Who responds to risperidone and zuclopenthixol long-acting injections? A comparative observational study

Abstract

Background and aims:

Few studies are available comparing the effectiveness of Risperidone long-acting injection (RLAI) against conventional depot antipsychotics. We aimed to study patients who were prescribed the long-acting injections Risperidone and Zuclopenthixol decanoate in routine clinical practice, to identify predictors of continuing longer-term treatment.

Methods:

From a data set of 11,250 electronic patient records, we retrospectively identified all secondary care psychiatric patients Risperidone and Zuclopenthixol depots during a three years period (2002-2005). We calculated the duration of treatment ratio (DoTR) (duration of mention of medication divided by total duration of psychiatric record) as a measure of effectiveness. We examined clinical and demographic variables associated with high and low DoTRs, i.e. patients likely to continue versus those likely to discontinue treatment.

Results:

98 records were identified for Risperidone LAI, 70 for Zuclopenthixol. Patients who continued longer-term treatment were similar for both compounds in terms of age, sex, diagnosis, length of contact with services, previous Clozapine treatment and co-prescription with other psychotropics. Individuals continuing on RLAI long-term were on a higher maximum mean dose (42 mg every 2 weeks) compared to those who discontinued early (30 mg every 2 weeks) p=0.0002. Discontinuation due to adverse effects was less with RLAI than with Zuclopenthixol (26% versus 63%, p=0.06).

Conclusions:

Both RLAI and Zuclopenthixol depot are clinically effective in longer-term treatment of psychotic disorders. Patients established on higher dose RLAI (37.5 mg and 50 mg per fortnight) were more likely on to continue long-term treatment.