CLINICAL HANDBOOK OF SCHIZOPHRENIA

162 III. SOMATIC TREATMENTantipsychotics include clozapine, risperidone, olanzapine, quetiapine, ziprasidone, andaripiprazole. The term atypical originated from the idea that these medications reduce therisk of extrapyramidal side effects (EPS).Most recently the classification of these medications has been changed based onpharmacology. The terms first-generation antipsychotics (FGAs), second-generation antipsychotics(SGAs), and third-generation antipsychotics (TGAs) have replaced typical andatypical. This newer classification is used in this chapter.It is important to note that all antipsychotic medications have equal efficacy in thetreatment of positive symptoms of schizophrenia when equally dosed, although responsesof individual patients may vary. Dosing until side effects emerge without efficacy is not standardof practice. Subsets of research suggest that the utilization of clozapine provides betterefficacy than all other antipsychotic medications in the treatment of refractory patients.First-Generation AntipsychoticsThese medications are oftentimes referred to as typical antipsychotic medications. Theycan be subclassified into low-potency, high-potency, and very-high-potency agents. Thisclassification also helps clinicians understand the adverse effect profiles of these medications,which are discussed by Dolder in Chapter 17, this volume. All of these medicationshave a similar mechanism of action by antagonizing dopamine receptors in the mesolimbicpathway, subsequently decreasing positive symptoms. Additionally, various actionsmay cause bothersome adverse events. Potency levels provide a simplified explanation ofthe medications. The high-potency medications are for the most part pure dopamine receptorantagonists and have little to no other mechanisms. Whereas the low-potencymedications are pure dopamine receptor antagonists, they also have other mechanisms tovarious degrees, including anticholinergic, calcium channel–blocking, alpha-blocking,and antihistamine properties.Dosing of these medications should be conservative and take place once (preferred)to twice daily to avoid unwanted side effects. It is recommended that clinicians start atthe lowest available dosage strength and increase the dosage as needed during the acutephase of the illness. Dosage minimization should be attempted once the patient hasreached the stabilization phase of the illness. Equivalent dosing of FGA medications isprovided in Table 16.3.For patients with poor compliance two first-generation medications are available ina long-acting, intramuscular, injectable form. Haloperidol and fluphenazine are availableas decanoate injections utilized every 4 weeks and every 1–3 weeks, respectively. Z-trackintramuscular administration is required for both medications. Dosing of these medicationsis recommended only after the patient has been stabilized on oral medications toprovide an adequate conversion to the long-acting formulation. Conversion from oral todecanoate therapy is recommended as follows.Haloperidol DecanoateVarious strategies exist for dosing haloperidol decanoate. Loading dose and dose conversionstrategies have been utilized. The first dose (load dose) starts at 20 times the oraldose, then 15 times for the second dose, and then 10 times for the third dose (dosing oncea month). It is recommended, if the first dose is over 100 mg, to utilize two injections: alwaysgiving a test dose for the first injection, followed by a second injection 3–5 dayslater. Steady states of haloperidol decanoate are not reached for about 3 months, so across-taper from the oral medication is suggested, especially if the loading dose is notused.