Ziagen

Name: Ziagen

What Is Abacavir?

Abacavir is an antiviral medication that prevents human immunodeficiency virus (HIV) cells from multiplying in your body.

Abacavir is used to treat HIV, which causes the acquired immunodeficiency syndrome (AIDS). This medicine is for adults and children who are at least 3 months old. Abacavir is not a cure for HIV or AIDS.

Abacavir may also be used for purposes not listed in this medication guide.

You should not take this medicine if you have ever had an allergic reaction to any medicine that contains abacavir, or if you have moderate to severe liver disease.

Stop using abacavir and call your doctor at once if you have any of these signs of an allergic reaction: fever; rash; nausea, vomiting, diarrhea, stomach pain; general ill feeling, extreme tiredness, body aches; shortness of breath, cough, sore throat.

This medicine may cause a serious condition called lactic acidosis. Get emergency medical help if you have even mild symptoms such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

Abacavir can also cause severe or life-threatening effects on your liver. Call your doctor at once if you have any of these symptoms while taking abacavir: pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

You should not use abacavir if you have had an allergic reaction to any medicine that contains abacavir (Ziagen, Epzicom, Triumeq, or Trizivir).

Abacavir can also cause severe or life-threatening effects on your liver. You should not take abacavir if you have moderate or severe liver disease.

Many combination HIV medicines have abacavir as an ingredient. Ziagen should not be taken together with any other medicine that contains abacavir.

Some people taking abacavir develop a serious condition called lactic acidosis. This may be more likely in women, in people who are overweight or have liver disease, and in people who have taken HIV/AIDS medication for a long time. Talk with your doctor about your risk.

To make sure abacavir is safe for you, tell your doctor if you have:

  • heart disease, high blood pressure;
  • a gene variation called HLA-B*5701 allele (your doctor will test you for this);
  • liver disease;
  • a risk factor for heart disease such as smoking, diabetes, or high cholesterol; or
  • if you have used any other HIV medication in the past.

It is not known whether abacavir will harm an unborn baby. HIV can be passed to your baby if you are not properly treated during pregnancy. Tell your doctor if you are pregnant or plan to become pregnant during treatment. Take all of your HIV medicines as directed to control your infection.

If you are pregnant, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of abacavir on the baby.

Women with HIV or AIDS should not breast feed a baby. Even if your baby is born without HIV, the virus may be passed to the baby in your breast milk.

Abacavir Side Effects

Stop using abacavir and call your doctor at once if you have symptoms of an allergic reaction from two or more of these specific side effect groups:

  • Group 1 - fever;
  • Group 2 - rash;
  • Group 3 - nausea, vomiting, diarrhea, stomach pain;
  • Group 4 - general ill feeling, extreme tiredness, body aches;
  • Group 5 - shortness of breath, cough, sore throat.

Once you have had an allergic reaction to abacavir, you must never use it again. If you stop taking abacavir for any reason, talk to your doctor before you start taking the medication again.

Abacavir can cause other serious side effects that may not be signs of an allergic reaction. Call your doctor at once if you have:

  • the first sign of any skin rash, no matter how mild;
  • chest pain or pressure, pain spreading to your jaw or shoulder;
  • severe pain in your upper stomach spreading to your back, nausea and vomiting, fast heart rate; or
  • liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Early symptoms of lactic acidosis may get worse over time and this condition can be fatal. Get emergency medical help if you have even mild symptoms: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

Abacavir may increase your risk of certain infections or autoimmune disorders by changing the way your immune system works. Symptoms may occur weeks or months after you start treatment with abacavir. Tell your doctor if you have:

  • signs of a new infection--fever, night sweats, swollen glands, mouth sores, diarrhea, stomach pain, weight loss;
  • chest pain (especially when you breathe), dry cough, wheezing, feeling short of breath;
  • cold sores, sores on your genital or anal area;
  • rapid heart rate, feeling anxious or irritable, weakness or prickly feeling, problems with balance or eye movement;
  • trouble speaking or swallowing, severe lower back pain, loss of bladder or bowel control; or
  • swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence, loss of interest in sex.

Common side effects may include:

  • sleep problems, strange dreams;
  • headache, tiredness;
  • nausea or vomiting;
  • changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and waist); or
  • (in children) stuffy nose, sneezing, sore throat, ear pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What brand names are available for abacavir?

