OASIS 4: oral semaglutide 25 mg for weight loss in adults

Why this study matters

Semaglutide (Wegovy, Ozempic) for weight management is usually a weekly 2.4 mg injection. An earlier trial, OASIS 1, tested a daily 50 mg tablet. OASIS 4 asked whether a lower 25 mg tablet could also produce meaningful weight loss. A lower dose might mean fewer side effects or a simpler product, so this trial matters to Canadian readers interested in a pill. The tablet regimen here is a research description, not a statement about what is available in Canada.

Who was in the study

OASIS 4 enrolled adults without diabetes at 22 sites in four countries. The summary we reviewed does not name the countries. Everyone had a BMI of 30 or higher, or 27 or higher with at least one weight-related health condition. BMI (body mass index) compares weight with height.

In total, 205 people were assigned to oral semaglutide and 102 to placebo. The trial lasted 71 weeks, with the main outcomes measured at week 64.

What the researchers did

This was a double-blind, randomized, placebo-controlled trial. Randomized means chance decided the treatment, in a 2:1 ratio. Double-blind means neither participants nor staff knew who was on the medicine. Placebo means an inactive tablet that looked the same.

People took oral semaglutide 25 mg or placebo once a day, plus lifestyle interventions to support changes in food and activity. The two main outcomes at week 64 were percentage change in body weight and the share of people who lost at least 5% of their starting weight. Confirmatory secondary outcomes were losing at least 10%, 15% and 20%, and the change in a physical function score from a questionnaire called IWQOL-Lite-CT, which asks people how their weight affects daily activities. The PubMed record labels the trial as phase 2, but the abstract does not state a phase, so we do not make a phase claim. How missing data were handled was not extracted.

What they found

The estimated mean change in body weight from the start to week 64 was -13.6% with oral semaglutide 25 mg and -2.2% with placebo (R32-C23). The estimated difference was -11.4 percentage points, with a 95% confidence interval of -13.9 to -9.0. A confidence interval is the range where the true difference most likely lies. The result was very unlikely to be chance (P less than 0.001).

People on oral semaglutide were significantly more likely than those on placebo to lose at least 5%, 10%, 15% and 20% of their body weight (P less than 0.001 for each), and more likely to have an improved physical function score (P less than 0.001). The summary we reviewed does not report the percentages of people reaching each weight-loss mark.

Side effects and people who stopped

Stomach and gut side effects were more common with oral semaglutide than placebo: 74.0% versus 42.2% (R32-C24). The summary we reviewed does not report how many people stopped treatment, or how many stopped because of side effects.

What this study does not tell you

• The 25 mg tablet was compared with placebo only. It was not tested against the 50 mg tablet or the weekly injection, so this trial cannot say how the three compare.
• With 205 people on the tablet and 102 on placebo, it was a smaller trial than OASIS 1.
• No one had diabetes.
• Both groups had lifestyle support, so the result shows what the tablet added on top of it.
• It measured weight and a questionnaire score, not heart attacks, strokes or other long-term outcomes, and not what happens after stopping.
• The trial was funded by the maker of semaglutide, and our data extraction relied on the abstract only.

What it means in Canada

OASIS 4 shows what a daily 25 mg semaglutide tablet did over 64 weeks in a research setting. This page does not state whether an oral form is approved or covered for weight management in Canada, or at what dose. See semaglutide in Canada and public drug coverage by province.

Related reading

Other studies in this library that bear on the same question.

Source