Antipsychotics comparisons between

Coley KC, Carter CS, DaPos SV, et al (1999). Effectiveness of antipsychotic therapy in a naturalistic setting a comparison between risperidone, perphenazine, and haloperidol./ Clin Psychiatry 60, 850-6. 

More recently, two methodologically advanced studies have been published a comparison between four antipsychotic drugs in a trial of 14 weeks duration (Bilder et al., 2002, see Box 7.1) and a study of 2 years duration comparing an atypical with an older typical antipsychotic drug (Green et al., 2002). 

Box 7.1 A Controlled Comparison between Four Antipsychotic Drugs... 

Two dose effect studies with haloperidol allow a statement to be made regarding adequate doses, at least for this antipsychotic a double-blind comparison between daily doses of 10, 30 and 80 mg of haloperidol in 87 recently hospitalized patients with schizophrenia revealed no advantage of the two higher doses over the dose of lOmg per day (Rifkin ei al., 1991), and a study by McEvoy et cd. (1991) in 106 patients with schizophrenia and schizoaffective psychoses showed that an increase in dose above an individually optimal level (mostly less than lOmg per day in this study) produced no additional therapeutic effect but rather an increase in side effects, especially EPS. 

The effect size of a continuous variable is frequently expressed as the difference between the mean of the experimental minus the mean of the control group divided by the pooled standard deviation. For example, in Chapter 5, data from the National Institute of Mental Health collaborative study demonstrated that antipsychotic-treated patients averaged a 4.2-point increase on a 6-point improvement scale, whereas the placebo patients averaged only a 2.2-point increase (i.e., an average difference of 2 points). The standard deviation of these data was approximately 1.7, so in effect size units, the improvement was approximately 1.2 (i.e., 2.0 1.7) SD units. For discontinuous data, the effect size for a drug-placebo comparison is usually expressed as the difference between the percent improvement with the experimental drug and the percent improvement with placebo. 

Whether Asians are at greater risk of antipsychotic-induced parkinsonism is also uncertain. In one study, Asian patients developed symptoms of parkinsonism while taking lower weight-adjusted doses and exhibiting lower serum haloperidol concentrations in comparison with Caucasian patients (Lin et al. 1989). In contrast, another study found little difference between Asians and whites, with 40% of Asian patients developing parkinsonism within 2 weeks of initiation of haloperidol therapy, compared with 35% of Caucasians (Binder and Levy 1981). In a study conducted in Japan (Binder et al. 1987), the prevalence of antipsychotic-induced parkinsonism was found to be 18%-40%, comparable to rates reported in the United States. Thus the data concerning Asians are contradictory. 

In a 4-week, randomised, open-label comparison of ziprasidone and clozapine in the treatment of psychotic symptoms in Parkinson s disease, the most common initial adverse effect was somnolence [47 ]. There was no difference in movement disorder scales between the two antipsychotics. 

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