Nurses Compass
Drug Guide
Lamivudine and Zidovudine
Classification
Therapeutic: Antiretroviral Agent (HIV) - Nucleoside Reverse Transcriptase Inhibitors (NRTIs)
Pharmacological: Nucleoside analog Reverse Transcriptase Inhibitors
FDA Approved Indications
- HIV-1 infection in combination therapy
Mechanism of Action
Lamivudine and Zidovudine are nucleoside analog reverse transcriptase inhibitors that interfere with HIV viral replication by incorporating into viral DNA and terminating DNA chain elongation.
Dosage and Administration
Adult: Typically, 1 tablet twice daily, as per prescribing information; adjust based on clinical response.
Pediatric: Dose based on weight and age; consult specific pediatric dosing guidelines.
Geriatric: Start at lower end of dosing range due to potential renal impairment.
Renal Impairment: Adjust dose based on renal function; monitor serum creatinine and estimated glomerular filtration rate (eGFR).
Hepatic Impairment: No specific adjustment recommended for mild to moderate impairment; caution in severe impairment.
Pharmacokinetics
Absorption: Well absorbed orally.
Distribution: Wide distribution including into cerebrospinal fluid.
Metabolism: Not extensively metabolized; minimal hepatic metabolism.
Excretion: Primarily renal excretion via glomerular filtration and active tubular secretion.
Half Life: Lamivudine: ~5-7 hours; Zidovudine: ~1-2 hours.
Contraindications
- Hypersensitivity to any component.
- Lactic acidosis and hepatomegaly with steatosis risk in certain populations.
Precautions
- Use with caution in hepatic impairment; monitor for mitochondrial toxicity; renal function monitoring needed; consider resistance patterns.
Adverse Reactions - Common
- Headache (Common)
- Nausea (Common)
- Fatigue (Common)
Adverse Reactions - Serious
- Myelosuppression (anemia, neutropenia) (Less common)
- Lactic acidosis (Rare)
- Hepatic steatosis and hepatotoxicity (Rare)
Drug-Drug Interactions
- Rifampin (may reduce efficacy)
- Other hepatotoxic drugs
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Baseline and periodic liver function tests, renal function, complete blood count.
Diagnoses:
- Risk for infection
- Risk for ineffective tissue perfusion related to myelosuppression.
Implementation: Administer with or without food; monitor lab values regularly; counsel patient on adherence and side effects.
Evaluation: Assess viral load, CD4 count, and tolerance of therapy.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report symptoms of liver problems or unusual bleeding.
- Maintain regular lab appointments.
- Use contraception to prevent pregnancy while on therapy.
Special Considerations
Black Box Warnings:
- Lactic acidosis and severe hepatomegaly with steatosis.
Genetic Factors: Consider testing for hepatitis B infection, as withdrawal may lead to flare-up.
Lab Test Interference: Can cause increases in serum transaminases.
Overdose Management
Signs/Symptoms: Nausea, vomiting, pancreatitis, severe metabolic acidosis.
Treatment: Supportive care; no specific antidote. Dialysis may be considered in renal failure.
Storage and Handling
Storage: Store at room temperature, 20-25°C (68-77°F).
Stability: Stable under recommended storage conditions until expiration date.