Evaluation of the effectiveness and acceptability of intramuscular clozapine injection: illustrative case series

Abstract

Aims and method A series of eleven patients prescribed intramuscular clozapine at five UK sites is presented. Using routinely collected clinical data, we describe the use, efficacy and safety of this treatment modality. Results We administered 188 doses of intramuscular clozapine to eight patients. The remaining three patients accepted oral medication. With the exception of minor injection site pain and nodules, side-effects were as expected with oral clozapine, and there were no serious untoward events. Nine patients were successfully established on oral clozapine with significant improvement in their clinical presentations. Clinical implications Although a novel formulation in the UK, we have shown that intramuscular clozapine can be used safely and effectively when the oral route is initially refused.

A retrospective study of intramuscular clozapine prescription for treatment initiation and maintenance in treatment-resistant psychosis

“…This suggests that the prescription of intramuscular clozapine may achieve long-term clinical improvement and adherence to oral medication, even in those patients who are initially reluctant to engage with clozapine treatment, and that this is maintained even in a less restrictive setting. Consistent with previous studies, 9,11,13 our data found no evidence that intramuscular clozapine differs markedly from oral clozapine tolerability and adverse effects, with the one reported adverse event related to its formulation being swelling at the injection site. However, the lack of additional side-effects reported may be attributed to its short-term use, often during titration and therefore at low doses, and this study was not powered nor designed to assess safety.…”

“…This finding is in line with an observational study by Hoge et al, 21 according to which drug refusal developed into voluntary acceptance of treatment by most patients. Although preliminary, our data on discontinuation rates among those who did not require intramuscular administrations is in line with previous findings 9,11 that the mere prescription of intramuscular clozapine can increase adherence to clozapine without the need of intramuscular administration. Post hoc analysis also showed that those patients who accepted oral clozapine when offered the intramuscular had lower discontinuation rates compared with patients who declined oral and were administered intramuscular clozapine.…”

“…Presently, few naturalistic studies have demonstrated the potential of intramuscular clozapine in initiating treatment, with a total enrolment of approximately 100 patients. 9–13 To our knowledge, this is the largest study in the UK to report the use of short-acting intramuscular clozapine for treatment initiation and maintenance in patients with a treatment-resistant psychotic disorder. Our study further adds to the evidence for intramuscular clozapine as a viable tool to allow patients whose illness is compromising their capacity to consent to appropriate treatment for their treatment-resistant psychotic disorder to access and benefit from clozapine.…”

“…Although there is no upper limit, the protocol suggests not exceeding 14 days of injections; nonetheless, previous data report safe use of intramuscular clozapine for up to 96 days. 9 Therefore, the SLaM protocol (see Supplementary file 1 available at https:// doi.org/10.1192/bjp.2020.115) allows for intramuscular clozapine as a short-term intervention to initiate or re-initiate clozapine treatment in patients who refuse oral medication, with a view to converting to oral clozapine once adherence is achieved. The decision to prescribe intramuscular clozapine is undertaken on an individual basis and our local protocol states that it must be agreed by a multidisciplinary team, the Director of Pharmacy and a second-opinion doctor appointed by the Care Quality Commission under the provisions of the MHA 1983.…”

“…Although compulsory administration of medication is not uncommon in psychiatric care, this is rarely used with clozapine treatment, with only a few facilities worldwide reporting the use of nasogastric 8 and intramuscular clozapine. [9][10][11][12][13] In this study, we present our 3-year experience with short-acting intramuscular clozapine in the South London and Maudsley NHS Foundation Trust (SLaM).…”