DHEA, an OTC hormone supplement has been shown to aid in opiate withdrawal, significantly; Also, reducing drug seeking behavior and tolerance, according to several studies I have come upon. Watch out though, it can worsen benign-prostate-hypertrophy, if you currently have that disorder.
These are several highly-sited articles that I have been surprised to not see here yet.
http://www.sciencedirect.com/science/article/pii/S0014299997012946
http://www.europeanneuropsychopharmacology.com/article/S0924-977X(07)00248-9/abstract
http://www.sciencedirect.com/science/article/pii/S0149763410000485
These are several highly-sited articles that I have been surprised to not see here yet.
http://www.sciencedirect.com/science/article/pii/S0014299997012946
http://www.europeanneuropsychopharmacology.com/article/S0924-977X(07)00248-9/abstract
http://www.sciencedirect.com/science/article/pii/S0149763410000485