Caverject and Viridal Duo are both injectable forms of alprostadil used to treat erectile dysfunction. They both come in 10mcg, 20mcg, and 40mcg strength doses.
Viridal Duo is a closer equivalent to Caverject Dual Chamber than standard Caverject, because it contains two compartments in the plunger: one holding a powder, the other a solution. These mix together when you’re preparing the injection.
The medicines are clinically the same, but the plungers themselves (and the instructions for them) are slightly different.