emtricitabine

Brand: Emtriva, component of Truvada, Biktarvy, Descovy, etc.

⚠ BBW Prototype: tenofovir-disoproxil-fumarate

Drug Class: nucleoside reverse transcriptase inhibitor (NRTI)

Drug Family: antiretroviral

Subclass: cytidine analog NRTI

Organ Systems: infectious-disease

Mechanism of Action

Phosphorylated to emtricitabine triphosphate; competes with deoxycytidine triphosphate for incorporation into viral DNA; once incorporated, acts as a chain terminator. Also active against hepatitis B virus.

HIV reverse transcriptase (nucleoside active site)

Indications

HIV-1 infection (as part of combination ART — virtually always in combination, not used alone)
hepatitis B infection (also active)

Contraindications

emtricitabine hypersensitivity

Adverse Effects

Common

skin hyperpigmentation (palms/soles — occurs in darker-skinned patients)
nausea
headache

Serious

lactic acidosis and severe hepatomegaly with steatosis (class NRTI effect)
severe acute exacerbation of hepatitis B upon discontinuation

Pharmacokinetics (ADME)

Absorption	93% oral bioavailability; not significantly affected by food
Distribution	widely distributed; low protein binding
Metabolism	minimal; some oxidation and glucuronidation
Excretion	renal (86% as unchanged drug and metabolites); dose adjustment in CKD
Half-life	10 hours
Onset	1–2 hours
Peak	1–2 hours
Duration	24 hours
Protein Binding	<4%
Vd	moderate

Drug Interactions

Drug / Agent	Mechanism	Severity
lamivudine	cross-resistance and overlapping mechanism; do not combine	major
drugs causing lactic acidosis (metformin, NRTIs)	additive mitochondrial toxicity; lactic acidosis risk	moderate

Nursing Considerations

Emtricitabine is virtually always used in combination tablets (e.g., Truvada = emtricitabine + tenofovir DF; Biktarvy = bictegravir + emtricitabine + tenofovir AF); verify patient is not receiving duplicate NRTI therapy.
Monitor renal function (SCr, eGFR, urine protein) due to renal excretion; dose adjustment required when eGFR <50 mL/min.
If stopping emtricitabine in a patient with HIV/HBV co-infection, closely monitor LFTs for 4+ weeks — severe HBV flares have caused liver failure.
Counsel patients on the skin hyperpigmentation — benign and reversible.

Clinical Pearls

Emtricitabine and tenofovir are the most widely used NRTI backbone of modern ART; the emtricitabine/tenofovir combination (Truvada) is also the backbone of pre-exposure prophylaxis (PrEP) for HIV prevention.
Emtricitabine and lamivudine have virtually identical mechanisms, resistance profiles, and activity against HBV; they are considered interchangeable but should never be combined due to redundancy.

Safety Profile

Pregnancy safe

Lactation avoid

Renal Adjustment Required

Hepatic Adjustment Not required

TDM Not required

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Hepatitis B Infection (also Active) HIV-1 Infection (as Part Of Combination ART — Virtually Always In Combination, Not Used Alone) Nucleoside Reverse Transcriptase Inhibitor (NRTI)

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