Dosing and uses of Trizivir (lamivudine-zidovudine-abacavir)
Adult dosage forms and strengths
lamivudine/zidovudine/abacavir
tablet
- 150mg/300mg/300mg
HIV Infection
1 tablet PO q12hr
<40 kg: Not recommended
Renal Impairment
CrCl <50 mL/min: Not recommended
Hepatic Impairment
Contraindicated
Pediatric dosage forms and strengths
lamivudine/zidovudine/abacavir
tablet
- 150mg/300mg/300mg
HIV Infection
<12 years or <40 kg: Not recommended
>12 years or >40 kg: 1 tablet PO q12hr
Trizivir (lamivudine-zidovudine-abacavir) adverse (side) effects
>10%
Nausea
Headache
Fatigue
Malaise
Vomiting
1-10%
Rash
Fever/chills
Anxiety
Depression
Increased triglyceride levels
Diarrhea
Increased amylase
Neutropenia
Increased ALt
Increased CPK
Ear infection
Nose/throat infection
Viral infection
Frequency not defined
Immune reconstitution syndrome
GGT increased
Fat redistribution
Pancreatitis
Warnings
Black box warnings
abacavir
- Severe and sometimes fatal hypersensitivity reactions (discontinue immediately if hypersensitivity reaction suspected)
- Never restart after suspected hypersensitivity reaction as more severe symptoms can occur within hours and may include life-threatening hypotension and death
- Reintroduction of abacavir or any other abacavir containing product, even in patients who have no identified history or unrecognized symptoms of hypersensitivity to abacavir therapy, can result (within hours) in serious or fatal hypersensitivity reactions
- Hypersensitivity reaction to this drug is a multiorgan clinical syndrome usually characterized by a sign or symptom in 2 or more of the following groups: 1) fever, 2) rash, 3) gastrointestinal (including nausea, vomiting, diarrhea, or abdominal pain, 4) constitutional (eg, generalized malaise, fatigue, achiness), and 5) respiratory (eg, pharyngitis, dyspnea, cough); HLA-B*5701 allele carriers at high risk for hypersensitivity reaction; Prior to initiating therapy, screen for the HLA-B*5701 allele; this approach decreases risk of hypersensitivity reaction
- Screening also recommended prior to reinitiation in patients of unknown HLA-B*5701 status who have previously tolerated abacavir therapy
- HLA-B*5701 allele negative patients may develop hypersensitivity reaction; although frequency significantly less than in HLA-B*5701 positive patients
- Regardless of HLA-B*5701 status, permanently discontinue if hypersensitivity cannot be ruled out, even when other diagnoses are possible
- Lactic acidosis and hepatomegaly with steatosis (including fatal cases) reported with nucleoside analogues alone or in combination
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
- 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
- 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
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
CrCl <50 mL/min
Hepatic impairment
Patients requiring individual dose adjustments for each drug component
Presence of HLA-B*5701 allele
Cautions
Risk of immune reconstitution syndrome
(All NRTIs): Risk of potentially fatal lactic acidosis & severe hepatomegaly with steatosis
Use caution in patients with risks for coronary heart disease
Use caution when treating in combination with interferon alfa with or without ribavirin in HIV/HBV; monitor for hepatic decompensation, neutropenia, or anemia and reduce interferon dose and or ribavirin or discontinue if toxicity occurs
Discontinue therapy as medically appropriate and consider dose reduction or discontinuation of interferon alfa, ribavirin, or both in co-infected patients receiving combination antiretroviral therapy and interferon alfa with or without ribavirin
Exacerbation of anemia reported in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine; coadministration of ribavirin and zidovudine not advised
Immune reconstitution syndrome and redistribution/accumulation of body fat reported in patients treated with combination antiretroviral therapy
Not for administration with other products containing abacavir, lamivudine, or zidovudine; or emtricitabine-containing products
Pregnancy and lactation
Pregnancy category: C
Lactation: Not recommended; excreted in breast milk; HIV+ women shouldn't nurse anyway
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 Trizivir (lamivudine-zidovudine-abacavir)
Pharmacogenomics
Patients who carry the HLA-B*5701 allele are at high risk for experiencing a hypersensitivity reaction
Prior to initiating therapy with abacavir, screening for the HLA-B*5701 allele is recommended
For HLA-B*5701-positive patients, treatment with an abacavir-containing regimen is not recommended
Genetic testing laboratories
- The following companies provide genetic testing for HLA variants
- Kashi Clinical Laboratories (www.kashilab.com)
- LabCorp (https://www.labcorp.com/)
- Specialty Laboratories (https://www.specialtylabs.com)
- Quest (https://www.questdialgnotics.com)
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
Abacavir: NRTI; following phosphorylation, inhibits HIV reverse transcriptase by inhibiting viral replication; guanosine analogue
