SYSADOAs: do their origin and quality make a difference in efficacy and safety?

Symptomatic slow-acting drugs for osteoarthritis (SYSADOAs) comprise a heterogeneous group of drugs with a long-term effect on the symptoms of osteoarthritis. The most widely used agents—chondroitin sulfate, glucosamine, and diacerein—have been recommended by the European League Against Rheumatism (EULAR) and by the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis, and Musculoskeletal Diseases (ESCEO). However, prescription of SYSADOAs is challenging owing to the large number of agents available and the fact that variations in extraction and purification techniques can lead to differences in content, composition, purity, biological effects, and safety. Moreover, differences in the regulation of pharmaceutical-grade products and nutraceutical-grade products lead to variations in quality and content between the two classes of products. Despite criticisms that their symptom-modifying effects are mild or insignificant, SYSADOAs have been shown to reduce pain and stiffness and increase functional capacity while exerting a chondroprotective effect in patients with knee and hand osteoarthritis. Recent international guidelines have proposed that chondroitin and glucosamine be the treatment of choice in osteoarthritis, especially in patients with comorbidities taking multiple medications, owing to their safety profile. Safety and efficacy should therefore be evaluated when prescribing SYSADOAs taking into account these differences, and health care providers should make every effort to make patients aware of the existing differences between products. This review discusses the use of SYSADOAs in the treatment of osteoarthritis, with emphasis on safety and effectiveness and how these are affected by the quality and origin of the agents.