POSITIVELY AWARE MARCH/APRIL 2011
brand name: Emtriva
common name: emtricitabine or FTC
class: Nucleoside analog reverse transcriptase inhibitor
(nucleoside analog, NRTI, or nuke)
manufacturer: Gilead Sciences, Inc. | www.gilead.com, (800) GILEAD5 (445–3235)
Standard dose: One 200 mg capsule once a day, with or without food, with no dietary restrictions. The dosing needs to be adjusted for people who have decreased kidney function. It is also available as an oral solution; for children 0-3 months the dose is 3 mg per 2.2 lbs. and children 3 months–17 years, 6 mg per 2.2 lbs. up to a maximum of 240 mg. For children weighing more than 73 pounds who can swallow an intact capsule, one 200 mg capsule once daily. 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: $467.45 / month for 200 mg capsules; $110.38 for 170 ml solution (10 mg/ml)
Potential side effects and toxicity
Very tolerable. Side effects (rarely seen) may include headache, diarrhea, nausea, and rash. Flare-up of HBV (hepatitis B) in people co-infected with HIV/HBV has occurred when Emtriva was discontinued (see More Information). Skin discoloration (darkening of the skin on the palms and the soles of the feet) can occur, but is generally mild and without other symptoms. 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 liver.
Potential drug interactions
No significant drug interactions. Do not take Emtriva with Atripla, Combivir, Epivir, Epivir-HBV, Epzicom, Trizivir, or Truvada, since they contain Emtriva or medication equivalent to Emtriva.
More information
Emtriva (FTC) is similar to Epivir (3TC). However, unlike Epivir, Emtriva remains in blood cells in excess of the 24-hour dosing interval. Emtriva is known to be effective against chronic hepatitis B, but is not indicated for its treatment; stopping the medicine could thus stop the suppression of the hep B virus. Patients co-infected with HIV/HBV who stop taking Emtriva should be closely monitored by their physician. They should also use the Truvada formulation as their NRTI backbone to increase activity and avoid HBV resistance. Emtriva is available as a combination tablet with Viread (tenofovir DF), which is called Truvada. Truvada is the only NRTI combination on the preferred list of the U.S. HIV treatment guidelines for the NRTI component of an HIV regimen. Drug resistance that the virus develops against Emtriva, the M184V mutation, makes the virus less fit to replicate. It also slightly improves the antiviral activity of Retrovir (zidovudine) and Viread, and for that reason, some doctors keep Emtriva onboard in combination with those drugs after M184V resistance develops. In 2006, Emtriva was combined with Sustiva (efavirenz) and Viread (tenofovir) in one pill, which is known as Atripla. Atripla is used quite often as first-line treatment due to ease of taking one pill once a day. Emtriva oral solution should be kept in the refrigerator. If kept at room temperature, the oral solution should be used within three months. See package insert for more complete information on potential side effects and interactions.
Doctor’s comments
Few people take Emtriva itself; it’s almost always combined with tenofovir in the form of Truvada, or with tenofovir and efavirenz in the form of Atripla. The characteristics of FTC are similar to those of 3TC: it has the same resistance profile and is also safe and extremely well tolerated. The main difference between the two drugs is that FTC tends to be combined with tenofovir, while 3TC is usually taken in combination with AZT, abacavir, or both. Aside from the convenience of the co-formulations, there may be other reasons why these combinations make sense. Both tenofovir and FTC have similar half-lives, which are longer than those of other nucleoside analogs. This means they hang around longer in the blood and in CD4 cells. Combining two drugs with similar half-lives may help to prevent resistance if doses are missed or treatment is interrupted. Indeed, we seem to see less tenofovir resistance when tenofovir is combined with FTC than when it’s combined with 3TC, a consideration that may become relevant when 3TC becomes available in generic form. —Joel Gallant, MD, MPH
Activist’s comments
Gilead’s once-daily version of 3TC, they’ve conveniently combined it with Viread in Truvada, and with Viread and Sustiva in Atripla. It causes the same resistance mutation as 3TC that can make your virus more sensitive to AZT or Viread. It can also be useful for salvage patients with lots of drug resistance because it can make their virus “less fit” and help lower their viral load even when they’re resistant to it. Because of its activity against hepatitis B, patients should check before using this drug alone or in any of the fixed dose combinations containing Emtriva to prevent HBV cross resistance to both Emtriva and Epivir. —Jeff Taylor
