Lamivudine (3TC)

A to Z Drug Facts

 Action Inhibits replication of HIV and hepatitis B virus (HBV)

 Indications HIV infection: In combination with zidovudine when clinical or immunologic evidence demonstrates HIV progression.

Chronic hepatitis B: Treatment of chronic hepatitis B associated with evidence of hepatitis B viral replication and active liver inflammation.

 Contraindications Standard considerations.

 Route/Dosage

HIV Infection Adults: PO 150 mg bid or 300 mg once daily in combination with zidovudine if weight over 50 kg; 2 mg/kg bid in combination with zidovudine if weight less than 50 kg.

Children 3 mo to 16 yr: PO 4 mg/kg bid (max, 150 mg bid) in combination with zidovudine. Dosage adjustment needed because of renal impairment.

Adults: PO Ccr 30 to 49: 150 mg once/day; Ccr 15 to 29: 150 mg first dose, then 100 mg once/day; Ccr 5 to 14: 150 mg first dose, then 50 mg once/day; Ccr less than 5: 50 mg first dose, then 25 mg once/day.

Chronic Hepatitis B Adults: PO 100 mg/day. Safety and efficacy of treatment older than 1 yr not established.

Children 2 to 17 yr: PO 3 mg/kg/day (max, 100 mg/day). Safety and efficacy of treatment older than 1 yr not established.

Dosage Adjustments in Renal Impairment: Adults: PO Ccr at least 50: 100 mg/day; Ccr 30 to 49: 100 mg first dose then 50 mg/day; Ccr 15 to 29: 100 mg first dose then 25 mg/day; Ccr 5 to 14: 35 mg first dose then 15 mg/day; Ccr less than 5: 35 mg first dose then 10 mg/day.

 Interactions

Trimethoprim-sulfamethoxazole: May decrease clearance of lamivudine, causing increase in its serum concentration.

Zidovudine: Lamivudine may cause increase in zidovudine serum concentration.

 Lab Test Interferences None well documented.

 Adverse Reactions

CNS: Headache; neuropathy; dizziness; sleep disturbances; depression; insomnia and other sleep disorders; depressive disorders. DERMATOLOGIC: Rash; alopecia; pruritus. GI: Nausea; vomiting; diarrhea; anorexia; abdominal pain/cramps; dyspepsia; stomatitis. HEMATOLOGIC: Anemia; neutropenia; hyperglycemia; weakness; lactic acidosis; lymphadenopathy; splenomegaly; lactic steatosis. RESPIRATORY: Nasal signs and symptoms; cough; paresthesia; abnormal breath sounds/wheezing. OTHER: Malaise; fatigue; fever; chills; myalgia; arthralgia; pancreatitis; elevated liver enzymes; musculoskeletal pain; anaphylaxis; urticaria; rhabdomyolysis; peripheral neuropathy; hepatic steatosis; muscle weakness with CPK elevation; posttreatment exacerbation of hepatitis.

 Precautions

Pregnancy Category C. Lactation Undetermined. Children Hepatitis B Safety and efficacy in children under 2 yr not established. HIV infection Safety and efficacy in children under 2 mo not established. Excacerbation of hepatitis Exacerbations of hepatitis has occurred after discontinuation of lamivudine. Fat distribution Accumulation/redistribution of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and “cushingoid appearance” has occurred in patients receiving antiretroviral therapy. A causal relationship has not been established. Renal function impairment Dosage adjustment recommended. Lactic acidosis/Severe hepatomegaly with steatosis Exercise caution when administering lamivudine, particularly to those with known risk factors for liver disease. HIV-HBV coinfection Epivir-HBV tablets and oral solution contain a lower dose of the same active ingredient as Epivir tablets and oral solution (and lamivudine/zidovudine tablets used to treat HIV infection). The formulation and dosage of lamivudine in Epivir-HBV are not appropriate for patients infected with both HBV and HIV.

 Administration/Storage

• Administer lamivudine in combination with zidovudine or alone for patients not responding to zidovudine as prescribed.
• Adhere strictly to the prescribed dosage and schedule.
• A reduced dosage is recommended for patients with impaired renal function.
• Store tablets at room temperature in a tight, dry container.
• Store oral solution at room temperature in a tight container.

 Assessment/Interventions

• There is no known antidote.
• Obtain patient history.
• Monitor for signs and symptoms of infection or neurological changes.
• Monitor for emergence of resistance-associated HBV mutations.
• Assess patient for change in severity of symptoms.
• Monitor patient for signs and symptoms of pancreatitis, especially pediatric patients.
• Monitor BUN, serum creatinine, LFTs, amylase, and CBC during the course of therapy.
• If any clinical signs, symptoms, or laboratory tests suggest pancreatitis, notify health care provider immediately.
• In patients receiving lamivudine with zidovudine, monitor for increased risk of adverse effects including headache, fatigue, nausea, neuropathy, nasal signs and symptoms, cough, rash, and musculoskeletal pain.

 Patient/Family Education

• Instruct patient that the lamivudine tablets and oral solution are for oral ingestion only and to take only as prescribed.
• Instruct patient to avoid OTC medications unless prescribed by the health care provider.
• Instruct patient that lamivudine is not a cure for HIV or HBV infections and opportunistic infections and other complications of HIV and HBV infections may continue to develop.
• Caution patient or guardian that long-term effects of lamivudine and results from controlled clinical trials evaluating therapeutic and adverse effects are unknown.
• Inform patient of the potential adverse effects.
• Instruct patient to notify the health care provider if signs of infection such as a sore throat, fever, cough, and respiratory congestion occur.
• Instruct family to notify the health care provider of changes in neurological status such as memory loss or confusion.
• Advise patient that it may take at least 4 wk for maximum effect.
• Warn patient that the risk of transmission of HIV or HBV to others through sexual contact or exposure to the patient's blood is still present. Instruct patient in methods and precautions to prevent transmission of the HIV or HBV virus.
• Instruct parents or guardians to monitor patient, especially a pediatric patient, for signs and symptoms of pancreatitis.
• Caution mothers to discontinue nursing if receiving lamivudine because of the potential for adverse effects from lamivudine in nursing infants as well as transmission of the HIV virus.
• Caution women to inform health care provider if pregnant or planning to become pregnant, as lamivudine is transferred to the fetus through the placenta.
• Stress the importance of regular exams and laboratory work. Encourage patient to comply with the treatment regimen.
• Advise patient that Epivir-HBV tablets and oral solution contain a lower dose of the same active ingredient as Epivir oral solution, tablets, and lamivudine/zidovudine tablets. Advise patient not to take Epivir-HBV concurrently with Epivir or lamivudine/zidovudine.

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Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts