emtricitabine/tenofovir DF

Action and Spectrum

Actions and Spectrum:  

Action:  

emtricitabine works by inhibiting the reverse transcriptase enzyme, which is essential for the replication of the virus. This inhibition leads to the suppression of viral replication and reduces the viral load. tenofovir DF works similarly by inhibiting the reverse transcriptase enzyme and also acts as a chain terminator during viral DNA synthesis. 

combining these two drugs provides a synergistic effect and enhances their antiviral activity against HIV-1. Emtricitabine/Tenofovir DF has a broad spectrum of activity against HIV-1 strains, including those resistant to other antiretroviral drugs. 

In conclusion, emtricitabine/tenofovir DF is a potent fixed-dose combination drug that targets the replication of HIV-1 by inhibiting the reverse transcriptase enzyme. Its broad spectrum of activity against HIV-1 strains makes it an effective treatment option for HIV-1 infection in adults. 

Drug Interaction

Adverse Reaction

Frequency defined 

>10% 

Fatigue 

Headache 

Dizziness 

Depression 

Diarrhea 

Nausea 

Insomnia 

Abnormal dreams 

Rash 

1-10% 

Dizziness (8%) 

Rash event (7%) 

Headache (6%) 

Nasopharyngitis (5%) 

Diarrhea (9%) 

Nausea (9%) 

Fatigue (9%) 

Depression (9%) 

Insomnia (5%) 

Vomiting (2%) 

Black Box Warning

Black Box Warning:  

Patients with underlying liver disease or marked transaminase elevations may be at increased risk for developing hepatomegaly with steatosis when taking emtricitabine/tenofovir DF.

Treatment with emtricitabine/tenofovir DF should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity. 

emtricitabine/tenofovir DF is not approved for the treatment of chronic hepatitis B virus (HBV) infection.  

Contraindication / Caution

Contraindication/Caution:  

emtricitabine/tenofovir DF is contraindicated in patients with a known hypersensitivity to any component of the formulation. It should not be administered concomitantly with other medicinal products containing tenofovir, including adefovir dipivoxil, unless the potential benefits outweigh the risks and under strict medical supervision.

Additionally, the use of emtricitabine/tenofovir DF is contraindicated in patients with severe renal impairment (creatinine clearance below 30 mL/min), or who are receiving dialysis. 

In cases where emtricitabine/tenofovir DF is prescribed to patients with mild or moderate renal impairment, it should be used with caution and under close medical supervision. Furthermore, emtricitabine/tenofovir DF is not recommended for use in pediatric patients below the age of 18 years, as the safety and efficacy of this drug in this population have not been established. 

Pregnancy / Lactation

Pregnancy warnings:     

Pregnancy category: N/A 

Lactation: Excreted into human milk is unknown 

Pregnancy Categories:         

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester. 

Category B: There were a lack of studies on pregnant women and no evidence of risk to the fetus in animal experiments.   

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.   

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology: 

The pharmacology of emtricitabine/tenofovir DF is characterized by their ability to inhibit the reverse transcriptase enzyme of HIV-1 virus, thereby preventing the replication of the virus in the host cells. Emtricitabine and tenofovir DF act synergistically by targeting different stages of the viral replication cycle. 

Pharmacodynamics: 

The pharmacodynamic mechanism of emtricitabine/tenofovir DF involves the inhibition of the reverse transcriptase enzyme responsible for the replication of the HIV virus.  

MOA:  

emtricitabine is phosphorylated intracellularly to its active form, emtricitabine triphosphate, which competes with endogenous deoxycytidine triphosphate (dCTP) for incorporation into the viral DNA chain during reverse transcription. This incorporation leads to the termination of the viral DNA chain and prevents the formation of complete viral DNA.  

On the other hand, tenofovir DF is converted to its active form, tenofovir diphosphate, which is a competitive inhibitor of the viral reverse transcriptase enzyme. It competes with endogenous deoxyadenosine triphosphate (dATP) for incorporation into the viral DNA chain, resulting in chain termination and inhibition of viral replication.  

Pharmacokinetics: 

Absorption 

emtricitabine and tenofovir DF are orally administered drugs rapidly absorbed into the bloodstream. The bioavailability of emtricitabine is approximately 93%, while that of tenofovir DF is approximately 25%. emtricitabine is primarily absorbed in the proximal small intestine, whereas tenofovir DF is absorbed throughout the small intestine.  

Distribution 

emtricitabine and tenofovir DF are both distributed extensively throughout the body. emtricitabine has a relatively small volume of distribution of approximately 1.3 L/kg, while tenofovir DF has a larger volume of distribution of approximately 1.3-1.6 L/kg. Both drugs bind extensively to plasma proteins, with emtricitabine binding to albumin and tenofovir DF binding to plasma proteins at a lower extent. 

Metabolism 

emtricitabine and tenofovir DF are primarily metabolized in the liver. emtricitabine undergoes minimal hepatic metabolism, with less than 5% of the drug being metabolized into inactive metabolites. tenofovir DF undergoes extensive hepatic metabolism, with less than 1% of the drug being excreted unchanged in urine.  

Elimination and Excretion 

emtricitabine and tenofovir DF are eliminated primarily via the renal route, with approximately 86% and 70% of the drugs being excreted unchanged in urine, respectively. The elimination half-life of emtricitabine is approximately 10 hours, while that of tenofovir DF is approximately 17 hours 

Adminstartion

Administration:  

Dosage: The usual recommended dose for emtricitabine/tenofovir DF is one tablet (200 mg of emtricitabine and 300 mg of tenofovir DF) once a day, taken with or without food.  

Timing: It is important to take the medication at the same time each day to maintain a consistent level of the medication. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: emtricitabine/tenofovir DF 

Why do we use emtricitabine/tenofovir DF?  

emtricitabine/tenofovir DF is a combination drug used to treat HIV-1 infection in adults and adolescents. emtricitabine and tenofovir DF are both antiretroviral drugs that work by blocking the reverse transcriptase enzyme, which is essential for the replication of the virus. 

emtricitabine is a nucleoside reverse transcriptase inhibitor (NRTI) that is structurally like the building blocks of DNA. It works by inhibiting the reverse transcriptase enzyme, which is responsible for converting the virus’s RNA into DNA. By doing so, emtricitabine prevents the virus from replicating and spreading. 

tenofovir DF is a nucleotide reverse transcriptase inhibitor (NtRTI) that works by blocking the reverse transcriptase enzyme and stopping the virus from replicating. It also helps reduce the amount of virus in the blood and slows down the progression of the disease.