A client taking a calcium channel blocker (nifedipine) should be assessed for which potential interaction when also taking ranitidine?

When a patient is taking a calcium channel blocker like nifedipine, it is important to monitor for potential interactions, particularly with medications such as ranitidine. The correct response is bradycardia, which is a condition where the heart rate is slower than normal.

Nifedipine primarily acts by blocking calcium from entering the cells of the heart and blood vessel walls, leading to vasodilation and a decrease in blood pressure. However, while nifedipine is generally not known to cause significant bradycardia, when combined with ranitidine, which is an H2 antagonist often used to decrease stomach acid, there can be overlapping effects where the heart rate is influenced.

Ranitidine itself is not typically known to cause bradycardia, but the combination of multiple medications that have effects on the cardiovascular system can lead to unexpected changes in heart rate. Monitoring for bradycardia is essential since low heart rates can result in decreased cardiac output and potentially lead to further complications.

In this context, while the other options relate to heart and respiratory rates, they do not have the same direct clinical relevance when assessing the interaction between nifedipine and ranitidine as bradycardia does.