What effect may occur when taking the combination of nifedipine and digoxin?

When taking the combination of nifedipine and digoxin, a notable effect that may occur is a low heart rate. Nifedipine is a calcium channel blocker that can cause vasodilation and reduce systemic vascular resistance, which could lead to a compensatory reflex increased heart rate under certain circumstances. However, the combination with digoxin, a medication that acts to increase the force of cardiac contractions and generally stabilizes heart rate, can have bradycardic interactions. When these two medications are taken together, nifedipine might contribute to a more pronounced effect of digoxin, which can lead to a lower heart rate, especially since digoxin may have a direct effect on vagal tone, further promoting bradycardia.

Digoxin, particularly, is used to control heart rate in conditions like atrial fibrillation; thus, the interaction with nifedipine could enhance its rate-slowing effects rather than increasing heart activity. Therefore, low heart rate is a plausible outcome from the interaction of these two medications, as their combined actions on the cardiovascular system could lead to a significant drop in heart rate, unlike the other responses related to increased rates or levels.