Dose-Finding Safety Study Evaluating Remimazolam (CNS 7056) in Patients Undergoing Diagnostic Upper GI Endoscopy

Inclusion Criteria: * Male and female patients, aged 18 to 65 years inclusive, scheduled to undergo diagnostic upper GI endoscopy. * American Society of Anesthesiologists Physical Status (ASA PS) Score I or II. * Weight range 60 to 120 kg inclusive. * Body mass index (BMI) 18 to \< 30 kg/m2. * Patients with no clinically significant abnormalities in 12 lead ECG recorded at Screening. * Female with a negative serum human chorionic gonadotropin (hCG) pregnancy test result at Screening and negative urine hCG pregnancy test result on Day 1 before the endoscopy procedure. * Patients with negative drugs of abuse serum result at Screening and negative drugs of abuse urine result on Day 1 before the endoscopy procedure. * Patient has a negative serum ethanol test result at Screening and a negative ethanol saliva test result on Day 1 before the endoscopy procedure. * Patient voluntarily signs and dates an informed consent form (ICF) that is approved by an investigational review board (IRB) prior to the conduct of any study procedure. * Patient is willing and able to comply with study requirements and return for a Follow up Visit (Visit 3 ± 1 day) after the endoscopy procedure. Exclusion Criteria: * Patients with a suspected upper GI bleed an conditions predisposing to hemorrhage at the discretion of the investigator. * Has a known sensitivity to benzodiazepines, flumazenil, or anesthetic agents, or a medical condition such that these agents are contraindicated. * Patients with evidence of uncontrolled renal, hepatic, central nervous system, respiratory, cardiovascular, or metabolic dysfunction, in the opinion of the investigator or medical monitor. * Patients taking an agent that inhibits cytochrome P450 subtype 3A4 (CYP3A4) or patients who have taken such an agent within 14 days prior to study start or within the duration of 7 half lives of the drug, whichever is longer. * Patients in receipt of any investigational drug within 30 days or less than 7 half lives (whichever is longer) before the start of the study, or scheduled to receive one during the study period. * Chronic use of benzodiazepines for any indication (eg, insomnia, anxiety, spasticity). * Has known or suspected history of alcoholism or drug abuse or misuse within 2 years of Screening or evidence of tolerance or physical dependence before dosing with study drug. * Patients with clinically significant findings at Screening that, in the investigator's opinion, should exclude them from the study. * Patients with a history of laboratory results that show the presence of hepatitis B surface antigen (HBs Ag), hepatitis C antibody (HCV Ab), or human immunodeficiency virus (HIV). * Patients with an inability to communicate well in English with the investigator. * Lactating female patients. * Patients in whom management of airway is judged to be difficult due to: * obesity (weight \> 120 kg, or BMI ≥ 30 kg/m2), * thyro mental distance ≤ 4 cm ("short neck"), or * Mallampati score of 4 (Appendix IV).