emtricitabine: prescribing and clinical use
Focused clinical detail for use alongside current product information, local policy and patient-specific assessment.
emtricitabine: clinical details
Prescribing considerations
- Use only as part of combination antiretroviral therapy for HIV treatment.
- Review treatment history, adherence and resistance when changing therapy, particularly after virological failure.
- Renal impairment substantially increases exposure; assess formulation suitability.
- Establish hepatitis B status and plan specialist follow-up before interruption in HIV/HBV coinfection.
- Clinical experience is limited after multiple treatment failures and in adults over 65.
Contraindications and cautions
- Hypersensitivity to emtricitabine or a formulation excipient.
- Avoid concurrent lamivudine or another emtricitabine-containing product.
- Oral-solution colourings and preservatives may cause allergic reactions, including delayed reactions.
Monitoring
- Renal function before treatment and during therapy when clinically indicated.
- HIV viral load, response, adherence and resistance where appropriate.
- Liver function in pre-existing liver disease; close follow-up after stopping in HIV/HBV coinfection.
- Blood lipids and glucose as part of antiretroviral care.
- Investigate new inflammatory or autoimmune symptoms after treatment starts.
Clinical pharmacology
Emtricitabine is a cytidine analogue phosphorylated intracellularly to an active triphosphate that inhibits HIV reverse transcriptase and terminates viral DNA synthesis. It undergoes little metabolism, has low CYP interaction potential and is eliminated mainly by glomerular filtration and active tubular secretion. M184V/I mediates resistance and cross-resistance with lamivudine.
Formulation and product differences
- Oral solution has lower bioavailability than hard capsules and must not be substituted amount-for-amount without recalculation.
- Oral solution may be useful when capsules cannot be swallowed and allows paediatric or renal adjustment.
- The solution contains sunset yellow, parabens, propylene glycol, sodium and xylitol.
- Store unopened oral solution refrigerated. After opening, keep below the stated room-temperature limit and return or discard any remainder after 45 days.
- Hard capsules require no special storage conditions.
emtricitabine preparations and strengths
Capsule
Route: Oral
Strengths: 200 mg
Oral solution
Route: Oral
Strengths: 10 mg/mL
emtricitabine interactions
Emtricitabine has little potential for CYP450-mediated interactions, but duplicate treatment and renal elimination are important.
Lamivudine
Do not combine routinely because it is closely related and has overlapping activity and resistance.
Other emtricitabine-containing products
Avoid duplicate therapy by checking every component of fixed-dose antiretroviral combinations.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.