Under the term "chondroprotective agents"drugs and supplements capable of counteracting degenerative arthritic processes are grouped together, favoring the normalization of the articular cartilage and the synovial fluid in which it is immersed and from which it draws nourishment and protection. More specifically, chondroprotectors are compounds capable of expressing one or more of the following features:
- stimulate chondrocytes (cartilage cells) in the production of new cartilage matrix (synthesis of collagen and proteoglycans)
- they stimulate the synoviocytes (the cells of the synovium) in the synthesis of hyaluronic acid
- inhibit the degradation of cartilage by chondrolytic enzymes
- they prevent the formation of fibrin in the subchondral and synovial vasculature
Among the most studied chondroprotectors are listed endogenous molecules, therefore present in the articular cartilage of each individual:
- hyaluronic acid
- chondroitin sulfate (galactosaminglucuronoglycan sulfate)
- hydrolyzed collagen
- methylsulfonylmethane (MSM)
Chondroprotective agents are recommended in the conservative therapy of osteoarthritis, which to this day, especially in advanced stages, remains an irreversible disease, but which - through these substances - can be slowed down or countered.
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, albeit supported by numerous scientific studies, is often downsized by doctors who point the finger at the excessive emphasis on the beneficial effects disclosed by the manufacturers.
Due to poor absorption by mouth, this chondroprotective agent is typically used for joint infiltration. It is a glycosmaminoglycan 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 for intra-articular injections of hyaluronic acid therefore consists in increasing joint lubrication, but also in controlling the 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 cartilage matrix synthesis and the reaggregation 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 has begun to accumulate that re-evaluates the effectiveness of a specific oral hyaluronic acid supplementation.
DOSAGE: cycles of 5-6 infiltrations / week, each with 20-25 mg of hyaluronic acid, to be repeated 2-3 times a year.
Glucosamine is an aminosaccharide that acts as a precursor of the disaccharide unit in glycosaminoglycans. Normally, chondrocytes synthesize glucosamine from glucose. In addition to its structural role, as a chondroprotective agent, glucosamine stimulates the synthesis of proteoglycans and collagen from chondrocytes.
Since osteoarthritis occurs when the degeneration of the cartilage exceeds the cartilage synthesis capacity of the chondrocytes, the administration of glucosamine increases the synthesis of the cartilage matrix and seems to counteract or even reverse the arthritic 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 approximately 87% of the dose taken.
DOSES OF ASSUMPTION: 1 - 1,5 grams per day of elemental glucosamine (taking into account the molecular weight of the salt it is associated with; for example, 1334 mg of glucosamine HCl are needed to obtain one gram of elemental glucosamine). Repeated six-week cycles are recommended after a two-month interval.
Chondroitin sulfate is the most abundant glycosaminoglycan present in joint cartilage. It is composed of the repetition of disaccharide units of glucuronic acid and galactosamine sulfate. At the level of the articular cartilage, chondroitin sulphate plays an important structural role, which is concretized in the ability to bind to collagen fibrils. Furthermore, its chondroprotective properties derive from the ability to inhibit the enzymes that degrade the cartilage matrix and the synovial fluid in osteoarthritis. Chondroitin sulfate also helps prevent fibrin thrombi formation in the microvessels of the synovium and subchondral bone.
Despite being a large molecular weight molecule, chondroitin sulphate is well absorbed orally (70% of the dose taken).
DOSES OF RECRUITMENT: cycles of 800-1200 mg / day for at least three weeks
Synergistic integration of glucosamine and chondroitin sulfate
The chondroprotective treatment par excellence, to date the best known and most 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 sulphate
|Chondroprotective agents||Characteristics of chondroprotective agents|
|Glucosamine||It stimulates the metabolism of chondrocytes and synoviocytes|
|Chondroitin sulfate||It inhibits degradative enzymes|
|Chondroitin sulfate||Prevents the formation of fibrin in the periarticular tissues|
The alleged chondroprotective effects of hydrolyzed collagen are attributed to its structural accumulation in the articular cartilage and to the stimulation of collagen synthesis by chondrocytes. In fact, hydrolyzed collagen supplements are often associated with substances capable of promoting their synthesis: vitamin C, zinc, copper, gotu kola.
DOSES OF ASSUMPTION: cycles of 5-10 g / day of hydrolyzed collagen for at least three weeks