Will the FDA give potentially harmful painkillers a second chance?
A drug that was once used as a painkiller for those suffering with osteoarthritis, low back pain, or damage to the joints from wear and tear, as well as a few other conditions, was taken off the market in June 2010 by the U.S. Food and Drug Administration because about 500 people taking the drug in studies suffered severe damage to their joints and had to have them replaced. Rather than completely taking these drugs out of studies, Pfizer Inc (tanezumab), Regeneron Pharmaceuticals Inc (REGN475), and Johnson & Johnson (fulranumab) were allowed to continue testing on terminal cancer patients with extensive pain in their bones. It was deemed that the benefits might compensate for the risks. The companies would now like to begin studies on a wider market once again and are asking the FDA to reconsider the drugs.
These pain medications are from the class of anti-nerve growth factors. They block a protein called nerve growth factor (NGF) which is associated with nerve pain. NGF might also promote wound repair and new blood vessels to grow. The FDA thinks that the problems that are occurring with the joint damage may be due to it blocking these beneficial effects of the growth protein. The FDA considers the drugs to “represent a potentially significant and novel strategy for the treatment of pain.”
The FDA has a tough decision put before them this week. Pfizer and Johnson & Johnson claim that their forms only had negative reactions when it was mixed with anti-inflammatory painkillers like aspirin and Advil. Regeneron’s form is believed to have negative results in patients when they mix it with multiple other painkillers simultaneously. The FDA acknowledges these theories might be true, but in the case of Pfizer’s tanezumab, significant damage to the bones occurred even when it was used alone.
The FDA will make a decision soon whether they should allow these drugs to re-enter the market. Some of their options include limiting the doses to lower amounts or only allowing it to be presented to patients with few treatment options left. Tanezumab, Pfizer’s form of the anti-NGF drug was the furthest in development when they were forced to take it off the market. Pfizer had positive reports concerning the medicine: “We’ve had strong results from the clinical program. That’s why we’re so interested in progressing these compounds forward. They have the promise of offering chronic pain patients something they haven’t had in the past.” But another reason Pfizer must be so concerned with getting these potentially harming drugs back on the market is that before the drugs were stopped from trials analysts projected that peak global sales for tanezumab would bring well over $1 billion a year.
The request to start retesting is unusual. In most cases such as this, drug makers abandon research when there seems to be safety issues involved. However, in this case, it is potentially a multibillion dollar market since so many suffer from arthritis and other painful joint conditions and it just might be too big to abandon.