Schizophrenia

Schizophrenia

Schizophrenia is a mental disorder caused by some inherent dysfunction of the brain.
The main clinical features of the disease are as follow.
Positive symptoms
• Delusions.
• Hallucinations.
• Thought disorder.
• Abnormal, disorganised behaviour.
• Catatonia (can be apparent as immobility or purposeless motor activity).
Negative symptoms
• Withdrawal from social contacts.
• Flattening of emotional responses.
• an inability to experience pleasure.
• inability to perform everyday tasks.
Schizophrenia results from increased dopaminergic activity , brought about by a rise in the number of brain dopamine D2-receptors, or receptor supersensitivity, or excess availability of dopamine for D2 receptor activation from over production or reduced destruction through enzyme deficiency .
The neuroleptic drugs (also called antipsychotic drugs, or major tranquilizers) are used primarily to treat Schizophrenia. All currently available antipsychotic drugs that alleviate symptoms of schizophrenia decrease dopaminergic and/or serotonergic neurotransmission. The traditional or typical neuroleptic drugs ( first generation) have antipsychotic effects that reflect competitive blocking of dopamine receptors. These drugs vary in potency. For example, chlorpromazine is a low-potency drug, and fluphenazine is a high-potency agent. No one drug is clinically more effective than another. In contrast, the newer antipsychotic drugs are referred to as atypical (or second-generation antipsychotics), because they have fewer extrapyramidal adverse effects than the older, traditional agents. These drugs block both serotonin and dopamine receptors.
All of the atypical antipsychotics exhibit an efficacy that is equivalent to, or occasionally exceeds, that of the typical neuroleptic agents. Neuroleptic drugs are not curative and do not eliminate the fundamental and chronic thought disorder, but they often decrease the intensity of hallucinations and delusions and permit the person with schizophrenia to function in a supportive environment.

Examples
1- typical neuroleptics with low potency: chlorpromazine, prochlorperazine and thioridazine.
2- typical neuroleptics with high potency: fluphenazine, haloperidol, and thiothixene.
3- atypical neuroleptics: clozapine, olanzapine, risperidone, paliperidone and ziprasidone.