March/April 2009
Common Name: emtricitabine or FTC
Brand Name: Emtriva
Class: nucleoside analog (also called nucleoside reverse transcriptase inhibitor, NRTI or nuke)
Standard dose: One 200 mg capsule once a day, with no food restrictions (may be taken with or without food). The dosing needs to be adjusted for people who have decreased kidney function. It is also available as an oral solution, but the dose is 240 mg (or 24 mL). Take missed dose as soon as possible, but do not double up on your next dose. It may be given to children ages 0 to 3 months old at a dose of 3 mg/kg and children 3 months to 17 years old at a dose of 6 mg/kg up to a maximum of 240 mg of the oral solution.
AWP: $430.13 / month; $99.13 for 10 mg/mL, 170 mL
Manufacturer contact: Gilead Sciences,
www.gilead.com, 1 (800) GILEAD5 (445-3235)
AIDSInfo:
1 (800) HIV-0440 (448-0440), www.aidsinfo.nih.gov
Potential side effects and toxicity: Very tolerable. Side effects (rarely seen) may include headache, diarrhea, nausea, and rash. Skin discoloration (darkening of the skin on the palms and the soles of the feet) can occur. More hyperpigmentation seen in pediatric studies than adult studies. Rare but potentially fatal toxicity with all NRTIs: hepatomegaly with steatosis (enlarged, fatty liver) and lactic acidosis (accumulation of lactate in the blood and abnormal acid-base balance). Lactic acidosis has been seen in patients taking NRTIs, but is more common and more severe in women, people who are obese, and people who have been taking NRTIs for a long time; it is more common in people with liver disease, but can occur in people without a history of liver damage. People with lactic acidosis may experience persistent fatigue, abdominal pain or distension, nausea/vomiting, difficulty breathing or shortness of breath, and enlarged, fatty liver.
Potential drug interactions: No significant drug interactions. Do not take Truvada, Atripla, Epivir, Epivir-HBV, Epzicom, Combivir, or Trizivir while taking Emtriva, since they contain Emtriva or medication equivalent to Emtriva.
Tips: Emtriva (FTC) is called a "me-too" drug because of its similarity to Epivir (3TC). Both drugs are associated with the M184V mutation (which suggests drug resistance). However, unlike Epivir, Emtriva remains in blood cells in excess of the 24-hour dosing interval.
Flare-up of HBV in people co-infected with HIV/HBV has occurred when Emtriva was discontinued. This makes sense, since competitor Epivir is known to be effective against hepatitis B and has a hep B formulation; stopping the medicine could thus take the suppression off the hep B virus. Patients co-infected with HIV/HBV who stop taking Emtriva should be closely followed by their physician. Emtriva is available as a combination pill with Viread (tenofovir DF), which is called Truvada. Truvada is now the only NRTI combination on the preferred list of U.S. HIV treatment guidelines for the NRTI component of an HIV regimen. In 2006, Emtriva was combined with Sustiva (efavirenz) and Viread in one pill, which is known as Atripla. Atripla is probably the most commonly prescribed medication for people taking HIV medicine for the first time. Please see package insert for more complete potential side effects and interactions.
Doctor
Emtriva (emtricitabine, also known as FTC) was approved as a stand-alone antiretroviral for once-daily treatment of HIV infection in 2003, and in the fixed dose combinations Truvada (tenofovir/emtricitabine) in 2004, and Atripla (tenofovir/emtricitabine/efavirenz) in 2006. This antiretroviral is closely related to 3TC and should not be combined with this drug or the other fixed dose combinations (described above) in HAART therapy. In our clinic FTC is used primarily in the fixed dose combination formulations. While FTC has activity against hepatitis B, it is not currently approved for this viral infection. FTC is well tolerated, but a side effect observed in a number of individuals in our clinic is discoloration of the skin and nails. Like 3TC, FTC should be dose adjusted in those with decreased kidney function. If Truvada or Atripla is being used, separate the FTC from the other components of the fixed dose combination for correct dosing. Is there any difference between 3TC and FTC? Yes, FTC stays in the cell longer than 3TC and may be a reason why Truvada performs a little better than 3TC fixed dose combinations. FTC and 3TC share the M184V mutation and individuals resistant to 3TC will also be resistant to FTC. On the positive side, FTC (as with 3TC) may boost the activity of AZT and tenofovir when this mutation is present. -- Frank M. Graziano, M.D., Ph.D.
Activist
It's probably no small coincidence that Emtriva is also called FTC: it is very similar to 3TC (Epivir). So much so that Emtriva and Epivir should not be taken together; nor should Emtriva be taken with any fixed dosed combination containing it or its cousin Epivir (Truvada, Atripla, Combivir, Epzicom, or Trizivir). And like Epivir, Emtriva is effective in combating the hepatitis B virus (but has not been FDA approved to treat HBV). Emtriva has a longer half-life than Epivir, meaning that it stays in the bloodstream longer. This is why you can take a lower dose of Emtriva just once a day (200 mg) than Epivir (300 mg), and perhaps over time, Emtriva may be less toxic to the liver. Emtriva combined with Viread gives us Truvada, and is a component of Atripla (Truvada and Sustiva), further reducing pill burden. Potential for and actual incidence of side effects can vary, as always, from person to person, but also across races with Emtriva: hyperpigmentation (skin darkening of the palms of hands and soles of feet) can occur more often in Blacks/African Americans. -- Morris Jackson