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).

Avoid drinking alcohol. It may increase your risk of liver damage.

Taking this medicine will not prevent you from passing HIV to other people. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

Take abacavir exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. Also, do not stop taking abacavir without checking first with your doctor.

abacavir will come with a Medication Guide. Read and follow these instructions carefully. Ask your doctor if you have any questions.

It is important to take abacavir together with other HIV medicines. Take all of the medicines your doctor prescribed at the right time of day. These medicines work best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. If you need help with planning the best times to take your medicines, check with your doctor.

When your supply of abacavir runs low, get more from your pharmacy or from your doctor. The amount of virus in your blood may increase if the medicine is stopped, even for a short time. The virus may develop resistance to abacavir and be harder to treat.

You may take abacavir with or without food.

Measure the oral liquid with a marked measuring spoon, oral syringe, or medicine cup.

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.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

• For oral dosage forms (solution or tablets):
  • For HIV infection:
    • Adults—300 milligrams (mg) two times per day or 600 mg once per day.
    • Children 3 months of age and older—Dose is based on body weight and must be determined by your child's doctor. The dose is usually 8 milligrams (mg) per kilogram (kg) of body weight two times per day, or 16 mg per kg of body weight once a day. Your doctor may increase your dose as needed. However, the dose is usually not more than 600 mg per day.
    • Children weighing 14 kilograms (kg) or more who can take tablets—Dose is based on body weight and must be determined by your child's doctor. The dose is usually 300 to 600 mg per day, taken as a single dose once a day or in divided doses two times a day.
    • Children younger than 3 months of age—Use and dose must be determined by your child's doctor.

Missed Dose

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

Storage

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

You may also store the oral liquid in the refrigerator, but do not freeze it.

US labeling: There are no dosage adjustments provided in the manufacturer’s labeling (has not been studied).

Canadian labeling: No dosage adjustment necessary. Use of 600 mg once daily dosing has not been studied.

May be administered with or without food.

Cabozantinib: MRP2 Inhibitors may increase the serum concentration of Cabozantinib. Monitor therapy

Methadone: May diminish the therapeutic effect of Abacavir. Abacavir may decrease the serum concentration of Methadone. Monitor therapy

Orlistat: May decrease the serum concentration of Antiretroviral Agents. Monitor therapy

Protease Inhibitors: May decrease the serum concentration of Abacavir. Monitor therapy

Rates of adverse reactions were defined during combination therapy with other antiretrovirals. Frequency not always defined. *Incidence not specifically defined but reported in the range of >10%. **Incidence not specifically defined but reported in the range of 1% to 10%.

Central nervous system: Fatigue*, headache (adults: >10%; children: 1% to 10%), malaise*, abnormal dreams**, anxiety**, chills**, depression**, dizziness**, migraine**, sleep disorder**

Dermatologic: Skin rash**

Endocrine & metabolic: Hypertriglyceridemia**, increased gamma-glutamyl transferase

Gastrointestinal: Nausea*, abdominal pain**, diarrhea (increased incidence with once daily dosing)**, gastritis**, gastrointestinal disease**, increased serum amylase**, nausea and vomiting**, vomiting**, pancreatitis

Hematologic & oncologic: Neutropenia**, thrombocytopenia**

Hepatic: Increased serum ALT**, increased serum AST**

Hypersensitivity: Hypersensitivity reaction (including anaphylaxis and multiorgan failure; 8%; excluding subjects carrying the HLA-B*5701 allele: 1%)

Neuromuscular & skeletal: Increased creatine phosphokinase**, musculoskeletal pain**

Respiratory: Bronchitis**, ENT infection**, pneumonia (children)**, viral respiratory tract infection**

Miscellaneous: Fever**

<1% (Limited to important or life-threatening): Anemia, erythema multiforme, hepatomegaly, hepatotoxicity, hyperglycemia, immune reconstitution syndrome, lactic acidosis, leukopenia, liver steatosis, myocardial infarction, pain, redistribution of body fat, renal disease, Stevens-Johnson syndrome, toxic epidermal necrolysis

CBC with differential, serum creatine kinase, CD4 count, HIV RNA plasma levels, serum transaminases, triglycerides, serum amylase; HLA-B*5701 genotype status prior to initiation of therapy and prior to reinitiation of therapy in patients of unknown HLA-B*5701 status; signs and symptoms of hypersensitivity

Abacavir has a high level of transfer across the human placenta. No increased risk of overall birth defects has been observed following first trimester exposure according to data collected by the antiretroviral pregnancy registry. Maternal antiretroviral therapy may increase the risk of preterm delivery, although available information is conflicting possibly due to variability of maternal factors (disease severity; initiation of therapy); however, maternal antiretroviral medication should not be withheld due to concerns of preterm birth. Information related to stillbirth, low birth weight, and small for gestational age infants is limited. Long-term follow-up is recommended for all infants exposed to antiretroviral medications; children who develop significant organ system abnormalities of unknown etiology (particularly of the CNS or heart) should be evaluated for potential mitochondrial dysfunction. Cases of lactic acidosis and hepatic steatosis related to mitochondrial toxicity have been reported with use of nucleoside reverse transcriptase inhibitors (NRTIs). These adverse events are similar to other rare but life-threatening syndromes which occur during pregnancy (eg, HELLP syndrome). In general nucleoside reverse transcriptase inhibitors are well tolerated and the benefits of use generally outweigh potential risk.

