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Emtricitabine and Tenofovir Alafenamide

Pronunciation

(em trye SYE ta been & ten OF oh vir al a FEN a mide)

Index Terms

  • Emtricitabine and Tenofovir Alafenamide
  • Emtricitabine/Tenofov Alafenam
  • Tenofovir Alafenamide and Emtricitabine

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Descovy: Emtricitabine 200 mg and tenofovir alafenamide 25 mg [contains fd&c blue #2 aluminum lake]

Brand Names: U.S.

  • Descovy

Pharmacologic Category

  • Antiretroviral, Reverse Transcriptase Inhibitor, Nucleoside (Anti-HIV)
  • Antiretroviral, Reverse Transcriptase Inhibitor, Nucleotide (Anti-HIV)

Pharmacology

Nucleoside and nucleotide reverse transcriptase inhibitor combination; emtricitabine is a cytosine analogue while tenofovir alafenamide fumarate (TAF) is an analog of adenosine 5'-monophosphate. Each drug interferes with HIV viral RNA dependent DNA polymerase activities resulting in inhibition of viral replication.

Use: Labeled Indications

HIV-1 infection: Treatment of HIV-1 infection (in combination with other antiretroviral agents) in adults and pediatric patients 12 years of age and older

Limitations of use: Not indicated for use as pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV-1 in adults at high risk.

Contraindications

There are no contraindications listed in the manufacturer's labeling.

Dosing: Adult

HIV-1 infection: Oral: One tablet once daily

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

HIV-1 infection: Children and Adolescents ≥12 years and ≥35 kg: Oral: Refer to adult dosing.

Dosing: Renal Impairment

CrCl ≥30 mL/minute: No dosage adjustment necessary.

CrCl <30 mL/minute: Use is not recommended.

Dosing: Hepatic Impairment

Mild-to-moderate impairment (Child-Pugh class A or B): No dosage adjustment necessary.

Severe impairment (Child-Pugh class C): There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).

Administration

Oral: Administer with or without food.

Dietary Considerations

Consider calcium and vitamin D supplementation.

Storage

Store below 30°C (86°F). Keep container tightly closed; dispense in original container.

Drug Interactions

Acyclovir-Valacyclovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Acyclovir-Valacyclovir. Monitor therapy

Adefovir: May diminish the therapeutic effect of Tenofovir Products. Adefovir may increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Adefovir. Avoid combination

Aminoglycosides: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Aminoglycosides. Monitor therapy

Cabozantinib: MRP2 Inhibitors may increase the serum concentration of Cabozantinib. Monitor therapy

CarBAMazepine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Cidofovir: May increase the serum concentration of Tenofovir Products. Tenofovir Products may increase the serum concentration of Cidofovir. Monitor therapy

Cobicistat: May enhance the adverse/toxic effect of Tenofovir Products. More specifically, cobicistat may impair proper tenofovir monitoring and dosing. Monitor therapy

Diclofenac (Systemic): May enhance the nephrotoxic effect of Tenofovir Products. Management: Seek alternatives to this combination whenever possible. Avoid use of tenofovir with multiple NSAIDs or any NSAID given at a high dose. Consider therapy modification

Fosphenytoin-Phenytoin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Ganciclovir-Valganciclovir: May enhance the adverse/toxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Hematologic toxicity with zidovudine is of particular concern. Ganciclovir-Valganciclovir may increase the serum concentration of Reverse Transcriptase Inhibitors (Nucleoside). Management: Monitor patients receiving any of these combination closely for toxicity of the reverse transcriptase inhibitor. Avoid zidovudine. Intravitreal implants would not be affected. Consider therapy modification

LamiVUDine: May enhance the adverse/toxic effect of Emtricitabine. Avoid combination

Nonsteroidal Anti-Inflammatory Agents: May enhance the nephrotoxic effect of Tenofovir Products. Management: Seek alternatives to these combinations whenever possible. Avoid use of tenofovir with multiple NSAIDs or any NSAID given at a high dose. Consider therapy modification

Orlistat: May decrease the serum concentration of Antiretroviral Agents. Monitor therapy

OXcarbazepine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

PHENobarbital: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Primidone: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Ribavirin (Oral Inhalation): May enhance the hepatotoxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Monitor therapy

Ribavirin (Systemic): May enhance the hepatotoxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Monitor therapy

Rifabutin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

RifAMPin: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Rifapentine: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

St John's Wort: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Tipranavir: May decrease the serum concentration of Tenofovir Alafenamide. Avoid combination

Adverse Reactions

All adverse drug reactions are from combination therapy with cobistat plus elvitegravir in treatment-naïve and treatment-experienced patients. Also see individual agents.

1% to 10%:

Gastrointestinal: Nausea (10%)

Neuromuscular & skeletal: Decreased bone mineral density (≥5% decrease at lumbar spine: 1% to 10%; ≥7% decrease at femoral neck: 1% to 7%), bone fracture (≤1%; excluding fingers and toes)

Frequency not defined:

Endocrine & metabolic: Increased HDL cholesterol, increased LDL cholesterol, increased serum cholesterol, increased serum triglycerides

Hepatic: Exacerbation of hepatitis B

Renal: Increased serum creatinine (mean increase 0.1 mg/dL)

<1% (Limited to important or life-threatening): Acute renal failure, renal disease

ALERT: U.S. Boxed Warning

Lactic acidosis/severe hepatomegaly with steatosis:

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs in combination with other antiretrovirals.

