injectable antipsychotics

Researchers conducted an observational study to determine the effectiveness of various antipsychotic treatment strategies for schizophrenia. They found that injectable antipsychotics and clozapine were the most effective treatments.


Large scale randomized clinical trials are considered the gold standard in clinical research because they ensure that all variables are accounted for and there are no biases inherent to the methodology.  Unfortunately, randomized clinical trials are simply not possible or appropriate with some patient populations and research questions. The authors of this study have recognized that, due to the very nature of schizophrenia, randomized control trials may not be the most effective way of comparing treatment strategies.

To ensure statistical validity every randomized clinical trial will have “exclusion criteria” to identify participants who cannot be included in the clinical trial for a scientific reason. For example, a study on the effects of a reading strategy on dyslexia may choose to exclude children who also have other diagnosed learning disorders, or children who have already tried that particular strategy.

Randomized control trials of psychiatric patients generally exclude participants who are unwilling to participate, taking other prescription or non-prescription medications or street drugs, or have a history of not reliably taking their medication. In fact, up to 80% -90% of schizophrenic patients can be excluded from a trial due to refusal, substance abuse, suicidal or antisocial behavior, or mental or physical comorbidity (having another physical or mental health illness in addition to schizophrenia).  In addition, up to 50% of the study participants will drop out of the study before completion, resulting in missing data. Unfortunately, the result is that the patients who are included in the studies are, in fact, not typical schizophrenic patients.

Even large scale observational studies have encountered problems due to variation in the study population over time. To address this issue, researchers in Sweden performed a large scale observational study using the participants as their own controls, a method referred to as “within-individual analysis”. The researchers used anonymized nationwide medical records including all individuals residing in Sweden who were 16 to 64 years of age in 2006 and who received a first-time diagnosis of schizophrenia between July 1, 2006, to December 31, 2013.

This study looked for treatment failures such as; psychiatric rehospitalizations (including rehospitalizations due to suicide attempt), switch to another medication, medication discontinuation and death. The results show that clozapine and long-acting injectable antipsychotic medications are substantially more effective than other oral antipsychotics in reducing the risk of rehospitalization or any other treatment failure. For example, the results showed that the risk of rehospitalization was 22% lower during treatment with long-acting injectable antipsychotic medications compared with treatment with equivalent oral formulations in the total population and 32% lower among newly diagnosed patients.

Remarkably the study also found that the highest risk of rehospitalization was found with quetiapine, which is the most commonly used antipsychotic in many countries. In fact, when used alone (monotherapy) 44% of patients were re-hospitalized. These results are in line with those of previous studies, suggesting that without a specific reason, quetiapine should not be used routinely as monotherapy for patients with schizophrenia.

This study provides important new information about the effectiveness of treatment medications for schizophrenic patients. The study design allows for real-world application of the results. It clearly indicates that injectable antipsychotic medications are superior than oral medications for schizophrenic patients and should be the treatment of choice when possible.


Written By: Lisa Borsellino, B.Sc.

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