The purpose of this study is to evaluate the effectiveness (level of pain control) and safety of the administration of 3 different dose levels of CG5503 compared with oxycodone and with placebo in patients who have had a bunionectomy, and to assess the safety of the drug for 9 days after patients are discharged from the hospital.
Inclusion Criteria: * Patients must undergo primary unilateral first metatarsal bunionectomy * pain intensity must be moderate to severe following stoppage of a continuous popliteal sciatic block (a nerve block with local anesthetic that numbs the foot) * female patients must be postmenopausal, surgically sterile, or practicing an effective method of birth control if they are sexually active. Exclusion Criteria: * Patients will be excluded from the study if they have a history of seizure disorder or epilepsy * history of malignancy within the past 2 years before starting the study * history of alcohol or drug abuse * evidence of active infections that may spread to other areas of the body * clinical laboratory values reflecting moderate or severe renal insufficiency * currently treated with anticonvulsants, monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), neuroleptics, or serotonin norepinephrine reuptake inhibitor (SNRI).