Papaverine, Phentolamine, Alprostadil, Atropine
Quad mix is a combination of alprostadil, atropine, papaverine and phentolamine. The atropine in the Quad-Mix causes smooth muscle relaxation in the penis and works synergistically with the other components. Israilov and colleagues conducted a study in which 13 patients who had failed tri-mix showed positive response to quad-mix. 53.8% (Seven) of the patients responded successfully with atropine addition.
The usual prescribed strength of Quad-Mix is Papaverine 20-25mg, Phentolamine 1.5-2.0mg, Prostaglandin E1 20-25mcg, and, atropine 0.02-0.08mg/ml.