A new study finds that among adults with schizophrenia or schizoaffective disorder, treatment with newer, more costly antipsychotic medications results in outcomes similar to those of older medications.
As discussed in the Journal of the American Medical Association (JAMA), a comparison between paliperidone palmitate, with the older antipsychotic haloperidol decanoate, found no significant difference on a measure of effectiveness.
As noted in an accompanying editorial, “Setting aside the substantial differences in cost between haloperidol decanoate and paliperidone palmitate [approximately $35 vs. $1,000, respectively, per injection], the results from [this] trial suggest that drug selection should be based on anticipated adverse effects rather than efficacy,” writes Donald C. Goff, M.D.
“This is true for most antipsychotics, with the notable exception of clozapine, which has established superior efficacy for treatment-resistant schizophrenia but is limited in use due to more serious adverse effects.”
Researchers say that while patients may try a variety of medications to identify one that works best for their disorder, this approach may be problematic if adverse effects persist after drug discontinuation, such as weight gain or involuntary movements.
In the study, side effects of paliperidone palmitate included progressive weight gain over time while those taking haloperidol decanoate lost weight.
Additionally, treatment with paliperidone palmitate was associated with greater increases in serum prolactin (a hormone), whereas haloperidol decanoate was associated with more akathisia (a movement disorder).
Specialists explain that long-acting injectable antipsychotic medications are prescribed to reduce nonadherence to drug therapy and relapse in people diagnosed with a schizophrenia-spectrum disorder.
However, the relative effectiveness of long-acting injectable versions of second-generation and older antipsychotic medications has not been previously assessed.
In the new study, Joseph P. McEvoy, M.D., and colleagues randomly assigned 311 patients diagnosed with schizophrenia or schizoaffective disorder to receive monthly injections of haloperidol decanoate or paliperidone palmitate for as long as 24 months.
Researchers compared the number of psychiatric hospitalizations, episodes of crisis stabilization, increases in frequency of outpatient visits, a clinician’s decision that oral antipsychotic could not be discontinued within eight weeks after starting the long-acting injectable antipsychotics, or a clinician’s decision to discontinue the assigned long-acting injectable due to inadequate therapeutic benefit.
The authors found no significant difference in the rate of efficacy failure for patients in the paliperidone palmitate group vs those in the haloperidol decanoate group.
The most common reasons for efficacy failure were psychiatric hospitalization and clinician discontinuation of study medication due to inadequate therapeutic effect.
The researchers note that their findings do not rule out the possibility of a clinically meaningful advantage with paliperidone palmitate.
“The results [of this study] are consistent with previous research that has not found large differences in the effectiveness of newer and older antipsychotic medications,” the authors conclude.