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# Tenvir-EM (Emtricitabine/Tenofovir Disoproxil Fumarate)
## Overview
Tenvir-EM is a fixed-dose combination of emtricitabine (a nucleoside reverse transcriptase inhibitor, NRTI) and tenofovir disoproxil fumarate (TDF, a nucleotide reverse transcriptase inhibitor, NtRTI). It is used for the treatment of HIV-1 infection and for pre-exposure prophylaxis (PrEP).
## Primary Indications
* Treatment of Human Immunodeficiency Virus type 1 (HIV-1) infection in combination with other antiretroviral agents.
* Pre-exposure prophylaxis (PrEP) to reduce the risk of sexually acquired HIV-1 infection in adults and adolescents.
## Adult Dosing
* **HIV Treatment:** One tablet (200 mg emtricitabine / 300 mg TDF) once daily.
* **HIV PrEP:** One tablet (200 mg emtricitabine / 300 mg TDF) once daily. For individuals at high risk of HIV infection, daily use is recommended. For MSM, it can be taken daily or as an on-demand regimen (2 tablets taken 2-24 hours before sex, 1 tablet 24 hours after the first dose, and 1 tablet 24 hours after the second dose).
## Pediatric Dosing
* **HIV Treatment (for use in combination with other antiretroviral agents):**
* **12 to <18 years weighing at least 35 kg:** One tablet (200 mg emtricitabine / 300 mg TDF) once daily.
* Dosing for children younger than 12 years or weighing less than 35 kg should be based on weight-based recommendations for emtricitabine and tenofovir disoproxil fumarate separately, as weight-based Tenvir-EM tablets are not available.
## Dose Adjustments
* **Renal Impairment (Adults):**
* CrCl 30 to 49 mL/min: 200 mg emtricitabine / 300 mg TDF every 48 hours.
* CrCl <30 mL/min or end-stage renal disease requiring dialysis: Not recommended. Alternative regimens are preferred.
* **Hepatic Impairment:** No dose adjustment is necessary.
## Contraindications
* Known hypersensitivity to emtricitabine, tenofovir disoproxil fumarate, or any component of the tablet.
## Adverse Effects
* **Common:** Nausea, diarrhea, headache, rash, abdominal pain, dizziness.
* **Serious:** Lactic acidosis, severe hepatomegaly with steatosis (including fatalities), new or worsening renal impairment (including acute renal failure and Fanconi syndrome), bone demineralization (decreased bone mineral density), immune reconstitution inflammatory syndrome (IRIS).
## Key Drug Interactions
* **Drugs affecting renal function:** Concomitant use with nephrotoxic drugs (e.g., NSAIDs, certain antibiotics, diuretics) may increase the risk of renal adverse events.
* **Didanosine:** Avoid coadministration due to increased risk of pancreatitis and higher incidence of Grade 3 or 4 hyperlactatemia/asymptomatic hyperlactatemia and Grade 4 laboratory abnormalities.
* **Antiretrovirals:** Not intended for use as a single agent. Must be used in combination with other antiretrovirals for HIV treatment.
## Monitoring
* **Baseline and periodic renal function tests** (serum creatinine, CrCl, urinalysis for proteinuria).
* **Baseline and periodic liver function tests.**
* **Bone mineral density** should be considered for patients with a history of pathologic bone fractures.
* **Hepatitis B virus (HBV) testing** prior to initiating therapy. Discontinuation of emtricitabine or tenofovir can lead to severe acute exacerbations of hepatitis B.
## Clinical Pearls
* Tenvir-EM is available as a single tablet regimen and simplifies dosing for HIV treatment and PrEP.
* For PrEP, adherence is crucial for efficacy.
* TDF can be associated with renal toxicity and decreased bone mineral density. Monitor renal function closely, especially in patients with pre-existing renal disease or those taking other nephrotoxic agents.
* Consider HBV status before initiating therapy, as abrupt discontinuation can lead to severe HBV exacerbations.
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*This information is intended for healthcare professionals and does not substitute for current prescribing information. Always consult the official drug monograph and local protocols.*
