Lamivudine / Zidovudine Dosage

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Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for HIV Infection

1 tablet orally twice a day

Usual Adult Dose for Nonoccupational Exposure

(Not approved by FDA)

Centers for Disease Control and Prevention (CDC) recommendations: 1 tablet orally every 12 hours plus efavirenz or lopinavir-ritonavir
Duration: 28 days

Prophylaxis should be initiated as soon as possible, within 72 hours of exposure.

Usual Adult Dose for Occupational Exposure

(Not approved by FDA)

CDC recommendations:
Basic regimen for HIV postexposure prophylaxis: 1 tablet orally every 12 hours
Duration: Generally 28 days; however, the exact duration of therapy may differ based on the institution's protocol.

Therapy should begin promptly, preferably within 1 to 2 hours postexposure.

Usual Pediatric Dose for HIV Infection

30 kg or more: 1 tablet orally twice a day

Renal Dose Adjustments

CrCl less than 50 mL/min: Not recommended.

A reduction of both lamivudine and zidovudine dosages is recommended with this level of renal dysfunction, which is not possible with the fixed dose formulation.

Liver Dose Adjustments

Mild to moderate hepatic impairment or liver cirrhosis: Not recommended.

A reduction in the daily dose of zidovudine may be required with this level of hepatic dysfunction, which is not possible with the fixed dose formulation.

Precautions

Zidovudine may cause bone marrow toxicity, including neutropenia and anemia, particularly in patients with advanced HIV-1 disease. Lamivudine-zidovudine should be used with caution in patients with bone marrow suppression indicated by a granulocyte count below 1000 cells/mm3 or hemoglobin less than 9.5 g/dL. Frequent blood counts are strongly recommended during lamivudine-zidovudine therapy in patients with advanced HIV-1 disease. If bone marrow toxicity occurs, an interruption or discontinuation of lamivudine-zidovudine therapy may be necessary.

Hepatic decompensation (some fatal) has been reported in HIV-1/HCV coinfected patients receiving combination antiretroviral treatment for HIV-1 and interferon alfa with or without ribavirin. Patients receiving interferon alfa with or without ribavirin and lamivudine-zidovudine should be closely monitored for treatment-associated toxicities including neutropenia, anemia, and hepatic decompensation. Lamivudine-zidovudine discontinuation should be considered as medically appropriate.

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 for lactic acidosis 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 should be suspended in any patient who develops findings suggestive of lactic acidosis or pronounced hepatotoxicity.

Severe acute exacerbations of hepatitis B, including fatalities, have been reported in patients with chronic hepatitis B virus (HBV) infections (including those coinfected with HIV-1) who have discontinued antihepatitis B therapy, including lamivudine. Patients who discontinue antihepatitis B therapy should have close monitoring of hepatic function with clinical and laboratory follow-up for at least several months. It is unknown if restarting lamivudine will alter the course of posttreatment exacerbations of hepatitis.

Lamivudine-zidovudine combination tablets contain a higher dose of lamivudine than the lamivudine-only product, Epivir-HBV(R), which is used to treat chronic HBV. The safety and efficacy of lamivudine for the treatment of HBV in HBV/HIV-1 coinfected patients have not been established.

Lamivudine-zidovudine should be used with caution in patients with a history of pancreatitis or other significant risk factors for pancreatitis development. Lamivudine-zidovudine should be discontinued immediately if clinical signs, symptoms, or laboratory abnormalities suggestive of pancreatitis develop.

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.

Patients experiencing dose-limiting adverse reactions may require a dosage adjustment of lamivudine and/or zidovudine. Because this is not possible with the fixed dose lamivudine-zidovudine combination tablet, this formulation should not be administered to these patients.

Related drugs not for coadministration with lamivudine-zidovudine include lamivudine, zidovudine, abacavir-lamivudine, and abacavir/ lamivudine/zidovudine, in which lamivudine and/or zidovudine is one of the active components. Due to similar resistance profiles and lack of therapeutic benefit, the concomitant use of lamivudine- and emtricitabine-containing medications is not recommended.

The potential for HIV-1 cross-resistance among nucleoside reverse transcriptase inhibitors exists but has not been fully explored. It is unknown what effect lamivudine-zidovudine therapy will have on the activity of subsequently administered nucleoside reverse transcriptase inhibitors. Selection of antiretroviral agents for a patient's medication regimen should be done carefully and in consultation with an infectious disease specialist.

The fixed dose lamivudine-zidovudine combination tablet should not be administered to pediatric patients weighing less than 30 kg.

Dialysis

CrCl less than 50 mL/min: Not recommended.

A reduction of both lamivudine and zidovudine dosages is recommended with this level of renal dysfunction, which is not possible with the fixed dose formulation.

Other Comments

Lamivudine-zidovudine should always be used in combination with other antiretroviral agents.

If a patient is unable to reliably swallow a tablet, the oral liquid formulations of lamivudine and zidovudine should be used.

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