Ziagen

Is abacavir available as a generic drug?

GENERIC AVAILABLE: No

What else should I know about abacavir?

What preparations of abacavir are available?

Tablets: 300 mg; oral solution: 20 mg/ml

How should I keep abacavir stored?

Capsules and solution should be stored at room temperature, 15C to 30 C (59 F to 86F). The oral solution may be refrigerated but should not be frozen.

In case of emergency/overdose

In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

Ziagen Overview

Ziagen is a prescription medication used to treat human immunodeficiency virus (HIV) infection. Ziagen belongs to a group of drugs called nucleoside analogue reverse transcriptase inhibitors (NRTIs). It works by preventing the virus from multiplying.

This medication comes in tablet and liquid forms and is usually taken once or twice daily.

Common side effects of Ziagen include nausea, vomiting, tiredness, and headaches.

Ziagen Usage

  • Take Ziagen by mouth exactly as your doctor prescribes it. Your doctor will tell you the right dose to take. The usual doses are 1 tablet twice a day or 2 tablets once a day. Do not skip doses.
  • Children aged 3 months and older can also take Ziagen . The child's healthcare professional will decide the right dose and formulation based on the child's weight. The dose should not exceed the recommended adult dose.
  • You can take Ziagen with or without food.
  • If you miss a dose of Ziagen, take the missed dose right away. Then, take the next dose at the usual time.
  • Do not let your Ziagen run out.
  • Starting Ziagen again can cause a serious allergic or life-threatening reaction, even if you never had an allergic reaction to it before. If you run out of Ziagen even for a few days, you must ask your doctor if you can start Ziagen again. If your doctor tells you that you can take Ziagen again, start taking it when you are around medical help or people who can call a doctor if you need one.
  • If you stop your anti-HIV drugs, even for a short time, the amount of virus in your blood may increase and the virus may become harder to treat.
  • If you take too much Ziagen , call your doctor or poison control center right away.

What you should avoid while taking Ziagen:

  • Do not take Epzicom or Trizivir while taking Ziagen.

Avoid doing things that can spread HIV infection, as Ziagen does not stop you from passing the HIV infection to others.

  • Do not share needles or other injection equipment.
  • Do not share personal items that can have blood or body fluids on them, like toothbrushes and razor blades.
  • Do not have any kind of sex without protection. Always practice safe sex by using a latex or polyurethane condom or other barrier method to lower the chance of sexual contact with semen, vaginal secretions, or blood.
  • Do not breastfeed. It is not known if Ziagen can be passed to your baby in your breast milk and whether it could harm your baby. Also, mothers with HIV should not breastfeed because HIV can be passed to the baby in the breast milk.

What is the most important information I should know about Ziagen (abacavir)?

You should not take this medicine if you have ever had an allergic reaction to any medicine that contains abacavir, or if you have moderate to severe liver disease.

Stop using abacavir and call your doctor at once if you have any of these signs of an allergic reaction: fever; rash; nausea, vomiting, diarrhea, stomach pain; general ill feeling, extreme tiredness, body aches; shortness of breath, cough, sore throat.

This medicine may cause a serious condition called lactic acidosis. Get emergency medical help if you have even mild symptoms such as: muscle pain or weakness, numb or cold feeling in your arms and legs, trouble breathing, stomach pain, nausea with vomiting, fast or uneven heart rate, dizziness, or feeling very weak or tired.

Abacavir can also cause severe or life-threatening effects on your liver. Call your doctor at once if you have any of these symptoms while taking abacavir: pain in your upper stomach, itching, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Cautions for Ziagen

Contraindications

  • Abacavir, abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: HLA-B*5701-positive patients.1 228 229 240 (See Hypersensitivity Reactions under Cautions.)

  • Abacavir, abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Previous hypersensitivity reaction to abacavir or any ingredient in the formulation.1 228 229 240 (See Hypersensitivity Reactions under Cautions.)

