Although backed to the throne by his father-in-law, Prince Constantin Brâncoveanu of Wallachia, Constantine Ducas had indebted himself to Constantinople creditors. This made him raise taxes and reintroduce the văcărit (the confiscation of every tenth head of cattle).

He sealed matrimonial alliances with the Costineşti boyar family (to which Miron Costin belonged) and persecuted the Cantemirs, the family of his predecessor Constantin.

After delaying payments of the tribute and ordering the killing of the inspecting kapucu, Ducas was deposed by the Ottoman overlord.

He came to the throne for a second time, after Brâncoveanu had obtained the removal of their common rival Antioh Cantemir. Yet again reacting against the Cantemireşti (who fled the country), doubling taxes and enforcing the văcărit, Ducas only fell into disgrace after his relations with Brâncoveanu soured.