Procardia (a.k.a. Nifedipine) is a calcium channel blocker used primarily as an anti-hypertensive medication (blood pressure lowering medication). Procardia achieves this by relaxing the muscular fibers, which compose the vessels, allowing the blood to flow more freely. Because the uterine muscle responds the same way to Procardia, the medication causes relaxation of the uterine muscle fibers and thus stops preterm contractions. Although Procardia can be used throughout the entire pregnancy, it achieves its best results when used after 15 weeks gestation.