Home Drug Guide Abacavir; Lamivudine

Drug Guide

Generic Name

Abacavir; Lamivudine

Brand Names Epzicom

Classification

Therapeutic: Antiretroviral Agent, Nucleoside Reverse Transcriptase Inhibitor (NRTI)

Pharmacological: Nucleoside Analog Reverse Transcriptase Inhibitor

FDA Approved Indications

HIV-1 infection in combination with other antiretroviral agents

Mechanism of Action

Abacavir and Lamivudine are NRTIs that inhibit HIV-1 reverse transcriptase by incorporating into viral DNA and causing chain termination, thereby preventing viral replication.

Dosage and Administration

Adult: 300 mg abacavir + 300 mg lamivudine orally once daily or as divided doses twice daily

Pediatric: Dosing based on weight; typically 8 mg/kg (Abacavir) and 4 mg/kg (Lamivudine) twice daily, not to exceed adult doses

Geriatric: Use with caution; no specific dose adjustment but consider comorbidities and drug interactions

Renal Impairment: Adjustments recommended for renal impairment, especially for lamivudine

Hepatic Impairment: Use caution; no specific dose adjustment for mild impairment, avoid in severe impairment

Pharmacokinetics

Absorption: Orally absorbed with good bioavailability

Distribution: Widely distributed in tissues, crosses blood-brain barrier

Metabolism: Minimal metabolic transformation; abacavir undergoes hepatic metabolism, lamivudine is metabolized mainly by phosphorylation within cells

Excretion: Primarily renal; dose adjustments needed in renal impairment

Half Life: Abacavir approximately 2.5 hours; lamivudine approximately 5-7 hours

Contraindications

Hypersensitivity to abacavir or lamivudine
History of hypersensitivity reaction to any component

Precautions

Screen for HLA-B*5701 allele before initiation due to risk of hypersensitivity reaction; caution in hepatic impairment; renal impairment may require dose adjustment

Adverse Reactions - Common

Nausea (Common)
Headache (Common)
Fatigue (Common)
Rash (Common)

Adverse Reactions - Serious

Hypersensitivity reactions (including hypersensitivity syndrome, potentially fatal) (Rare but serious)
Lactic acidosis and hepatic steatosis (Rare)

Drug-Drug Interactions

Other nephrotoxic drugs, hepatotoxic drugs, or drugs causing mitochondrial toxicity

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function, liver function, and signs of hypersensitivity reactions

Diagnoses:

Risk for hypersensitivity reaction
Imbalanced nutrition: less than body requirements due to gastrointestinal side effects

Implementation: Administer as prescribed, monitor for side effects, educate about hypersensitivity symptoms

Evaluation: Assess for effectiveness of therapy and adverse reactions

Patient/Family Teaching

Take medication exactly as prescribed
Report symptoms of hypersensitivity (fever, rash, nausea, vomiting, diarrhea, abdominal pain, malaise) immediately
Do not restart medication after an allergic reaction without medical advice
Maintain regular follow-up appointments

Special Considerations

Black Box Warnings:

Hypersensitivity reaction associated with HLA-B*5701 allele; testing recommended before initiation

Genetic Factors: Presence of HLA-B*5701 allele increases risk of hypersensitivity

Lab Test Interference: May affect certain laboratory tests, consult lab if needed

Overdose Management

Signs/Symptoms: Nausea, vomiting, diarrhea, hypersensitivity reactions, lactic acidosis, hepatic failure, coma

Treatment: Supportive care; no specific antidote; dialysis may be beneficial in renal impairment cases

Storage and Handling

Storage: Store at room temperature (20°C to 25°C), protected from moisture

Stability: Stable under recommended storage conditions for at least the shelf life