HIV-1 and hepatitis B coinfection:

Emtricitabine/tenofovir alafenamide is not approved for the treatment of chronic hepatitis B virus (HBV) infection, and the safety and efficacy of emtricitabine/tenofovir alafenamide have not been established in patients coinfected with human immunodeficiency virus-1 (HIV-1) and HBV. Severe acute exacerbations of hepatitis B have been reported in patients who are coinfected with HIV-1 and HBV and have discontinued products containing emtricitabine and/or tenofovir disoproxil fumarate, and may occur with discontinuation of emtricitabine/tenofovir alafenamide. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who are coinfected with HIV-1 and HBV and discontinue emtricitabine/tenofovir alafenamide. If appropriate, initiation of antihepatitis B therapy may be warranted.

Warnings/Precautions

Concerns related to adverse effects:

• Decreased bone mineral density: In clinical trials, tenofovir has been associated with decreases in bone mineral density in HIV-1 infected adults and increases in bone metabolism markers. Consider monitoring of bone density in adult and pediatric patients with a history of pathologic fractures or with other risk factors for bone loss or osteoporosis. Calcium and vitamin D supplementation may be beneficial for all patients. Long-term significance of these changes are unknown. If abnormalities are suspected, expert assessment is recommended.

• Fat redistribution: May cause redistribution of fat (eg, buffalo hump, peripheral wasting with increased abdominal girth, cushingoid appearance).

• Immune reconstitution syndrome: Patients may develop immune reconstitution syndrome resulting in the occurrence of an inflammatory response to an indolent or residual opportunistic infection during initial HIV treatment or activation of autoimmune disorders (eg, Graves' disease, polymyositis, Guillain-Barré syndrome) later in therapy; further evaluation and treatment may be required.

• Lactic acidosis/hepatomegaly: [US Boxed Warning]: Lactic acidosis and severe hepatomegaly with steatosis have been reported with nucleoside analogues (eg, tenofovir), including fatal cases; use with caution in patients with risk factors for liver disease (risk may be increased with female gender, obesity or prolonged nucleoside exposure) and suspend treatment in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or hepatotoxicity (transaminase elevation may/may not accompany hepatomegaly and steatosis). Some cases of hepatotoxicity have occurred in patients with no hepatic disease prior to treatment.

• Osteomalacia and renal dysfunction: In patients taking tenofovir disoproxil fumarate, cases of osteomalacia associated with proximal renal tubulopathy with bone pain or extremity pain (which may contribute to fractures) have been reported; hypophosphatemia and osteomalacia secondary to proximal renal tubulopathy have also occurred in patients at risk for renal dysfunction who present with persistent or worsening bone or muscle symptoms. The risk of osteomalacia in patients taking tenofovir alafenamide is not known. In patients at risk for renal dysfunction, persistent or worsening bone or muscle symptoms should be evaluated for renal dysfunction, hypophosphatemia and osteomalacia

• Renal toxicity: Cases of acute renal failure and/or Fanconi syndrome have been reported with use of tenofovir prodrugs; patients with preexisting renal impairment and those taking nephrotoxic agents (including NSAIDs) are at increased risk. Assess estimated creatinine clearance, urine protein, and urine glucose prior to initiation of therapy and during therapy. Monitor serum phosphorus in patients with chronic kidney disease (increased risk of developing Fanconi syndrome). Discontinue therapy in patients that develop clinically significant decreases in renal function or evidence of Fanconi syndrome.

Disease-related concerns:

• Chronic hepatitis B: [US Boxed Warning]: Safety and efficacy during coinfection of HIV and HBV have not been established; acute, severe exacerbations of HBV have been reported following discontinuation of antiretroviral therapy. Not indicated for treatment of chronic hepatitis B. All patients with HIV should be tested for HBV prior to initiation of treatment. Monitor clinical and laboratory indices closely for several months following discontinuation in patients coinfected with HIV-1 and HBV. If appropriate, initiation of HBV therapy may be needed, especially in patients with advanced liver disease or cirrhosis (post-treatment HBV exacerbations lead to hepatic decompensation and liver failure).

• Renal impairment: Use is not recommended in patients with CrCl <30 mL/minute.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Monitoring Parameters

CD4 count, HIV RNA plasma levels; serum creatinine, urine glucose, urine protein (prior to initiation and as clinically indicated during therapy); serum phosphorus (in patients with chronic kidney disease); hepatic function tests, BMD (patients with a history of bone fracture or have risk factors for bone loss); testing for HBV is recommended prior to the initiation of antiretroviral therapy. Patients with HIV and HBV coinfection should be monitored for several months following therapy discontinuation.

Pregnancy Considerations

Adverse events were not observed following administration of emtricitabine or tenofovir alafenamide in animal reproduction studies. Also refer to the Emtricitabine monograph.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience nausea. Have patient report immediately to prescriber signs of infection, signs of kidney problems (urinary retention, hematuria, change in amount of urine passed, or weight gain), signs of liver problems (dark urine, fatigue, lack of appetite, nausea, abdominal pain, light-colored stools, vomiting, or jaundice), signs of lactic acidosis (fast breathing, tachycardia, abnormal heartbeat, vomiting, fatigue, shortness of breath, severe loss of strength and energy, severe dizziness, feeling cold, or muscle pain or cramps), bone pain, or change in body fat (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

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