Long acting injectable antipsychotics in the treatment of schizophrenia: a review of literature

Abstract

Antipsychotic medications are the key of the treatment in schizophrenia, and a large body of data confirms the value of ongoing and continuous antipsychotic pharmacotherapy in controlling symptoms and preventing relapse. Even so medication non-adherence in patients with schizophrenia continues to be a significant problem and threatens successful treatment outcomes. Estimates is ranging from 40% to 90%. The introduction of the long acting injectable antipsychotics (LAI) had as its primary objective to overcome the poor adherence. This review focuses on the role of LAI in the treatment of schizophrenia, particularly on new generation antipsychotics. The existing literature, with an emphasis on clinical evidence, is assessed. Both advantages and limitations are discussed. Clinical evidence suggest that treatment with LAI is associated with a better outcome, both global and as a reduced number of rehospitalization, and better adherence. The LAI ensure a better bioavailability, more predictable correlation between drug dose and plasma concentrations, a better pharmacokinetic profile allowing the prescription of lower doses and less risk of side effects. First generation antipsychotic LAI (FGA-LAI) share with their equivalent oral compounds an increased susceptibility to induce extrapyramidal symptoms and tardive dyskinesia, with minor differences between the compounds. The second-generation LAI (SGA-LAI), as their oral formulations, compared to first generation antipsychotics, have the advantage of not causing movement disorders, but their use is complicated by the delayed release (risperidone) and the risk of the syndrome post-injection (olanzapine) and the high cost (paliperidone). Despite identified advantages, LAIs are not used as widely as might be expected. It would seem that clinicians are at least partly responsible for this, influenced by our own misperceptions (e.g., that LAIs are not acceptable to patients) and misinformation (e.g., increate side effect risk). Current guidelines on the treatment of schizophrenia recommend the use of LAI in patients who have demonstrated non-adherence or recurrent relapses related to poor or no adherence and underline the importance of patient preference. The prescription of LAI will increase in coming years as more number of LAI will be available and the increasing use of compulsory community treatment may contribute to this.