New clinical data suggest that a subcutaneous formulation of olanzapine could expand long‑acting injectable (LAI) options for people with schizophrenia, while sidestepping the safety concerns that have limited the drug’s intramuscular version.
Phase 3 SOLARIS trial shows efficacy comparable to oral olanzapine
The phase 3 SOLARIS study, a double‑blind, randomized controlled trial, enrolled 675 adults diagnosed with schizophrenia. Participants received a once‑monthly subcutaneous injection of TV‑44749 at doses equivalent to 10 mg, 15 mg, or 20 mg of oral olanzapine, or a placebo. Over the eight‑week acute phase, patients on TV‑44749 experienced an average reduction of about 20 points on the Positive and Negative Syndrome Scale (PANSS), a change representing roughly a 9.5 % improvement in symptom severity.
Secondary measures also moved in a favorable direction. The Clinical Global Impression‑Severity (CGI‑S) score fell by an average of 1.26 points, indicating reduced overall illness severity. Functional capacity, assessed with the Personal and Social Performance (PSP) scale, rose by roughly 10 points, suggesting better daily functioning.
These outcomes align with earlier meta‑analyses that identified olanzapine as one of the more effective oral antipsychotics for schizophrenia, though the American Psychiatric Association does not prescribe a single preferred agent.
Safety profile highlights weight gain and injection‑site reactions
Adverse events (AEs) were reported by 74 % of participants, with 8 % discontinuing treatment because of side effects. The most common AEs were weight gain, injection‑site reactions, and somnolence. During the acute phase, patients on TV‑44749 gained an average of 6.87 kg, compared with 2.31 kg in the placebo group. Over the longer 48‑week open‑label extension, the mean weight increase was 5.61 kg, mirroring changes observed in long‑term studies of oral olanzapine.
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Weight management will be essential.
Importantly, the trial recorded no cases of post‑injection delirium/sedation syndrome (PDSS), a rare but serious reaction that has plagued the intramuscular olanzapine formulation. Over roughly 3,600 injections administered during development, investigators observed zero PDSS events.
While the absence of PDSS is reassuring, the weight gain noted with TV‑44749 remains a concern, especially given the metabolic risks associated with many antipsychotics.
One cautious observation is that the subcutaneous route may reduce the need for the three‑hour monitoring required under the current REMS program for intramuscular olanzapine. If the safety profile holds in broader practice, clinicians could allocate less time to observation and more to therapeutic engagement, though real‑world data will be needed to confirm this shift.
Implications for pharmacists and prescribing clinicians
Pharmacists, as medication experts, will likely play a key role in educating patients about the new formulation. The subcutaneous delivery method eliminates the intravascular exposure that contributed to PDSS in the intramuscular version, potentially simplifying storage and handling requirements.
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Because TV‑44749 uses BEPO technology licensed from MedinCell, the drug forms a depot after injection, allowing for controlled, sustained release. This technology has already supported a subcutaneous risperidone product approved by the FDA in 2023, suggesting a growing platform for LAI antipsychotics.
For prescribers, the availability of a subcutaneous olanzapine option adds flexibility to treatment plans, particularly for patients who struggle with daily oral adherence—a challenge reported in about half of individuals with schizophrenia.
Regulatory oversight may be less burdensome than the REMS program that governs the intramuscular formulation. The FDA’s current REMS for Zyprexa Relprevv requires a three‑hour observation period, a requirement that could be waived for TV‑44749 if post‑marketing surveillance confirms its safety.
Overall, the subcutaneous olanzapine candidate appears to preserve the efficacy of oral therapy while addressing a critical safety issue. Ongoing monitoring will determine whether the weight‑gain profile can be managed effectively, and whether real‑world use confirms the trial’s promising results.