diphenoxylate-atropine in the US by 430%, from $16 to $84.00. Regulation In the United States, drugs containing diphenoxylate combined with atropine salts are classified as Schedule V controlled substances. (Diphenoxlate by itself is a Schedule II controlled substance.) It is on Schedule III of the Single Convention on Narcotic Drugs, only in forms that contain, according to the Yellow List: "not more than 2.5 milligrams of diphenoxylate calculated as base and a quantity of atropine sulfate equivalent to at least 1 per cent of the dose of diphenoxylate". Research Diphenoxylate and atropine have been studied in small trials as a treatment for fecal incontinence; it appears to be less efficacious and have more adverse effects when compared with loperamide or codeine. References Synthetic opioids Antidiarrhoeals Nitriles 4-Phenylpiperidines Mu-opioid receptor agonists Janssen Pharmaceutica Belgian inventions