Amongst oral antipsychotics, tolerance and adherence are thought to be higher with atypicals versus conventional agents. Fewer data exist for parenteral antipsychotics regarding the atypical–conventional comparison.

to compare adherence rates and subjective response between long-acting risperidone (LAR) and conventional depots.

Cross-sectional, naturalistic, one-site study of all outpatients with severe mental disorders treated with injectable antipsychotics over a 12–month period at one Spanish mental health unit. Different sets of broadly– and narrowly–defined criteria for adherence were calculated from mental health nurse´s registry data. Patients´ subjective response was self-assessed with the Subjective Well-being under Neuroleptic treatment (SWN) and the Drug Attitude Inventory (DAI-10).

Subjects treated with LAR (n=27) and conventional depots (n=22) were similar in clinical and demographic terms. Both groups reported mostly positive subjective responses with the SWN (LAR=71.8+18.4 vs depots=81.7+15.3) and the DAI-10 (LAR=3.0+4.8 vs depots=4.0+4.5), with non-significant differences. Regardless the criteria of adherence used, rates of non-adherent subjects were also comparable, ranging from 36% (narrowly–defined) to 82% (broadly–defined). Although mean telephone prompts were higher for the LAR group (p=0.002), this difference disappeared when interval of administration (14 vs 28 days) was taken into account (ANCOVA: F=0.76; p=0.4).

In this small study, atipicity would not influence attitudes or subjective response to parenteral antipsychotics. Furthermore, the two–fold administration frequency of long-acting risperidone compared to depots does not seem to lead to higher rates of non–compliance amongst outpatients with severe mental disorders.