FDA approves Weltruza, a monthly olanzapine injection for schizophrenia

The Food and Drug Administration has approved a new way of giving an old antipsychotic. The drug is olanzapine, in wide use since the 1990s; what is new is the delivery — a long-acting injection, given under the skin, that releases the medicine slowly over about a month. The approval was recorded in the agency's Drugs@FDA database on 8 October 2026 under new drug application 219007, held by Teva Neuroscience, which markets the product as Weltruza [s2]. It comes as an extended-release injectable suspension in three strengths: 318 mg, 425 mg and 531 mg [s2].

Long-acting injectable antipsychotics matter because schizophrenia is a lifelong illness in which staying on treatment is the hardest part. A monthly shot given by a clinician removes the daily decision to take a tablet, and that is the main argument for the class.

Why an olanzapine shot was a problem

Olanzapine already had a long-acting injectable form, and it is a cautionary tale. The earlier intramuscular depot, olanzapine pamoate, carried a risk of post-injection delirium/sedation syndrome (PDSS) — an abrupt flood of drug into the blood that could cause heavy sedation or delirium within hours of a dose. That hazard forced a restrictive safety programme requiring patients to be watched for three hours after every injection, which blunted the formulation's uptake.

Weltruza — developed as the Teva compound TV-44749 — is engineered specifically to avoid that problem [s3]. It uses a copolymer "in situ-forming depot": on contact with plasma the carrier precipitates into a solid matrix that traps the olanzapine particles, so the drug leaches out gradually instead of dumping into the circulation [s3]. In laboratory work the formulation was compared against the older intramuscular olanzapine pamoate to test that controlled release, and animal studies checked that manipulating the injection site did not force the drug out faster [s3].

The pharmacokinetics bear out the slow-release design. In a phase 1 study of 71 patients with schizophrenia or schizoaffective disorder, subcutaneous Weltruza reached clinically relevant plasma concentrations within one to two days, peaked at 11 to 14 days, and then held a sustained level across the month, with a beta half-life of 5 to 10 days [s4]. That is a gradual rise, not the spike that drives PDSS.

What the pivotal trial found

The efficacy case rests on SOLARIS, a multinational, randomised, double-blind, placebo-controlled trial that enrolled 675 adults with schizophrenia [s1]. Its main test was the change in the Positive and Negative Syndrome Scale (PANSS) — a standard measure of psychotic symptoms — from the start of treatment to week 8 [s1].

All three doses separated clearly from placebo. Patients on placebo improved by a least-squares mean of 12.17 points; those on the 318 mg dose improved by 21.91, on 425 mg by 23.44, and on 531 mg by 21.93 [s1]. Against placebo that worked out to differences of 9.75 points for 318 mg (95% confidence interval 5.89 to 13.60), 11.27 for 425 mg (7.53 to 15.01) and 9.76 for 531 mg (6.02 to 13.50), each with p less than 0.0001 [s1]. Two secondary measures — the Clinical Global Impression-Severity scale and the Personal and Social Performance scale — moved in the same direction and also favoured the drug [s1]. The trial reported the drug worked without the post-injection syndrome the formulation was built to prevent [s1][s3].

How to read it

The headline is encouraging but worth reading plainly. The symptom benefit is real and statistically strong, yet the three doses landed close together, so there is no clear signal that going higher buys more effect over the eight-week window [s1]. And eight weeks is short for a disease managed over decades. SOLARIS carried an open-label long-term phase, and it is that extension, not the double-blind result, that will show whether the benefit and the clean safety profile hold with repeated monthly dosing [s1].

What is genuinely new here is not the molecule but the engineering around it: a subcutaneous depot that tries to deliver olanzapine's known benefit in a once-a-month form while designing out the specific hazard that made the first injectable version so hard to use [s3]. Whether that translates into the lighter monitoring burden clinicians will hope for is a question the labelling and real-world use will settle.

Red flags: anyone who, in the hours after an antipsychotic injection, becomes profoundly drowsy, confused or difficult to rouse needs urgent medical attention. This article describes research and regulatory news and is not medical advice. Decisions about antipsychotic treatment are for patients and their treating clinicians.