Abacavir

ABACAVIR

Complete information on Abacavir including dosage, side effects, interactions and pregnancy & breastfeeding warnings for patient and professional use.

Overview and uses

Abacavir is a medicine used to treat HIV infection. Abacavir does not cure HIV, but it slows down the progression of HIV within the body. HIV destroys CD4+ T Lymphocytes – a type of white blood cells (WBC) that gives immunity to the body. In other words, these cells protect the body against the infections or illness caused by various organisms like bacteria, viruses and other germs. Thus, one may conclude that HIV infection, if left untreated, may make the body susceptible to this infections/illness.

Abacavir is generally prescribed by a doctor along with other anti HIV medicines as a part of combination therapy. Taking two or three medicines i.e., combination therapy, reduces the risk of virus getting resistant to any one particular medicine. Also, combination therapy increases the efficacy of treatment. These medicines have to be taken throughout an individual’s life span. Some brands of Abacavir are available in combination as it helps to reduce the number of total tablets that an individual has to take.

Brand names of Abacavir:

Ziagen, Abavir, Abamune

Brand names of Abacavir with other medicine:

  • Triumeq contains Abacavir with Dolutegravir and Lamivudine
  • Epzicom contains Abacavir with Lamivudine
  • Trizivir contains Abacavir with Lamivudine and Zidovudine

Pharmacological classification:

Nucleoside reverse transcriptase inhibitor – anti-retroviral drug

Indication (used for):

For the treatment of HIV-1 infection

Dosage:

  • For adults: 300 mg twice a day or 600 mg once a day in combination with other anti HIV medicines.
  • Adult dose for nonoccupational exposure: 300 mg orally twice a day or 600 mg orally once a day for a duration of 28 days. Prophylaxis should be started as soon as possible within 72 hours of exposure.
  • Adult dose for occupational exposure: 300 mg orally twice a day or 600 mg orally once a day for a duration of 28 days (if tolerated). Prophylaxis should be started as soon as possible preferably within hours of exposure.
  • Paediatric dose (for children with 3 months or older than 3 months):
    • Oral solution: 8 mg/kg twice a day or 16 mg/kg once a day but not more than 600 mg/kg.
    • Tablets:
      • Child weight – 14 kg to less than 20 kg: 150 mg twice a day or 300 mg once a day.
      • Child weight – 20 kg to less than 25 kg: 150 mg in the morning and 300 mg in the evening or 450 mg once a day.
      • Child weight – 25 kg or more: 300 mg twice a day or 600 mg once a day
    • Liver dose adjustments:
      • Abacavir is contraindicated in moderate to severe liver dysfunction.
      • Mild liver dysfunction (score- Child – Pugh A): 200 mg twice a day.

Dosage form (available as):

Tablets and oral liquids

Pregnancy:

Category C, which means that Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Mechanism of action:

Abacavir – a guanosine analogue, gets intracellularly converted into active form carbovir triphosphate, which terminates the elongation of proviral DNA. It gets incorporated into nascent DNA by reverse transcriptase but it lacks 3’-OH (hydroxyl) group.

Metabolism:

Abacavir is metabolised by alcohol dehydrogenase and by glucuronidation.

Unwanted or side effects of Abacavir

Although everyone may not experience it, but most medicines causes unwanted/side effects along with their useful effects. Below mentioned are some of the most important side effects of Abacvir:

  • Unique and a potentially fatal hypersensitivity reaction of Abacavir is characterized by Fever, Abdominal (tummy) pain and gastrointestinal complaints like mild maculopapular rash (skin rash), and malaise (feeling of discomfort, illness or unease) or fatigue (tiredness).
    • If you encounter any one of the above mentioned symptom, ask your pharmacist to recommend a suitable medicine and seek your doctor’s advice. If additional symptoms appear, seek medical attention as soon as possible.
    • If you encounter most of the above mentioned symptoms, seek medical attention as soon as possible. This may require immediate discontinuation of Abacavir therapy.
    • Abacavir therapy can never be restarted in patients for whom the therapy was stopped due to above mentioned symptoms. If done so, it leads to rapid recurrence of symptoms accompanied by hypotension, a shock like state and possibly death.
  • Occurrence of respiratory complaints like coughing, pharyngitis and dyspnea, musculoskeletal complaints, headache and paresthesias are less common.
    • If you encounter any one of the above mentioned symptom, ask your pharmacist to recommend a suitable medicine and seek your doctor’s advice. If additional symptoms appear, seek medical attention as soon as possible.
    • If you encounter most of the above mentioned symptoms, seek medical attention as soon as possible.
  • Lactic acidosis caused by Abacavir is characterized by: feeling or being sick, abdominal pain (tummy) pain, loss of appetite, loss of weight, feeling dizzy and fast or gasping breathing.
    • Consult your doctor as soon as possible if you observe any of the above mentioned symptoms as they may worsen and become life threatening.
  • Hepatomegaly: symptoms of hepatomegaly or hepatotoxicity may be overshadowed by the symptoms from hypersensitivity or allergic reactions of Abacavir like fever, rash, fatigue and abdominal pain. This usually occurs within first month to third month (1 to 3) from the start of Abacavir therapy.
    • Consult your doctor as soon as possible and seek medical help.
  • Fat redistribution or accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement and “cushingoid appearance” have been observed in patients receiving anti HIV therapy.
  • Myocardial infacrtion: patients undertaking Abacavir treatment have a high risk of myocardial infarction during the first 6 months (12 weeks) of the treatment.
  • Immune reconstitution syndrome: during the initial phase of the treatment, patients whose immune systems respond may develop an inflammatory response to opportunistic infections, which may necessitate further evaluation and treatment. Auto immune disorders have also been reported to occur in some people at any time after the initiation of the treatment.

