Emtricitabine/Tenofovir Dosage

Usual Adult Dose for HIV Infection

1 tablet orally once every 24 hours

Usual Adult Dose for Nonoccupational Exposure

1 tablet orally once every 24 hours plus efavirenz
Prophylaxis should be initiated as soon as possible, within 72 hours of exposure.
Duration: 28 days

Usual Pediatric Dose for HIV Infection

12 years or older with body weight 35 kg or more: 1 tablet orally once every 24 hours

Renal Dose Adjustments

Adults:
CrCl 30 to 49 mL/min: 1 tablet orally every 48 hours
Safety and efficacy of these dosing guidelines have not been clinically evaluated: therefore, clinical response to treatment and renal function should be closely monitored in these patients.

CrCl less than 30 mL/min: Not recommended.

Pediatric patients 12 years or older: Data not available

Liver Dose Adjustments

Data not available

Precautions

Lactic acidosis and severe hepatomegaly with steatosis, including fatalities, have been reported with the use of nucleoside/nucleotide analogs, including tenofovir, in combination with other antiretrovirals. 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 clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity.

It is recommended that all patients with HIV-1 be tested for the presence of chronic hepatitis B virus (HBV) before initiating antiretroviral therapy. Emtricitabine-tenofovir is not approved for the treatment of chronic HBV infection and its safety and efficacy have not been established in patients coinfected with HBV and HIV-1. Severe acute exacerbations of hepatitis B have been reported in patients coinfected with HBV and HIV-1 after discontinuation of emtricitabine-tenofovir and were associated with liver failure and liver decompensation in some emtricitabine-treated patients. Coinfected patients should be closely monitored with clinical and laboratory follow-up for at least several months after discontinuation of emtricitabine-tenofovir. If appropriate, resumption of antihepatitis B therapy may be necessary.

Renal impairment, including acute renal failure and Fanconi syndrome, has been reported with tenofovir. Creatinine clearance should be calculated in all patients before starting emtricitabine-tenofovir treatment and during treatment when clinically appropriate. Routine monitoring of calculated creatinine clearance and serum phosphorus is recommended for patients at risk of or with a history of renal dysfunction, including patients with previous renal events while using adefovir. Emtricitabine-tenofovir should be avoided in patients who are currently using or have recently used nephrotoxic drugs.

Tenofovir has been associated with decreases in bone mineral density (BMD) and increases in biochemical markers of bone metabolism in HIV-1 infected patients. Assessment of BMD should be considered for patients who have a history of pathologic bone fracture or other risk factors for osteoporosis or bone loss. Consultation is recommended if bone abnormalities are suspected or observed.

Immune reconstitution syndrome has occurred during combination treatment with antiretrovirals (CART). Patients responding to CART may develop an inflammatory response to indolent or residual opportunistic infections and require evaluation and treatment.

Clinical studies of emtricitabine or tenofovir did not contain sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects. In general, dose selection for the elderly patient should be cautious, keeping in mind the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.

Emtricitabine-tenofovir should always be used in combination with other antiretroviral agents (such as nonnucleoside reverse transcriptase inhibitors or protease inhibitors).

Related drugs not for coadministration with emtricitabine-tenofovir include emtricitabine, tenofovir DF, and efavirenz/emtricitabine/tenofovir, which contain the same active components as emtricitabine-tenofovir. Due to similar resistance profiles and lack of therapeutic benefit, the concomitant use of emtricitabine- and lamivudine-containing medications is not recommended. Emtricitabine-tenofovir should not be administered in combination with adefovir dipivoxil.

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

During clinical trials, regimens that only contain 3 NRTIs have generally been less successful than 3-drug regimens containing 2 NRTIs plus a nonnucleoside reverse transcriptase inhibitor or an HIV-1 protease inhibitor. Early virological failure and high rates of resistance substitutions have been reported. Triple nucleoside therapy should be used with caution. Careful monitoring and treatment modification should be considered for patients using such a regimen. Emtricitabine-tenofovir is not recommended as a component of a triple nucleoside regimen.

Safety and efficacy have not been established in pediatric patients less than 12 years of age or weighing less than 35 kg. Emtricitabine-tenofovir should not be administered to these patients.

Dialysis

Not recommended.

Other Comments

May be given with or without food; however, the AUC of tenofovir is 35% higher when given with a high-fat meal.

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