Deltoid versus gluteal: Which intramuscular injection site do mental health patients prefer?

Long-acting injectable intramuscular (IM) (LAIs or depot) antipsychotic medications have been prescribed for over 60 years and are known to reduce relapse in schizophrenia. Interestingly, no one has systematically asked the recipients of these injections which of the gluteal or deltoid injection sites they prefer. Patient choice is regarded as beneficial in medicine, as is shared decision-making (SDM) and Nott et al. (2018) found that SDM can enhance adherence to treatment and rapport between prescriber and patient.

We asked all individuals attending a large Australian public hospital out-patient clinic delivering LAI antipsychotics about their preferred IM injection site. We also noted their demographic details but not ethnicity.

All 245 individuals receiving LAIs (all monthly apart from Trinza which is quarterly) agreed to participate, 173 men (mean age: 40 years) and 72 women (mean age: 42 years). A total of 81% were detained under the Mental Health Act. A total of 80 people were receiving paliperidone palmitate (modal dose = 100 mg); 50 were on Aripiprazole Maintena (mode = 400 mg); 45 had zuclopenthixol decanoate (mode = 400 mg/month, wider dose range); 25 had paliperidone Trinza (mode = 350 mg every 3/12). The remaining 45 individuals were receiving (in order) flupenthixol, olanzapine, risperidone, haloperidol and fluphenazine LAIs.

Nursing staff in our clinic offer the patient (regardless of detention status) a choice of injection site, i.e. deltoid versus gluteal, and whether they wished to rotate the site between injections. A total of 65% of out-patients preferred the deltoid, with 35% opting for a gluteal injection; 84% chose to rotate the injection site between left and right sides.

The only other study (published in French) which includes data on injection site preference is from 281 patients, with ‘the majority’ preferring deltoid to gluteal (Millet et al., 2012). A survey (Geerts et al., 2013) of 891 European healthcare professionals found 86% preferred having a choice of LAI injection site, with most feeling deltoid injections reduced patient embarrassment. The pharmacokinetics of the two injection sites are also different, with the C_max of the deltoid site being 65% higher after one injection and 30% higher after four deltoid injections, compared to the gluteal site. It is worth noting that some LAIs or depots are officially only licensed for gluteal administration, e.g. zuclopenthixol decanoate and olanzapine pamoate.

In summary, both prescribers and nurses administering LAIs should be aware of patient preferences regarding injection site, in the spirit of SDM, as well as the differing pharmacokinetics of the differing routes.