There are different methods of administering HA. Some formulations have a treatment schedule of five weeks, with one injection every week. While others require three injections over a three week period, while another only requires just one injection.
The number of injections required relates to the molecular weight of the drug, and how long the drug is estimated to remain in the joint after injection. We know that, the lower the molecular weight, the less time that it stays in the joint. However, the way in which the synovium reacts to the HA can be different with a higher molecular weight drug. These larger drugs stay longer in the synovium and can cause some reactions.
The number of injections should therefore be clarified, depending on whether the patient needs five injections in a row, three injections in a row or maybe just one injection. The clinical studies published so far have not been able to determine which number of injections achieves the best results.
One practice used by some people who use the product that recommends the 5 injections is to give three injections and then evaluate their success, or ‘efficacy’. Patients can then have two further injections three months later, if required, to prolong the efficacy of the HA, as there are five injections in a package.
The efficacy of the treatment should be assessed between six months and 12 months after the initial injection, and the symptoms should decrease during that timeframe. A patient can therefore expect to have one series of injections every year, if needed.