Viread
Common Name: tenofovir disoproxil fumarate
Brand Name: Viread
Class: nucleotide analogs (also called nucleoside reverse transcriptase inhibitors, NRTIs, or nukes)
Standard dose: One 300 mg tablet once a day, with or without food, and no food restrictions. Dosing frequency needs to be adjusted for people with decreased kidney function. Take missed dose as soon as possible, unless it is almost time for your next dose. Do not double up on your next dose.
AWP: $771.54 / month
Manufacturer contact: Gilead Sciences, Inc.,
www.viread.com, 1 (800) GILEAD5 (445–3235)
Potential side effects and toxicity: Overall, fairly well tolerated; however, individuals may experience diarrhea, nausea, vomiting, and gas as the most common side effects of Viread. Decreases in bone mineral density (BMD) have been observed with the use of Viread in HIV-positive people. BMD monitoring should be considered in people who have a history of pathologic bone fracture or are at risk for osteopenia. Creatinine clearance (CrCl) should be assessed before initiating treatment with Viread. CrCl and serum phosphorus should be monitored in patients at risk. Less common side effects of Viread, occurring with undetermined incidence, include kidney toxicities and low blood phosphate. Rare but potentially serious toxicity with all NRTIs: enlarged, fatty liver (hepatomegaly with steatosis) and lactic acidosis (accumulation of lactate in the blood and abnormal acid-base balance). Lactic acidosis may cause persistent fatigue, abdominal pain or distension, nausea/vomiting, difficulty breathing or shortness of breath, and enlarged, fatty liver.
The effect of Viread on children and individuals with severe liver impairment was not studied during drug development. However, since Viread is not metabolized by the liver (and appears to have less toxicity in the liver than the majority of the NRTIs), it is believed the impact on individuals with liver disease should be minimal.
Potential drug interactions: Videx levels are increased with Viread (a drug also found in Truvada and Atripla); therefore, use with caution and monitor closely when taking Viread, Truvada, or Atripla with Videx or Videx EC to avoid Videx-related toxicity, including neuropathy. See tips. Viread decreases the concentration levels of Reyataz. In addition, both Reyataz and Kaletra increase Viread concentrations. Higher Viread concentrations could increase the risk of Viread-associated adverse events, including kidney disorders. Patients receiving Reyataz and Viread should be monitored for Viread-associated adverse events. When taken with Viread, it is recommended that Reyataz 300 mg is given with Norvir 100 mg (all as a single daily dose with food). Unboosted Reyataz (without Norvir) should not be taken with Viread. No dosage adjustment is needed when used with Kaletra. Do not take with Truvada or Atripla, since Viread is in these medications. You should not take Viread with Hepsera, a hepatitis B treatment.
Tips: Viread combined with Emtriva (also available as Truvada) is considered the preferred NRTI combination by U.S. HIV treatment guidelines. Viread is also combined with Emtriva and Sustiva (NNRTI) to make up Atripla, the first single-tablet HIV regimen. The body clears most of Viread through the kidneys and dosing adjustment is recommended for those with impaired kidney function. Serious kidney problems have been rare and most have been in those with pre-existing kidney disease or receiving kidney-toxic drugs. However, the characteristics of kidney toxicity are still being defined. The manufacturer recommends that individuals with impaired kidney function be monitored closely, especially people with advanced HIV disease, even in those who did not start out with kidney disease. There have been reports of individuals who experienced severe kidney disorder, including some taking Kaletra with Viread. Since Kaletra increases blood levels of Viread, it may increase the likelihood of Viread side effects.
According to the DHHS guidelines, the combination of Viread and Videx is not recommended as initial therapy due to high rates of early virologic failure, rapid selection of resistant mutations (K65R), and potential for immunologic non-response (CD4 decline).
Like Epivir and Emtriva, Viread has activity against hepatitis B, which may flare up when Viread is discontinued. These patients should be closely monitored by their physician. Patients co-infected with HIV/HBV should use Epivir or Emtriva with Viread as their nucleoside backbone to increase activity and avoid HBV resistance. Viread may have prolonged activity against hepatitis B even when resistant to Epivir. Please see package insert for more complete potential side effects and interactions.
Doctor
Viread (tenofovir, also known as TDF) was approved (with once-daily dosing) by the FDA in 2001 for the treatment of HIV and in 2008 for the treatment of chronic hepatitis B. Also available are once-daily fixed dose combinations of emtricitabine and tenofovir (Truvada) and tenofovir, emtricitabine, and efavirenz (Atripla). In studies comparing tenofovir to other choices, there are many factors which have led tenofovir (in combination with FTC) to be listed as preferred versus all other choices by the DHHS 2009 guidelines, including better virologic response rates, and fewer side effect issues versus other antivirals. However, as with any drug, there are a few factors to be aware of when tenofovir is used. As tenofovir is cleared by the kidneys, it is important when starting on this drug to have regular monitoring of kidney function with standard lab tests—about 1 or 2% of people starting tenofovir experience important declines in kidney function that are reversed when promptly stopping this drug. Also, in someone with markedly reduced renal function, Truvada must be dose reduced. In addition, when tenofovir is used with Reyataz, Norvir must be added to the HAART regimen to compensate for the effect that tenofovir has on lowering blood levels of reyataz. Finally, there is a 1% difference of more bone loss in some, but not all, measures during the first year on tenofovir versus what’s seen with some other antivirals—after one year this difference stabilizes. The clinical relevance of this 1% difference is still not clear. —Cal Cohen, MD
Activist
The preferred backbone of many regimens, Viread has much to recommend it with its once-daily dosing and few side effects. But given the potential for kidney toxicity, and that this is the kind of drug people may stay on for decades, patients and their doctors should be vigilant about kidney problems and concomitant meds that may cause them. The only side effect most patients might notice is stomach gas. Viread, like Epivir, has some activity against hepatitis B, so those with hep B should consult with their doctors before starting this drug. —Jeff Taylor
