Zidovudine, a component of abacavir, lamivudine and zidovudine tablet, has been associated with hematologic toxicity including neutropenia and anemia, particularly in patients with advanced HIV-1 disease. Abacavir, lamivudine and zidovudine tablets should be used with caution in patients who have bone marrow compromise evidenced by granulocyte count less than 1,000 cells per mm3 or hemoglobin less than 9.5 grams per dL [see ADVERSE REACTIONS (6.1)].
Frequent blood counts are strongly recommended in patients with advanced HIV-1 disease who are treated with abacavir, lamivudine and zidovudine tablets. Periodic blood counts are 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, have been associated with prolonged use of zidovudine, and therefore may occur with therapy with abacavir, lamivudine and zidovudine tablets.
Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues, including abacavir, lamivudine and zidovudine (components of abacavir, lamivudine and zidovudine tablets). A majority of these cases have been in women. Female sex and obesity may be risk factors for the development of lactic acidosis and severe hepatomegaly with steatosis in patients treated with antiretroviral nucleoside analogues. See full prescribing information for ZIAGEN® (abacavir), EPIVIR® (lamivudine), and RETROVIR® (zidovudine). Treatment with abacavir, lamivudine and zidovudine tablets should be suspended in any patient who develops 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. See full prescribing information for EPIVIR® (lamivudine). Patients should be closely monitored with both clinical and laboratory follow-up for at least several months after stopping treatment.
Emergence of Lamivudine-Resistant HBV
Safety and efficacy of lamivudine have not been established for treatment of chronic hepatitis B in subjects dually infected with HIV-1 and HBV. Emergence of hepatitis B virus variants associated with resistance to lamivudine has been reported in HIV–1-infected subjects who have received lamivudine-containing antiretroviral regimens in the presence of concurrent infection with hepatitis B virus. See full prescribing information for EPIVIR® (lamivudine).
Patients receiving interferon alfa with or without ribavirin and abacavir, lamivudine and zidovudine tablets should be closely monitored for treatment-associated toxicities, especially hepatic decompensation, neutropenia, and anemia. See full prescribing information for RETROVIR® (zidovudine). Discontinuation of abacavir, lamivudine and zidovudine tablets should be considered 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) (see full prescribing information for interferon and ribavirin).
Exacerbation of anemia has been reported in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine. Coadministration of ribavirin and abacavir, lamivudine and zidovudine tablet is not advised.
Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including abacavir, lamivudine and zidovudine tablets. During the initial phase of combination antiretroviral treatment, patients whose immune systems respond may develop an 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 also been reported to occur in the setting of immune reconstitution; however, the time to onset is more variable, and can occur many months after initiation of treatment.
Treatment with zidovudine, a component of abacavir, lamivudine and zidovudine tablets, has been associated with loss of subcutaneous fat. The incidence and severity of lipoatrophy are related to cumulative exposure. This fat loss, which is most evident in the face, limbs, and buttocks, may be only partially reversible and improvement may take months to years after switching to a non-zidovudine-containing regimen. Patients should be regularly assessed for signs of lipoatrophy during therapy with zidovudine-containing products, and if feasible, therapy should be switched to an alternative regimen if there is suspicion of lipoatrophy.
Several prospective, observational, epidemiological studies have reported an association with the use of abacavir and the risk of myocardial infarction (MI). Meta-analyses of randomized, controlled clinical trials have observed no excess risk of MI in abacavir-treated subjects as compared with control subjects. To date, there is no established biological mechanism to explain a potential increase in risk. In totality, the available data from the observational studies and from controlled clinical trials show inconsistency; therefore, evidence for a causal relationship between abacavir treatment and the risk of MI is inconclusive.
As a precaution, the underlying risk of coronary heart disease should be considered when prescribing antiretroviral therapies, including abacavir, and action taken to minimize all modifiable risk factors (e.g., hypertension, hyperlipidemia, diabetes mellitus, smoking).
In clinical trials, subjects with prolonged prior nucleoside reverse transcriptase inhibitor (NRTI) exposure or who had HIV-1 isolates that contained multiple mutations conferring resistance to NRTIs had limited response to abacavir. The potential for cross-resistance between abacavir and other NRTIs should be considered when choosing new therapeutic regimens in therapy- experienced patients [see Microbiology (12.4)].
- Serious and sometimes fatal hypersensitivity reactions [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.1)].
