Which medication works by inhibiting biliary cholesterol secretion in the treatment of gallstones?

The medication that works by inhibiting biliary cholesterol secretion is effective in the management of gallstones because it directly targets one of the key contributing factors to gallstone formation. Gallstones, particularly cholesterol stones, form when there is an imbalance in the composition of bile, most notably when there is excessive cholesterol relative to bile salts and phospholipids.

By inhibiting the secretion of cholesterol into the bile, this medication decreases the total cholesterol concentration in the bile. This alteration helps to prevent the supersaturation of bile with cholesterol, thereby reducing the likelihood of gallstone formation. The mechanism effectively modifies the bile composition to favor a healthier balance, making the bile less conducive to gallstone formation.

In contrast, other mechanisms such as decreased gallbladder muscle contractility could potentially lead to stasis and promote gallstone formation, while increased gastrin production is more involved in gastric function rather than biliary issues. Increased metabolism of bile salts is not directly related to the inhibition of cholesterol secretion but rather pertains to their recycling and efficiency in emulsifying fats.

Thus, the choice that accurately describes the action of the medication in question is the one that highlights its role in inhibiting biliary cholesterol secretion.