He chaired the committee that wrote the ASAM National Practice Guideline for the Use of Medications in the Treatment of Addiction Involving Opioid Use. He has conducted a number of trials testing medications for the treatment of cocaine alcohol and opiate dependence and is a recognized authority on the cocaine withdrawal syndrome. In addition to research, he works at the Addiction Recovery Unit of the Philadelphia VA Medical Center where he continues to treat cocaine, alcohol and opiate dependent patients with both medications and psychotherapy.