Can I take verapamil and calcium carbonate together?

Yes, you can take Verapamil (calcium channel blocker) and calcium carbonate together, but your doctor may have to monitor you (at least initially), as there is a moderate drug interaction between verapamil and calcium carbonate.

Calcium-containing products may decrease the effectiveness of calcium channel blockers by saturating calcium channels with calcium. Calcium chloride has been used to manage acute severe verapamil toxicity.

Management consists of monitoring the effectiveness of calcium channel blocker therapy during coadministration with calcium products.

http://www.drugs.com/drug_interactions.php