Abacavir


Concise Prescribing Info
Indications/Uses
HIV infection.
Dosage/Direction for Use
Adult : PO Combined w/ other antiretrovirals: 300 mg bid or 600 mg once daily.
Dosage Details
Oral
HIV infection
Adult: Combined w/ other antiretrovirals: 300 mg bid or 600 mg once daily.
Child: ≥3 mth 14 to <20 kg: 150 mg bid or 300 mg once daily; ≥20 kg to <25 kg: 150 mg in the morning and 300 mg in the evening or 450 mg once daily; ≥25 kg: Same as adult dose.
Special Patient Group
Pharmacogenomics

Human leukocyte antigen B (HLA-B) plays a critical role in immune recognition of pathogens. A variant allele HLA-B*57:01 is associated with increased risk of life-threatening hypersensitivity reactions to abacavir. The prevalence of this variant allele is estimated in 11% of Southwest Asians, 6.8 % of Europeans, 2.6% of South Americans, 2.5% of Middle Easterners, 2.2% of Mexicans, 1.6% of Asians, and 1% of Africans.

Patients who are positive to HLA-B*57:01 allele have higher risk of developing hypersensitivity reactions with abacavir. CPIC does not recommend use of abacavir for these patients. Genetic screening is recommended prior to initiation of treatment. However, a negative test result for HLA-B*57:01 does not absolutely rule out the possibility of developing hypersensitivity reactions.
Renal Impairment
ESRD: Not recommended.
Hepatic Impairment
Mild (Child-Pugh score 5-6): 200 mg bid. Moderate to severe: Contraindicated.
Administration
May be taken with or without food.
Contraindications
Hypersensitivity to abacavir. Patients who are positive for HLA-B*57:01 allele. Moderate to severe hepatic impairment. Lactation.
Special Precautions
Patient w/ risk factors for liver disease (e.g. obesity) and those w/ risk factors for coronary heart disease (e.g. HTN, DM, smoking). Renal or mild hepatic impairment. Pregnancy.
Adverse Reactions
Fever, rash, cough, dyspnoea, lethargy, malaise, headache, myalgia, GI disturbances, particularly nausea, vomiting, diarrhoea and abdominal pain; pancreatitis and elevated liver enzyme values, osteonecrosis, immune reconstitution syndrome, MI, lipodystrophy syndrome. Rarely, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis.
Potentially Fatal: Serious and fatal hypersensitivity reactions w/ multiple organ involvement, lactic acidosis and severe hepatomegaly w/ steatosis.
MonitoringParameters
Monitor blood lipids and glucose reference.
Drug Interactions
Decreased serum concentrations of methadone. Slightly decreased plasma concentration w/ potent enzymatic inducers (e.g. rifampicin, phenobarbital, phenytoin). Ribavirin may enhance the hepatotoxic effect of nucleoside reverse transcriptase inhibitors.
Action
Description: Abacavir competitively inhibits the reverse transcriptase of retroviruses, interfering w/ HIV viral RNA-dependent DNA polymerase resulting in inhibition of viral replication.
Pharmacokinetics:
Absorption: Rapidly absorbed from the GI tract. Absorption slightly delayed by food. Bioavailability: Approx 80%. Time to peak plasma concentration: 0.7-1.7 hr.
Distribution: Distributed into CSF. Crosses the placenta and blood brain barrier. Volume of distribution: 0.86 ± 0.15 L/kg. Plasma protein binding: Approx 50%.
Metabolism: Undergoes intracellular metabolism to carbovir triphosphate (active metabolite); hepatic metabolism via alcohol dehydrogenase and glucuronidation to inactive carboxylate and glucuronide metabolites.
Excretion: Mainly via urine. Elimination half-life: About 1.5 hr.
Chemical Structure

Chemical Structure Image
Abacavir

Source: National Center for Biotechnology Information. PubChem Database. Abacavir, CID=441300, https://pubchem.ncbi.nlm.nih.gov/compound/Abacavir (accessed on Jan. 20, 2020)

Storage
Store between 20-25°C. Oral soln may be refrigerated, do not freeze.
MIMS Class
ATC Classification
J05AF06 - abacavir ; Belongs to the class of nucleoside and nucleotide reverse transcriptase inhibitors. Used in the systemic treatment of viral infections.
References
Dean, L. Abacavir Therapy and HLA-B*57:01 Genotype. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US). Accessed 11/09/2018. PMID: 28520363

Martin M, Hoffman J, Freimuth et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) Guidelines for HLA-B Genotype and Abacavir Dosing: 2014 Update. Clinical Pharmacogenetics Implementation Consortium. Accessed 17/10/2018

Martin MA, Klein TE, Dong BJ, et al. Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing. Nature Publishing Group. 91. doi: 10.1038/clpt.2011.355. Accessed 17/10/2018

Abacavir Overview. Pharmacogenomics Knowledgebase (PharmGKB). https://www.pharmgkb.org/. Accessed 11/09/2018.

Abacavir Sulfate Tablet, Film Coated (Apotex Corp). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 18/08/2016.

Anon. Abacavir. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 15/02/2016.

Buckingham R (ed). Abacavir. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 15/02/2016.

Clinical Pharmacogenetics Implementation Consortium Guidelines for HLA-B Genotype and Abacavir Dosing. Clinical Pharmacogenetics Implementation Consortium (CPIC). https://cpicpgx.org/. Accessed 17/10/2018.

Joint Formulary Committee. Abacavir. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. Accessed 15/02/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Abacavir Sulfate. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 15/02/2016.

Supplemental Material CPIC Guidelines for HLA-B Genotype and Abacavir Dosing: 2014 Update. Clinical Pharmacogenetics Implementation Consortium (CPIC). https://cpicpgx.org/. Accessed 17/10/2018.

Disclaimer: This information is independently developed by MIMS based on Abacavir from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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