A First-in-Human Study to Learn How Well a Bi-Layer Calcium Carbonate Antacid Tablet Works Compared to a Standard, Non-Layered Calcium Carbonate Tablet in Healthy Male Participants

Researchers are looking for a better way to treat people who have heartburn, indigestion, and problems due to excessive stomach acid. These are common problems which can affect daily life and disturb sleep during the night-time. Heartburn is the burning sensation or pain in the chest which occurs when stomach acid rises up in the food pipe (esophagus).

Calcium carbonate tablets are used to treat heartburn, indigestion, and related digestive problems. Calcium carbonate works by neutralizing the excess acid in the stomach. The study treatment is a new bi-layer calcium carbonate tablet that has two layers. One layer quickly releases calcium carbonate aimed to provide quick relief (called immediate release) while the other layer releases calcium carbonate slowly to make the relief last longer (called sustained release).

In this study, bi-layer calcium carbonate tablets will be given to healthy men for the first time. This study will provide information on how the new bi-layer tablet works inside the body.

The main purpose of this study is to learn about how the new bi-layer calcium carbonate tablet changes the average acidity levels (measured using pH) compared to the standard calcium carbonate tablet during the night-time.

For this, researchers will measure the acidity levels in the upper part of the stomach at regular intervals during the night-time.

The participants will be randomly (by chance) assigned to one of two treatment groups:

Participants in the first group will take the treatments at night.

Participants in the second group will take the treatments during the day.

All participants in both groups will take 2 bi-layer tablets and 2 standard tablets after a meal with a gap of 6 to 8 days between treatments. However, in each group, half the participants will receive the bi-layer tablets first while the other half will receive the standard tablets first.

Each participant will be in the study for around 52 days with up to 4 visits to the study site. This includes:

1. visit about 28 days before the treatment starts during which the doctors will confirm that the participant can take part in the study 2. visits for treatment with a gap of 6-8 days between each treatment, and

1 visit 7 to 14 days after the treatment ends during which the doctors will monitor the participants' health.

During the study, the doctors and their study team will:

check participants' overall health by performing tests such as blood and urine tests, and check heart health using an electrocardiogram (ECG)

take images of the stomach at different times after taking the treatment

measure acidity level (pH) using a device called pH probe that is inserted into the upper part of the stomach

ask the participants questions about how easy it is to take the study treatment

ask the participants what adverse events they are having.

An adverse event is any medical problem that a participant has during a study. Doctors keep track of all adverse events, irrespective of whether they think it is related to the study treatment, or not.

As this study is conducted in healthy men who will not gain any benefit from this treatment, access to the study treatment after the study is not planned.