Emtriva

Common Name: emtricitabine or FTC

Brand Name: Emtriva

Class: nucleoside analogs (also called nucleoside reverse transcriptase inhibitors, NRTIs or nukes)

Standard dose: One 200 mg capsule once a day, with or without food, and no food 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: $437.28 / month for 200 mg capsules; $103.25 for 10 mg/ml, 170 ml

Manufacturer contact: Gilead Sciences, Inc., www.gilead.com, 1 (800) GILEAD5 (445-3235)

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 tips). 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, 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 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 should use the Truvada formulation as their nucleoside backbone to increase activity and avoid HBV resistance. Patients co-infected with HIV/HBV who stop taking Emtriva should be closely monitored 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 (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. 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 chemically and clinically very similar to 3TC and thus is often considered interchangeable in any regimen in which 3TC is used. There are a few differences however, including a longer half-life for FTC, and data showing that FTC is modestly more active when studied as a single drug in short term studies. The importance of these attributes is not clear, but may be one reason why Truvada has shown more virologic activity than Epzicom in one large study of patients with a high viral load at baseline. In almost all settings, FTC is only used in one of the fixed dose combinations previously listed. While its use is often associated with long term successful virus suppression, it is one of the drugs in the regimen to which resistance is commonly observed if there is less than complete virus suppression. Resistance to FTC leads to cross resistance to 3TC as well. The expected FTC resistance mutation, referred to as M184V, slightly improves the antiretroviral activity of AZT and tenofovir, which leads some clinicians to maintain the use of these combinations even after resistance occurs. Also of interest is that this mutation causes HIV to be less "fit" than wild type, meaning that despite resistance development, HIV is still partially suppressed by about one-half log due to the impact of this M184V mutation. It is also active against hepatitis B virus, but like 3TC, its use alone is associated with the development of viral resistance by the hep B virus to the drug and should therefore only be used in combination with another agent, typically tenofovir as it is also active against hep B virus. FTC is very well tolerated. Early clinical trials reported an infrequent association with discoloration of the skin and nails, but this has not been a toxicity associated with the use of the combination "Atripla" nor Truvada to any important extent. Like 3TC, FTC needs to be dose adjusted in those with significantly decreased kidney function. -- Cal Cohen, M.D.

Activist

Emtriva (FTC) is Gilead's version of 3TC for combining with Viread in their combo drugs Truvada and Atripla (Emtriva+Viread+Sustiva). It has the same favorable resistance profile as 3TC -- making it part of a good nuke backbone for many regimens. Like 3TC, it has activity against the hepatitis B virus, so those with hep B should consult with their doctors before using this drug so they don't unwittingly develop resistance to a potentially useful HBV drug. -- Jeff Taylor