A Study to Evaluate the Effectiveness and Safety of Tapentadol (CG5503) in the Treatment of Acute Pain From Bunionectomy.

The purpose of this study is to evaluate the effectiveness (level of pain control) and safety of the administration of 2 different dose levels of tapentadol (CG5503) compared with oxycodone and with placebo in subjects who have had a bunionectomy.

Patients undergoing bunionectomy often experience moderate to severe acute pain post-surgery. Normally such pain is controlled when patients receive repeated doses of opioid analgesics. However, opioid therapy is commonly associated with side effects such as nausea, vomiting, sedation, constipation, and less frequently, respiratory depression. Tapentadol (CG5503), a newly synthesized drug with an immediate release (IR) formulation, also acts as a centrally acting analgesic but has a dual mode of action. The aim of this study is to investigate the effectiveness (level of pain control) and safety (side effects) of 2 dose levels of tapentadol (CG5503) IR compared to no drug (placebo) or one dose level of oxycodone (an opioid commonly used to treat post-surgical pain). This study is a randomized, double-blind (neither investigator nor patient will know which treatment is received), active- and placebo-controlled, parallel-group, multicenter study to evaluate treatment of the acute pain from bunionectomy. The study will include a blinded 72 hour inpatient (the patient will stay in the facility where the procedure is done) phase immediately following bunionectomy, during which patients will be treated with either 50- or 75-mg tapentadol (CG5503) IR, a placebo, or 10-mg oxycodone IR, and pain relief will be periodically assessed. Assessments of pain intensity (PI) and pain relief (PAR) are obtained using the numerical rating scale, and the patient global impression of change scale (PGIC) will measure overall patient status. Safety evaluations include monitoring of adverse events, physical examinations, and clinical laboratory tests. Venous blood samples will be collected for the determination of serum concentrations of tapentadol (CG5503) and oxycodone. The study hypotheses are that at least one tapentadol (CG5503) IR dose will be different from placebo in controlling patients pain at 48 hours, followed by establishing that at least one tapentadol (CG5503) IR dose will be non-inferior compared with oxycodone IR (oxycodone IR is not clinically significantly better than a tapentadol (CG5503) IR dose). A comparison of the incidence rate of the adverse events of nausea and/or vomiting, and the incidence rate of the adverse event of constipation, between tapentadol (CG5503) IR and oxycodone IR will also be performed. Tapentadol (CG5503) IR 50 or 75 mg, or oxycodone 10 mg, or placebo, 1 capsule taken by mouth every 4 to 6 hours during the 72-hour postsurgery phase of the study (acetaminophen is also allowed during the first 12 hours on Day 1, if needed for pain). All doses of study treatment will be taken with approximately 120 mL of water with or without food.

Eligibility Criteria:
Inclusion Criteria:

* Patients must undergo primary unilateral first metatarsal bunionectomy
* Pain intensity must be moderate to severe following removal of a continuous popliteal sciatic block
* 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 severe renal insufficiency
* Moderately or severely impaired hepatic function
* Currently treated with anticonvulsants, monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), neuroleptics, or serotonin norepinephrine reuptake inhibitor (SNRI).