Taking
hepatitis B drug with interferon potentially dangerous: Health Canada.
Health
Canada is warning consumers being treated with telbivudine (Tyzeka/Sebivo) for
hepatitis B not to combine the medication with any interferon products because
of potentially serious drug interactions.
Taking both telbivudine and
interferon may increase the risk of peripheral neuropathy, a potentially serious
condition characterized by weakness, numbness, tingling and burning sensations
in the arms and/or legs.
Telbivudine is authorized by Health Canada and
by the FDA in the U.S. for use as monotherapy, not for use in combination with
any interferon products, including standard or pegylated types of interferon alfa
(e.g., Pegasys, PegIntron, Intron A, Roferon A, and Infergen) and of interferon
beta (marketed under brand names such as Rebif, Betaseron, and Avonex).
The
drug's manufacturer, Novartis Pharmaceuticals Canada Inc., said that in a small
clinical trial testing the use of both telbivudine and Pegasys (peginterferon
alfa-2a), serious peripheral neuropathy occurred in five out of 48 patients (10
percent), and was occasionally disabling. The condition usually started about
three months after initiation of treatment.
Health Canada said Wednesday
it is not yet known if this adverse event is reversible once treatment is stopped,
or whether it might also occur when the drug is used with interferon products
other than Pegasys.
Consumers are advised to tell their doctors if they
are taking telbivudine and an interferon product, but should not discontinue or
modify telbivudine without first consulting their physician, due to the risk of
worsening the hepatitis B infection.
Peripheral neuropathy has been reported
in five out of 2,000 patients (less than one percent) using telbivudine alone
in clinical trials. The disorder also is a common adverse side effect of Pegasys
(reported on average in one to five out of 100 patients in clinical trials).
Consumer
information for telbivudine is being updated and Novartis has issued a letter
to health professionals advising them of the new safety information.
