A Comparison of the Analgesic Efficacy and Safety of Once Daily Tramadol HCl / Contramid® Tablets to Twice Daily Tramadol HCl (SR) for the Treatment of Osteoarthritis of the Knee

A randomised, multi-centre, double-blind, double dummy, two arm parallel design study to compare the efficacy, safety, and clinical benefit of the test and reference product after treatment for 84 days in patients with osteoarthritis of the knee.


Eligibility Criteria:
Inclusion Criteria:

1. Males or Females between the ages of 40 and 75 with a diagnosis of Osteoarthritis (OA) of the knee consistent with the American College of Rheumatology (ACR) Clinical Classification Criteria for Arthritis of the Knee (Altman, R. et al., 1986):

   * Knee pain at study enrolment,
   * Less than 30 minutes of morning stiffness with or without crepitus on active motion.
   * Confirmation either by arthroscopy or radiologist's report (X-rays showing osteophytes, joint space narrowing or subchondral bone sclerosis {eburnation}) within 1 year prior to entry into the study.
2. ESR \< 40 mm/h
3. Western Ontario and McMaster University Osteoarthritis Index (WOMAC) Pain Subscales total score equal to or more than 150 mm at baseline.
4. Oral and written language comprehension at a level sufficient to comply with the protocol and complete study-related materials.
5. The Patient signed and dated the (IEC) approved, written, informed consent prior to study participation

Exclusion Criteria:

1. Known rheumatoid arthritis or any other rheumatoid disease.
2. Secondary arthritis i.e. any of the following: septic arthritis; inflammatory joint disease; gout; pseudogout; Paget's disease; joint fracture; acromegaly; fibromyalgia; Wilson's disease; Ochronosis; Haemochromatosis; Osteochondromatosis; heritable arthritic disorders; or collagen gene mutations.
3. Obesity Class II \[body mass index (BMI) equal to or more than 35 kg/m2\] (NIH, 2000)
4. Major illness that required hospitalisation during the 3 months before commencement of the screening period.
5. Unwillingness to cease taking medication other than the study medication for arthritic pain, any other concomitant pain, or OA medications.
6. Patients who had previously failed tramadol HCl therapy or those who discontinued tramadol HCl due to AEs.
7. Patients who within the 3 weeks prior to study entry took the following medications: monoamine oxidase inhibitors; tricyclic antidepressants and other tricyclic compounds (e.g. cyclobenzaprine, promethazine); neuroleptics; selective serotonin reuptake inhibitors; or other drugs which reduce seizure threshold.
8. Patients who took another investigational agent within the 30 days prior to study entry.
9. Patients with a history of seizure disorder other than Infantile Febrile Seizures.
10. Patients who were opioid dependent.
11. Patients with bowel disease causing malabsorption.
12. Patients who were pregnant or lactating or patients of child-bearing potential who were unwilling to utilise a medically approved method of contraception during participation in this clinical trial.
13. Patients with significant liver disease, defined as active hepatitis or elevated liver enzymes \>3 times the upper boundary of the normal range.
14. Patients with significant renal disease, defined as creatinine clearance \<30 mL/min as estimated by the method of Levey et al., 1999.
15. Current substance abuse or dependence, other than nicotine.
16. Allergy or adverse reaction to tramadol or any structurally similar drugs e.g. opiates.
17. Any other condition that, in the opinion of the investigators, adversely affected the patient's ability to complete the study or its measures.