Abacavir belongs to a class of medication called nucleoside reverse transcriptase inhibitors (NRTI). Reverse transcriptase is a part of the human immunodeficiency virus (HIV) required to infect cells and make more virus. Abacavir prevents reverse transcriptase from working properly. Abacavir is used in combination with other medications to stop the growth of HIV. HIV is responsible for acquired immune deficiency syndrome (AIDS).

Abacavir does not cure AIDS and does not prevent it from being spread to others. It does slow further growth or reproduction of HIV when used in combination with other medications, and it seems to slow down the destruction of the immune system. This may also help to delay the development of problems that are related to HIV infection or AIDS.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. 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.

Adults (18 to 65 years): The recommended dose is 300 mg twice a day, or 600 mg once a day, taken with or without food.

Seniors (over 65 years): The recommended dose is 300 mg twice a day taken with or without food.

Adolescents (12 to 17 years): The recommended dose is 300 mg twice a day taken with or without food.

Children (3 months to 11 years): The recommended dose is based on body weight as calculated by your doctor. The usual dose is 8 mg per kg body weight 2 times a day (up to a maximum of 300 mg twice a day), taken with or without food.

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, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing 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, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Oral Solution

Each mL of clear to opalescent, yellowish, strawberry-banana flavoured liquid, contains abacavir sulfate equivalent to abacavir 20 mg. Nonmedicinal ingredients: artificial strawberry and banana flavours, citric acid (anhydrous), hydrochloric acid, methylparaben, propylene glycol, propylparaben, saccharin sodium, sodium citrate (dihydrate), sodium hydroxide, and sorbitol solution.

Tablets

Each yellow, biconvex, capsule-shaped, film-coated tablet, scored and imprinted with "GX 623" on both sides, contains abacavir 300 mg. Nonmedicinal ingredients: colloidal silicon dioxide, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polysorbate 80, sodium starch glycolate, titanium dioxide, triacetin, and yellow iron oxide.

Abacavir should not be taken by anyone who:

• is allergic to abacavir or to any of the ingredients of the medication
• has moderate to severe liver problems

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.

• decreased appetite
• diarrhea
• headache
• nausea
• rash (without any other symptoms)
• unusual tiredness or weakness
• vomiting

Although most of these 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:

• changes in body fat locations (e.g., more body fat around the waist and less on the arms and legs; breast enlargement; lump of fat on the back near the shoulder area, also called "buffalo hump")

Stop taking the medication and seek immediate medical attention if any of the following occur:

• severe skin rash, including skin blistering and peeling (possibly with headache, fever, coughing, or aching before the rash begins)
• signs of a serious allergic reaction: skin rash, or two or more of the following sets of symptoms:
  • fever
  • inflammation of the eye, mouth ulcers, or low blood pressure may occasionally occur
  • nausea, vomiting, diarrhea, or abdominal pain
  • severe tiredness, achiness, or general ill feeling
  • sore throat, shortness of breath, or coughing
• signs of an enlarged liver (nausea, vomiting, abdominal pain, weakness, diarrhea)
• signs of lactic acidosis (muscle pain, nausea and vomiting, weakness, abdominal pain, difficulty breathing, rapid breathing, loss of appetite)

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 using 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 use this medication.

Allergic reactions: At the time of receiving this medication, make sure you are given a leaflet and warning card that will help you to recognize the signs and symptoms of allergy to abacavir. Abacavir causes an allergic reaction in approximately 8% of people. The symptoms usually appear within the first 6 weeks of treatment, but may occur at any time during therapy. People who suffer an allergic reaction to abacavir should never take the medication again. Some people are at higher risk of this allergic reaction. Your doctor can perform a blood test to see if you are at greater risk. If you have 2 or more of the following sets of symptoms, you may be experiencing a serious allergic reaction:

• fever
• inflammation of the eye, mouth ulcers, or low blood pressure that may occasionally occur
• nausea, vomiting, diarrhea, or abdominal pain
• severe tiredness, aches, or general ill feeling
• skin rash
• sore throat, shortness of breath, or coughing

Heart attack: The use of abacavir is associated with an increased risk of heart attack. Due to this increased risk, people with the following conditions or risk factors should tell their doctor about them:

• diseases that increase your risk of heart disease, such as high blood pressure and diabetes
• heart problems
• smoking

Kidney disease: People with very poor kidney function should not use abacavir.

Lactic acidosis and enlarged liver: This medication can cause a rare but serious condition called lactic acidosis together with an enlarged fatty liver. You may be more likely to experience these problems if you are female, obese, have known risk factors for liver disease, or have been taking nucleoside analog medications such as abacavir for a long time. If you experience weakness, loss of appetite, sudden unexplained weight loss, abdominal pain, and difficulty or rapid breathing, contact your doctor immediately or seek immediate medical attention.

Liver disease: People with moderate-to-severe liver disease should not use abacavir.

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

Breast-feeding: This medication may pass into breast milk. Breast-feeding is not recommended for HIV-positive women.

Children: The safety and effectiveness of this medication have not been established for children under 3 months of age.

There may be an interaction between abacavir and any of the following:

• alcohol
• methadone
• retinoids (medications that are chemically related to vitamin A; e.g., isotretinoin)

If you are taking any of these 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.

Medications other than those listed above may interact with this medication. 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.