Olanzapine for Extended-Release Injectable Suspension for Subcutaneous Use (TV-44749) Designed to Avoid the Risk of PDSS: In Vitro Release Studies in Human Plasma and In Vivo Impact of Extrinsic Factors on Pharmacokinetics

Background: TV-44749 is a subcutaneous (sc) long-acting injectable (LAI) formulation of olanzapine that recently demonstrated efficacy and safety as a treatment for schizophrenia in adults without the occurrence of post-injection delirium/sedation syndrome (PDSS) in the phase 3 SOLARIS trial (NCT05693935). TV-44749’s sc route of administration and formulation were designed to provide prolonged olanzapine release over a monthly dosing interval and to avoid the risk of post-injection delirium/sedation syndrome (PDSS). It was designed as a copolymer in situ-forming depot technology to provide a LAI formulation that could withstand physiological and environmental factors that could affect controlled-release kinetics. Methods: To evaluate the robustness of the TV-44749 formulation, an in vitro release (IVR) study in human plasma was conducted, comparing TV-44749 to the commercially available intramuscular (im) long-acting injection formulation of olanzapine pamoate monohydrate. In addition, in vivo studies in rats were conducted to assess the effect of injection site manipulation following TV-44749 sc injection on olanzapine release from the depot. Results: The IVR study showed that upon contact with human plasma, copolymers comprising TV-44749 formulation instantly precipitate and form a solid matrix that entraps olanzapine particles. This prevents an uncontrolled release of olanzapine. Additionally, in vivo rat studies found that manipulation of the injection site after TV-44749 administration, by either heating or rubbing at different time-points, resulted in no meaningful effect on overall olanzapine exposure. Conclusions: The presented findings support the robustness of the TV-44749 formulation in maintaining controlled-release properties, even under conditions that could otherwise compromise release performance.