Which of the following medications can contribute to constipation?

Opioids are known to significantly contribute to constipation due to their mode of action. They work by binding to the opioid receptors in the brain and gastrointestinal tract, which decreases gastrointestinal motility and increases the time it takes for contents to move through the intestines. This prolonged transit time can lead to harder and drier stools, making bowel movements more difficult and less frequent, a condition commonly referred to as opioid-induced constipation.

In contrast, the other categories of medications may have varying side effects, but they do not primarily cause constipation to the same extent or through similar mechanisms as opioids. Antimalarials, antihypertensives, and anticonvulsants can have different gastrointestinal effects, but they generally do not have the same direct, constipating effect on the bowel as opioids do.