Atypical antipsychotic drugs are agents designed to treat schizo-phrenia. They include aripiprazole, clozapine, olanzapine, paliperi-done, quetiapine, risperidone, and ziprasidone.
Atypical antipsychotics are absorbed after oral administration.
Atypical antipsychotics are metabolized by the liver. Metabolites of clozapine, olanzapine, quetiapine, and ziprasidone are inactive, whereas risperidone and paliperidone have active metabolites.
They’re highly plasma protein-bound and eliminated in urine, with a small portion eliminated in stool.
Atypical antipsychotics typically block the dopamine receptors, but to a lesser extent than the typical antipsychotics, resulting in far fewer extrapyramidal adverse effects. Additionally, atypical an-tipsychotics block serotonin receptor activity.
These combined actions account for their effectiveness against the positive and negative symptoms of schizophrenia with mini-mal extrapyramidal effects.
Atypical antipsychotics are considered the first line of treatment for patients with schizophrenia because of equal or improved ef-fectiveness combined with improved tolerability.
Atypical antipsychotics are commonly used to treat behavioral and psychotic symptoms in patients with dementia. Dosages are significantly lower for these patients than for patients with schizo-phrenia.
Drugs that alter the P-450 enzyme system alter the metabolism of some atypical antipsychotics.
Atypical antipsychotics counteract the effects of levodopa and other dopamine agonists. (See Adverse reactions to atypical an-tipsychotics.)