Glucosamine and chondroitin are marketed to people with osteoarthritis and to athletes who experience overuse injuries as a way to relieve pain and increase range of motion. They are sometimes referred to as slow acting osteoarthritis drugs.
Glucosamine is made from glucose and glutamine. It is incorporated into glycosaminoglycans (unbranched polysaccharides) which are incorporated into proteoglycans (proteins that contain glycosaminoglycans). Proteoglycans are found in every tissue in the body, primarily in the extracellular matrix, and are remarkable for their ability to attract water.
Chondroitin is one of at least seven glycosaminoglycans and is a primary component of cartilage. Because of its ability to attract water, chondroitin sulfate helps to lubricate the joints.

Indications and Usage:
Arthritis Treatments, Osteoarthritis Treatments, Dry eye syndrome Treatments, Dry eyes Treatments, Keratoconjunctivitis sicca Treatments.

Mechanism of Action:
The mechanism of action of glucosamine or chondroitin is unknown but it is hypothesized that each may inhibit lysosomal enzymes or may stimulate proteoglycan synthesis. The mechanism is different from NSAIDs, which inhibit cyclooxygenase.

Pharmacokinetics:
Pharmacokinetic studies performed on humans and experimental animals after oral administration of Glucosamine and chondroitin revealed that it can be absorbed orally. Chondroitin shows first-order kinetics up to single doses of 3,000 mg. multiple doses of 800 mg in patients with osteoarthritis do not alter the kinetics of chondroitin. The bioavailability of chondroitin and glucosamine ranges from 15% to 24% of the orally administered dose. Chondroitin and glucosamine is not rapidly absorbed in the gastro-intestinal tract and a high content of labelled chondroitin sulfate is found in the synovial fluid and cartilage.

Contraindications:
Allergy to shellfish, Asthma, Use of warfarin or diabetes medications.

Side Effects:
Glucosamine and Chondroitin is LIKELY SAFE for most people. It can cause some mild stomach pain and nausea. Other side effects that have been reported are diarrhea, constipation and swollen eyelids.

Storage:
Tablets should be kept at room temperature, between 20 ° C and 25° C (68-77° F).