FDA Approves Fampridine SR, Now Called Ampyra, to Improve Walking for People with All Types of MS
The U.S. Food and Drug Administration has approved the marketing of Ampyra™ (dalfampridine, formerly known as fampridine SR, from Acorda Therapeutics) for its ability to improve walking speed in people with any type of multiple sclerosis. This is the first therapy specifically approved to treat a symptom of MS, and it represents a big step forward for the many people who may benefit.
Comment: "The FDA's approval of Ampyra is wonderful news for many people with MS who experience problems with walking," said John R. Richert, MD, Executive Vice President for Research & Clinical Programs at the National MS Society. "This brings a welcome symptomatic therapy that may restore some function and make a real difference in quality of life for a large number of people with different types of MS." Further study and clinical practice may help determine the extent to which the drug may impact other functions not measured in the clinical trials, and provide hints as to which individuals are most likely to respond.
Q. What is Ampyra? (pronounced ahmPEERah)
A. Ampyra, formerly known as fampridine SR, is a tablet containing a sustained-release formula of 4-aminopyridine, which blocks tiny pores, or potassium channels, on the surface of nerve fibers. This blocking ability may improve the conduction of nerve signals in nerve fibers whose insulating myelin coating has been damaged by MS. The first studies of this potassium-blocking approach in people with MS were supported by the National MS Society.
Q. How is a "symptomatic therapy" different from the approved disease-modifying therapies for MS?
A. A symptomatic therapy is usually a drug that addresses a particular aspect of a disease, but taking it does not change the underlying course of the disease or limit the damage caused by the disease. There are many medications taken by people with MS to manage specific symptoms, such as spasticity, fatigue or depression (http://www.nationalmssociety.org/about-multiple-sclerosis/symptoms/index.aspx). While there are FDA-approved disease-modifying therapies (http://www.nationalmssociety.org/about-multiple-sclerosis/treatments/index.aspx) that are partially effective against some forms of the disease, as well as rehabilitation and symptomatic treatments for some symptoms, until now there was no pharmacologic treatment available for MS-related difficulty walking.
Q. How common are walking problems among people with MS?
A. A recent survey among more than 1,000 individuals with MS and many of their family members examined the impact of difficulty walking on quality of life among people with MS and their families. Some two-thirds of patients reported difficulty walking and of these, 70% reported that such difficulty was the most challenging part of their MS, and most reported that difficulty walking restricts their daily activities significantly, including their ability to travel. (Read more about survey results http://www.nationalmssociety.org/news/news-detail/index.aspx?nid=199)
Q. How Effective is Ampyra?
A. Two phase III clinical trials of the drug were sponsored by Acorda Therapeutics. In the first, involving 301 people with any type of MS, walking speed increased by 25% compared with placebo. Results of this study have been published (February 28, 2009 issue of The Lancet (2009 373;732-738 (http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(09)60442-6/abstract), summarized here: http://www.nationalmssociety.org/research/research-news/news-detail/index.aspx?nid=951). Results from a later, second phase III study involving 240 people with MS (http://www.nationalmssociety.org/research/research-news/news-detail/index.aspx?nid=237), announced in 2008, confirmed the benefits seen in the first, finding that a significantly greater proportion of people on the therapy had a consistent improvement in walking speed compared to those who took placebo. Among those taking Ampyra who improved in walking speed, there was a statistically significant improvement in leg strength.
Q. What are the potential side effects of Ampyra?
A. In the first phase III study, common adverse events (side effects) experienced more often by those on active treatment included back pain, dizziness, insomnia, fatigue, nausea and balance disorder. Two serious adverse events led participants to discontinue taking the drug (one case of anxiety and one seizure in a person who developed sepsis from a urinary tract infection). In the second phase III study, additional common adverse events in those on therapy included urinary tract infection, falls, and headache.
Q. How is Ampyra taken?
A. In clinical trials, participants on active therapy took one tablet of the drug by mouth two times per day. According to a company press release, Ampyra will be taken two times a day, approximately 12 hours apart.
Q. When and how will Ampyra become available for prescription?
A. According to the sponsor, Ampyra is expected to be ready for prescription by March 2010. The drug will be distributed through a network of specialty pharmacies and coordinated by a team providing support services to facilitate access to the drug for patients and healthcare providers.
Q. Who might benefit from taking Ampyra?
A. There is no way of knowing in advance whether any particular individual who has MS might benefit from taking Ampyra. In clinical trials, a proportion of people with all types of MS were found to benefit in terms of walking speed. This proportion ranged from 35% to 43% of those who took the drug in the two phase III clinical trials.
Q. Can anyone with MS take Ampyra?
A. Ampyra was approved for persons with any type of multiple sclerosis. However, the FDA's approval of Ampyra comes with the warning that the drug should NOT be taken by individuals with a history of seizures, or by those with moderate to severe renal impairment (CrCl 51-80 mL/min).
Q. What is renal impairment, and why is it important that those taking Ampyra have adequate renal function?
A. "Renal" refers to the kidneys, which in essence clean the blood. If a person has adequate kidney function, then Ampyra will be cleared from the blood to a sufficient degree between doses so as to maintain a steady drug level in the blood. If a person has moderate to severe kidney impairment, then there is a danger that the concentration of the drug will increase in the blood beyond the amount considered safe. The result could be increased side effects including seizures, which in clinical trials occurred infrequently. For the same reasons, Ampyra should not be taken in combination with other forms of 4-aminopyridine (4-AP, fampridine), since the active ingredient is the same.
Q. Will taking Ampyra make it possible to stop using my walking aids?
A. There are many different types of walking aids and they address many different types of movement issues, so there is no single answer to this question. It is important that people who try the drug NOT make changes related to walking aids until they determine whether and how the drug affects them. One concern is that in the second clinical trial, a side effect experienced by some participants was increased falling. For that reason, it is important that people taking this medication continue to use caution and discuss any proposed changes in walking aids with their health care provider.
Q. What will Ampyra cost?
A. At the present time, no information has been released about how much Ampyra therapy will cost. The company expects to release that information in coming weeks.
Q. Will Ampyra be covered by my health insurance plan?
A. Coverage for Ampyra will depend on individual insurance plans. Acorda has established a team to provide support services to help patients and healthcare professionals access the drug, including working with insurance carriers and providing patient assistance programs, details of which will be available in coming weeks. |
