Figure 2. Total intravenous morphine consumption in milligrams over 48 h as assessed by the use of the patient-controlled analgesia pump in patients (n = 10 for each group) given intra-articular saline, neostigmine (125, 250, or 500 micro gram), morphine (2 mg), or subcutaneous neostigmine (500 micro gram). Data are presented as means +/- SD. A significant difference (P < 0.05) between groups and saline is marked by an asterisk and between groups and 500 micro gram neostigmine given subcutaneously is indicated by #.