Hepsera (Adefovir Dipivoxil)

What are Hepsera's Possible Side Effects?

Hepsera® (adefovir dipivoxil) was compared to a sugar pill (placebo) in clinical trials. The most common side effects observed were weakness, headache, stomach pain and nausea.

Hepsera also can cause the following serious side effects (See Important Safety Information): very serious hepatitis if you stop taking it, a severe kidney problem called nephrotoxicity, lactic acidosis (buildup of acid in the blood) and liver problems.

The most common side effects in patients with liver transplants and chronic hepatitis B were weakness, headache, stomach pain and itching. Some patients with liver transplants also had changes in the way their kidneys worked. If you notice any side effects while taking Hepsera, talk to your healthcare provider about what to do.

Important Safety Information

1. Some people who stop taking Hepsera get a very serious hepatitis. This usually happens within 12 weeks after stopping. You will need to have regular blood tests to check for liver function and hepatitis B virus levels if you stop taking Hepsera.

2. Hepsera may cause a severe kidney problem called nephrotoxicity. It usually happens in people that already have a kidney problem, but it can happen to anyone that uses Hepsera. You will need to have regular blood tests to check for kidney function while you are taking Hepsera.

3. Some people who have taken medicines like Hepsera that are called nucleoside or nucleotide analogs have developed a serious condition called lactic acidosis (build up of an acid in the blood). Lactic acidosis is a medical emergency and must be treated in the hospital. Call your doctor right away if you get any of the following signs of lactic acidosis:

Some people who have taken medicines like Hepsera have developed serious liver problems called hepatotoxicity, with liver enlargement (hepatomegaly) and fat in the liver (steatosis). Call your doctor right away if you get any of the following signs of liver problems.

You may be more likely to get lactic acidosis or serious liver problems if you are very overweight (obese) or have been taking nucleoside analog medicines [Atripla™ (efavirenz plus emtricitabine plus tenofovir disoproxil fumarate), Combivir® (zidovudine plus lamivudine), Emtriva® (emtricitabine), Epivir® Epivir-HBV® (lamivudine), Epzicom™ (abacavir plus lamivudine), Hivid® (zalcitabine), Retrovir® (zidovudine), Trizivir® (zidovudine plus lamivudine plus abacavir), Truvada® (emtricitabine plus tenofovir disoproxil), Videx® (didanosine), Viread® (tenofovir disoproxil fumarate), Zerit® (stavudine) and Ziagen® (abacavir)] for a long time.

4. If you get or have HIV that isn't being treated with medicines, Hepsera may increase the chances your HIV infection cannot be helped with usual HIV medicines. This can happen if you get or have HIV and don't know it, or if your HIV is not being treated while you are taking Hepsera. You should get an HIV test before you start taking Hepsera and any time after that when there's a chance you were exposed to HIV.

Is There Resistance to Hepsera?

Drug resistance is a primary concern of infectious disease specialists around the world. Any virus can develop drug resistance, and may even develop resistance to more than one drug. Resistance occurs when viruses acquire ways to survive the effects of the drugs that were designed to weaken them. Resistance to antiviral drugs presents an obstacle to providing effective long-term treatment of viral diseases, such as chronic hepatitis B.

Hepsera® was studied in clinical trials to find out whether or not resistance would develop. Through 144 weeks (about 3 years), resistance mutations were identified that may reduce the effectiveness of Hepsera. After 3 years of continuous treatment, 4/100 patients developed resistance to Hepsera in clinical trials.

In clinical trials, Hepsera was found to work well in people who had hepatitis B virus that was resistant to the currently approved chronic hepatitis B treatment, lamivudine.