Emtricitabine (commonly called FTC, systematic name 2',3'-dideoxy-5-fluoro-3'-thiacytidine), with trade name Emtriva (formerly Coviracil), is a nucleoside

reverse-transcriptase inhibitor Reverse-transcriptase inhibitors (RTIs) are a class of antiretroviral drugs used to treat HIV infection or AIDS, and in some cases hepatitis B. RTIs inhibit activity of reverse transcriptase, a viral DNA polymerase that is required for replicati ...

(NRTI) for the prevention and treatment of HIV infection in adults and children. Emtricitabine is also marketed in a fixed-dose combination with tenofovir disoproxil (Viread) under the brand name Truvada, and with

tenofovir alafenamide Tenofovir alafenamide, sold under the brand name Vemlidy, is a hepatitis B virus (HBV) nucleotide reverse transcriptase inhibitor medication for the treatment of chronic hepatitis B virus (HBV) infection in adults with compensated liver dise ...

(Vemlidy) under the brand name Descovy. A fixed-dose triple combination of emtricitabine, tenofovir and

efavirenz Efavirenz (EFV), sold under the brand names Sustiva among others, is an antiretroviral medication used to treat and prevent HIV/AIDS. It is generally recommended for use with other antiretrovirals. It may be used for prevention after a needle ...

(Sustiva, marketed by Bristol-Myers Squibb) was approved by the U.S. Food and Drug Administration (FDA) on July 12, 2006, under the brand name

Atripla Efavirenz/emtricitabine/tenofovir, sold under the brand name Atripla among others, is a fixed-dose combination antiretroviral medication used to treat HIV/AIDS. It contains efavirenz, emtricitabine, and tenofovir disoproxil. It can be used by ...

. Emtricitabine makes up one fourth of the Quad pill (brand names: Stribild and Genvoya). In fixed-dose combinations with tenofovir or with efavirenz and tenofovir it is on the World Health Organization's List of Essential Medicines. In 2019, it was the 494th most commonly prescribed medication in the United States, with more than 3thousand prescriptions.

Medical uses

HIV infection

Emtricitabine is indicated in combination with other

antiretroviral The management of HIV/AIDS normally includes the use of multiple antiretroviral drugs as a strategy to control HIV infection. There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle. The use of multipl ...

agents for the prevention and treatment of HIV-1 infection.

HBV infection

Emtricitabine exhibits clinical activity against the hepatitis B virus (HBV), but is not approved by the U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

(FDA) for the treatment of HBV infection. Among individuals with chronic HBV infection, emtricitabine treatment results in significant histologic, virologic, and biochemical improvement. The safety profile of emtricitabine during treatment is similar to that of a placebo. Emtricitabine, like all other FDA approved drugs, cures neither HIV nor HBV infection. In a study involving individuals with HBV infection, symptoms of infection returned in 23% of emtricitabine-treated individuals who were taken off therapy. In studies involving individuals with ''chronic'' HIV infection, viral replication also resumes when study subjects are taken off therapy. As with drugs used to treat HIV infection, drugs used to treat HBV infection may have to be used in combination to prevent the evolution of drug resistant strains. The effectiveness of emtricitabine in combination with other anti-HBV drugs has not been established.

Side effects

In clinical practice,

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...

with emtricitabine is unusual. The most common treatment-related adverse events are

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

headache Headache is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Headaches can occur as a result ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of th ...

, and

rash A rash is a change of the human skin which affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, c ...

. These symptoms are generally mild to moderate in severity, but they caused 1% of clinical trial patients to give up treatment. Skin discoloration, which is typically reported as

hyperpigmentation Hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin. Causes Hyperpigmentation can be caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris.James, William; Be ...

and usually affects either the palms of the hands or the soles of the feet, is reported in less than 2% of individuals and is almost exclusive to patients of African origin. Among the more severe side effects patients may experience are a hepatotoxicity or a lactic acidosis.

Mechanism of action

Emtricitabine is an analogue of cytidine. The drug works by inhibiting

reverse transcriptase A reverse transcriptase (RT) is an enzyme used to generate complementary DNA (cDNA) from an RNA template, a process termed reverse transcription. Reverse transcriptases are used by viruses such as HIV and hepatitis B to replicate their genom ...

, the enzyme that copies HIV RNA into new viral DNA. By interfering with this process, which is central to the replication of HIV, emtricitabine can help to lower the amount of HIV, or " viral load", in a patient's body and can indirectly increase the number of

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

cells (namely

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

s/ CD4+ T-cells). Both of these changes are associated with healthier immune systems and decreased likelihood of serious illness.

History

Emtricitabine was discovered by Dennis C. Liotta,

Raymond F. Schinazi Raymond F. Schinazi is an American organic medicinal chemist with expertise in antiviral agents, pharmacology, and biotechnology. His research focuses on developing treatments for infections caused by human immunodeficiency virus (HIV), hepatitis ...

, and Woo-Baeg Choi of

Emory University Emory University is a private research university in Atlanta, Georgia. Founded in 1836 as "Emory College" by the Methodist Episcopal Church and named in honor of Methodist bishop John Emory, Emory is the second-oldest private institution of ...

and licensed to Triangle Pharmaceuticals by Emory in 1996. Triangle Pharmaceuticals was acquired in 2003 by Gilead Sciences, which completed development and now markets the product with the brand name Emtriva. It was approved by the FDA July 2, 2003.Standard & Poor's 500 Guide
Standard & Poor's, McGraw-Hill, (2004), p. 83. It is very similar to lamivudine (3TC) and cross-resistance between the two is near-universal.

References

External links

* {{Portal bar , Medicine , Viruses Gilead Sciences Hepatotoxins Nucleoside analog reverse transcriptase inhibitors Oxathiolanes Organofluorides Pyrimidones World Health Organization essential medicines Hydroxymethyl compounds