In the U.S.—

• Antiviral, systemic

Abacavir ( a-BAK-a-veer) is used, in combination with other medicines, in the treatment of the infection caused by the human immunodeficiency virus (HIV). HIV is the virus that causes acquired immunodeficiency syndrome (AIDS).

Abacavir will not cure or prevent HIV infection or AIDS; however, it helps keep HIV from reproducing and appears to slow down the destruction of the immune system. This may help delay the development of problems usually related to AIDS or HIV disease. Abacavir will not keep you from spreading HIV to other people. People who receive this medicine may continue to have other problems usually related to AIDS or HIV disease.

This medicine is available only with your doctor's prescription, in the following dosage forms:

Oral
• Oral solution (U.S.)
• Tablets (U.S.)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For abacavir, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to abacavir. This medicine should not be taken if you have ever had an allergic reaction to it, because it could cause another severe reaction that may result in death. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Abacavir has not been studied in pregnant women. However, it has been found to cause birth defects and other problems in animals at doses many times the human dose. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—It is not known whether abacavir passes into breast milk. However, because of the possibility that this medicine could cause unwanted effects in nursing babies and the risk of passing HIV on to the infant, breast-feeding is not recommended. Mothers who are taking this medicine and who wish to breast-feed should discuss this with their doctor.

Children—This medicine has been tested in children 3 months of age and older and, in effective doses, has not been shown to cause different side effects or problems than it does in adults.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of abacavir in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your health care professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

• Allergy to abacavir or any ingredients in the medicine—You should tell your doctor immediately if you have signs of an allergic reaction. If you have ever taken abacavir in the past, you should tell your doctor right away.

• Liver problems, moderate or severe—Abacavir has not been studied in patient with liver problems, so it should not be used.

• Risk factors for liver disease such as:
• Being overweight or
• Taking other HIV medicines for long periods of time—Serious side effects could occur; caution should be used

Take this medicine exactly as directed by your doctor. Do not take it more often, and do not take it for a longer time than your doctor ordered.

Dosing—

The dose of abacavir will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of abacavir. If your dose is different, do not change it unless your doctor tells you to do so.

• For oral dosage form (oral solution or tablets):
  • For HIV infection:
    • Adults and adolescents 16 years of age and older—300 milligrams (mg) two times a day or 600 mg once a day. This medicine can be taken with or without food.
    • Children 3 months to 16 years of age—Dose is based on body weight and must be determined by your doctor. The usual dose is 8 mg per kilogram (kg) (3.6 mg per pound) of body weight two times a day.

Missed dose—

If you miss a dose of this medicine, take it as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the oral solution from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

This medicine may cause a severe allergic reaction in some patients. This reaction usually occurs within 6 weeks after the medicine is started but may occur at any time. If untreated, it can lead to severe low blood pressure and even death. Stop taking this medicine and check with your doctor immediately if you notice sudden fever, skin rash, diarrhea, nausea, stomach pain, vomiting, or a feeling of unusual tiredness or illness, cough, shortness of breath, or sore throat.

When you begin taking this medicine, you will be given a warning card which describes symptoms of severe allergic reactions that may be caused by abacavir. The warning card also provides information about how to treat these allergic reactions. For your safety, you should carry the warning card with you at all times.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Stop taking this medicine and get emergency help immediately if any of the following side effects occur:

• Less common
  • Abdominal or stomach pain;  cough;  diarrhea;  difficult or labored breathing ;  fever;  headache;  joint or muscle pain;  nausea;  numbness or tingling of hands, feet, or face;  redness and soreness of eyes;  shortness of breath ;  skin rash;  sore throat ;  sores in mouth;  swelling of feet or lower legs;  vomiting;  unusual feeling of discomfort or illness;  unusual tiredness 
  
  

• Incidence not known—occurred during clinical practice
  • Blistering, peeling, loosening of skin;  chills;  dark urine;  itching ;  light-colored stools;  red, irritated eyes;  red skin lesions, often with a purple center;  sores, ulcers or white spots in mouth or on lips;  unusual weakness;  upper right abdominal pain;  yellow eyes and skin 
  
  

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

• Rare
  • Abdominal swelling;  decreased appetite ;  fast, shallow breathing;  sleepiness 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Headache 
  
  

• Less common
  • Trouble in sleeping 
  
  

• Incidence not known—occurred during clinical practice
  • Breast enlargement;  buffalo hump;  central obesity;  facial wasting;  peripheral wasting 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.