Aug. 8, 2012 -- A new pill may soon offer people with rheumatoid arthritis an alternative to the injections and intravenous infusions that many rely on to treat their disease.
The drug, tofacitinib, is a twice-daily pill that works by turning down the body's immune attack on its own joints and organs. It works in a slightly different way than currently available treatments for rheumatoid arthritis, or RA.
"It's pretty important and pretty exciting, and some have described it as a biologic drug in a pill," says Jeffrey R. Curtis, MD, MPH, director of the Arthritis Clinical Intervention Program at the University of Alabama at Birmingham. Curtis worked on early trials of the treatment, but was not involved in the current research.
Biologics have revolutionized the treatment of RA, but they must be taken by injection or IV infusion. They are made from natural sources that use a biologic method, instead of a chemical method, to make them.
A pair of studies published in the New England Journal of Medicine show that the treatment works at least as well as Humira, an older biologic. Tofacitinib also reduced the number of swollen and painful joints in about twice as many patients compared to a placebo pill. That was true whether or not it was used in combination with methotrexate, the standard initial treatment for the disease.
The studies included a total of more than 1,300 people with RA. Significant improvements in physical function were seen as early as the second week on the drug.
The studies didn't follow patients long enough to show whether tofacitinib might slow the physical destruction of the joints as other disease-modifying anti-rheumatic (DMARD) drugs do.
Both studies were paid for by Pfizer, the company that hopes to market the drug.
The FDA is weighing whether or not to approve tofacitinib, which works in a new way by blocking Janus kinase (JAK) enzymes inside cells. These enzymes help to control the chemical messengers that ramp up the immune response. Because the drug acts earlier in the immune response than most biologics, it has broader effects in the body.
Having a broader action sometimes makes a medication very powerful, but it can also increase the drug's potential for side effects since it affects more processes that take place downstream.
In the current studies, common side effects included upper respiratory tract infection, headache, and diarrhea. Tofacitinib was also linked to reduced white blood cell counts. White blood cells help the body fight infections.