.  Second generation antipsychotics have
weak D2 blocking but potent 5-HT2
antagonistic activity. Extrapyramidal side
effects are minimal, and they may improve
the impaired cognitive function in
psychotics.

31. Modern Advancement
In February, 2011, Jonathan Sebat, at the University of
California, and his colleagues, published research
identifying a gene which holds particular promise in
the treatment of schizophrenia. According to Dr.
Sebat’s research, Vasoactive Intestinal Peptide
Receptor 2 or VIPR2 is much more likely to be found
in those with schizophrenia. Because VIPR2 responds
to synthetic peptides, already available, targeting this
gene is a promising treatment strategy.

32. References
 Katzung Pharmacology, 12th Edition.
Rang & Dale Pharmacology, 6th Edition.
 Lippincott’s Pharmacology, 5th Edition.
 Alstrom, D. Schizophrenia Research Breakthrough.
The Irish Times. (April 2011).
 LaFee, S. Schizophrenia Gene Mutation Found;
Target for New Drugs. UC San Diego. (February,
2011).