  • Abacavir, abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Moderate or severe hepatic impairment.1 228 229 240

  • Abacavir/dolutegravir/lamivudine: Concomitant use with dofetilide.240

Warnings/Precautions

Warnings

Hypersensitivity Reactions

Serious, sometimes fatal, hypersensitivity reactions reported with abacavir or fixed combinations containing abacavir (abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine).1 228 229 240

Hypersensitivity manifestations usually involve ≥2 of the following groups: fever, rash, GI (e.g., nausea, vomiting, diarrhea, abdominal pain), constitutional (e.g., generalized malaise, fatigue, achiness), and respiratory (e.g., pharyngitis, dyspnea, cough).1 47 228 229 240 Lethargy, myalgia, chills, myolysis, headache, arthralgia, edema, tachycardia, abnormal chest radiographs (predominantly infiltrates, which may be localized), paresthesia, lymphadenopathy, and mucous membrane lesions (e.g., conjunctivitis, mouth ulceration) also may occur.1 47 228 229 240

Usually apparent within first 6 weeks of abacavir therapy (median time to onset is 9 days), but may occur at any time during therapy.1 50 228 229 240 Incidence may be greater in those receiving once-daily abacavir than in those receiving twice-daily abacavir.1 80 81

Patients carrying the HLA-B*5701 allele are at higher risk for abacavir hypersensitivity,1 71 85 86 87 89 228 229 240 although hypersensitivity reactions also reported in those who do not carry the HLA-B*5701 allele.1 228 229 240 Negative result on HLA-B*5701 testing does not absolutely rule out possibility of some form of hypersensitivity reaction.71 86 87 90 98

Screen all patients for HLA-B*5701 allele prior to initiating or reinitiating abacavir or fixed combination containing abacavir.1 200 201 228 229 240

Abacavir and abacavir-containing preparations contraindicated in patients positive for HLA-B*5701 allele and in those with history of prior hypersensitivity reactions to abacavir.1 200 201 228 229 240

Immediately discontinue abacavir or abacavir-containing preparation as soon as a hypersensitivity reaction is first suspected.1 228 229 240 Monitor clinical status, including liver function tests, and initiate appropriate therapy.1 228 229 240 Never reinitiate abacavir or abacavir-containing preparation following a hypersensitivity reaction, regardless of HLA-B*5701 allele status and even when other diagnoses are possible (e.g., acute-onset respiratory disease, gastroenteritis, reactions to other drugs).1 228 229 240 If hypersensitivity is ruled out, manufacturer states abacavir or other abacavir-containing preparation may be reinitiated, but only if medical care is readily accessible.1 228 229 240 Severe or fatal hypersensitivity reactions can occur within hours after reintroduction of the drug in patients with no identified history of abacavir hypersensitivity or with unrecognized manifestations of hypersensitivity to the drug.1 65 69 228 229 240

Stevens-Johnson syndrome and toxic epidermal necrolysis reported during postmarketing experience in patients receiving abacavir concomitantly with other drugs known to be associated with these severe adverse effects.1 228 229 240 In such cases, discontinue abacavir and do not reinitiate the drug because patient may have multiple drug sensitivities.1 228 229 240 Manifestations of Stevens-Johnson syndrome and toxic epidermal necrolysis are similar to those of abacavir hypersensitivity.1 228 229 240 Erythema multiforme also reported with abacavir.1 228 229 240

Lactic Acidosis and Severe Hepatomegaly with Steatosis

Lactic acidosis and severe hepatomegaly with steatosis (sometimes fatal) reported in patients receiving HIV NRTIs (including abacavir) alone or in conjunction with other antiretrovirals.1 228 229 240 Reported most frequently in women; obesity and long-term NRTI therapy also may be risk factors.1 Has been reported in patients with no known risk factors.1

Use particular caution in patients with known risk factors for liver disease.1

Discontinue abacavir or abacavir-containing preparation if there are clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (e.g., hepatomegaly and steatosis even in the absence of markedly increased serum aminotransferase concentrations).1 228 229 240

Other Warnings and Precautions

Cardiovascular Effects

MI reported in some patients receiving abacavir.1

In response to conflicting data regarding a possible association between abacavir and MI,1 102 106 108 228 229 240 FDA conducted a meta-analysis of 26 randomized clinical trials that evaluated use of abacavir in adults.107 109 This meta-analysis did not identify an increased risk of MI in patients receiving abacavir.1 107 109 228 229 240 FDA recommends that clinicians continue to prescribe abacavir according to approved labeling1 107 and that patients not discontinue abacavir without consulting their clinician.107