- Hematologic toxicity, including neutropenia and anemia [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.2)].
- Symptomatic myopathy [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.3)].
- Lactic acidosis and severe hepatomegaly with steatosis [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.4)].
- Exacerbations of hepatitis B [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.5)].
- Hepatic decompensation in patients co-infected with HIV-1 and hepatitis C [see WARNINGS AND PRECAUTIONS (5.6)].
- Exacerbation of anemia in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine [see WARNINGS AND PRECAUTIONS (5.6)].
- Immune reconstitution syndrome [see WARNINGS AND PRECAUTIONS (5.7)].
- Lipoatrophy [see WARNINGS AND PRECAUTIONS (5.8)].
- Myocardial infarction [see WARNINGS AND PRECAUTIONS (5.9)].
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
Serious and Fatal Abacavir-Associated Hypersensitivity Reactions
In clinical trials, serious and sometimes fatal hypersensitivity reactions have occurred with abacavir, a component of abacavir, lamivudine and zidovudine tablets [see BOXED WARNING, WARNINGS AND PRECAUTIONS (5.1)]. These reactions have been characterized by 2 or more of the following signs or symptoms: (1) fever; (2) rash; (3) gastrointestinal symptoms (including nausea, vomiting, diarrhea, or abdominal pain); (4) constitutional symptoms (including generalized malaise, fatigue, or achiness); (5) respiratory symptoms (including dyspnea, cough, or pharyngitis). Almost all abacavir hypersensitivity reactions include fever and/or rash as part of the syndrome.
Other signs and symptoms have included lethargy, headache, myalgia, edema, arthralgia, and paresthesia. Anaphylaxis, liver failure, renal failure, hypotension, adult respiratory distress syndrome, respiratory failure, myolysis, and death have occurred in association with these hypersensitivity reactions. Physical findings have included lymphadenopathy, mucous membrane lesions (conjunctivitis and mouth ulcerations), and maculopapular or urticarial rash (although some patients had other types of rashes and others did not have a rash). There were reports of erythema multiforme. Laboratory abnormalities included elevated liver chemistries, elevated creatine phosphokinase, elevated creatinine, and lymphopenia, and abnormal chest x-ray findings (predominantly infiltrates, which were localized).
Additional Adverse Reactions with Use of Abacavir, Lamivudine and Zidovudine Tablets
Treatment-emergent clinical adverse reactions (rated by the investigator as moderate or severe) with a frequency greater than or equal to 5% during therapy with abacavir 300 mg twice daily, lamivudine 150 mg twice daily, and zidovudine 300 mg twice daily compared with indinavir 800 mg 3 times daily, lamivudine 150 mg twice daily, and zidovudine 300 mg twice daily from CNA3005 are listed in Table 1.
|Adverse Reaction||ZIAGEN ® plus Lamivudine / Zidovudine ( n = 262 )||Indinavir plus Lamivudine / Zidovudine ( n = 264 )|
|Malaise and fatigue||12%||12%|
|Nausea and vomiting||10%||10%|
|Fever and/or chills||6%||3%|
|Viral respiratory infections||5%||5%|
Five subjects receiving abacavir in CNA3005 experienced worsening of pre-existing depression compared to none in the indinavir arm. The background rates of pre-existing depression were similar in the 2 treatment arms.
Laboratory abnormalities in CNA3005 are listed in Table 2.
ULN = Upper limit of normal.
n = Number of subjects assessed.
|Laboratory Parameter||ZIAGEN ® plus Lamivudine / Zidovudine ( n = 262 )||Indinavir plus Lamivudine / Zidovudine ( n = 264 )|
|Elevated CPK (>4 x ULN)||18 (7%)||18 (7%)|
|ALT (>5.0 x ULN)||16 (6%)||16 (6%)|
|Neutropenia (<750/mm3)||13 (5%)||13 (5%)|
|Hypertriglyceridemia (>750 mg/dL)||5 (2%)||3 (1%)|
|Hyperamylasemia (>2.0 x ULN)||5 (2%)||1 (<1%)|
|Hyperglycemia (>13.9 mmol/L)||2 (<1%)||2 (<1%)|
|Anemia (Hgb ≤6.9 g/dL)||0 (0%)||3 (1%)|
In addition to adverse reactions in Tables 1 and 2, other adverse events observed in the expanded access program for abacavir were pancreatitis and increased GGT.
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