Class: nucleoside analog (also called nucleoside reverse transcriptase inhibitor, NRTI, or nuke)
Standard Dose: One 300 mg tablet once-a-day (or one 150 mg tablet twice daily), with no food restrictions (may be taken with or without food). Dose is lowered for people with kidney impairment and in children, to 4 mg/kg/day (a kilogram equals 2.2 pounds). A strawberry/banana flavored liquid is also available. Take missed dose as soon as possible, but do not double up on your next dose.
This remains one of the most easily tolerated HIV medications. Potential side effects/toxicities (rarely seen) may include headache, nausea, vomiting, diarrhea, fever, fatigue, hair loss, insomnia, malaise (general ill feeling), nasal symptoms, cough, peripheral neuropathy, low white blood cells and anemia.
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. Pancreatitis (inflammation of the pancreas) can be life-threatening and may cause pain in the stomach and back, along with nausea, vomiting and blood. Children should be watched for signs of pancreatitis.
Potential drug interactions:
No significant drug interactions. Do not take Epzicom, Combivir, Trizivir, Truvada, or Atripla while taking Epivir, since they contain Epivir or medication equivalent to Epivir.
Tips:
Exciting benefit: drug resistance that the virus develops against Epivir -- the M184V mutation -- makes the virus less fit to replicate and has even been shown to keep T-cells from dropping during a treatment interruption as much as they would have otherwise. It is also approved for treatment of hepatitis B virus (HBV), under the brand name Epivir HBV. So if you have hepatitis B and HIV, this drug works for both diseases, but make sure you are taking Epivir at HIV doses -- always ask your doctor or pharmacist. Worsening of hepatitis B (HBV) in people co-infected with HIV/HBV has occurred when Epivir was discontinued. These patients should be closely followed by their physician. Epivir is also available combined with zidovudine (Combivir, one tablet twice-a-day), in a once-a-day formula with Ziagen (Epzicom, one tablet daily) and in a triple combination with both zidovudine and Ziagen (Trizivir, one tablet twice-a-day). Please see package insert for more complete potential side effects and interactions.
Doctor
Epivir, usually called 3TC, has been and continues to be an incredibly important drug. It's hard to imagine that development of 3TC was almost stopped because resistance occurred so quickly when it was used alone! The mutation that causes resistance to 3TC (M184V) improves the activity of Retrovir, Zerit, and Viread. It can delay resistance to those drugs, and can partially restore their activity if resistance has already occurred. Few drugs in the pharmacy are as safe and well tolerated as 3TC. Either 3TC or its cousin, Emtriva (FTC), should be a part of any initial treatment regimen and of any combination that contains abacavir or AZT. (For convenience, use FTC if you're taking tenofovir, to take advantage of the combined forms: Truvada and Atripla). -- Joel Gallant, M.D.
Activist
Epivir has long been a favorite of HIV-treating doctors and is one of the most widely used drugs. On the surface, this has also seemed a little strange because HIV develops resistance to Epivir perhaps more quickly than any other HIV drug. So why does it remain popular? There are a number of reasons. It works well and is one of the more potent drugs of this class. It has a reputation for minimal side effects. But most importantly, it was noted early on that when used with AZT or some other combinations, it seemed to remain effective despite the development of resistance to the drug. The study of this unusual phenomenon led to new knowledge about the interaction of certain antivirals and HIV. Sometimes, a resistant mutation could be a good thing rather than a bad thing. Scientists realized that certain mutations, while giving the virus resistance against a particular drug, weakened the virus in other ways. The mutations that occurred most commonly with Epivir appeared to make the virus more susceptible to AZT and to a lesser extent, to d4T. Additionally, it appeared to make HIV "less fit" or less aggressive in its ability to replicate. This property came to be known as "viral fitness," and Epivir resistance seemed to reduce that fitness. Good thing for Epivir and its maker, GlaxoSmithKline, since these discoveries kept the drug alive and in wide use despite the rapid development of resistance. This not only made Epivir a lasting money maker but helped keep AZT in use for many more years in the form of Combivir. -- Martin Delaney
