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VIREAD (tenofovir disoproxil fumerate) Label Update
On July 1, 2004, the VIREAD (tenofovir disoproxil fumerate) label was updated to include the following information.
The Box Warning was updated to include the following:
VIREAD IS NOT INDICATED FOR THE TREATMENT OF CHRONIC HEPATITIS B VIRUS (HBV) INFECTION AND THE SAFETY AND EFFICACY OF VIREAD HAVE NOT BEEN ESTABLISHED IN PATIENTS CO-INFECTED WITH HBV AND HIV. SEVERE ACUTE EXACERBATIONS OF HEPATITIS B HAVE BEEN REPORTED IN PATIENTS WHO ARE CO-INFECTED WITH HBV AND HIV AND HAVE DISCONTINUED VIREAD. HEPATIC FUNCTION SHOULD BE MONITORED CLOSELY WITH BOTH CLINICAL AND LABORATORY FOLLOW-UP FOR AT LEAST SEVERAL MONTHS IN PATIENTS WHO DISCONTINUE VIREAD AND ARE CO-INFECTED WITH HIV AND HBV. IF APPROPRIATE, INITIATION OF ANTI-HEPATITIS B THERAPY MAY BE WARRANTED (SEE WARNINGS).
The Warning section was also updated to include the following:
Patients Co-infected with HIV and Hepatitis B Virus
It is recommended that all patients with HIV be tested for the presence of chronic hepatitis B virus (HBV) before initiating antiretroviral therapy. VIREAD is not indicated for the treatment of chronic HBV infection and the safety and efficacy of VIREAD have not been established in patients co-infected with HBV and HIV. Severe acute exacerbations of hepatitis B have been reported in patients who are co-infected with HBV and HIV and have discontinued VIREAD. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue VIREAD and are co-infected with HIV and HBV. If appropriate, initiation of anti-hepatitis B therapy may be warranted.
Additionally, the Clinical Pharmacology and Precaution sections were updated to include information regarding drug-drug interactions with atazanavir, adefovir and ribavirin.
No drug-drug interaction was seen between tenofovir and adefovir or tenofovir and ribavirin.
The following text was added to the Precaution section.
Higher tenofovir concentrations could potentiate VIREAD-associated adverse events, including renal disorders.
Atazanavir and lopinavir/ritonavir have been shown to increase tenofovir concentrations. The mechanism of this interaction is unknown. Patients receiving atazanavir and lopinavir/ritonavir and VIREAD should be monitored for VIREAD- associated adverse events. VIREAD should be discontinued in patients who develop VIREAD-associated adverse events.
VIREAD decreases the Area Under the Curve (AUC) and Minimum Concentration (Cmin) of atazanavir. When coadministered with VIREAD, it is recommended that atazanavir 300 mg is given with ritonavir 100 mg. Atazanavir without ritonavir should not be coadministered with VIREAD.
The Carcinogenesis, Mutagenesis, Impairment of Fertility section was revised to include results of the long-term carcinogenicity studies in mice and rats. The following information was included in this section.
Long-term oral carcinogenicity studies of tenofovir disoproxil fumarate in mice and rats were carried out at exposures up to approximately 16 times (mice) and 5 times (rats) those observed in humans at the therapeutic dose for HIV infection. At the high dose in female mice, liver adenomas were increased at exposures 16 times that in humans. In rats, the study was negative for carcinogenic findings at exposures up to 5 times that observed in humans at the therapeutic dose.
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