Effect of a Topical Cetylated Fatty Acid Cream on Pain Relief in Patients With Knee Osteoarthritis

Inclusion Criteria: 1. Signed and dated written informed consent. 2. Male or female participants aged 40 to 75 years. 3. Diagnosis of idiopathic knee osteoarthritis according to American College of Rheumatology (ACR) criteria. 4. Compliance of the disease course with the following criteria: 1. symptoms for at least 6 months prior to screening 2. index knee pain for at least 15 days of the preceding month (periarticular knee pain due to OA and not due to other conditions such as bursitis, tendinitis, etc.); 3. walking arthritis pain required the periodic use of acetaminophen or NSAIDs (topical or oral products) on demand. 5. Presence of X-ray (taken no more than 3 months before baseline) showing evidence of osteoarthritis with Kellgren-Lawrence grade 2-3 in the index knee. 6. The average walking pain intensity during previous 24 hours in the index knee should be ≥40 mm on VAS (100 mm) at screening and prior to planned start of treatment. 7. In case the patient uses helper (cane) during the walking, he/she should have been using it routinely during at least previous 6 months. The same helper should be used during the study. 8. Patients who can use cream for 28-32 consecutive days (through the trial). 9. Women of childbearing potential must agree to use an acceptable barrier method of contraception during study participation. Exclusion Criteria: 1. Intolerance or allergic reactions to any component of the study therapy. Severe hypersensitivity reactions to any drugs in past medical history. 2. Usage of NSAIDs within 3 days or steroids within 7 days prior to planned start of treatment. In case when drug elimination exceeds defined period, it should be cancelled for the period of at least 5 half-lives. 3. Usage of intra-articular hyaluronic acid injections for period less than 3 months prior to the planned start of treatment. 4. Usage of DMOADs (disease-modifying osteoarthritis drugs) for period less than 3 months prior to the planned start of treatment. 5. Open skin lesions or dermatological conditions at the site of cream application. 6. Data on another etiology of the index knee joint lesion: gout, chondrocalcinosis, septic arthritis, infectious arthritis, Paget disease, aseptic osteonecrosis, seronegative spondyloarthropathies (psoriatic arthritis, ankylosing spondyloarthritis), metabolic (ochronosis, hemochromatosis) or autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus). 7. Surgery or major trauma of the index knee within the previous 12 months. 8. Presence of pain that could interfere with the assessment of knee pain (e.g. pain in any other part of the target lower extremity, pain radiating to the knee). 9. BMI≥35 kg/m2. 10. History of clinically relevant concomitant pathology at exacerbation or decompensation stage, specifically: verified heart failure (III-IV NYHA functional class), thrombosis, hemophilia and other coagulation disorders, decompensated diabetes mellitus type 2, uncontrollable seizures or any other pathology which, according to the investigator's opinion, prevents from the subject enrollment for safety reasons or may affect the study result. 11. Liver damage (e.g. acute hepatitis, active chronic hepatitis, cirrhosis, hepatic encephalopathy) or hepatic enzyme levels (AST and/or ALT) \>2 UNL (upper normal level). 12. History of expressed renal failure (creatinine clearance \< 30 mL/min) or blood creatinine and/or urea level \> 1,5 UNL (upper normal level). 13. Uncontrollable hypertension: systolic blood pressure \> 180 mm Hg and/or diastolic blood pressure \> 110 mm Hg. 14. Pregnant or breast-feeding women. 15. Necessity to take any drugs and/or dietary supplements from the list of treatments prohibited by the protocol (see Section 7.6) during the period of the study. 16. Consumption of more than 5 portions of alcoholic drinks per week or alcohol addiction, drug addiction or drug abuse in the past. One portion of an alcoholic drink means 360 ml of beer, 120 ml of wine or 30 ml of a strong alcoholic drink. 17. The patient's supposed low treatment compliance or inability to fulfill the procedures and observe the restrictions prescribed by the study protocol (e.g. due to mental disorders). 18. Active cancer in medical history. 19. Hepatitis B, hepatitis C or HIV in medical history. 20. Participation in any other clinical study during 4 weeks or 5 half-life periods (in case of the study of an experimental drug) (depending on which is longer) before the randomization. 21. Subjects qualified by law as legally incapable or under custody. 22. Employees of the study site, personnel of Sponsor's company or involved clinical research organization (CRO), investigator or his close family members. 23. Any reasons that may (in the investigator's opinion) prevent the patient from following the protocol.