Final answer:
Calcium Channel Blockers (CCBs) serve as tocolytics by preventing calcium entry into uterine muscle cells, thus inhibiting contractions and suppressing premature labor.
Step-by-step explanation:
Calcium Channel Blockers (CCBs) function as tocolytics by inhibiting calcium entry into uterine smooth muscle cells, subsequently causing relaxation. Tocolytics are medications that are used to suppress premature labor. CCBs, such as nifedipine, are effective in this role because they prevent the contractions necessitated for labor by reducing intracellular calcium, which is critical for smooth muscle contraction. Unlike ß-blockers like metoprolol and propanolol that affect the sympathetic nervous system by blocking the ß-receptors associated with vasoconstriction and cardioacceleration, CCBs specifically target the voltage-dependent L-type calcium channels in the smooth muscle cells of the uterus.