NEUROLEPTICS

NEUROLEPTICS


NEUROLEPTICS

  • Also known as “Antipsychotics”.
  • Mainstay of treatment for schizophrenia, schizoaffective disorders & delusional disorders.
Classification:
  • Typical antipsychotics/1st generation antipsychotics/dopamine receptor antagonists (DRAs).
  • Atypical antipsychotics/2nd generation antipsychotics/serotonin-dopamine antagonists.
TYPICAL ANTIPSYCHOTICS:
  • MOA: Mainly act through dopamine, D2 receptor antagonism in mesolimbic tract.
  • Actions:
    • Effective against positive symptoms.
    • Minimal effect on negative symptoms.
Sub-classifications:
  • According to chemical groups – 
    • Phenothiazines: Chlorpromazine, Thioridazine, Trifluoperazine, Prochlorperazine, Triflupromazine, Fluphenazine, Perphenazine.
    • Thioxanthenes: Thiothixene, flupenthixol.
    • BuUrophenonesi Haloperidol, droperidol, penfluridol.
    • Miscellaneous: Pimozide, loxapine, molindone.
  • According to potency – 
    • Low potency – Chlorpromazine & thioridazine.
    • High potency – Haloperidol & fluphenazine.
Side effects:
  • Movement disorders – Extrapyramidal symptoms (acute dystonia, acute akathisia, drug-induced parkinsonism, tardive dyskinesia, neuroleptic malignant syndrome, hyperprolactinemia, sedation, orthostatic hypotension & anticholinergic side effects.
ATYPICAL ANTIPSYCHOTICS:
  • MOA:
    • Act through antagonism of 5Ht-2 receptors & D2 receptors.
    • Higher ratio of 5 HT2 to D2 blockade.
  • Actions: 
    • Effective in treatment of both positive & negative symptoms.
    • Lesser risk of causing extrapyramidal side effects as well as hyperprolactinemia – Due to lesser D2 blockade.
  • Drugs included –
    • Clozapine, Olanzapine, Risperidone, Paliperidon, Iloperidone, Quetiapine, Ziprasidone, Aripiprazol, Sertindole, Zotepine, Lurasidone, Asenapine & Amisulpride
  • Side effects – 
    • Movement disorder – Lesser incidence.
    • Hyperprolactinemia – Lesser incidence.
    • Weight gain.
    • Increased risk of dyslipidemia, diabetes & cardiovascular disease.
    • Sedation, QTc prolongation (especially with ziprasidone).
    • Seizures.
Important points on antipsychotics:

  • Long-acting injectable antipsychotics (Depot anti-psychotics):
    • Used in poorly compliant patients.
    • IM injection once a month/fortnight.
    • Durgs: 
      • Flupenthixol, Fluphenazine, Haloperidol, Pipotiazine, Zuclopenthixol, Risperidone, Olanzapine, Paliperidone & Aripiprazole.
  • Thioridazine:
    • Cause irreversible retinal pigmentatlon.
    • Cause cardiac arrhythmias (prolongation of QT interval)
    • Drug with least extrapyramidal side effects (Among typical antipsychotics).
  • Chlorpromazine:
    • Cause corneal & lenticular deposits.
  • Penfluridol:
    • Longest acting antipsychotic.
  • Ziprasidone:
    • Cause cardiac arrhythmias (prolongation of QT interval)
  • Aripiprazole:
    • Partial agonist at D2 receptors
    • (all other antipsychotics are D2 antagonists).

Exam Important

  • Neuroleptics are also known as “Antipsychotics”.
  • Antipsychotics are mainstay of treatment for schizophrenia, schizoaffective disorders & delusional disorders.
  • Typical antipsychotics mainly acts through dopamine, D2 receptor antagonism in mesolimbic tract.
  • Extrapyramidal symptoms (acute dystonia, acute akathisia, drug-induced parkinsonism, tardive dyskinesia, neuroleptic malignant syndrome, hyperprolactinemia, sedation, orthostatic hypotension & anticholinergic side effects are all most important side effects associated with typical antipsychotics.
  • Atypical antipsychotics act via antagonism of 5Ht-2 receptors & D2 receptors.
  • Lesser risk of extrapyramidal side effects & hyperprolactinemia is observed with atypical antipsychotics due to lesser D2 blockade.
  • Lesser incidence of movement disorder & hyperprolactinemia is seen with atypical antipsychotics.
  • Long-acting injectable antipsychotics (Depot anti-psychotics) are used in poorly compliant patients.
  • Thioridazine causes irreversible retinal pigmentation & cardiac arrhythmias.
  • Chlorpromazine causes corneal & lenticular deposits.
  • Penfluridol is longest acting antipsychotic.
  • Ziprasidone cause cardiac arrhythmias
  • Aripiprazole is a partial agonist at D2 receptors (all other antipsychotics are D2 antagonists).
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