Meperidine Hydrochloride/Promethazine Hydrochloride

The investigators study is the randomized controlled study for analyzing clinical benefit of pain focused sedation with combination of fentanyl and propofol during Endoscopic retrograde cholangiopancreatography (ERCP). The investigators will assess recovery time and adverse effect during ERCP as the primary end point between two group. The investigators will also access satisfaction score for endoscopist and patients as the secondary end point.