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 frequency 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.
Very tolerable. Most common side effects (rarely seen) include headache, diarrhea, nausea and rash. Skin discoloration observed as darkening of the skin on the palms and the soles of the feet can occur and usually does not cause any symptoms. More hyperpigmentation seen in pediatric studies than adult studies. Rare but potentially fatal toxicity with all NRTIs is 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 nukes for a long time; and 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, and difficulty breathing or shortness of breath; and enlarged, fatty liver.
Potential drug interactions:
No significant drug interactions. Do not take Truvada, Atripla, Epivir, 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 (it remains inside of the cell longer).
Flare up of HBV in people co-infected with HIV/HBV has occurred when Emtriva was discontinued. 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. In 2006, Emtriva was combined with Sustiva (efavirenz) and Viread in one pill, which is known as Atripla. Please see package insert for more complete potential side effects and interactions.
Doctor
Emtricitabine (FTC) can be viewed as a long-acting form of lamivudine (3TC) withAlthough it hasn't been around as long, most of my comments about 3TC apply to Emtriva (FTC) as well. I can't think of a reason to use Viread without using FTC, which is why my patients on tenofovir are almost always taking it in the form of Truvada or Atripla, which both contain tenofovir and FTC. FTC may also have an advantage over 3TC, at least when it's combined with tenofovir, as it may be less prone to resistance. The reason may be due to the fact that FTC and tenofovir have long and similar half-lives (they stick around for a long time in the blood and the cells). As a result, they're forgiving of the occasional skipped dose (not that I'm recommending skipping doses!). -- Joel Gallant, M.D.
Activist
Emtriva, also known as FTC, is very similar to 3TC (Epivir), though it appears to have small competitive advantages over 3TC. The history of the drug is interesting in that, like 3TC, it was once owned by the company known today as GlaxoSmithKline. Many years ago, the company made the decision to develop 3TC as they believed it was the better and safer of the two drugs. Neither had originally been created at the company but were purchased for development. For many years after the launch of 3TC, no one thought or heard of FTC until it was quietly purchased from Glaxo by a small but rapidly growing West Coast company known as Gilead Sciences. Gilead was committed to becoming a major player in the HIV drug field, both by creating new drugs and by purchasing compounds from other companies. Despite the belief of many that FTC/Emtriva offered little or no advantage over 3TC, Gilead invested in its development and conducted the necessary clinical studies to win FDA approval. Over time, FTC/Emtriva was shown to have slightly better efficacy and freedom from developing resistance than 3TC/Epivir. To match and better the simplification advantages of rival Combivir, Gilead quickly developed a pill called Truvada that combined FTC/Emtriva with a second antiviral, tenofovir/Viread. -- Martin Delaney
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