Typicals Versus Atypicals
While the atypical (second-generation) antipsychotics were marketed as offering greater efficacy in reducing psychotic symptoms while reducing side effects (and Extrapyramidal symptoms in particular) than typical medications, the results showing these effects often lacked robustness, and the assumption was increasingly challenged even as atypical prescriptions were soaring. One review concluded there were no differences while another found that atypicals were "only moderately more efficacious". These conclusions were, however, questioned by another review, which found that clozapine, amisulpride, and olanzapine and risperidone were more effective Clozapine has appeared to be more effective than other atypical antipsychotics, although it has previously been banned due to its potentially lethal side effects. While controlled clinical trials of atypicals reported that extrapyramidal symptoms occurred in 5–15% of patients, a study of bipolar disorder in a real world clinical setting found a rate of 63%, questioning the generalizability of the trials.
In 2005 the US government body NIMH published the results of a major independent (not funded by the pharmaceutical companies) multi-site, double-blind study (the CATIE project). This study compared several atypical antipsychotics to an older typical antipsychotic, perphenazine, among 1493 persons with schizophrenia. The study found that only olanzapine outperformed perphenazine in discontinuation rate (the rate at which people stopped taking it due to its effects). The authors noted an apparent superior efficacy of olanzapine to the other drugs in terms of reduction in psychopathology and rate of hospitalizations, but olanzapine was associated with relatively severe metabolic effects such as a major weight gain problem (averaging 44 pounds (20 kg) over 18 months) and increases in glucose, cholesterol, and triglycerides. The mean and maximal doses used for olanzapine were considerably higher than standard practice, and this has been postulated as a biasing factor that may explain olanzapine's superior efficacy over the other atypical antipsychotics studied, where doses were more in line with clinically relevant practices. No other atypical studied (risperidone, quetiapine, and ziprasidone) did better than the typical perphenazine on the measures used, nor did they produce fewer adverse effects than the typical antipsychotic perphenazine (a result supported by a meta-analysis by Dr. Leucht published in Lancet), although more patients discontinued perphenazine owing to extrapyramidal effects compared to the atypical agents (8% vs. 2% to 4%, P=0.002).
A phase 2 part of this CATIE study roughly replicated these findings. This phase consisted of a second randomization of the patients that discontinued taking medication in the first phase. Olanzapine was again the only medication to stand out in the outcome measures, although the results did not always reach statistical significance (which means they were not reliable findings) due in part to the decrease of power. The atypicals again did not produce fewer extrapyramidal effects than perphenazine. A subsequent phase was conducted that allowed clinicians to offer clozapine which was more effective at reducing medication drop-outs than other neuroleptic agents. However, the potential for clozapine to cause toxic side effects, including agranulocytosis, limits its usefulness.
It had been hoped that patient adherence to antipsychotics would be higher with the atypicals, but a 2008 review found that the data have failed to substantiate the notion that novel antipsychotic drug use leads to improved medication compliance and favorable clinical outcomes.
Overall evaluations of the CATIE and other studies have led many researchers to question the first-line prescribing of atypicals over typicals, or even to question the distinction between the two classes. In contrast, other researchers point to the significantly higher risk of tardive dyskinesia and EPS with the typicals and for this reason alone recommend first-line treatment with the atypicals, notwithstanding a greater propensity for metabolic adverse effects in the latter. The UK government organization NICE recently revised its recommendation favoring atypicals, to advise that the choice should be an individual one based on the particular profiles of the individual drug and on the patient's preferences.
The re-evaluation of the evidence has not necessarily slowed the bias towards prescribing the atypicals, however.
Read more about this topic: Antipsychotic, Efficacy