3TC - General Information
A reverse transcriptase inhibitor and zalcitabine analog in which a sulfur atom replaces the 3TC
Pharmacology of 3TC
3TC is a nucleoside reverse transcriptase inhibitor (NRTI) with activity against Human Immunodeficiency Virus Type 1 (HIV-1) and hepatitis B (HBV). 3TC is phosphorylated to active metabolites that compete for incorporation into viral DNA. They inhibit the HIV reverse transcriptase enzyme competitively and act as a chain terminator of DNA synthesis. The lack of a 3'-OH group in the incorporated nucleoside analogue prevents the formation of the 5' to 3' phosphodiester linkage essential for DNA chain elongation, and therefore, the viral DNA growth is terminated.
3TC for patients
EPIVIR is not a cure for HIV infection and patients may continue to experience illnes ses associated with HIV infection, including opportunistic infections. Patients should remain under the care of a physician when using EPIVIR. Patients should be advised that the use of EPIVIR has not been shown to reduce the risk of transmission of HIV to others through sexual contact or blood contamination. Patients should be advised that EPIVIR Tablets and Oral Solution contain a higher dose of the same active ingredient (lamivudine) as EPIVIR-HBV Tablets and Oral Solution. If a decision is made to include lamivudine in the HIV treatment regimen of a patient dually infected with HIV and HBV, the formulation and dosage of lamivudine in EPIVIR (not EPIVIR-HBV) should be used. Patients co -infected with HIV and HBV should be informed that deterioration of liver disease has occurred in some cases when treatment with lamivudine was discontinued. Patients should be advised to discuss any changes in regimen with their physician. Patients should be advised that the long-term effects of EPIVIR are unknown at this time. EPIVIR Tablets and Oral Solution are for oral ingestion only. Patients should be advised of the importance of taking EPIVIR with combination therapy on a regular dosing schedule and to avoid missing doses. Parents or guardians should be advised to monitor pediatric patients for signs and symptoms of pancreatitis. Patients should be informed that redistribution or accumulation of body fat may occur in patients receiving antiretroviral therapy and that the cause and long-term health effects of these conditions are not known at this time. Diabetic patients should be advised that each 15-mL dose of EPIVIR Oral Solution contains 3 grams of sucrose.
Lamivudine is predominantly eliminated in the urine by active organic cationic secretion. The possibility of interactions with other drugs administered concurrently should be considered, particularly when their main route of elimination is active renal secretion via the organic cationic transport system (e.g., trimethoprim).
TMP 160 mg/SMX 800 mg once daily has been shown to increase lamivudine exposure (AUC) by 44%. No change in dose of either drug is recommended. There is no information regarding the effect on lamivudine pharmacokinetics of higher doses of TMP/SMX such as those used to treat Pneumocystis carinii pneumonia. No data are available regarding interactions with other drugs that have renal clearance mechanisms similar to that of lamivudine.
Lamivudine and zalcitabine may inhibit the intracellular phosphorylation of one another. Therefore, use of lamivudine in combination with zalcitabine is not recommended.
EPIVIR Tablets and Oral Solution are contraindicated in patients with previously demonstrated clinically significant hypersensitivity to any of the components of the products.
Additional information about 3TC
3TC Indication: For the treatment of HIV infection and chronic hepatitis B (HBV).
Mechanism Of Action: 3TC is a synthetic nucleoside analogue and is phosphorylated intracellularly to its active 5'-triphosphate metabolite, lamivudine triphosphate (L-TP). This nucleoside analogue is incorporated into viral DNA by HIV reverse transcriptase and HBV polymerase, resulting in DNA chain termination.
Drug Interactions: Zalcitabine 3TC decreases the efficacy of zalcitabine
Food Interactions: Take without regard to meals. Food does not decrease the extent of absorption, but it decreases the Cmax by slowing the rate of absorption.
Generic Name: Lamivudine
Synonyms: Lamivudine [Usan-Ban-Inn]
Drug Category: Anti-HIV Agents; Nucleoside and Nucleotide Reverse Transcriptase Inhibitors
Drug Type: Small Molecule; Approved
Other Brand Names containing Lamivudine: 3TC; Epivir; Epivir-HBV; Hepitec; Heptovir; Zeffix.
Absorption: Lamivudine was rapidly absorbed after oral administration in HIV-infected patients. Absolute bioavailability in adults is 86% ± 16% for the tablet and 87% ± 13% for the oral solution.
Toxicity (Overdose): Not Available
Protein Binding: 36%
Biotransformation: The only detected metabolite of lamivudine is trans-sulfoxide.
Half Life: 5 to 7 hours
Dosage Forms of 3TC: Tablet Oral
Chemical IUPAC Name: 4-amino-1-[(2R,5S)-2-(hydroxymethyl)-1,3-oxathiolan-5-yl]pyrimidin-2-one
Chemical Formula: C8H11N3O3S
Lamivudine on Wikipedia: http://en.wikipedia.org/wiki/Lamivudine
Organisms Affected: Human Immunodeficiency Virus; Hepatitis B virus