What are
Under the term " chondroprotective agents " drugs and supplements are grouped capable of counteracting degenerative arthrosic processes, favoring the normalization of articular cartilage and the synovial fluid in which it is immersed and from which it draws nourishment and protection. More particularly, chondroprotectors are compounds capable of expressing one or more of the following characteristics:
- stimulate chondrocytes (cartilage cells) in the production of new cartilaginous matrix (synthesis of collagen and proteoglycans)
- they stimulate the synoviocytes (synovium cells) in the synthesis of hyaluronic acid
- inhibit cartilage degradation by chondrolytic enzymes
- prevent the formation of fibrin in the subchondral and synovial vasculature
Endogenous molecules are listed among the most studied chondroprotectors, therefore present in the articular cartilage of each individual:
- hyaluronic acid
- glucosamine
- chondroitin sulfate (galactosaminglucuronoglycan sulfate)
- hydrolyzed collagen
- methylsulfonylmethane (MSM)
When used
Cartilage transplantation in younger people and surgical replacement of the joint with a mechanical prosthesis remain the extreme (and most effective) solutions to the problem of arthrosis; for this reason, the chondroprotective efficacy of certain substances, although supported by numerous scientific studies, is often reduced by doctors who point the finger at the excessive emphasis on the beneficial effects disclosed by the manufacturing companies.
Hyaluronic acid
Due to poor absorption by mouth, this chondroprotective agent is typically used for joint infiltration. It is a glycosaminaminoglycan composed of glucuronic acid and N-acetylglucosamine. At the joint level, hyaluronic acid acts as a lubricating agent capable of absorbing shocks in the synovial fluid. The rationale of intra-articular injections of hyaluronic acid consists therefore in the increase of joint lubrication, but also in the control of permeability of the synovial membrane (prevents joint effusions and the consequent swelling) and in the anti-radical action. Other possible mechanisms of action, although less certain, include the promotion of cartilaginous matrix synthesis and the aggregation of proteoglycans. Well tolerated and of rapid therapeutic action, the infiltrations of hyaluronic acid are burdened by the high cost and the impossibility of injection in some joints; only in recent years, evidence is beginning to accumulate that re-evaluate the effectiveness of a specific supplementation of oral hyaluronic acid.
DOSAGE: cycles of 5-6 infiltrations / week, each of 20-25 mg of hyaluronic acid, to be repeated 2-3 times a year.
Glucosamine
Glucosamine is an aminosaccharide that acts as a precursor of the disaccharide unit in glycosaminoglycans. Normally, chondrocytes synthesize glucosamine from glucose. In addition to the structural role, as a chondroprotective agent, glucosamine stimulates the synthesis of proteoglycans and collagen from chondrocytes.
Since osteoarthritis is established when the cartilage degeneration exceeds the capacity of cartilaginous synthesis of chondrocytes, the administration of glucosamine increases cartilaginous matrix synthesis and seems to counteract or even reverse the arthrosic phenomena, thanks also to its moderate anti-inflammatory activity. Glucosamine taken orally (in the form of glucosamine hydrochloride, glucosamine sulfate or glucosamine hydroiodide) is absorbed in an amount equal to about 87% of the dose taken.
ASSUMPTION DOSES: 1 - 1.5 grams per day of elemental glucosamine (taking into account the molecular weight of the salt to which it is associated; for example, 1334 mg of glucosamine HCl are needed to obtain one gram of elementary glucosamine). Repeated six-week cycles are recommended after two months of interval.
Chondroitin Sulfate
Chondroitin sulfate is the most abundant glycosaminoglycan present in articular cartilage. It is composed of the repetition of disaccharide units of glucuronic acid and galactosamine sulfate. At the level of articular cartilage, chondroitin sulfate plays an important structural role, which is realized in the ability to bind to collagen fibrils. Moreover, its chondroprotective properties derive from the ability to inhibit the enzymes that degrade the cartilaginous matrix and the synovial fluid in arthrosis. Chondroitin sulfate also helps to prevent fibrin thrombus formation in synovial and subchondral bone microvessels.
Despite being a large molecular weight molecule, chondroitin sulfate is well absorbed orally (70% of the dose taken).
RECRUITMENT DOSES: cycles of 800-1200 mg / day for at least three weeks
Synergistic integration of glucosamine and chondroitin sulfate
The chondroprotector treatment par excellence, today the most known and used, involves the association in the same product of glucosamine and chondroitin, in order to express all the characteristics of the ideal chondroprotector listed in the introductory part.
Postulated mechanism of synergy between Glucosamine and Chondroitin sulfate
| Chondroprotective agents | Characteristics of chondroprotective agents |
| Glucosamine | It stimulates the metabolism of chondrocytes and synoviocytes |
| Chondroitin sulfate | Inhibits degradative enzymes |
| Chondroitin sulfate | Prevents fibrin formation in periarticular tissues |
Hydrolyzed collagen
The presumed chondroprotective effects of hydrolyzed collagen are attributed to its structural accumulation in articular cartilage and to stimulation of collagen synthesis by chondrocytes. Often, in fact, hydrolyzed collagen supplements are also associated with substances that can promote their synthesis: vitamin C, zinc, copper, centella asiatica.
RECRUITMENT DOSES: cycles of 5-10 g / day of hydrolyzed collagen for at least three weeks
