Assess the Blood-Oxygen-Level-Dependent (BOLD) Signal Changes in the Brain by Paracetamol as Measured by Functional Magnetic Resonance Imaging (fMRI) in Subjects With Osteoarthritis (OA)

A Randomised, Double-blind, Evaluation of the Effects of Paracetamol on the BOLD fMRI Response to Painful Stimuli in Subjects With Osteoarthritis

Blood-Oxygen-Level-Dependent (BOLD) responses to painful mechanical stimulation of the OA knee following treatment with four consecutive doses (at 8 hour intervals) on giving sustained released paracetamol treatment or placebo will be compared. The fMRI and pain assessments will occur approximately 2-5 hours after taking the final dose.

The objective of this study is to investigate if functional magnetic response imaging (fMRI) can detect the effects of a known pain medicine at over-the-counter doses in people with osteoarthritis (OA) of the knee. The fMRI is a harmless and painless technique that is used in the current study to collect images of brain activity to see if is changed when feeling pain. In this study, BOLD response to mechanical stimulation via pressure stimuli applied to the tibio-femoral joint and patello-femoral in participants with knee OA following four treatment doses of any of three treatment will be compared.

Inclusion Criteria:

• Diagnosis of osteoarthritis of at least one knee for 3 months
• Male or female at least 45 years of age
• Score a minimum of 4 out of 10 on the numerical pain rating and a maximum of 8 at screening

Exclusion Criteria:

• If female, is pregnant, lactating, or breast feeding
• Has secondary cause of knee arthritis
• Lower extremity surgery in the last 6 months
• Prior injury in the last twelve months to the index knee
• Used any analgesics (NSAIDs, COX2 inhibitor, etc) within 5 half lives of study start
• Recently used oral or injected glucocorticoids