Abacavir (Oral)

Abacavir is an anti-retroviral drug that is administered orally and used in the treatment of HIV and AIDS.

Overview

Abacavir is a medication which is most commonly used to prevent and treat HIV and AIDS. It's a nucleoside reverse transcriptase inhibitor (NRTI), a type of drug that's used to inhibit viral replication. It works by competing with the molecules within the HIV virus, becoming incorporated into the DNA of the virus and scrambling the instructions that allow the virus to reproduce.

It's not used on its own, but normally used together in a combination of drugs known colloquially as a "cocktail."

Abacavir has been approved for use within the United States since 1998. The patent expired in 2009, and since then it's been available as a generic medication. Abacavir is on the World Health Organization's list of essential medicines. This is a list of the safest and most effective medicines available to be used in a healthcare system. In developing countries, Abacavir doses can be had for as little as 36 cents per day. In the United States, Abacavir is sold wholesale for as little as $70.50 for a typical month of medication.

Conditions Treated

  • Human Immunodeficiency Virus

Type of Medicine

  • Anti-retroviral
  • Nucleoside reverse transcriptase inhibitor (NRTI)

Side Effects

Abacavir may cause side effects in some who use it. Most of the side effects are manageable, but some can be more serious. Some side effects may be your body's reaction to Abacavir and may cause an immediate problem for your quality of life and functionality, while others may be symptoms of other health problems which Abacavir can sometimes trigger. Any side effect you experience should be reported to your doctor, even if it is mild.

As your immune system strengthens, you may experience symptoms of previous infections. This is a side effect of many antiretroviral medications and means that your immune system is able to recognize and begin to fight off infections which may still be active or dormant in your system. This is in itself not a sign of an additional serious health problem, but the symptoms of your infections may cause physical or medical distress which should be treated as normal under the supervision of your physician.

Mild Side Effects

Many patients experience occasional or mild side effects, which can be managed with the help of a doctor or supervising physician. Ten to twenty percent of all patients using Abacavir have these symptoms, which may subside over time as your system adapts to the drug. Contact your physician if any of these symptoms get worse, or do not go away or begin to subside after approximately six weeks. Common, manageable side effects may include:

  • Occasional headaches
  • Mild malaise or fatigue
  • Nausea, or nausea to the point of occasional vomiting
  • Diarrhea or other mild gastrointestinal distress

You may also experience an unusual change in your body fat distribution, with less fat in your extremities (legs, arms) and more carried around your stomach or upper back.

These symptoms may be frustrating to deal with, but do not necessarily indicate serious danger on their own. If your symptoms are beginning to interfere seriously with your life or well-being, consult a doctor to rule out more serious problems and to seek symptom management strategies.

Less Common Side Effects

Some less common side effects may be indications that Abacavir is causing problems in your body, and are grounds to see your doctor and get medical help as quickly as possible. If you experience these, do not wait to see if they subside before you seek medical assistance or speak to your prescribing physician. Fewer than ten percent of Abacavir users experience these side effects. They may also be symptoms of other conditions that Abacavir can aggravate. These include:

  • Severe exhaustion, tiredness, or fatigue on a chronic level
  • Severe or long-lasting headaches, such as migraines or cluster headaches
  • Muscle or joint pain that doesn't go away, or episodes of pain that may last for a long time
  • Vision changes, such as blurriness, dimness, or other sight problems
  • Numbness or tingling in your extremities (such as hands, feet, arms, or legs), which may be indicative of nerve damage
  • Unexplained weight loss, or sudden weight loss stemming from nausea or a loss of appetite
  • Serious or unusual anxiety, or panic attacks
  • Depression, sadness, or mood swings
  • Loss of appetite (whether nausea is involved or not)
  • Trouble sleeping, restlessness, interrupted sleep schedule, disturbing dreams

Pre-Existing Infections

Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of infections you have already had in your body or experienced as your immune system adapts to your new drug. Signs of infection on Abacavir may include:

  • Temperature changes such as chills or fever
  • Respiratory symptoms such as a persistent cough or trouble breathing,
  • Swollen lymph nodes
  • Neck sores that won't heal
  • Erythema multiforme, a painful and itchy rash that forms in bulls-eye-shaped lesions and can be triggered by a viral infection

Stevens-Johnson syndrome, a blistering rash that causes widespread skin pain and is often accompanied by fever-like and cold-like symptoms

If you experience these symptoms, or if you experience the recurrence of any other infections you've had, contact your doctor for an appropriate course of treatment. Depending on your condition, your doctor may decide to discontinue Abacavir or may decide to continue your treatment.

Symptoms of Other Health Problems

You may also experience symptoms of other conditions while taking Abacavir, all of which require medical intervention. When this occurs, Abacavir may have aggravated a pre-existing condition you have or triggered a new condition within your body. If you notice these symptoms of any of these conditions, cease taking Abacavir and seek medical help immediately. These conditions require additional treatment and care.

