Comparison of Gluteal Muscle Intramuscular Injection Sites of Japanese Healthy Subjects: Considerations for Optimal Insertion of Injection Needle Length

Long Acting Injectable (LAI) medications for patients with schizophrenia is commonly administered to relieve their symptoms. Through shared decision-making and clinical evidence-based, psychiatrists should systematically offer LAIs to all patients requiring long-term antipsychotic treatment as a first-line treatment. Gluteal intramuscular (IM) injection requires accurate insertion of needles into the specific muscle area, often the outer upper quadrant of the buttocks, in order to achieve the required blood concentration. The purposes of this study were to compare the “Distance from the Epidermis to the Under-Fascia (DEUF)” and “Distance from the Epidermis to the Iliac Bone (DEB)” of the buttocks IM injection sites at the dorsogluteal and ventrogluteal sites among healthy Japanese volunteer subjects, and to identify the optimal insertion injection needle length. The DEUF and DEB at the gluteal regions were measured by ultrasonography. Welch’s one-way analysis of variance was used to compare the DEUF and the DEB at the gluteal IM injection regions. There was no statistically significant difference observed between the right and left mean values of DEUF for Hochstetter and Clark’s point at the ventrogluteal sites, and the Four and Three-way split or Double Cross point at the dorsogluteal sites. However in the DEB, the Hochstetter’s point (P < 0.01) at ventrogluteal site on the right side, and Clark’s point (P < 0.05) were significantly shorter than the Double Cross point at dorsogluteal sites (F = 4.38). The left buttocks Hochstetter’s point was significantly shorter than the Double Cross point (F = 4.38, P < 0.01). These results, however, did not establish a statistically significant difference in the DEUF among injection sites. It was considered that the difference in the DEB depended on muscle volume and thickness in the gluteal injection sites.

Intramuscular Diffusion Status of Risperidone and Aripiprazole Long Acting Injectable (LAI) by Ultrasonography

The aim of this study was to consider the characteristics of intramuscular diffusion status of risperidone and aripiprazole long acting injectable (LAI) by ultrasonography. Subjects were 40 adult subjects diagnosed with schizophrenia and treated with LAI [32 patients were risperidone LAI (RLAI) and 8 patients were aripiprazole LAI (ALAI)]. However, in this paper, only three cases (one RLAI case and 2 ALAI cases) were selected to illustrate the diffusion effects of both LAI. Dorsogluteal intramuscular (IM) injection sites were measured at prone position using the “double cross” method. Before LAI injection, the distance from the epidermis to the under-fascia (DEUF), and distance from the epidermis to the iliac bone (DEI) at the IM injection site were assessed by using ultrasonography: 1) the injection needle was inserted to the gluteus medius, and 2) observed the diffusion status within the muscle injected RLAI and ALAI were confirmed using the B-mode ultrasonography. Both RLAI and ALAI were depicted as high echogenicity with acoustic shadowing. It was considered that the diffusion states of LAIs by ultrasonography were important time course evaluations providing objective evidence.