As a precaution in patients receiving antiretroviral therapy (including abacavir), consider patient’s underlying risk of CHD and minimize any modifiable risk factors (e.g., hypertension, hyperlipidemia, diabetes mellitus, smoking).1 228 229 240

Precautions Related to Use of Fixed Combinations

Abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Consider cautions, precautions, contraindications, and drug interactions associated with each drug in the fixed combination.228 229 240 Consider cautionary information applicable to specific populations (e.g., pregnant or nursing women, individuals with hepatic or renal impairment, geriatric patients) for each drug.228 229 240

Because the antiretrovirals contained in abacavir/lamivudine, abacavir/dolutegravir/lamivudine, and abacavir/lamivudine/zidovudine also are available in single-entity or other fixed-combination preparations, take care to ensure that therapy not duplicated when a fixed combination is used in conjunction with other antiretrovirals.228 229 240

Do not use multiple abacavir-containing preparations concomitantly.1 228 229 240

Do not use abacavir/lamivudine concomitantly with any preparation containing abacavir or lamivudine.228 In addition, do not use concomitantly with any preparation containing emtricitabine.228

Do not use abacavir/dolutegravir/lamivudine concomitantly with any preparation containing abacavir or lamivudine.240 In addition, do not use concomitantly with any preparation containing emtricitabine.240

Do not use abacavir/lamivudine/zidovudine concomitantly with any preparation containing abacavir, lamivudine, or zidovudine.229 In addition, do not use concomitantly with any preparation containing emtricitabine.229

Adipogenic Effects

Possible redistribution or accumulation of body fat, including central obesity, dorsocervical fat enlargement (“buffalo hump”), peripheral wasting, breast enlargement, and general cushingoid appearance.1 228 229 240

Mechanisms and long-term consequences of adipogenic effects unknown;1 228 229 240 causal relationship not established.1 228 229 240

Immune Reconstitution Syndrome

During initial treatment, patients who respond to antiretroviral therapy may develop an inflammatory response to indolent or residual opportunistic infections (e.g., Mycobacterium avium complex [MAC], M. tuberculosis, cytomegalovirus [CMV], Pneumocystis jirovecii [formerly P. carinii]); this may necessitate further evaluation and treatment.1 228 229 240

Autoimmune disorders (e.g., Graves' disease, polymyositis, Guillain-Barré syndrome) also reported in the setting of immune reconstitution; time to onset is more variable and can occur many months after initiation of antiretroviral therapy.1 228 229 240

Specific Populations

Pregnancy

Antiretroviral Pregnancy Registry at 800-258-4263 or .1 202 228 229 240

Data from the Antiretroviral Pregnancy Registry show no difference in the risk of overall major birth defects for abacavir compared with background rate for major birth defects.1 202 228

Experts state that abacavir and lamivudine is a preferred dual NRTI option for initial antiretroviral regimens in antiretroviral-naive pregnant women, but use only in those negative for HLA-B*5701.202

A triple NRTI regimen of abacavir, lamivudine, and zidovudine not recommended for initial treatment in antiretroviral-naive pregnant women because of inferior virologic efficacy.202

Lactation

Abacavir distributed into human milk and has been detected in plasma of at least 1 breast-feeding child.202 (See Distribution under Pharmacokinetics.)

Instruct HIV-infected women not to breast-feed because of risk of HIV transmission and risk of adverse effects in the infant.1 202

Pediatric Use

Abacavir (Ziagen): Safety and efficacy not established in neonates and infants <3 months of age.1 Adverse effects reported in children similar to those reported in adults (e.g., hypersensitivity reactions, GI effects).1 6 23 34

Abacavir/lamivudine (Epzicom): Do not use in pediatric patients weighing <25 kg.228

Abacavir/lamivudine/zidovudine (Trizivir): Do not use in pediatric patients or in adolescents weighing <40 kg.229

Abacavir/dolutegravir/lamivudine (Triumeq): Safety and efficacy not established in pediatric patients <18 years of age.240

Geriatric Use

Abacavir (Ziagen): Insufficient experience in those ≥65 years of age to determine whether they respond differently than younger adults.1 Select dosage with caution because of age-related decreases in hepatic, renal, and/or cardiac function and concomitant disease and drug therapy.1 228 229 240

Abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Insufficient experience in those ≥65 years of age to determine whether they respond differently than younger adults.228 229 240 Use with caution because of age-related decreases in hepatic, renal, and/or cardiac function and potential for concomitant disease and drug therapy.228 229 240