Lactic Acidosis

Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of problems linked to lactic acidosis or a buildup of lactic acid in the organs and bloodstream. This can lower the pH of your blood and cause symptoms such as:

  • Unusual muscle pain, either in unusual places or particularly painful
  • Difficulty breathing
  • Feeling lightheaded or dizzy
  • Feeling tired or unusually weak
  • An irregular or fast heartbeat
  • Stomach pain, which may lead to nausea and vomiting
  • Liver Ailments

Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of problems linked to decreased liver function or liver failure. Watch for symptoms of liver problems such as:

  • Jaundice, or a yellowing of the skin and the whites of the eyes
  • Loss of appetite for at least several days, possibly accompanied by nausea
  • Aching, sharp pain, or unusual tenderness on the right side of your stomach and abdomen
  • Unusually light bowel movements
  • Unusually dark urine
  • Overactive thyroid

Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of problems linked to an overactive thyroid, or hyperthyroidism. You may experience signs of an overactive thyroid, such as:

  • Being unusually nervous or irritable
  • Sudden and extreme inability to tolerate heat
  • Goiters, or other unusual growths in the neck or thyroid area
  • Bulging eyes
  • A fast, pounding, or irregular heartbeat
  • Guillain-Barre Syndrome

Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of Guillain-Barre syndrome. You may experience the signs of Guillain-Barre syndrome, a nerve condition which includes:

  • Trouble breathing and swallowing
  • Difficulty speaking
  • The inability to move one's eyes
  • A drooping face, or facial paralysis

Any of these symptoms or symptom clusters are signs of a serious reaction and require medical care.

Allergic or Hypersensitive Reactions to Abacavir

Abacavir may cause allergic or hypersensitivity reactions in patients. Patients with the HLA-B*5701 allele are most at risk, although you do not have to have this allele to have a bad reaction to Abacavir. Ensure you have been screened for this allele before beginning a medication regime that includes Abacavir.

Some of these reactions may produce no obvious symptoms but can contribute to ongoing health problems or can even cause organ failure. Your doctor should be able to identify most of these issues through routine blood tests. Usage of Abacavir or conditions aggravated by usage of Abacavir may cause an onset of reactions, including:

  • A low blood platelet count, known as thrombocytopenia
  • High blood pressure in the lungs, known as pulmonary hypertension
  • Heightened triglyceride levels, which can lead to heart disease
  • Heightened AST (liver enzyme) levels, which can lead to liver failure
  • Lactic acidosis, or a buildup of lactic acid in the organs
  • Pancreatitis, or inflammation of the pancreas, characterized by abdominal pain
  • Hepatic steatosis, or fatty liver disease
  • Hepatomegaly, or an enlarged (often inflamed) liver

Left untreated, all of these conditions can lead to organ failure

Allergic Reaction

Some patients may also experience anaphylactoid reactions. Anaphylactoid reactions are a response to elevated levels of histamine in the blood. Anaphylactoid reactions may not be dangerous immediately and can be treated quickly, but each recurring anaphylactoid reaction heightens the chances of going into anaphylactic shock during an allergic episode.

Anaphylactic reactions include symptoms such as:

  • Hives, or small, raised, itchy bumps on the skin
  • Skin that is suddenly red and flushed or very pale, especially around the lips and mouth
  • Swollen tongue or swollen lips
  • Difficulty breathing, or wheezing when you try to breathe
  • Partial or full closure of the esophagus, resulting in a feeling of a lump in the throat or difficulty in swallowing
  • Sudden and recurrent sneezing
  • A runny nose or other unusual mucous activity
  • Abdominal pain
  • Nausea, diarrhea, or vomiting
  • A sudden feeling of being too warm
  • A tingling feeling in the mouth, or tingling feeling in the extremities such as hands, feet, or scalp
  • A weak or unusually rapid pulse
  • A feeling that something is wrong with your body

These symptoms may vary in intensity, and each one may not be life-threatening on its own. However, an anaphylactic reaction can quickly turn into anaphylactic shock if not properly treated. Anaphylactic shock is very serious and includes symptoms such as:

  • Dizziness
  • Severe difficulty or struggle breathing
  • A sudden onset of weakness
  • Confusion
  • Loss of consciousness

Anaphylactic reactions and anaphylactic shock should be treated immediately.

Dosage

Abacavir is available in an oral solution of 20 mg/mL, as well as in a 300 mg tablet.

The tablets are yellow, coated in film, and shaped like a capsule. They read "GX 623" on both sides. The oral solution is yellowish, with a strawberry or banana taste.

The dosage of Abacavir you will take is based on your response to treatment and the state of your medical condition. The recommended standard dosage for adults is 600 mg daily, taken in 300 mg tablets twice per day or once per day as directed by a doctor. The recommended dose for patients with mild hepatic impairment (liver problems) is 200 mg twice daily, while doses for children are based on weight and will vary. Scored tablets are available for smaller doses.

