Abstract
Chondroitin (Ch) is a glycosaminoglycan (GAG); and glucosamine (Ga) is an aminosaccharide acting as a substrate for biosynthesis of GAG. Ch undergoes hydrolysis in the intestine; being administered orally, it can also be regarded as a source of precursors for GAG. Hyaluronic acid (HA) is a GAG used for intra-articular injections. These substances are applied for the treatment of osteoarthritis and named chondroprotectants or chondroprotectives. The oral GAG have been discussed within the group of Symptomatic Slow-Acting Drugs in Osteoarthritis (SYSADOA) (Bruyère et al., 2016), which is hardly justified: these drugs are supposed to act primarily not upon symptoms but upon the pathogenesis – to compensate for a deficiency of cartilage constituents.

Key words: Glycosaminoglycans, Precursors, Osteoarthritis