General Information

Synvisc is a gel-like mixture that is made up of hylan A fluid, hylan B gel, and salt water. Hylan A and hylan B are made from a substance called hyaluronan also known as sodium hyaluronate. This is a natural substance found in the body and is present in very high amounts in joints. The body’s own hyaluronan acts like a lubricant and a shock absorber in the joint and is needed for the joint to work properly. In osteoarthritis there may not be enough hyaluronan, and there may be a decrease in the quality of the hyaluronan in the joint.

Synvisc is specifically indicated for the treatment of pain in osteoarthritis of the knee in patients who have failed to respond adequately to conservative nonpharmacologic therapy and simple analgesics.

Mechanism of Action

Synvisc is a gel-like mixture that is made up of hylan A fluid, hylan B gel, and salt water. Hylan A and hylan B are made from a substance called hyaluronan, also known as sodium hyaluronate. This is a natural substance found in the body and is present in very high amounts in joints. The body’s own hyaluronan acts like a lubricant and a shock absorber in the joint and is needed for the joint to work properly. In osteoarthritis there may not be enough hyaluronan, and there may be a decrease in the quality of the hyaluronan in the joint.

Side Effects

Adverse events associated with the use of Synvsic may include, but are not limited to, the following:

• pain
• swelling
• heat
• redness
• fluid build-up around the knee
• rashes
• hives
• itching

Dosing/Administration

Synvisc is supplied as a gel for intra-articular injection. The recommended initial dose of the drug is an intra-articular injection once a week (one week apart) for a total of three injections.

Clinical Trial Results

The FDA approval of Synvisc was based on the results of three clinical studies.

Study 1
 This multicenter, randomized, double-blind prospective clinical trial enrolled 103 subjects at four sites in Germany. The study compared the safety and effectiveness of three weekly intra-articular injections of Synvisc and of physiological saline over a 26-week period. A significantly greater number of saline-treated patients took concurrent osteoarthritis medications than did patients treated with Synvisc. While both the Synvisc and the saline-treated groups improved significantly as compared to baseline in all effectiveness measures, the Synvisc group showed a significantly greater improvement in all outcome measures than did the saline-treated group.

Study 2 
This controlled, randomized, double-blind, prospective clinical trial enrolled 29 subjects at a single center in Germany. The subjects received three weekly intra-articular injections of Synvisc or physiological saline and compared for safety and effectiveness over a 26-week period. The results of the study were similar to those in the German multicenter study, except that the significance levels in most comparisons were smaller. In both of these studies the most pain relief and the greatest amount of treatment success occurred eight to 12 weeks after Synvisc treatment began.

Study 3 
This prospective, concurrently controlled, randomized, double-blind multicenter study enrolled 90 subjects at five U.S. sites. The study compared the safety and effectiveness of three weekly intra-articular injections of Synvisc and of three weekly arthrocenteses in subjects with osteoarthritis of the knee over a four-week period after the first injection or arthrocentesis. Both the Synvisc-treated and the arthrocentesis-treated groups improved significantly as compared to baseline in all effectiveness measures. However, there were no significant differences between the Synvisc-treated and arthrocentesis-treated patients at any time during the four-week evaluation period.