Brand Names: Cosequin, Dasuquin, Glycoflex, Flexadin, Caniflex, Synovi, and Numerous (Nearly Uncountable) Others

Available in tablets, capsules, powders, and oral liquids

Glucosamine is frequently included in joint support diets

History and Background

The knee joint. Original illustration Courtesy of MarVistaVet.

Degenerative arthritis is a painful condition frequently treated with pain relievers, anti-inflammatory medications, supplements, physical therapy, and even weight loss. It has long been accepted that treatment best involves a combination of complementary therapies. Glucosamine and chondroitin sulfate are not only cartilage building blocks, but they can have anti-inflammatory properties of their own, making them excellent additions to any joint support protocol.

In a normal joint, cartilage breakdown is balanced by cartilage production. In the diseased joint, there is more breakdown than production. Glucosamine and chondroitin sulfates are components of cartilage, and the theory is that by taking these precursors orally (by mouth), a body can use them to repair and rebuild damaged cartilage. This has actually been borne out, and studies show that cartilage "building blocks" taken orally are indeed utilized in cartilage repair. The cartilage cells of the joint are able to manufacture their own glucosamine, but this ability appears to decrease with disease and age, and may not be able to keep up with the need for glucosamine when there is an increased demand. It has further been suggested that these substances may have anti-inflammatory properties of their own and/or may act by stimulating the synthesis of joint lubricants and collagen within the damaged joint, thus contributing further therapeutic benefit.

Glucosamine and chondroitin sulfates are extracted from sea mollusks (such as Perna canaliculus, also known as the New Zealand green-lipped mussel), from shark skeletons, as well as from cattle and chicken bones. Different brands use different sources, and it is controversial whether the origin is important therapeutically or not. Manganese is a co-factor in joint fluid synthesis and is often included in glucosamine/chondroitin sulfate supplements, as are numerous other supplements such as omega-3 fatty acids, creatine, and more.

Glucosamine and chondroitin sulfate are considered nutritional supplements. This means that the FDA does not hold them to the same standards of proof as drugs. Studies showing definitively that they reduce pain are frequently biased or not properly scientifically controlled. (We know they are absorbed into the body and used in cartilage repair but do not scientifically know how much pain relief results.) Regardless, they are well-accepted as part of arthritis management.

Uses of this Medication

Glucosamine and chondroitin sulfates might be used in any joint condition involving the classical joint structure (2 bones with cartilage-covered ends articulating, a fibrous capsule with ligaments connecting the bones, and lubricating fluid assisting the smooth motion of the joint). Glucosamine and chondroitin sulfates are not likely to be helpful with diseases involving other types of joints (i.e. the vertebrae and intervertebral discs).

Usually, an initial higher dose is given for the first month or so and then a lower maintenance dose is given long-term thereafter. The general belief is that 2-6 weeks of glucosamine/chondroitin sulfate administration is necessary before a response can be seen.

Side Effects

In humans, glucosamine supplements can adversely impact asthma symptoms. This appears to be a human situation, but it may be prudent to avoid it in patients with airway constriction.

An upset stomach has been reported in small animals as a rare side effect.

Interactions with Other Drugs

None have ever been reported.

Special Cautions

Be sure to store the product away from moisture and away from light.