Abacavir / Lamivudine Dosage

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Usual Adult Dose for:

Additional dosage information:

Usual Adult Dose for HIV Infection

1 tablet orally once every 24 hours

Usual Adult Dose for Nonoccupational Exposure

(Not approved by FDA)

Centers for Disease Control and Prevention recommendations: 1 tablet orally once every 24 hours
Duration: 28 days

Prophylaxis should be initiated as soon as possible, within 72 hours of exposure. In general, the alternative regimens recommended for nonoccupational postexposure HIV prophylaxis include abacavir-lamivudine as part of nonnucleoside reverse transcriptase inhibitor (NNRTI)-based, protease inhibitor (PI)-based, or triple nucleoside reverse transcriptase inhibitor (NRTI) regimens.

Renal Dose Adjustments

CrCl less than 50 mL/min: Not recommended.

Liver Dose Adjustments

Contraindicated in patients with hepatic impairment

Precautions

Serious and sometimes fatal hypersensitivity reactions have been associated with abacavir therapy and usually appear within the first 6 weeks of treatment. Patients with the HLA-B*5701 allele are at increased risk of hypersensitivity reaction to abacavir; therefore, screening for the HLA-B*5701 allele is recommended prior to starting abacavir treatment. Therapy with an abacavir-containing regimen is not recommended for HLA-B*5701-positive patients and should be considered only with close medical supervision under exceptional conditions where potential benefit outweighs the risk. Considerably less frequently, HLA-B*5701-negative patients may experience hypersensitivity reaction with abacavir. Frequently observed signs and symptoms include, but are not limited to, fever, skin rash, fatigue, nausea, vomiting, diarrhea, abdominal pain, muscle aches, malaise, pharyngitis, dyspnea, and cough. Abacavir should be discontinued as soon as a hypersensitivity reaction is suspected and should not be restarted because more severe symptoms will occur within hours and may include life-threatening hypotension and death.

Severe or fatal hypersensitivity reactions can also occur within hours after restarting abacavir in patients who have no identified history or unrecognized symptoms of this reaction. Screening for the HLA-B*5701 allele is also recommended prior to restarting abacavir treatment in patients whose HLA-B*5701 status is unknown. Abacavir therapy should be permanently discontinued if hypersensitivity cannot be ruled out, even when other diagnoses are possible, to minimize the risk of a life-threatening hypersensitivity reaction. Once-daily dosing of abacavir was associated with more severe reactions in a clinical study.

The manufacturer's Medication Guide and Warning Card with information about the abacavir hypersensitivity reaction must be dispensed with each new and refill prescription.

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with other antiretroviral agents. Risk factors may include female gender, obesity, and prolonged nucleoside exposure. Caution is recommended in patients with risk factors for liver disease; however, cases have also been reported in patients with no known risk factors. Treatment with abacavir-lamivudine should be suspended in any patient who develops clinical or laboratory signs suggestive of lactic acidosis or pronounced hepatotoxicity.

Severe acute exacerbations of hepatitis, including fatalities, have been reported in patients coinfected with hepatitis B (HBV) and HIV-1 who have discontinued antihepatitis B therapy, including lamivudine. Patients who discontinue antihepatitis B therapy should have close monitoring of hepatic function with both clinical and laboratory follow-up for at least several months. If appropriate, resumption of antihepatitis B therapy may be necessary.

The safety and efficacy of lamivudine have not been established for the treatment of chronic HBV in patients coinfected with HIV-1 and HBV.

Patients receiving interferon alfa with or without ribavirin and abacavir-lamivudine should be closely monitored for treatment-associated toxicities, especially hepatic decompensation. Discontinuation of abacavir-lamivudine should be considered as medically appropriate. Dose reduction or discontinuation of interferon alfa, ribavirin, or both should be considered if worsening clinical toxicities are observed, including hepatic decompensation.

Immune reconstitution syndrome has occurred during combination antiretroviral therapy. Patients responding to therapy may develop an inflammatory response to indolent or residual opportunistic infections and require evaluation and treatment.

The potential for HIV cross-resistance among nucleoside reverse transcriptase inhibitors (NRTIs) exists but has not been fully explored. It is unknown what effect abacavir or lamivudine therapy will have on the activity of subsequently administered NRTIs. Selection of antiretroviral agents for a patient's medication regimen should be done carefully, and HIV-genotyping/phenotyping should be considered, if available.

Abacavir-lamivudine should always be used in combination with other antiretroviral agents. When used as part of a triple-drug regimen, abacavir-lamivudine should be used with antiretroviral agents from different pharmacological classes and not with other nucleoside/nucleotide reverse transcriptase inhibitors. The potential for cross-resistance between other NRTIs should be considered with selecting therapeutic regimens in treatment-experienced patients.

Abacavir-lamivudine should not be administered concurrently with other abacavir-containing and/or lamivudine-containing products (abacavir, lamivudine, abacavir/lamivudine/zidovudine, or lamivudine-zidovudine). Due to similar resistance profiles and lack of therapeutic benefit, the concomitant use of lamivudine and emtricitabine-containing medications is not recommended.

Safety and efficacy have not been established in pediatric patients (less than 18 years of age).

Dialysis

Not recommended.

Other Comments

May be taken with or without food

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