June 25, 1998 -- Early this month, the Food and Drug
Administration approved Rebetron combination therapy for chronic
hepatitis C but only for patients who have relapsed following
previous treatment with interferon alone. Rebetron comprises fixed
doses of Intron A (interferon alfa-2b, recombinant) injection and
Rebetol (ribavirin) capsules packaged together. While the new
treatment promises to be almost 10 times better than standard
treatment, it doesn't come without serious side effects and major
concern about its packaging.
On May 4 of this year, the Antiviral Drugs Advisory Committee of
the FDA unanimously concluded that Schering-Plough's Rebetron
combination therapy was safe and effective as a treatment for
chronic hepatitis C as long as patients are carefully selected and
sufficiently monitored for adverse effects. The Committee noted
that of the patients studied in clinical trials, 70-percent of
those on the combination therapy had significant side effects. The
panel had concerns that packaging these two drugs together might
not serve the best interests of patients or physicians who intend
to follow the best medical practices.
This sentiment was voiced in a letter sent to the FDA Advisory
Committee for Antiviral Drugs by Thomas Najarian, M.D, a
hepatologist from Belmont, Massachusetts. "As a physician with
clinical experience treating Hepatitis C patients, it is my belief
that providing these two drugs in a fixed dose package would likely
lead to increased medical costs because the dosage of both drugs
must be altered often due to side effects of the medication," wrote
Najarian. "When two medications are to be given by different routes
as with Intron A and ribavirin, especially when both medications
have common but different side effects that require dose
adjustment, it makes no sense to package them together." Intron A
is administered by injection three times a week, and ribavirin is
taken orally on a twice-daily schedule. In addition, Dr. Najarian
expressed his concern that doctors might be misled into thinking
that the pre-packaged doses are appropriate for all hepatitis C
patients and will neglect to monitor side effects and make dose
adjustments.
At the May 4 hearing, a member of the Antiviral Drugs Advisory
Committee, Judith Feinberg, M.D., said about the packaging, "I'm
concerned that we don't exactly have the optimum doses of either
component in this regimen." Her concerns included questions about
the toxicity of the drugs separately and in combination, and the
difficulty physicians will have in customizing therapy in response
to monitoring the side effects, changes in viral load, and other
measures of treatment outcome. She concluded, "I'd hate to see
physicians locked into one way of doing this."
Doctors prescribing Rebetol will also be discouraged from
prescribing such other types of interferon as Roferon-A (interferon
alfa-2a) made by Roche, or Infergen (interferon alfacon-1) by
Amgen, which has performed well in clinical studies. One
randomized, multi-center study comparing the efficacy of two
different doses of Infergen with interferon alfa-2a showed that
response rates at the end of treatment were 70% and 66% for the two
dose levels of Infergen and 54% for interferon alfa-2a. At the end
of a six month observation period of the same patients, the
response rates of the patients given Infergen were 79% and 58% for
the two doses as compared to 53% of those given interferon
alfa-2a.
Hepatitis C is as a major worldwide health problem with rates of
infection reaching 15% of the population in some parts of Eastern
Europe and Africa. According to the Centers for Disease Control and
Prevention, some four million Americans are now chronically
infected with the virus, which contributes to the death of 8,000 to
10,000 Americans each year. This toll is expected to triple by the
year 2010 at which point it will have surpassed the death rate from
AIDS.
The cost of treatment for hepatitis C is expected to become a
significant global expense in the near future. Packaging such
promising drugs as Intron A, Infergen, and Rebetol separately in
variable doses would theoretically decrease the cost of treating
hepatitis C on a global scale. In addition, doctors and patients
would be more able to choose the most beneficial combination of
drugs and doses with the least amount of side effects.
Source: www.shn.net
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