Interactions

As with any drug, Abacavir may have unforeseen interactions and should be taken with caution. However, there are some drugs that do have frequent or consistent negative effects when taken with Abacavir.

Some drugs may decrease the serum concentration of Abacavir. Those taking protease inhibitors such as Aptivus or tipranavir, as well as Norvir or ritonavir, should be carefully monitored when adding an Abacavir prescription to their regimen. Orlistat, also known as Alli or Xenical (usually used to treat obesity), can have a similar effect. Cabozantinib, which is used to treat certain types of cancers and carcinoma, can also have this effect. It's possible to take these drugs while on Abacavir, but they should only be taken under the strict supervision of a doctor and with monitoring for any interactive effects.

Other drugs may have other effects or be interacted upon by the presence of Abacavir in the body. Methadone diminishes many of the therapeutic effects of Abacavir, while the Abacavir can decrease the serum concentration and effects of methadone and cause withdrawal in some patients. Your methadone dose may need to be adjusted if that is the case.

Abacavir is metabolized by alcohol, using some of the same mechanisms that alcohol uses to get into your bloodstream. Excess amounts of alcohol in the bloodstream can increase the amount of Abacavir in the body, possibly leading to an overdose. Alcohol or ethanol should be consumed with caution or a doctor's supervision.

Abacavir should not be given to patients who are already taking a cocktail or combination with Abacavir as an ingredient, or overdose may occur.

Warnings

Before you start Abacavir, get a screening for the HLA-B*5701 allele. This allele places you at high risk for having a hypersensitive or allergic reaction to Abacavir, which can be life-threatening. This screening is recommended even if you have previously undergone Abacavir therapy without a negative or hypersensitive reaction. Even patients who do not have the HLA-B*5701 allele may have or may develop a hypersensitivity to Abacavir.

When patients have a hypersensitive reaction to Abacavir, they experience symptoms in multiple organs. Signs or symptoms from two or more of these symptom groups may be a hypersensitive reaction to Abacavir:

Group 1 symptoms: Fever (heightened body temperature)

Group 2 symptoms: Skin symptoms, such as a rash

Group 3 symptoms: Gastrointestinal distress such as abdominal pain, nausea, vomiting, diarrhea

Group 4 symptoms: General constitutional distress such as achiness in muscles or joints, unusual fatigue or weakness

Group 5 symptoms: Respiratory symptoms such as a cough, a sore throat, shortness of breath

If you experience symptoms of Abacavir hypersensitivity, you may need to stop taking Abacavir. Your doctor may decide that it's in your best interests to stop taking Abacavir even if you find another diagnosis for your symptoms. If you need to stop taking Abacavir after a hypersensitive reaction, do not take Abacavir again. You may experience more symptoms or even have another reaction, which can lead to life-threateningly low blood pressure and even death. These symptoms may manifest within hours and without warning. Permanently discontinue Abacavir if you cannot rule out an allergic or hypersensitive reaction.

Do not take Abacavir if you are already taking a medication which contains Abacavir. The medications on the market which already contain a form of Abacavir include:

  • Epzicom contains abacavir in addition to lamivudine
  • Trivizir includes abacavir in addition to lamivudine and zidovudine
  • Triumeq contains abacavir in addition to lamivudine and dolutegravir

If you have had allergic or hypersensitive reactions to any of these medications, do not take Abacavir unless you are able to reach medical help immediately.

Storage

How do I safely store my Abacavir?

If the original seal on your bottle or container of Abacavir is missing, do not use and return to your pharmacist for replacement.

Store your Abacavir at room temperature, anywhere from 68°F to 77°F or 20°C to 25°C. You may store your Abacavir oral solution in the refrigerator without it losing effectiveness, but do not freeze it.

If your Abacavir is expired or past its expiration date, do not use it. Past its expiration date, Abacavir's effectiveness decreases and it may not provide the therapeutic and antiretroviral effects you need. Check with your pharmacist to see if there's a drug take-back program or disposal kiosk near you.

Always keep Abacavir out of the reach of children.

Summary

Abacavir is an antiretroviral for HIV and AIDS, most commonly used in conjunction with other drugs. It can be taken as a tablet or oral solution, with most patients taking 600 mg per day.

Abacavir can cause mild side effects like nausea or headaches, but can also cause more serious side effects. You may experience a recurrence of some infections while taking Abacavir, which occurs as your immune system gets ready to work again. Abacavir can also cause thyroid problems, liver problems, hypersensitivity, or allergic reactions, all of which need immediate medical care.

Abacavir should not be taken with other protease inhibitors or other Abacavir-containing medications, unless under the advice of a physician. It should not be taken in conjunction with methadone or alcohol.

Abacavir is a yellow tablet that's printed with the code "GX 623." In solution form, it is yellowish and tastes like strawberry or banana. It can be stored at room temperature.

Resources
Last Reviewed:
March 05, 2018
Last Updated:
October 08, 2018