Once-Monthly Olanzapine Injection: 1st FDA Approval Revealed

The once-monthly olanzapine injection Weltruza has been approved by the US Food and Drug Administration for adults with schizophrenia, according to an announcement from Teva Pharmaceuticals dated 9 October 2026. Teva describes it as the first and only long-acting olanzapine given under the skin once a month, with no loading doses, no oral supplementation and no monitoring period after the injection.

US availability is expected in the coming weeks. This report explains what was approved, how it differs from the older olanzapine depot injection, what the trial and safety data show, and what the announcement leaves unsaid.

Key takeaways

• The once-monthly olanzapine injection is olanzapine extended-release injectable suspension, given once a month to adults with schizophrenia.
• Teva says it needs no loading doses, no oral supplementation and no post-injection monitoring. The announcement did not say whether the label carries a boxed warning.
• The pivotal SOLARIS study randomised 675 adults. The company reports improvement on all three measures but gave no numbers in the announcement.
• Long-term company data show a mean weight gain of 5.6 kg in people treated for at least 48 weeks.
• Europe has not approved it yet. The European Medicines Agency accepted the application in May 2026.

What the once-monthly olanzapine injection is

Weltruza is olanzapine in a slow-release form. It comes in three strengths, 318 mg, 425 mg and 531 mg, which Teva says correspond to daily oral olanzapine of 10 mg, 15 mg and 20 mg. The release system, called SteadyTeq, is a copolymer technology developed by Medincell and is what lets the drug seep out over a month after a single injection under the skin.

In its daily tablet form, Teva notes, olanzapine is the most widely prescribed atypical antipsychotic for schizophrenia. The company puts the number of people diagnosed with schizophrenia in the United States at about 2.1 million, and the National Institute of Mental Health offers general background on the condition for readers who want it.

Long-acting injectables exist because missing daily tablets is a common route to relapse. A depot injection replaces that daily decision with a scheduled visit, which is the case Teva makes for this product.

How the once-monthly olanzapine injection differs from the older depot

Until now the only long-acting olanzapine on the US market has been Zyprexa Relprevv, which is injected into muscle every two to four weeks. It carries a boxed warning for post-injection delirium/sedation syndrome (PDSS), a rare but serious reaction, and patients must be watched in a healthcare setting for several hours after each dose.

The practical pitch for the once-monthly olanzapine injection is that it removes that observation requirement. Teva says no post-injection monitoring is needed. The safety information in the announcement still lists PDSS and says it is not known whether the reaction occurs with Weltruza, so the careful reading is that none was seen in the studies, not that it cannot happen. The announcement does not say whether the label carries a boxed warning for it.

What the SOLARIS trial tested

• Design: an 8-week, multinational, randomised, double-blind, placebo-controlled study in adults aged 18 to 64, followed by a 48-week open-label period.
• Size: 675 patients, randomised 1:1:1:1 to low, medium or high-dose Weltruza, or placebo.
• Main measure: the PANSS total score, a standard scale of symptom severity.
• Secondary measures: CGI-S, a clinician rating of severity, and PSP, a scale of personal and social functioning.
• Result: Teva reports improvement on all three. The approval announcement gives no figures.

Earlier topline reports on SOLARIS in 2024 put the placebo-adjusted improvement in PANSS at roughly 9.7 to 11.3 points across the three doses, all statistically significant. We have not checked those against the final label, and they come from company announcements, not a peer-reviewed paper. By our calculation, a 1:1:1:1 split of 675 people means about 169 in each of the four groups. That is our own arithmetic, not a figure from the announcement.

Safety of the once-monthly olanzapine injection

In the approval announcement, the most common adverse events were increased weight, sleepiness, headache, constipation and injection-site reactions. Discontinuations because of common adverse events were 5% and 4%, which Teva describes as consistent with placebo.

Long-term data released by Medincell, covering up to 56 weeks, reported no suspected or confirmed PDSS events across 3,470 injections. Weight increased in 36% of participants, and the mean gain was 5.6 kg among the 137 people treated for at least 48 weeks. These are company figures on file. In our conversion, 5.6 kg is about 12 pounds, and 36% is a little over one in three participants.

The Important Safety Information lists the usual class warnings, among them increased mortality in elderly patients with dementia-related psychosis, stroke in elderly patients, neuroleptic malignant syndrome, DRESS, metabolic changes, tardive dyskinesia, falls, low white blood cell counts, seizures and raised prolactin. Risks in pregnancy and breastfeeding are also described. The FDA’s drugs pages hold the full label once it is posted.

A quick look at the dose arithmetic

By our calculation, the 318 mg strength is about 32 times the 10 mg daily oral dose, the 425 mg strength about 28 times the 15 mg dose and the 531 mg strength about 27 times the 20 mg dose. The ratio falls as the dose rises, which shows the injection strengths are not a straight monthly multiple of the oral dose. This is our own arithmetic and not dosing guidance.

What the once-monthly olanzapine injection could change for patients and clinics

For a patient who struggles with daily tablets, a monthly injection can make adherence visible and give the care team a regular contact point. For others, the idea of a depot that cannot be stopped at will is a worry, which is why the choice stays a shared decision between patient and prescriber.

For clinics, the biggest change is logistical. If the no-monitoring claim holds up in everyday use, a visit no longer needs a block of observation time, which has been a practical barrier to the older olanzapine depot. For Teva, which already sells the long-acting risperidone injection Uzedy, the approval extends its range to a second major antipsychotic.

Our assessment

In our assessment, the once-monthly olanzapine injection is meaningful mainly for its convenience profile, and that depends on the no-monitoring claim surviving real-world use. The trade-off is the familiar one for olanzapine. A mean gain of 5.6 kg over a year is substantial, so clinicians will need to track weight, glucose and lipids. Commercial success will depend on price, payer coverage and early safety experience.

For related coverage, see our report on the FDA’s safety concerns in Newron’s schizophrenia drug trials and on Viatris’s $1.65 billion Pacira deal, or browse more pharmaceutical news.

What to watch next for the once-monthly olanzapine injection

• The US launch date, price and payer coverage.
• The final label wording on PDSS and any monitoring requirement.
• Real-world weight and metabolic data from early users.
• The European Medicines Agency decision.

Frequently asked questions

What is the once-monthly olanzapine injection approved by the FDA?

Weltruza, an olanzapine extended-release injectable suspension for adults with schizophrenia, announced by Teva on 9 October 2026.

How is the once-monthly olanzapine injection given?

Under the skin, once a month, in strengths of 318 mg, 425 mg or 531 mg.

Does it need monitoring after injection?

Teva says it needs no post-injection monitoring, no loading doses and no oral supplementation.

What are the main side effects?

Weight gain, sleepiness, headache, constipation and injection-site reactions.

Is it available yet?

Teva expects US availability in the coming weeks. It is not yet approved in the EU.

How we reported this: we relied on Teva’s announcement of 9 October 2026 and on company reports of the SOLARIS trial. Background on the older injection is general knowledge. Figures labelled as ours are our own calculations. Last updated: 10 October 2026. This article is news reporting and not medical advice.