Antipsychotics

Definition

• Antipsychotics are neuroleptic drugs in the following groups: phenothiazines, thioxanthenes, dibenzoxazepines, dihydroindoles, butyrophenones, and diphenylbutylpiperidine and alkali metal. Typical antipsychotics: chlorpromazine (Thorazine), fluphenazine (Permitil), thioridazine (Mellaril), thioxanthene, haloperidol (Haldol), and loxapine (Loxitane). Atypical antipsychotics: clozapine (Clozaril), olanzapine (Zyprexa), quetiapine (Seroquel), and risperidone (Risperdal).
• Other agent: lithium (Lithobid).
• Normal range: see Table 16.10.

TABLE 16 " 10Normal Levels of AntipsychoticsView LargeTABLE 16 " 10Normal Levels of Antipsychotics Normal Range Toxic Level Lithium 0.4 " 1.0 mEq/L (serum trough " 12 h postdose) >1.5 mEq/L Haloperidol 2.0 " 15.0 ng/mL Olanzapine 5 " 75 ng/mL Clozapine 100 " 700 ng/mL Fluphenazine 0.2 " 2.0 ng/mL Chlorpromazine Adult therapeutic: 50 " 300 ng/mL Adult: >500 ng/mL Child therapeutic: 30 " 80 ng/mL Child: >200 ng/mL

Use

• Treatment of psychoses, schizophrenia, mania, Tourette syndrome (haloperidol)

Limitations

• Immunoassay: RIA " nonspecific, semiquantitative due to varying cross-reactivity with parent drug and metabolites.
• Fluorometry: nonspecific, semiquantitative due to interferences from metabolites.
• Hemolyzed specimens are unacceptable. Remove serum from clot as soon as possible.
• Lithium: Lithium heparin and sodium fluoride/potassium oxalate tubes are unacceptable.