Adefovir belongs to a group of medications known as antivirals. It is used to treat people with chronic hepatitis B infection who also have active liver damage. It works by stopping the hepatitis B virus from reproducing. While there is no cure for hepatitis B infection, adefovir can decrease the amount of hepatitis B virus in the body and may reduce the damage done to the liver by the hepatitis B virus.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The usual recommended dose of adefovir is 10 mg once daily, taken with or without food. Taking adefovir at the same time each day may help you to remember to take your medication. People with reduced kidney function may need longer periods of time between doses.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, but remember it that same day, take the missed dose immediately and continue with your regular schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature in the original container and keep it out of the reach of children.

Each white-to-off-white, round, flat-faced, bevelled-edge tablet engraved "APO" on one side and "A10" on the other side, contains 10 mg of adefovir. Nonmedicinal ingredients: lactose monohydrate, starch, croscarmellose sodium, magnesium stearate, and talc.

Adefovir should not be taken by anyone who is allergic to adefovir or to any of the ingredients of the medication.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• gas
• headache
• indigestion
• nausea
• skin rash or itching
• stomach pain
• tiredness
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• bone pain and softening of the bone
• muscle pain or weakness
• signs of kidney problems (e.g., change in the amount or colour of urine, increased urination at night, blood in the urine, swelling in the feet or legs)
• symptoms of liver problems (e.g., yellowing of the skin or whites of eyes, dark urine, pale stools, loss of appetite, nausea, lower stomach pain)

Seek immediate medical attention if any of the following occur:

• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• symptoms of lactic acidosis (e.g., unusual weakness or tiredness, unusual muscle pain, stomach pain with nausea and vomiting, feeling cold especially in the arms and legs, dizziness or lightheadedness, fast or irregular heartbeat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Hepatitis B transmission: The hepatitis B infection can still be transmitted to other people through blood contamination or sexual contact while you are taking this medication. Continue to take appropriate precautions to prevent the transmission of hepatitis B throughout your treatment with adefovir.

HIV and hepatitis B co-infections: If you get or have HIV infection and are not taking medication to treat HIV, adefovir may increase the chance that your HIV infection will not respond to usual treatment. Therefore, it is important to be tested for HIV before starting treatment with adefovir and whenever there is a risk of HIV exposure during treatment. Adefovir should not be taken in combination with certain other medications used to treat HIV infection.

Kidney problems: This medication may cause kidney problems, especially for people who have or are at risk of developing reduced kidney function (e.g., taking other medications that can cause kidney problems, high blood pressure, diabetes). Your doctor will monitor your kidney function while you are taking this medication. If you have reduced kidney function, you may require longer periods of time between doses.

Lactic acidosis and enlarged liver: Adefovir can cause a condition called lactic acidosis (buildup of lactic acid) together with an enlarged liver. If you experience any of the following symptoms, call your doctor immediately:

• abdominal pain with nausea and vomiting
• dark yellow or brown urine
• difficulty breathing
• dizziness or lightheadedness
• fast or irregular heartbeat
• feeling cold, especially in the arms and legs
• loss of appetite
• pale stools
• unusual muscle pain
• unusual tiredness or weakness
• yellowing of the skin or eyes

Your doctor will periodically monitor you and perform laboratory tests to check your liver function.

Stopping the medication: People with hepatitis may experience a worsening of their condition usually within 12 weeks of stopping this medication. If you and your doctor decide that you should stop taking adefovir, you will need to have regular blood tests to check liver function and hepatitis B virus levels.

Pregnancy: This medication should not be taken during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if adefovir passes into breast milk. Breast-feeding is not recommended while taking this medication.

Children: The safety and effectiveness of this medication have not been established for children.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.