Hepatic decompensation, some fatal, has occurred in HIV-1/HCV co-infected patients receiving combination antiretroviral therapy and interferon alfa with or without ribavirin. Discontinue abacavir, lamivudine and zidovudine tablets as medically appropriate and consider dose reduction or discontinuation of interferon alfa, ribavirin, or both. Exacerbation of anemia has been reported in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine. Coadministration of ribavirin and zidovudine is not advised. Immune reconstitution syndrome and lipoatrophy have been reported in patients treated with combination antiretroviral therapy. ( 5. 7, 5.8 ) 5.1 Hypersensitivity Reactions Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir, a component of abacavir, lamivudine and zidovudine tablets. These hypersensitivity reactions have included multi-organ failure and anaphylaxis and typically occurred within the first 6 weeks of treatment with abacavir (median time to onset was 9 days); although abacavir hypersensitivity reactions have occurred any time during treatment . Patients who carry the HLA-B*5701 allele are at a higher risk of abacavir hypersensitivity reactions; although, patients who do not carry the HLA-B*5701 allele have developed hypersensitivity reactions. Hypersensitivity to abacavir was reported in approximately 206 (8%) of 2,670 patients in 9 clinical trials with abacavir-containing products where HLA-B*5701 screening was not performed. The incidence of suspected abacavir hypersensitivity reactions in clinical trials was 1% when subjects carrying the HLA-B*5701 allele were excluded. In any patient treated with abacavir, the clinical diagnosis of hypersensitivity reaction must remain the basis of clinical decision making. Due to the potential for severe, serious, and possibly fatal hypersensitivity reactions with abacavir: All patients should be screened for the HLA-B*5701 allele prior to initiating therapy with abacavir, lamivudine and zidovudine tablets or reinitiation of therapy with abacavir, lamivudine and zidovudine tablets, unless patients have a previously documented HLA-B*5701 allele assessment. Abacavir, lamivudine, and zidovudine tablets are contraindicated in patients with a prior hypersensitivity reaction to abacavir and in HLA-B*5701-positive patients. Before starting abacavir, lamivudine and zidovudine tablets, review medical history for prior exposure to any abacavir-containing product. NEVER restart abacavir, lamivudine and zidovudine tablets or any other abacavir-containing product following a hypersensitivity reaction to abacavir, regardless of HLA-B*5701 status. To reduce the risk of a life-threatening hypersensitivity reaction, regardless of HLA-B*5701 status, discontinue abacavir, lamivudine and zidovudine tablets immediately if a hypersensitivity reaction is suspected, even when other diagnoses are possible (e.g., acute onset respiratory diseases such as pneumonia, bronchitis, pharyngitis, or influenza; gastroenteritis; or reactions to other medications). If a hypersensitivity reaction cannot be ruled out, do not restart abacavir, lamivudine and zidovudine tablets or any other abacavir-containing products because more severe symptoms, which may include life-threatening hypotension and death, can occur within hours. If a hypersensitivity reaction is ruled out, patients may restart abacavir, lamivudine and zidovudine tablets. Rarely, patients who have stopped abacavir for reasons other than symptoms of hypersensitivity have also experienced life-threatening reactions within hours of reinitiating abacavir therapy. Therefore, reintroduction of abacavir, lamivudine and zidovudine tablets or any other abacavir-containing product is recommended only if medical care can be readily accessed. A Medication Guide and Warning Card that provide information about recognition of abacavir hypersensitivity reactions should be dispensed with each new prescription and refill
Hematologic Toxicity/Bone Marrow Suppression 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 mm 3 or hemoglobin less than 9.5 grams per dL . 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 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 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)
Patients with Hepatitis B Virus Co-infection Posttreatment Exacerbations of Hepatitis 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)
Use with Interferon- and Ribavirin-Based Regimens 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) . 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 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
Lipoatrophy 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
Myocardial Infarction 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)
Therapy-Experienced Patients 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 .