Arthritis Treatment: Medicine Strategies For Treating Osteoarthritis

Osteoarthritis (OA) is the most common form of arthritis and affects more than 20 million Americans. It is a condition that affects hyaline articular cartilage, the tough gristle that caps the ends of long bones.

Hyaline cartilage consists of a matrix made up of a combination of proteoglycans (complexes of proteins and sugars) and chondrocytes. Chondrocytes are cartilage cells that manufacture matrix under normal circumstances. They are responsible for nourishing the matrix as well.

However, when OA develops, a distinct change in the milieu of the joint environment occurs. Chondrocytes begin to elaborate destructive enzymes causing cracks in the cartilage, the synovium (lining of the joint) becomes inflamed, and the underlying bone becomes hard and forms spurs.

What causes OA to develop is usually injury or trauma. In any event an injury to the joint appears to be the inciting factor. Genetics play a role as well.

The treatment of osteoarthritis usually begins with non-drug therapies such as weight loss, patient education, exercise and physical therapy.

Medications do play a major role in the management of symptoms related to OA.

Acetaminophen is usually recommended as the first line treatment for OA. While it's more effective than placebo, it is less effective than non-steroidal anti-inflammatory drugs (NSAIDS). Acetaminophen is used much more commonly than NSAIDS. Recent data has shown that its effect on pain from OA is not that great and the long term consequences of acetaminophen usage are not inconsequential. Potential side effects from long term use include kidney damage, hypertension, and possibly stroke. In addition, it is the most common cause of drug-induced liver failure in the United States.

NSAIDS are more effective than acetaminophen for pain control in OA. They are divided into two groups: NSAIDS that are non-selective in regards to cyclooxygenase (the major enzyme pathway that is blocked by these drugs) and selective COX-2 inhibitors (drugs which block the inflammatory cyclooxygenase pathway only).

The COX-2 drugs have a better profile as far as gastrointestinal side effects but both types of NSAIDS carry an increased risk of cardiovascular events.

Topical formulations of NSAIDS containing diclofenac are effective for patients with a limited area of OA. They have a much better gastrointestinal risk profile than oral NSAIDS but do have more dermatological problems associated with their use.

Injections are also helpful. Glucocorticoids are effective for treating pain short term and there is evidence that they also help restore quadriceps muscle (thigh muscle) strength in patients with OA. They should not be administered more often than three times per year per affected joint because of the danger of inducing further cartilage damage.

Injections of hyaluronates, lubricants that reduce OA pain, are also helpful. These are particularly useful in those patients for whom joint replacement surgery is not a viable option.

Another drug is duloxetine (Cymbalta). This was initially approved as a treatment for depression. However, it also has analgesic properties and was approved by the FDA for treatment of chronic musculoskeletal pain related to OA. This drug can be used either alone or in combination with acetaminophen or NSIADS. The side effects are those found typically with antidepressant therapy.