Long-acting injectable antipsychotics have undergone a great development in recent years, becoming useful tools to facilitate therapeutic adherence. Once-monthly risperidone ISM is a new way of treatment which has been commercialized in Spain since September 2022.

In this study we will analyze our clinical experience with this treatment, especially in terms of tolerance and efficacy, during its first year of widespread use.

Longitudinal retrospective study of monhtly risperidone users in a mental health center in the Autonomous Community of Madrid (Spain), between September 2022 and September 2023.

A sample of 13 patients was selected, collecting both sociodemographic (age, gender) and clinical variables (diagnosis, dose, time elapsed, number of hospital readmissions, adverse effects and monotherapy or combined use). A descriptive analysis of the collected data was then carried out.

Monthly risperidone was used in 13 patients: 15% (n=2) were women, and 85% (n=11) were male. The mean age of the patients was 43.6 years. The most frequent diganosis of these patients was “psychotic disorders” (84,6%, n= 11), with other diagnoses such as schizoaffective disorder (7,7%, n=1) and obsessive compulsive disorder (7,7%, n=1).

The doses used of risperidone were 100mg every month in 61,5% of patients (n=8) and 75mg in 38,5% of patients (n=5). The mean time since the first administration was 4.35 months.

Concerning monotherapy, 84,6% (n=11) of patients on monthly risperidone were on antipsychotic monotherapy, while 15,4% (n=2) required more than one antipsychotic. Among the switches made to monthly risperidone, 69,2% (n=9) were previously treated with oral risperidone, 15,4% (n=2) were treated with once-biweekly risperidone long-acting injectable, 7,9% (n=1) with oral paliperidone and 7,9% with aripiprazole monthly injectable.

During the study period, hospital readmissions for psychiatric descompensations occurred in one patient (7,9%, n=1), while the rest of the patients (92,1%, n=12) did not present decompensations that required psychiatric admission.

Moderate or severe effects occurred in one patient (7,9%, n=1), in the form of acute dystonia, which led to the interruption of injectable treatment. The rest of the patients (92,1%, n=12)) did not present severe adverse effects. Minor adverse effects appeared in 3 patients (25%); these adverse effects were already present in the previous treatment with oral risperidone and did not condition the suspension of the treatment.

In the sample analyzed, once-monthly Risperidone ISM had reasonable tolerance levels. Also, it´s shown to be effective in preventing psychotic decompensations and hospital admissions.

Therefore, this new injectable of monthly risperidone represents a therapeutic alternative to consider in order to guarantee therapeutic adherence and improve the quality of life of patients with psychotic symptoms.

None Declared