A Study To Assess The Ability Of Tramadol, Naproxen And Oxycodone To Affect The Pain Thresholds Of Patients With Osteoarthritis Of The Thumb

• Drug: Placebo
  Oral, a double-dummy approach will be used to maintain the blind between active tablet and capsule doses
• Drug: Oxycodone
  Oral, 1 x 20mg controlled-release tablets
  Other Name: Oxycontin
• Drug: Tramadol
  Oral, 2 x 50mg immediate release capsules
  Other Name: Dolzam
• Drug: Naproxen
  Oral, 1 x 500mg enteric-coated
  Other Name: Naprosyne

• Placebo Comparator: A
  Intervention: Drug: Placebo
• Active Comparator: B
  Intervention: Drug: Oxycodone
• Active Comparator: C
  Intervention: Drug: Tramadol
• Active Comparator: D
  Intervention: Drug: Naproxen

Inclusion Criteria:

• The clinical diagnosis of osteoarthritis of the hand, of at least 6 months duration.
• Pain around one of the thumb joints due to osteoarthritis. The patient must report the average pain in this joint, in the week prior to screening, as at least 5 on an 11-point numerical pain rating scale at the time of screening.
• The patient must demonstrate pressure pain at a thumb joint by reporting a pressure pain threshold lower than 300 kPa.

Exclusion Criteria:

• Pregnant (as judged by a urine pregnancy test) or lactating female.
• Other severe pain which may impair the assessment of the pain due to osteoarthritis.
• Skin condition over the thumb joint, which will be used for pain threshold testing, that could interfere with the assessment of pain thresholds.
• Known hypersensitivity to oxycodone, NSAIDS or tramadol.
• Patients in whom NSAIDS, oxycodone or tramadol are contraindicated, or patients taking any concurrent medications which are contraindicated with any of the study medications .
• An estimated renal clearance of less than 30 mL/min based on the Cockcroft Gault equation.
• Use of prohibited medications as listed below, in the absence of appropriate washout periods:
• Oral or intramuscular corticosteroids within 4 weeks prior to screening.
• Monoamine oxidase inhibitors within 2 weeks of screening.
• Analgesic agents, other than aspirin, or acetaminophen within 1 week prior to screening. (Aspirin use less than or equal to 325 mg per day for cardiovascular prophylaxis is permitted)
• Acetaminophen up to 4 g/day may be used, provided it is not used in the 24 hours prior to any assessment of pain thresholds.
• Intra-articular steroid injections into the study joint within 12 weeks, or to any other joint within 4 weeks, prior to screening.
• History of chronic constipation, or of any condition which, in the opinion of the investigator, may put the patient at increased risk of respiratory depression.