Abacavir – Lamivudine

1. Introduction

Abacavir sulfate-lamivudine is a fixed-dose combination antiretroviral (ARV) medication used for the treatment of HIV-1 infection. It contains abacavir (a nucleoside reverse transcriptase inhibitor, NRTI) and lamivudine (another NRTI), working together to inhibit viral replication and reduce viral load.

2. Indications

  • HIV-1 Infection (as part of combination antiretroviral therapy, ART)
  • Post-Exposure Prophylaxis (PEP) (Off-Label Use)

3. Dosage

Adults & Adolescents (>25 kg):

  • One tablet (600 mg abacavir / 300 mg lamivudine) once daily.

Paediatric Use (≥3 months, <25 kg):

  • 10 mg/kg abacavir + 4 mg/kg lamivudine (dosed separately if under 25 kg).

Elderly:

  • No specific dose adjustment, but monitor for hypersensitivity reactions.

Renal Impairment:

  • CrCl <50 mL/min: Avoid fixed-dose combination; dose separately.

Hepatic Impairment:

  • Mild impairment: Use with caution.
  • Moderate/severe impairment: Contraindicated.

4. Administration

  • Take with or without food.
  • Do not crush or split tablets.
  • Ensure HLA-B*5701 testing before starting therapy (to prevent abacavir hypersensitivity reaction).

5. Forms Available

  • Fixed-Dose Tablets: 600 mg abacavir / 300 mg lamivudine
  • Separate Oral Solution Forms:
    • Abacavir: 20 mg/mL
    • Lamivudine: 10 mg/mL

6. Side Effects

6.1 Common Side Effects:

  • Nausea
  • Headache
  • Fatigue
  • Diarrhoea

6.2 Less Common Side Effects:

  • Rash
  • Insomnia
  • Abdominal pain

6.3 Rare but Serious Side Effects:

  • Abacavir Hypersensitivity Reaction (HSR) (potentially fatal)
  • Lactic Acidosis
  • Hepatotoxicity
  • Pancreatitis (Rare, but more common in children)

7. Warnings

  • Hypersensitivity Reaction (HSR) Risk:
    • Test for HLA-B*5701 before starting treatment—if positive, DO NOT USE.
    • Symptoms include fever, rash, nausea, respiratory issues—discontinue immediately if suspected.
  • Lactic Acidosis & Hepatomegaly:
    • Monitor for abdominal pain, nausea, and liver dysfunction.
  • Risk of Immune Reconstitution Syndrome:
    • May cause worsening of underlying opportunistic infections.

8. Precautions

  • Monitor liver function in patients with hepatitis B or C co-infection.
  • Not for monotherapy—must be combined with other ARVs.
  • Avoid alcohol—may increase abacavir toxicity.

9. Interactions

  • Methadone: Decreases abacavir levels—may require methadone dose adjustment.
  • Ribavirin: Increases risk of anaemia—use with caution.
  • Other NRTIs (e.g., tenofovir): Increased lactic acidosis risk.

10. Monitoring Parameters

  • HLA-B*5701 genetic testing before initiation.
  • Liver function tests (LFTs) every 3–6 months.
  • Renal function monitoring (if CrCl <50 mL/min).
  • Lactate levels if metabolic acidosis suspected.

11. Use in Children

  • Approved for children >3 months (doses adjusted by weight).
  • Monitor for pancreatitis and lactic acidosis.

12. Use in Pregnancy

  • Category C:
    • Considered safe in pregnancy, but alternative regimens preferred if available.
    • Monitor for lactic acidosis.

13. Use in Elderly

  • Use with caution due to increased risk of hypersensitivity reactions.

14. Use in Kidney Disease

  • CrCl <50 mL/min: Dose separately—avoid fixed-dose tablet.

15. Use in Liver Disease

  • Contraindicated in moderate/severe hepatic impairment.
  • Use with caution in mild impairment (monitor closely).

16. Patient Counselling Points

  • Take once daily, with or without food.
  • Do not stop suddenly—stopping may cause HIV resistance.
  • Report any rash, fever, nausea, or breathing difficulty immediately (signs of hypersensitivity).
  • Avoid alcohol—it may worsen side effects.
  • Regular blood tests needed to monitor liver and kidney function.

17. Table of Brand Names, Manufacturer, and Prices in USD

Brand NameManufacturerStrength/Dosage FormPrice (USD)
EpzicomViiv Healthcare600 mg/300 mg Tablets$1,200 (30 tabs)
KivexaViiv Healthcare600 mg/300 mg Tablets$1,100 (30 tabs)
Generic Abacavir-LamivudineVarious600 mg/300 mg Tablets$600 (30 tabs)

18. 15 FAQs (Frequently Asked Questions)

1. What is Abacavir-Lamivudine used for?
It is used for HIV-1 treatment as part of combination therapy.

2. How does Abacavir-Lamivudine work?
It inhibits reverse transcriptase, preventing HIV replication.

3. Can Abacavir-Lamivudine cure HIV?
No, but it reduces viral load and helps manage the disease.

4. How long does it take to work?
HIV viral load reduction starts within weeks, but full suppression may take months.

5. Can I take Abacavir-Lamivudine alone?
No, it must be combined with at least one other antiretroviral.

6. What happens if I miss a dose?
Take it as soon as you remember, but do not double the dose.

7. Can I stop taking it if I feel better?
No, stopping may cause HIV resistance—consult your doctor before stopping.

8. Does Abacavir-Lamivudine cause weight gain?
It can cause weight changes, but varies by individual.

9. Can I drink alcohol while taking it?
Avoid alcohol—it may increase liver toxicity.

10. Can pregnant women take Abacavir-Lamivudine?
Yes, but alternative regimens are preferred if available.

11. Does it interact with other HIV drugs?
Yes, it should not be combined with tenofovir without careful monitoring.

12. What should I do if I develop a rash?
Stop the medication immediately and seek emergency medical attention.

13. Is Abacavir-Lamivudine safe in children?
Yes, it is approved for children over 3 months.

14. How should I store the medication?
Store at room temperature, away from heat and moisture.

15. Can I take Abacavir-Lamivudine with food?
Yes, it can be taken with or without food.