By: Ellen Whipple Guthrie, Pharm D
The treatment options for multiple sclerosis have changed dramatically over the last 16 years. The first disease-modifying drug, Betaseron®, became commercially available in 1993. With the release of this product, the transformation in the treatment of MS began.
Today, there is a lot of excitement in the MS community because several oral products have shown promising results in clinical trials. Within the next several years, many if not all of these products are expected to be approved to treat MS.
However, just because a product is administered orally does not make it better or safer than existing therapies. The decision to change to an orally administered product is going to be a complicated one. People with MS are encouraged to discuss the pros and cons of the oral agents with their physicians. They are discouraged from switching based solely on route of administration.
“We've come a long way in our ability to potentially slow the course of MS for many people. Future therapeutic goals would include more therapies for progressive forms of MS, therapies to repair damage in the central nervous system, and more effective and convenient therapies. We appear to be very close to having more convenient therapies in the form of oral medications,” says MSF Medical Advisor, Ben Thrower, M.D.
“As these oral medications become available we will need to think about how to use them safely and effectively. If you are stable on your current injectable medication and are having no side effects, it's fair to ask whether a switch to a new oral drug is worth it.”
Many factors will go into that decision, according to Dr. Thrower. These include what information is known and not known about the safety and effectiveness of the new drug. Will your insurance cover the new medication right away or will it take a while for the drug to get on your formulary? If it's on your formulary, what will the co-pay be?
“One thing I love about working with the MS community is the sense of partnership that we have in making decisions. We'll need that same partnership to help decide who is most appropriate for a switch to one of the new oral medications,” he says.
The following are some of the oral therapies that in the future may expand the menu of treatment options for MS.
This product is currently approved as an injectable agent for Hairy Cell Leukemia. It is however being studied as an oral cell-killing agent in MS. Cladribine has cytotoxic (cell-killing) properties and works by depleting lymphocytes. Data suggests that cladribine reduces or eliminates many of the cell types (such as T cells and B cells) involved in MS. While cladribine does appear to be very effective in treating MS, people with MS who receiving cladribine appear more likely to develop serious infections and cancers.
This product is sometimes referred to as the “sister/brother of Copaxone®.” It is currently being studied as a once-per-day oral medication for MS. Exactly how laquinimod works in MS is not fully understood. It appears to decrease inflammation in the central nervous system by increasing “good” T-cells (Th2) and by decreasing “bad” T-cells (Th1). It also appears to reduce leukocyte infiltration into the central nervous system, which decreases demyelination and axonal damage. Laquinimod appears to be the safest of the orally-administered products being studied in MS. No serious adverse effects have yet emerged in the clinical trials.
This product has a unique mechanism of action. It is a sphingosine-1-phosphate receptor agonist. It works by sequestering circulating lymphocytes into secondary lymphoid organs. This product has anti-inflammatory properties because it reduces the infiltration of T-cells and macrophages into the central nervous system. Data also suggests that fingolimod may have some neuroprotective properties. Significant safety issues are associated with fingolimod. First, this product causes lymphopenia (decreased lymphocytes).
Second, fingolimod produces bradycardia (decreased heart rate) with the first dose. In some of the clinical trials, patients were actually hospitalized for the first dose because of the severe bradycardia that could occur. Third, this product can affect the electrical impulses within the heart. This condition, known as second degree Wenchebach atrioventricular block, is also common with the first dose. Fourth, patients using fingolimod are more likely to experience serious opportunistic infections (such as shingles). Finally, fingolimod may predispose patients to malignancies.
Dimethyl fumarate (BG 00012)
This product is classified as a second-generation fumaric acid ester. However, its exact mechanism of action is unknown. It appears to induce “good” T-cells to kill activated “bad” T-cells. This leads to a reduced migration of lymphocytes into the central nervous system. Data suggests that dimethyl fumarate has both anti-inflammatory and neuroprotective properties. Unlike the other oral products, dimethyl fumarate must be given three times per day. Remembering to take a medication three times per day can be challenging for the most compliant of patients. While not life threatening or serious, dimethyl fumarate is associated with some very annoying side effects, including gastro-intestinal problems and flushing. Fortunately, the side effects do dissipate in about six weeks.
Ellen Guthrie received her doctorate of pharmacy degree from the University of Georgia College of Pharmacy in 1994 and has been a medical advisor with the MSF since 2002. She is an Assistant Clinical Professor at the University of Georgia College of Pharmacy, here she lectures primarily on MS. She practices pharmacy at Children’s Healthcare of Atlanta, where she is a pediatric pharmacist. She is a member of the American Pharmaceutical Association, the Atlanta Academy of Institutional Pharmacists, and the Consortium of MS Centers.
(Last reviewed 7/2009)