Dosing and uses of Combivir, 3tc/zdv (lamivudine-zidovudine)
Adult dosage forms and strengths
lamivudine/zidovudine
tablet
- 150mg/300mg
HIV Infection
150 mg/300 mg (1 tablet) PO q12hr
Monitor amylase q4-8wk
Because of fixed dose, avoid administering to patients < 30 kg, patients with CrCl < 50 mL/min, or in hepatic impairment
Pediatric dosage forms and strengths
lamivudine/zidovudine
tablet
- 150mg/300mg
HIV Infection
<12 years: Not recommended; fixed-dose combination cannot be adjusted for children
> 12 years and < 30 kg: Not recommended
>12 years and >30 kg: As adults; 150 mg/300 mg (1 tablet) PO q12hr
Monitor amylase q4-8wk
Combivir, 3tc/zdv (lamivudine-zidovudine) adverse (side) effects
>10%
Headache (35%)
Nausea (33%)
Malaise & fatigue (27%)
Cough (18%)
Diarrhea (18%)
Vomiting (13%)
Musculoskeletal pain (12%)
Neuropathy (12%)
Insomnia & other sleep disorders (11%)
1-10%
Anorexia &/or decreased appetite (10%)
Dizziness (10%)
Fever or chills (10%)
Abdominal pain (9%)
Depressive disorders (9%)
Skin rashes (9%)
Myalgia (8%)
Neutropenia (7.2% )
Abdominal cramps (6%)
Arthralgia (5%)
Dyspepsia (5%)
Anemia (2.9% )
Frequency not defined (serious)
Erythema multiforme
Stevens-Johnson syndrome
Lactic acidosis
Pancreatitis
Hepatomegaly (Severe)
Steatosis of liver (Severe)
Anaphylaxis
Immune hypersensitivity reaction
Rhabdomyolysis
Postmarketing reports
Immune reconstitution syndrome and fat redistribution
Warnings
Black box warnings
lamivudine
- Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases have been reported with the use of nucleoside analogues alone or in combination with other antiretrovirals
- Not FDA approved for the treatment of chronic hepatitis B virus (HBV) infection and the safety and efficacy of this drug have not been established in patients coinfected with HBV and HIV
- Tablets and oral solution formulations used to treat HIV infection contain a higher dose of lamivudine than formulations indicated for chronic hepatitis B infection; HIV patients should receive only formulation specific for HIV
- Exacerbations of hepatitis reported after discontinuation of lamivudine; monitor patients closely with both clinical and laboratory follow-up for at least several months after stopping treatment; if appropriate, initiate anti-hepatitis B therapy
zidovudine
- Neutropenia and severe anemia reported, particularly in patients with advanced HIV disease
- Myopathy associated with prolonged use
- Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) reported with nucleoside analogues alone or in combination
Contraindications
Hypersensitivity
Patients requiring separate lamivudine or zidovudine dose reduction
Cautions
Risk of immune reconstitution syndrome
Zidovudine use has been associated with hematologic toxicity including neutropenia and anemia, particularly in patients with advanced HIV-1 disease; use with caution in patients who have bone marrow compromise evidenced by granulocyte count < 1,000 cells per mm³ or hemoglobin < 9.5 g/dL; frequent blood counts strongly recommended in patients with advanced HIV-1 disease; periodic blood counts recommended for other HIV-1-infected patients; if anemia or neutropenia develops, dosage interruption may be needed
Myopathy and myositis, with pathological changes similar to that produced by HIV-1 disease associated with prolonged use of zidovudine
Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, reported with use of nucleoside analogues and other antiretrovirals; suspend treatment in patients who develop clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations)
Clinical and laboratory evidence of exacerbations of hepatitis have occurred after discontinuation of lamivudine; monitor patients closely with both clinical and laboratory follow-up for at least several months after stopping treatment
Emergence of hepatitis B virus variants associated with resistance to lamivudine reported in HIV-1-infected subjects who received lamivudine-containing antiretroviral regimens in the presence of concurrent infection with hepatitis B virus
Concomitant administration with other products containing lamivudine or zidovudine not recommended
Closely monitor patients receiving interferon alfa with or without ribavirin for treatment-associated toxicities, especially hepatic decompensation, neutropenia, and anemia; consider discontinuation of therapy as medically appropriate; dose reduction or discontinuation of interferon alfa, ribavirin, or both should also be considered if worsening clinical toxicities are observed, including hepatic decompensation (e.g., Child-Pugh greater than 6)
Use with caution in patients with a history of pancreatitis or other significant risk factors for the development of pancreatitis; treatment should be stopped immediately if clinical signs, symptoms, or laboratory abnormalities suggestive of pancreatitis occur Immune reconstitution syndrome reported
During initial phase of combination antiretroviral treatment, patients whose immune systems respond may develop inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia [PCP], or tuberculosis), which may necessitate further evaluation and treatment
Autoimmune disorders (such as Graves’ disease, polymyositis, and Guillain-Barré syndrome) have been reported to occur in setting of immune reconstitution; however, time to onset is more variable, and can occur many months after initiation of treatment
Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and “cushingoid appearance” have been observed in patients receiving antiretroviral therapy; mechanism and long-term consequences of these events are currently unknown; causal relationship not established
Not recommended for use in patients with hepatic or renal (CrCl< 50 mL/min) impairment
See also individual monographs
- lamivudine
- zidovudine
Pregnancy and lactation
Pregnancy category: C
Lactation: not recommended
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Combivir, 3tc/zdv (lamivudine-zidovudine)
Mechanism of action
Lamivudine: NRTI; following phosphorylation, inhibits HIV reverse transcriptase by viral DNA chain termination; cytosine analog
Zidovudine: NRTI; interferes with HIV viral RNA-dependent DNA polymerase (inhibits viral replication); thymidine analog
