As midazolam was reported to increase the sedation effect and the level of satisfaction of patients when used in combination with opioid (meperidine), a combination of midazolam and meperidine has been the most widely used regimen so far. The American Society for Gastrointestinal Endoscopy recommends a combination of midazolam and meperidine as a standard regimen for inducing sedation in upper and lower gastrointestinal endoscopy.