Home Drug Guide Lamivudine; Tenofovir Disoproxil Fumarate

Drug Guide

Generic Name

Lamivudine; Tenofovir Disoproxil Fumarate

Brand Names Cimduo, Lamivudine And Tenofovir Disoproxil Fumarate, Temixys

Classification

Therapeutic: Antiretroviral Agent (HIV-1, Chronic Hepatitis B)

Pharmacological: Nucleoside Reverse Transcriptase Inhibitor (NRTI)

FDA Approved Indications

Treatment of HIV-1 infection in combination with other antiretroviral agents
Chronic hepatitis B virus infection

Mechanism of Action

Lamivudine and Tenofovir Disoproxil Fumarate are reverse transcriptase inhibitors. Lamivudine incorporates into viral DNA causing chain termination. Tenofovir inhibits the viral reverse transcriptase enzyme through chain termination, preventing viral DNA synthesis.

Dosage and Administration

Adult: Typically, 300 mg lamivudine and 300 mg tenofovir disoproxil fumarate once daily, in combination with other antiretrovirals.

Pediatric: Dosage based on weight and age; consult specific pediatric guidelines.

Geriatric: Adjusted as needed; consider renal function.

Renal Impairment: Dose adjustment required based on creatinine clearance.

Hepatic Impairment: Use with caution; no specific dose adjustment necessary.

Pharmacokinetics

Absorption: Well absorbed after oral administration.

Distribution: Widely distributed into tissues and fluids including cerebrospinal fluid.

Metabolism: Lamivudine minimally metabolized; Tenofovir is minimally metabolized.

Excretion: Primarily via renal excretion; dose adjustments needed for renal impairment.

Half Life: Approximately 5-7 hours for lamivudine and 17 hours for tenofovir.

Contraindications

Hypersensitivity to lamivudine or tenofovir.
Concurrent use with other medications containing lamivudine or tenofovir.

Precautions

Lactic acidosis and severe hepatomegaly with steatosis, particularly in women; renal impairment; consider hepatitis B monitoring during and after therapy.

Adverse Reactions - Common

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

Adverse Reactions - Serious

Lactic acidosis (Rare)
Severe hepatomegaly with steatosis (Rare)
Renal toxicity (Uncommon)

Drug-Drug Interactions

Concurrent nephrotoxic drugs (e.g., NSAIDs, aminoglycosides)
Other antiretrovirals that can affect renal function

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function tests, hepatic function, and virological response.

Diagnoses:

Risk for renal impairment
Risk for ineffective tissue perfusion due to renal dysfunction

Implementation: Administer on empty stomach if tolerated; monitor labs regularly.

Evaluation: Assess viral load, CD4 count, renal and hepatic function periodically.

Patient/Family Teaching

Take medication exactly as prescribed.
Report any signs of lactic acidosis (e.g., muscle weakness, unusual fatigue, hyperventilation).
Maintain regular follow-up appointments.

Special Considerations

Black Box Warnings:

Lactic acidosis and severe hepatomegaly with steatosis

Genetic Factors: Hepatitis B reactivation upon discontinuation.

Lab Test Interference: None specified.

Overdose Management

Signs/Symptoms: Nausea, vomiting, increased mitochondrial side effects, lactic acidosis.

Treatment: Supportive care; no specific antidote. Hemodialysis may be considered for severe overdose.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F).

Stability: Stable for the duration of the labeled shelf life when stored properly.