Hypersensitivity reaction can occur at any time during the therapy. But, most commonly it occurs within first week to sixth week from the initiation of the therapy. If you observe any other symptom that you suspect it to be associated with your anti HIV treatment, consult your doctor as soon as possible.

Interactions

Drug – drug interactions of Abacavir

  • An increased dose of Mehtadone may be required in some patients taking Methadone along with Abacavir. Also, methadone may decrease the therapeutic effects of Abacavir.
  • Protease inhibitors like Ritonavir, Indinavir, Nelfinavir, Saquinavir, Amprenavir and Lopinavir may decrease the serum concentrations of Abacavir.
  • Orlistat may decrease the serum concentrations of anti HIV medicines.
  • Abacavir may increase the serum concentrations of Cabozantinib.

Abacavir is metabolized by alcohol dehydrogenase and by glucuronidation. Any drug (medicine) having the same metabolic pathway i.e., by alcohol dehydrogenase enzyme or by glucuronidation, will affect the therapeutic activity or serum concentrations for either or both of the drugs (medicines).

If you are taking any of the above mentioned medicines with your anti HIV medicines, consult your doctor and pharmacist as soon as possible.

Drug food interactions of Abacavir

  • Meals/food does affect the serum concentrations of Abacavir.
  • Avoid alcohol with Abacavir as it increases the duration of activity and serum concentrations of Abacavir.

Contraindications of Abacavir

  • Do not take any medicine containing Abacavir if the patient is allergic or hypersensitive to Abacavir.
  • Do not restart any medicine containing Abacavir if it was stopped before due to hypersensitivity reaction.
  • Abacavir and HLA-b*5701: Do not start any medicine containing Abacavir if the patient is carrying HLA-B*5701 allele as these people are at high risk of experiencing hypersensitivity reactions to Abacavir.

How to store Abacavir?

  • Keep it in cool and dry place, away from direct heat and sunlight.
  • Keep it out of sight and reach of children.

Important information on Abacavir

  • Oral bioavailability is more than 80% regardless of food intake.
  • Abacavir is neither a substrate nor an inhibitor of CYPs.
  • Abacavir, when combined with other medicines for the treatment of HIV, reduces the chances of viral resistance by up to 10 times.

Important information on anti HIV and anti AIDS medicines

Benefits of taking your anti HIV medicines regularly

  • Sustained viral suppression.
  • Reduced risk of resistance.
  • Reduced risk of treatment failure.
  • Improved quality of life and overall health.
  • Reduced risk of HIV transmission.

Getting the most from your treatment

  • Precisely follow every advice given to you by your doctor and pharmacist regarding your medications. Take your dose regularly without missing out a single one.
  • Make all the necessary changes in your lifestyle and eating/food habits as advised by your doctor and pharmacist. This may include quitting smoking, alcohol, other substances of abuse, taking up exercise and some/many others that your doctor finds it best in your interest.
  • Do not make any changes in your dose unless suggested/recommended by your doctor.
  • Keep your regular appointments with your doctor so that the progress can be monitored. This may involve blood tests and other test that a doctor finds necessary.
  • Consult your doctor if you develop an infection or an allergy after you start the treatment.
  • Consult your doctor if you feel low or even depressed. This is common especially after diagnosis and during the early stages of treatment.
  • Some people who have taken anti HIV medicines for a long period of time may develop Osteonecrosis – a condition where bone tissue dies due to reduced blood supply. This causes joint pain, stiffness and difficulty in movement. Consult your doctor if you if you notice any of this symptoms.
  • If you are going to take any operation/surgery or a dental treatment, tell doctor who is going to carry out operation/surgery or dental procedure about all the medicines that you are taking. If possible, carry your containers with you to the doctor even if it is empty.
  • If you buy any medicines, supplements including your vitamin supplements, herbal medicines or even the medicines that do not require a prescription, check with your pharmacist whether they can be taken along with your anti HIV medicines or not.
  • Treatment of HIV is life-long. Continue taking your anti HIV medicines even if you feel well. This should be done to keep your immune system healthy.

Forgot to take your medicine?

  • Forgetting a dose/frequent missed out doses may lead to viral resistance or treatment failure.
  • If you forget to take a dose, take it immediately as soon as you remember unless it’s almost the time for your next dose.
  • Do not take two doses at the same time to make up for the missed out dose.
  • If you are forgetting/missing your dose frequently or very often, try using pill boxes that are available as weekly or monthly dose boxes. Alternatively, you can also try posting reminder notes on places like doors of refrigerator, wardrobe, bathroom, side tables of your bed, above or below switch boards etc. You can also set a reminder on your cell phone.
  • If possible, ask your family members and friends to remind you of your dose.

Click here to go to Abacavir forums

Abacavir wikipedia

Note: The sole purpose of every information shared on this article is to bring awareness. Do not use this information as a medical advice or prescription advice or as a tool for the treatment, diagnosis or prevention of the disease.

By |2018-12-29T07:31:10+00:00May 2nd, 2017|medicines|Comments Off on Abacavir

About the Author:

B. Pharm (K.L.E. society's S.V.V. Patil College of Pharmacy, Bengaluru) M. Pharm (Maharishi Arvind Institute of Pharmacy, Jaipur)

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