Combination antiretroviral therapy (cART) therapy is recommended for all HIV-infected pregnant women to keep the viral load below the limit of detection and reduce the risk of perinatal transmission. When HIV is diagnosed during pregnancy in a woman who has never received antiretroviral therapy, cART should begin as soon as possible after diagnosis. The Health and Human Services (HHS) Perinatal HIV Guidelines consider abacavir in combination with lamivudine to be a preferred NRTI backbone for initial therapy in antiretroviral-naive pregnant women (do not use in women who are positive for the HLA-B*5701 allele). This backbone is not recommended with atazanavir/ritonavir or efavirenz if pretreatment HIV RNA is >100,000 copies/mL. The pharmacokinetics of abacavir are not significantly changed by pregnancy and dose adjustment is not needed for pregnant women. In general, women who become pregnant on a stable cART regimen may continue that regimen if viral suppression is effective, appropriate drug exposure can be achieved, contraindications for use in pregnancy are not present, and the regimen is well tolerated. Monitoring during pregnancy is more frequent than in non-pregnant adults; cART should be continued postpartum.

For HIV-infected couples planning a pregnancy, maximum viral suppression with combination antiretroviral therapy (cART) is recommended prior to conception for the HIV-infected partner(s) and expert consultation is recommended; modification of therapy (if needed) and optimization of the woman’s health should be done prior to conception. HIV-infected women not planning a pregnancy may use any available type of contraception, considering possible drug interactions and contraindications of the specific method. In addition, consistent use of condoms is also recommended (even during pregnancy) to prevent transmission of HIV or other sexually transmitted diseases.

Health care providers are encouraged to enroll pregnant women exposed to antiretroviral medications as early in pregnancy as possible in the Antiretroviral Pregnancy Registry (1-800-258-4263 or www.APRegistry.com). Health care providers caring for HIV-infected women and their infants may contact the National Perinatal HIV Hotline (888-448-8765) for clinical consultation (HHS [perinatal] 2016).

Abacavir is an oral medication that is used for the treatment of infections with the human immunodeficiency virus (HIV). It is in a class of drugs called reverse transcriptase inhibitors which also includes zalcitabine (Hivid), zidovudine (Retrovir), didanosine (Videx), lamivudine (Epivir), emtricitabine (Emtriva), and stavudine (Zerit). During infection with HIV, the HIV virus multiplies within the body's cells. The newly-formed viruses then are released from the cells and spread throughout the body where they infect other cells. In this manner, the infection continually spreads to new, uninfected cells that the body is continually producing, and HIV infection is perpetuated. When producing new viruses, the HIV virus must manufacture new DNA for each virus. Reverse transcriptase is the enzyme that the virus uses to form this new DNA. Specifically, abacavir is converted within the body to its active form (carbovir triphosphate). This active form is similar to a compound (deoxyguanosine triphosphate), a chemical that is required by the HIV virus to make new DNA. The reverse transcriptase uses carbovir triphosphate instead of deoxyguanosine triphosphate for making DNA, and it is the carbovir triphosphate that interferes with the reverse transcriptase. Abacavir does not kill existing HIV virus, and it is not a cure for HIV. The FDA approved abacavir in December 1998.

The recommended dose for adults is 300 mg twice daily or 600 mg once daily. Children (3 months and older) should receive 8 mg/kg twice daily of the solution, and the maximum recommended dose is 300 mg twice daily. Pediatric patients weighing 14 kg or more may also be treated with abacavir tablets at doses of 300, 450, or 600 mg daily based on weight. Abacavir may be administered with or without food since food does not affect its absorption.

Applies to abacavir: oral solution, oral tablet

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

Check with your doctor immediately if any of the following side effects occur while taking abacavir:

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

• Abdominal or stomach swelling
• decreased appetite
• fast, shallow breathing
• sleepiness

• Blistering, peeling, or loosening of the skin
• chest pain or discomfort
• chills
• dark urine
• itching
• light-colored stools
• pain or discomfort in the arms, jaw, back, or neck
• red, irritated eyes
• red skin lesions, often with a purple center
• sores, ulcers, or white spots in the mouth or on the lips
• sweating
• unusual weakness
• upper right abdominal or stomach pain
• yellow eyes and skin

Some side effects of abacavir may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Headache

• Trouble sleeping

• Breast enlargement
• buffalo hump
• central obesity
• facial wasting
• gaining weight around your neck, upper back, breast, face, or waist
• peripheral wasting

Data not available

Breast milk from 15 women and blood samples from 9 of their partially or exclusively breastfed infants were collected about 1 month postpartum; the mothers were using abacavir 300 mg twice a day (with lamivudine and zidovudine). Breast milk was obtained right before a dose; whole breast milk abacavir levels averaged 0.057 mg/L (about 85% of maternal blood levels). Infant blood was obtained 11 to 18 hours after the last maternal dose and about 1 hour (range: 6 minutes to 35 hours) after the last breastfeeding; plasma drug levels were undetectable (less than 16 mcg/L) in 8 of 9 infants.

Breastfeeding is not recommended during use of this drug; if replacement feeding is not an option, a different drug may be preferred. Excreted into human milk: Yes Comments: -The effects in the nursing infant are unknown. -The US CDC, American Academy of Pediatrics, and manufacturer advise HIV-infected women not to breastfeed to avoid postnatal transmission of HIV to a child who may not yet be infected. -Local guidelines should be consulted if replacement feeding is not an option.