Names and pronunciation
(em-tri-sit′uh-bean/ten-oh- foh′veer) Descovy
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Drug reference
(em-tri-sit′uh-bean/ten-oh- foh′veer) Descovy
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Func. class.: Antiretroviral
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Chem. class.: Nucleoside reverse transcriptase inhibitor (NRTI)
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ACTION: • Emtricitabine: inhibits viral reverse transcriptase and is active both on HIV-1 and HBV • Tenofovir: inhibits viral reverse tran- scriptase and acts as a DNA chain termi- nator
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USES: Human immunodeficiency virus (HIV) infection used in combination with other antiretrovirals
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CONTRAINDICATIONS: Hyper- sensitivity, CCr <30 mL/min Precautions:
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Black Box Warning: Hepatitis B exacer- bation Alcoholism, autoimmune disease, bone fractures, breastfeeding, children, depression, females, Graves’ disease, Guillain-Barré syndrome, hepatic dis- ease, hepatitis, hepatitis B and HIV coin- fection, hepatitis C and HIV coinfection, hepatomegaly, HIV resistance, hyper- cholesterolemia, hyperlipidemia, hyper- triglyceridemia, hypophosphatemia, immune reconstitution syndrome, obe- sity, osteomalacia, osteoporosis, preg- nancy, QT prolongation, renal failure, renal impairment, serious rash, suicidal ideation, torsades de pointes, hepato- toxicity, lactic acidosis Black Box Warning: Hepatitis B exacer- bation: those with coexisting HBV and HIV infections who discontinue emtricitabine or tenofovir may experience severe acute hepatitis B exacerbation with hepatic de- compensation/failure. Those coinfected with HBV and HIV who discontinue this product, monitor LFTs q6wk × the first 3 mo and q3-6mo. Resumption of anti– hepatitis B treatment may be required • Monitor serum bilirubin (total and di- rect), serum creatinine, urinalysis, LFTs, amylase, lipase periodically • Pregnancy/breastfeeding: obtain pregnancy testing prior to use
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SIDE EFFECTS CNS: Weakness GI: Nausea, hepatomegaly with stenosis (may be fatal), hepatic failure/decompen- sation, hepatitis MS: Myalgia, bone pain, osteopenia, os- teoporosis GU: Breast enlargement, renal failure SYST: Change in body fat distribution, lactic acidosis, Fanconi syndrome META: Hypercholesterolemia, hypertri- glyceridemia, hypophosphatemia
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INTERACTIONS • Do not use with efavirenz, lamiVUDine; treatment duplication Decrease: emtricitabine level—interferons Increase: QT prolongation—class IA/III antidysrhythmics, some phenothiazines, beta-agonists, local anesthetics, tricyclics, haloperidol, chloroquine, droperidol, pentamidine; CYP3A4 inhibitors (amioda- rone, clarithromycin, erythromycin, telithromycin, troleandomycin), arsenic trioxide; CYP3A4 substrates (methadone, pimozide, QUEtiapine, quiNIDine, risperi- DONE, ziprasidone)
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DOSAGE AND ROUTES • Adult/adolescent/child ≥12 yr and weighing ≥35 kg: PO 1 tablet (200 mg emtricitabine; 25 mg tenofovir) daily
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Available forms: Tablets 200 mg emtricitabine; 25 mg tenofovir
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Administer: • Antiretroviral drug resistance testing (preferably genotypic testing) is recom- mended prior to use in treatment-naive patients and prior to changing therapy for treatment failure • For adults, use in all patients to re- duce the risk of disease progression and to prevent the transmission of HIV, in- cluding perinatal transmission and trans- mission to sexual partners • For pregnant women, therapy should begin immediately after HIV di- agnosis • Avoid use of tenofovir-containing regi- mens in those with renal disease and osteoporosis
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Assess: • HIV infection: assess symptoms of HIV, including opportunistic infections, prior to and during treatment, some may be life- threatening; monitor plasma CD4+, CD8 cell counts, serum beta-2 microglobulin; treatment failures occur more often in those with baseline HIV-1 RNA concentra- tions >100,000 copies/mL than in those <100,000 copies/mL; monitor blood glu- cose, CBC with differential, serum choles- terol, lipid panel • Hepatotoxicity/lactic acidosis: mon- itor hepatitis B serology, LFTs, plasma hepatitis C RNA, lactic acidosis levels. If lab reports confirm these conditions, dis- continue product. More common in fe- males or those who are overweight. Avoid use in alcoholism
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Evaluate: • Improvement in CD4, HIV RNC counts, decreasing signs and symp- toms of HIV
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • That hepatitis and HIV coinfected pa- tients should avoid consuming alcohol; offer vaccinations against hepatitis A and hepatitis B as needed • That GI complaints resolve after 2-3 wk of treatment • To take at the same time of day to maintain blood level; not to crush, break, E or chew • That product controls the symptoms of HIV but does not cure; that patient is still able to infect others, that other products may be necessary to prevent other infec- tions • Lactic acidosis: to notify prescriber if fatigue, muscle aches/pains, abdominal pain, difficulty breathing, nausea, vomit- ing, change in heart rhythm occur • Hepatotoxicity: to notify prescriber of dark urine, yellowing skin or eyes, clay-colored stools, anorexia, nausea, vomiting • To report suspected or planned preg- nancy, not to breastfeed
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PHARMACOKINETICS • Emtricitabine: protein binding <4%, metabolized via oxidation, half-life 10 hr, excreted renally (86%) and via feces (14%); peak 1-2 hr • Tenofovir: protein binding <0.7%, undergoes phosphorylation to its active metabolite, eliminated by glomerular fil- tration and active renal tubular secretion, 70%-80% excreted unchanged in urine by 72 hr; half-life 17 hr, bioavailability is increased with a high-fat meal
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• Adult/adolescent/child ≥12 yr and weighing ≥35 kg: PO 1 tablet (200 mg emtricitabine; 25 mg tenofovir) daily
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