Tenvir (Tenofovir Disoproxil Fumarate)

TDF and CHB

WHO estimates that about 254 million people were living with chronic hepatitis B (CHB) in 2022. Chronic HBV infection can lead to long-term complications such as cirrhosis, liver failure, and an increased risk of hepatocellular carcinoma (HCC). Over the last decade, HBV management has improved, and effective antiviral therapy options include tenofovir disoproxil fumarate (TDF).

TDF is an orally administered pro-drug of tenofovir, a nucleotide reverse transcriptase inhibitor active against both hepatitis B virus (HBV) and HIV-1. For HIV-1, TDF is used only in combination with other antiretroviral agents. For chronic hepatitis B, TDF is used as an antiviral therapy option; patients should be tested for HIV-1 before starting TDF for HBV.

Clinical trial data support that TDF can help suppress HBV DNA in many patients during long-term therapy. In adult trials, continued follow-up included long-term treatment up to 384 weeks in extension phases. In the treatment of chronic hepatitis B, the optimal duration of treatment is unknown.

Important safety note: severe acute exacerbations of hepatitis B have been reported after discontinuation of anti-hepatitis B therapy, including TDF. Hepatic function should be monitored with clinical and laboratory follow-up for at least several months after stopping therapy; if appropriate, resumption of treatment may be warranted.

Indications

VIREAD (tenofovir disoproxil fumarate, TDF) is indicated for the treatment of chronic hepatitis B virus (HBV) in adults and pediatric patients 2 years of age and older weighing at least 10 kg.

Drug interactions

TDF is primarily eliminated by the kidneys. Coadministration with drugs that are eliminated by active tubular secretion may increase concentrations of tenofovir and/or the coadministered drug; drugs that decrease renal function may increase tenofovir concentrations. In the treatment of chronic hepatitis B, TDF should not be administered in combination with adefovir dipivoxil.

• Coadministration decreases atazanavir concentrations. When coadministered with TDF, use atazanavir given with ritonavir. Certain HIV-1 protease inhibitors (including lopinavir/ritonavir) and some HCV regimens can increase tenofovir concentrations—monitor for evidence of tenofovir toxicity (including renal adverse reactions).
• TDF increases didanosine concentrations. Dose reduction and close monitoring for didanosine toxicity are warranted.
• Examples of drugs eliminated by active tubular secretion include acyclovir, cidofovir, ganciclovir, valacyclovir, valganciclovir, aminoglycosides (e.g., gentamicin), and high-dose or multiple NSAIDs. If coadministered, monitor renal function as clinically appropriate.

Possible side effects

Along with its desired action, this medicine may cause unwanted effects. Evaluation of adverse reactions in CHB with compensated liver disease is based on controlled clinical trials in 641 subjects who received treatment during a 48-week double-blind period.

In these trials, the most common adverse reaction (all grades) was nausea (9%). Other treatment-emergent adverse reactions reported in more than 5% of subjects included abdominal pain, diarrhea, headache, dizziness, fatigue, nasopharyngitis, back pain, and skin rash.

It should be noted that stopping therapy can lead to a flare (worsening) of hepatitis B. During follow-up after discontinuation, monitor liver function with clinical and laboratory parameters for at least several months. If appropriate, it may be advisable to resume treatment.

Storage

Store TDF tablets at 77°F (25°C); excursions permitted to 59–86°F (15–30°C) (USP Controlled Room Temperature). Keep the bottle tightly closed and dispense only in the original container. Do not use if the seal over the bottle opening is broken or missing. Keep out of reach of children.