Hepatic Impairment

Abacavir (Ziagen): Use with caution in those with known risk factors for liver disease.1 Dosage adjustment necessary in adults with mild hepatic impairment.1 (See Hepatic Impairment under Dosage and Administration.) Contraindicated in those with moderate or severe hepatic impairment.1

Abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Not recommended in patients with mild hepatic impairment.228 229 240 Contraindicated in patients with moderate or severe hepatic impairment.228 229 240

Renal Impairment

Abacavir (Ziagen): Pharmacokinetics not fully determined in patients with impaired renal function;1 renal excretion of unchanged abacavir only a minor route of elimination.1

Abacavir/lamivudine, abacavir/dolutegravir/lamivudine, abacavir/lamivudine/zidovudine: Do not use in patients with Clcr <50 mL/minute.228 229 240

Common Adverse Effects

Hypersensitivity reactions, GI effects (nausea, vomiting, diarrhea, anorexia), insomnia, fever and/or chills, headache, malaise, fatigue.1

Ziagen Pharmacokinetics

Absorption

Bioavailability

Mean absolute oral bioavailability of abacavir is 83%.1 46 Rapidly absorbed following oral administration.1 2 6 19 23 43

Commercially available abacavir tablets and oral solution are bioequivalent.46

Fixed-combination tablet containing abacavir 600 mg and lamivudine 300 mg (abacavir/lamivudine; Epzicom) is bioequivalent to two 300-mg tablets of abacavir and two 150-mg tablets of lamivudine given simultaneously.228

Fixed-combination tablet containing abacavir 600 mg, dolutegravir 50 mg, and lamivudine 300 mg (abacavir/dolutegravir/lamivudine; Triumeq) is bioequivalent to a 50-mg tablet of dolutegravir administered simultaneously with a fixed-combination tablet containing 600 mg of abacavir and 300 mg of lamivudine.240

Fixed-combination tablet containing abacavir 300 mg, lamivudine 150 mg, and zidovudine 300 mg (abacavir/lamivudine/zidovudine; Trizivir) is bioequivalent to a 300-mg abacavir tablet, 150-mg lamivudine tablet, and 300-mg zidovudine tablet given simultaneously.229 68

Food

Food does not have a clinically important effect on abacavir bioavailability.1 46 68

Abacavir/lamivudine, abacavir/lamivudine/zidovudine: Food does not affect AUC of abacavir, lamivudine, or zidovudine when the drugs are given as fixed combinations.68 228 229

Abacavir/dolutegravir/lamivudine: Administration with high-fat meal increases dolutegravir peak plasma concentrations and AUC by 37 and 48%, respectively, compared with administration in fasting state;240 abacavir peak plasma concentrations decreased by 23%;240 lamivudine exposures not affected.240

Special Populations

Pediatric patients: Plasma concentrations attained with abacavir oral solution are similar to those observed in adults;1 plasma concentrations attained with abacavir oral tablets are higher than those observed in pediatric patients receiving the oral solution.1

HIV-1-infected pediatric patients 3 months to 12 years of age: AUC of abacavir reported with once-daily regimen of oral solution or tablets is comparable to AUC of abacavir reported with twice-daily regimen of oral solution or tablets.1 Mean peak plasma concentrations 1.6- to 2.3-fold higher when abacavir is administered once daily compared with administration twice daily.1

Mild hepatic impairment (Child-Pugh score 5–6): AUC of abacavir is 89% higher than in those with normal hepatic function.1

Pregnant women: Pharmacokinetics similar to that in nonpregnant women;202 AUC in pregnant women similar to that reported in women 6–12 weeks postpartum and in nonpregnant individuals.202

Distribution

Extent

Abacavir is extensively distributed following oral administration.1

Abacavir is distributed into CSF following oral administration.1 6 20 46 62 84

Abacavir crosses human placenta.82 83 Concentrations in cord blood at time of delivery generally similar to maternal serum concentrations.82

Abacavir is distributed into human milk.202 In a study in 15 women receiving abacavir at 1 month postpartum, milk-to-plasma ratio was 0.85 and the drug was detected in the plasma of at least 1 breast-feeding child.202

Plasma Protein Binding

Abacavir is 50% bound to plasma proteins; binding independent of drug concentrations.1

