FDA has approved Trizivir for the treatment of HIV in adults and adolescents. Each dose of Trizivir is a fixed-dose combination of Ziagen (abacavir/ABC), Retrovir (zidovudine/AZT), and Epivir (lamivudine/3TC), three nucleoside reverse transcriptase inhibitors (NRTIs) already approved by FDA. Trizivir is not recommended for treatment in adults or adolescents who weigh less than 40 kilograms because it is a fixed-dose tablet.
Because Trizivir combines a single dose of three drugs into one pill, it may be easier for some patients to comply with their medication regimen. Each component of Trizivir is also available separately. This combination product should only be used by those whose treatment regimens would otherwise include these doses of these three nucleoside analogues. It may be used alone or in combination with other antiretroviral agents for the treatment of HIV infection, but should not be administered concomitantly with abacavir, lamivudine, or zidovudine, which are already contained in Trizivir. The recommended dose is one tablet twice a day.
Healthcare providers and patients should be aware of the serious and sometimes fatal adverse event of hypersensitivity caused by abacavir. In clinical studies of abacavir, a hypersensitivity reaction has occurred in about 5 percent of patients. Signs or symptoms of hypersensitivity include fever, skin rash, fatigue, gastrointestinal symptoms, and respiratory symptoms, such as pharyngitis, dyspnea, and cough. Rechallenge is contraindicated after a diagnosis of hypersensitivity has been made. Other possible side effects of Trizivir include lactic acidosis, severe liver problems, anemia, neutropenia, nausea, fatigue, and myopathy.
Ziagen and Trizivir both contain abacavir and neither of these drugs should be taken by someone who may have experienced symptoms of a hypersensitivity reaction to abacavir.
A medication guide has been written for patients to highlight the symptoms of hypersensitivity reactions to abacavir; the importance of discontinuation of abacavir when these symptoms occur; the dangers of restarting the drug after a hypersensitivity reaction and identification of the three names for abacavir with which patients must be familiar in order to prevent retaking these drugs after hypersensitivity.
Patients will also receive a wallet card similar to the one provided to patients with abacavir prescriptions that summarizes the most important points that patients need to know about hypersensitivity reactions. A patient may be having a hypersensitivity reaction if they have a rash, and/or two or more symptoms such as fever, nausea, vomiting, diarrhea, sore throat, cough, shortness of breath or extreme tiredness.
An Abacavir Hypersensitivity Registry has been established. Physicians should register patients by calling 1-800-270-0425.
Trizivir is manufactured by Glaxo Wellcome, Research Park Triangle, N.C.