Embodiments of calcium channel agonists, as well as methods of making and using the calcium channel agonists, are disclosed. The disclosed calcium channel agonists and corresponding salt forms have a structure according to general formula I: wherein each bond depicted as “” is a single bond or a double bond as needed to satisfy valence requirements; Z1, Z2, Z3, Z4, and Z5 independently are nitrogen or carbon; R1 and R3 are alkyl; R2 is alkyl, aryl, heteroaryl, arylalkyl, or heteroarylalkyl; and R4 is alkyl or hydroxyalkyl.