Elimination

Metabolism

Abacavir is metabolized in the liver by alcohol dehydrogenase and glucuronyltransferase to inactive metabolites.1

Intracellularly, abacavir is phosphorylated and then converted to the active carbovir triphosphate by cellular kinases.1 3 6 Intracellular (host cell) conversion to carbovir triphosphate is necessary for the antiviral activity of the drug.1 2 3 4 6 7 8 9

Elimination Route

82.2% of abacavir oral dose excreted in urine; 16% excreted in feces.1 46

Half-life

About 1.5 hours.1 6 7 46

Special Populations

Half-life of abacavir increased 58% in patients with mild hepatic impairment (Child-Pugh score 5–6).1

Half-life was 1.33 hours in 1 patient with renal failure (GFR <10 mL/minute) undergoing peritoneal dialysis.18

Uses For Ziagen

Abacavir is used together with other medicines to treat human immunodeficiency virus (HIV) infection. HIV is the virus that causes acquired immunodeficiency syndrome (AIDS).

Abacavir will not cure or prevent HIV infection or the symptoms of AIDS. It helps keep the HIV virus from reproducing, and appears to slow the destruction of the immune system. This may help delay the development of serious health problems that are usually related to AIDS or HIV infection. Abacavir will not keep you from spreading HIV to other people. People who receive this medicine may continue to have other problems related to AIDS or HIV infection.

This medicine is available only with your doctor's prescription.

Precautions While Using Ziagen

It is very important that your doctor check the progress of you or your child at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.

Do not use this medicine if you are also using other medicines containing abacavir (eg, Epzicom®, Triumeq®, Trizivir®).

This medicine may cause severe allergic reactions in some patients. These reactions usually occur 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. Check with your doctor immediately if you or your child notice sudden fever, skin rash, diarrhea, nausea, stomach pain, vomiting, or a feeling of unusual tiredness or illness, cough, trouble breathing, or sore throat.

When you begin taking this medicine, you or your child 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.

Do not stop using this medicine unless your doctor tells you to do so. If you stop using this medicine for any reason, do not start taking it again without talking first to your doctor.

If you must stop using abacavir because of an allergic reaction, you should never use the medicine again. Return the unused medicine to your doctor or pharmacist. A worse reaction, possibly even death, can occur if you use the medicine again. Tell your doctor right away if you or your child have ever taken abacavir, especially if you have experienced an allergic reaction to it in the past.

Two rare but serious reactions to this medicine are lactic acidosis (too much acid in the blood) and liver toxicity. These are more common if you are female, very overweight (obese), or have been taking anti-HIV medicines for a long time. Call your doctor right away if you or your child have more than one of these symptoms: stomach discomfort or cramping, dark urine, decreased appetite, diarrhea, general feeling of discomfort, light-colored stools, muscle cramping or pain, nausea, unusual tiredness or weakness, trouble breathing, vomiting, or yellow eyes or skin.

When you start taking HIV medicines, your immune system may get stronger. If you or your child have certain infections that are hidden in your body, such as pneumonia or tuberculosis, you may notice new symptoms when your body tries to fight them. Tell your doctor right away if you or your child notice any changes in health.

This medicine may cause you to have excess body fat. Tell your doctor if you or your child notice changes in your body shape, such as an increased amount of fat in the upper back and neck, or around the chest and stomach area, or a loss of fat from the legs, arms, and face.

This medicine may increase your risk of having a heart attack. This is more likely to occur if you smoke or already have heart disease, high blood pressure, or high cholesterol or fats in the blood. Call your doctor right away if you have chest pain or discomfort, nausea, pain or discomfort in the arms, jaw, back or neck, trouble breathing, sweating, or vomiting. These could be symptoms of a heart attack.

This medicine will not keep you from giving HIV to your partner during sex. Make sure you understand and practice safe sex, such as using latex condoms, even if your partner also has HIV. Do not share needles, toothbrushes, and razor blades with anyone.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

Drug Interactions

Methadone

In a trial of 11 HIV‑1‑infected subjects receiving methadone‑maintenance therapy with 600 mg of Ziagen twice daily (twice the currently recommended dose), oral methadone clearance increased [see Clinical Pharmacology (12.3)]. This alteration will not result in a methadone dose modification in the majority of patients; however, an increased methadone dose may be required in a small number of patients.

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