The Collaborative International Dictionary of English v.0.48:

Deobstruent \De*ob"stru*ent\, a. (Med.)
   Removing obstructions; having power to clear or open the
   natural ducts of the fluids and secretions of the body;
   aperient. -- n. (Med.) A medicine which removes obstructions;
   an aperient.
   [1913 Webster]