Cladribine was originally developed as a chemotherapy drug for fighting leukemia. This drug’s ability to inhibit the growth of lymphocytes, which are believed to be part of the multiple sclerosis disease process, make it a possible treatment for multiple sclerosis. As of October 2011 this drug was not approved for the treatment of multiple sclerosis in the US, because the US Federal Drug Administration (FDA) felt that further tests were needed.
Investigations of cladribine for multiple sclerosis have indicated that this drug may have some value as a treatment for relapsing types of multiple sclerosis due to its action on lymphocytes, disease-fighting white blood cells. Multiple sclerosis is an autoimmune disease, and researchers theorize that lymphocytes are key in the formation of the brain lesions that characterize this disease. A 2009 research study tested two different dosage levels of cladribine for multiple sclerosis. Study participants on the lower dose had a 58% lower recurrence of multiple sclerosis episodes, while those on the higher dose had a 55% lower rate of recurrence. According to this research, a reduction in brain lesions also occurred as a result of taking this drug.
Possible side effects of clabridine, however, may be severe. Lymphopenia, or a low level of lymphocytes in the blood, is an expected side effect of this drug. Lymphocytes are important to the body’s immune system, and an insufficient level of this white blood cell can result in greater susceptibility to infection. Increased risk of cancer was reportedly another possible side effect of the drug cladribine.
In addition to causing lymphopenia, cladribine can also induce headaches and inflammation of the nasal passages, according to some patients. Other side effects include nausea, diarrhea and loss of appetite. When this drug is used to treat leukemia, peripheral neuropathy — a condition in which the nerves in the arms and legs may become numb and sensitive to hot and cold &mdashl may also occur. Taking an analgesic like naproxen, ibuprofen,and aspirin is not recommended in combination with cladribine because it can hide signs of a fever that might indicate infection.
As of 22 June 2011, testing of cladribine for multiple sclerosis was suspended. According to the FDA, the testing drug company did not completely meet FDA standards. Although the use of cladribine for multiple sclerosis was generally not approved in Europe as of October 2011, it was approved in Russia and Australia.