Which of the following agents for gastrointestinal issues is contraindicated in pregnancy?

Misoprostol is contraindicated in pregnancy primarily because it is a synthetic prostaglandin that can induce uterine contractions, leading to abortion or premature labor. It is used in various contexts such as ulcer prevention and treatment, but its ability to stimulate uterine activity makes it a significant risk for pregnant individuals.

In contrast, other agents such as calcium carbonate, famotidine, and lansoprazole are generally considered safer for use during pregnancy. Calcium carbonate is an antacid that acts by neutralizing stomach acid and poses minimal risk. Famotidine and lansoprazole are medications that reduce gastric acid production; while they should still be used cautiously, they have been studied more extensively in pregnant populations and have established safety profiles compared to misoprostol. Thus, it’s the action of misoprostol on the uterus that defines its contraindication during pregnancy, making it critical for patients to avoid this medication when pregnant or planning to conceive.