This will be a double-blind, randomized, parallel-group, multicenter, dose-ranging study, in age \>/= 65 years, and/or weight \< 60 kg, and/or American Society of Anesthesiologists (ASA) Physical Classification Status 3 or 4 subjects using either the approved dose modification or 1 lower dose, to achieve a moderate level of sedation required to complete the scheduled diagnostic or therapeutic procedure. Three subgroups of subjects will be included. For Subgroup 1 and Subgroup 2, approximately equal numbers of subjects will be enrolled into 2 strata: weight \>/= 55 kg and weight \< 55 kg. For Subgroup 1 and Subgroup 2, subjects will be randomly assigned to 1 of 2 dose groups in a 1:1 ratio within each stratum. For Subgroup 3, subjects will be randomly assigned to 1 of 2 dose groups in a 1:1 ratio.