Expanding Stomach Capsule Produces Sustained Weight Loss

A weight loss drug that expands in the stomach to create a sustained feeling of fullness has shown promising three-month Phase 2 clinical trial results.

The treatment, known as Sirona, is taken as a pill and is targeted at people who are overweight (defined as having a body mass index (BMI) of 25–29.9 kg/m²) or have class I obesity (a BMI of 30–34.9 kg/m²) and those transitioning off glucagon-like peptide-1 (GLP-1) medications.

With 30 million people expected to be using GLP-1s in the US alone by 2030, there is a need for a safe and cost-effective weight maintenance solution to assist individuals transitioning off of GLP-1s, helping to maintain their new weight long term.

Initial results from the trial (ISRCTN14083641) showed that participants taking Sirona continued to experience sustained weight loss at the three-month mark. Oxford Medical Products (OMP), who developed the therapy, states this early data suggests that Sirona could achieve an average of 10–12% total body weight loss at 52 weeks.

A complimentary solution to existing weight loss drugs

GLP-1 receptor agonists are a class of medicines used to treat type 2 diabetes and obesity. Existing GLP-1 agonists, such as Wegovy^TM (semaglutide) and Zepbound^TM (tirzepatide), indicate use in individuals with a BMI of 30 kg/m² or greater or 27 kg/m² with at least 1 weight-related comorbidity. Sirona is aimed at patients with a BMI of 25–40 kg/m², which includes the 43% of global adults who fall into the overweight category (BMI 25–29.9 kg/m²).

OMP describes Sirona as a complementary solution to GLP-1 agonists. One study found that a year after the withdrawal of once-weekly subcutaneous semaglutide and lifestyle intervention, participants regained two-thirds of their prior weight loss. Sirona is positioned to assist individuals transitioning off GLP-1s, helping to prevent weight regain.

Sirona utilizes an oral hydrogel capsule technology for drug delivery, which expands rapidly upon reaching the stomach where it remains in situ for several days before breaking down and passing naturally. The therapy has a weight-loss mechanism analogous to surgery and gastric balloons in that it reduces available stomach volume to suppress appetite.

The Phase 2 trial of Sirona took place across three NHS hospitals in the UK and evaluated the safety and acceptability of Sirona in healthy individuals with a BMI of 30–40 kg/m² seeking to lose weight.

Participants with class I obesity, on average, lost more than 6.3% total body weight whilst on Sirona, without any ongoing lifestyle interventions such as dietary and exercise support. Further analysis of the 12-week data showed that participants on Sirona consumed on average 400 fewer calories per day than those on a placebo.

Importantly, OMP reported no serious adverse events in the trial with 96% of patients adhering to the dosing regimen at 12 weeks.

“Our approach is highly differentiated and complementary to existing and emerging GLP-1 therapies, offering a unique, tailored solution—particularly for individuals in the overweight category,” said Dr. Camilla Easter, CEO of Oxford Medical Products, in a press release. “Sirona provides an optimal risk-benefit profile, enabling safe and cost-effective weight loss. In the coming years, we will advance two pivotal trials focused on both weight loss and long-term weight maintenance.”

OMP is set to advance Sirona into a larger pivotal trial in both the US and the UK later this year.