Tramadol Versus Placebo and Morphine in the Management of Post-Operative Pain Abdominoplasty

Inclusion Criteria: * The patient is male or female 18-75 years of age * Willing to give consent and able to understand the study procedures * Female patients must be of non-childbearing potential or be practicing a highly effective contraption * The patient must be willing to be housed in a healthcare facility and able to receive parenteral analgesia for at least 48 hours after surgery * The patient meets definition of American Society of Anesthesiologists (ASA) Physical Class 1, or 2. Exclusion Criteria: * The patient is undergoing an abdominoplasty of significant complexity defined as pre-planned surgical time of greater than 180 mins. * The patient has a recent (within 5 years) and/or current history of chronic analgesic, opiate or tranquilizer abuse or dependence or is a user of illicit drugs or has had a recent history (within 2 years) of drug or alcohol abuse. * The patient is taking herbal or dietary supplements or medications that are moderate or strong inhibitors of CYP2D6 or CYP3A4 (e.g., fluoxetine, paroxetine, amitriptyline, quinidine, ketoconazole, erythromycin, grapefruit juice) or inducers of CYP3A4 (e.g., carbamazepine, rifampin, St. John's Wort) and cannot go through a minimum washout period of 14 days prior to surgery. * The patient has a history of epilepsy, is susceptible to seizures. * The patient cannot be withdrawn from medications (at least 7 days prior to surgery) that may lower the seizure threshold (e.g. anti-psychotic agents, MAOI inhibitors) or which increase serotonergic tone (e.g. selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants, triptans, cyclobenzaprine triptans). * The patient has had a recent cardiovascular event or clinically significant abnormal ECG finding at screening or baseline. * The patient has a history of Long QT Syndrome or a relative with this condition. * The patient has expressed suicidal ideation or is considered to be at risk of suicide. * The patient is morbidly obese (body mass index \[BMI\] ≥ 40 kg/m2) or has documented sleep apnea requiring CPAP or other treatment. * Female patient is pregnant and/or undergoing a pregnancy-related surgery, or breastfeeding. * The patient has a history of cardiopulmonary, neurological or psychiatric or other medical condition that may confound the assessments of efficacy or safety. * The patient has cirrhosis, moderate or severe hepatic impairment or an alanine aminotransferase (ALT) or aspartate aminotransferase (AST) value \> 3X upper limit of normal (ULN) at Screening. * The patient has severe renal impairment or a serum creatinine value of \> 2.0 mg/dL at Screening. * The patient has potassium, sodium, calcium or magnesium levels outside of the normal range or any other clinically significant abnormalities in laboratory values at Screening.