Trifluridine (also called trifluorothymidine; abbreviation TFT or FTD) is an anti-

herpesvirus ''Herpesviridae'' is a large family of DNA viruses that cause infections and certain diseases in animals, including humans. The members of this family are also known as herpesviruses. The family name is derived from the Greek word ''ἕρπειν ...

antiviral drug Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do n ...

, used primarily on the eye. It was sold under the trade name Viroptic by Glaxo Wellcome, now merged into

GlaxoSmithKline GSK plc, formerly GlaxoSmithKline plc, is a British multinational pharmaceutical and biotechnology company with global headquarters in London, England. Established in 2000 by a merger of Glaxo Wellcome and SmithKline Beecham. GSK is the ten ...

. The brand is now owned by Monarch Pharmaceuticals, which is wholly owned by

King Pharmaceuticals King Pharmaceuticals, is a pharmaceutical company, a wholly owned subsidiary of Pfizer based in Bristol, Tennessee. Before being acquired by Pfizer, it was the world's 39th largest pharmaceutical company. On October 12, 2010, King was acquired by ...

. Trifluridine was approved for medical use in 1980. It is also a component of the anti-cancer drug trifluridine/tipiracil, which is taken by mouth.

Medical uses

Trifluridine eye drops are used for the treatment of

keratitis Keratitis is a condition in which the eye's cornea, the clear dome on the front surface of the eye, becomes inflamed. The condition is often marked by moderate to intense pain and usually involves any of the following symptoms: pain, impaired e ...

and

keratoconjunctivitis Keratoconjunctivitis is inflammation ("-itis") of the cornea and conjunctiva. When only the cornea is inflamed, it is called ''keratitis''; when only the conjunctiva is inflamed, it is called ''conjunctivitis''. Causes There are several potentia ...

caused by the

herpes simplex virus Herpes simplex virus 1 and 2 (HSV-1 and HSV-2), also known by their taxonomical names ''Human alphaherpesvirus 1'' and '' Human alphaherpesvirus 2'', are two members of the human ''Herpesviridae'' family, a set of viruses that produce viral inf ...

types 1 and 2, as well as for prevention and treatment of

vaccinia virus ''Vaccinia virus'' (VACV or VV) is a large, complex, enveloped virus belonging to the poxvirus family. It has a linear, double-stranded DNA genome approximately 190 kbp in length, which encodes approximately 250 genes. The dimensions of the ...

infections of the eye. A Cochrane Systematic Review showed that trifluridine and

aciclovir Aciclovir (ACV), also known as acyclovir, is an antiviral medication. It is primarily used for the treatment of herpes simplex virus infections, chickenpox, and shingles. Other uses include prevention of cytomegalovirus infections following tra ...

were a more effective treatment than

idoxuridine Idoxuridine is an anti-herpesvirus antiviral drug. It is a nucleoside analogue, a modified form of deoxyuridine, similar enough to be incorporated into viral DNA replication, but the iodine atom added to the uracil component blocks base pairing. I ...

vidarabine Vidarabine or 9-β-D-arabinofuranosyladenine (ara-A) is an antiviral drug which is active against herpes simplex and varicella zoster viruses. Discovery In the 1950s two nucleosides were isolated from the Caribbean sea sponge, sponge ''Tethya c ...

, significantly increasing the relative number of successfully healed eyes in one to two weeks. For cancer treatment, the combination trifluridine/tipiracil is used.

Adverse effects

Common side effects of trifluridine eye drops include transient burning, stinging, local irritation, and

edema Edema, also spelled oedema, and also known as fluid retention, dropsy, hydropsy and swelling, is the build-up of fluid in the body's Tissue (biology), tissue. Most commonly, the legs or arms are affected. Symptoms may include skin which feels t ...

of the eyelids. Adverse effects of the anti-cancer formulation have only been evaluated for the combination trifluridine/tipiracil, not for the individual components.

Interactions

Only ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

'' interaction studies are available. In these, trifluridine used the concentrative nucleoside transporter 1 (CNT1) and equilibrative nucleoside transporters 1 (ENT1) and 2 (ENT2). Drugs that interact with these transporters could influence

blood plasma Blood plasma is a light amber-colored liquid component of blood in which blood cells are absent, but contains proteins and other constituents of whole blood in suspension. It makes up about 55% of the body's total blood volume. It is the intra ...

concentrations of trifluridine. Being a thymidine phosphorylase inhibitor, trifluridine could also interact with substrates of this enzyme such as

zidovudine Zidovudine (ZDV), also known as azidothymidine (AZT), is an antiretroviral medication used to prevent and treat HIV/AIDS. It is generally recommended for use in combination with other antiretrovirals. It may be used to prevent mother-to-child ...

. For the eye drops, trifluridine absorption is negligible, Drugs.com: for Trifluridine. rendering interactions basically irrelevant.

Pharmacology

Mechanism of action (eye drops)

It is a

nucleoside analogue Nucleoside analogues are nucleosides which contain a nucleic acid analogue and a sugar. Nucleotide analogs are nucleotides which contain a nucleic acid analogue, a sugar, and a phosphate group with one to three phosphates. Nucleoside and nucl ...

, a modified form of

deoxyuridine Deoxyuridine (dU) is a compound and a nucleoside.It belongs to a class of compounds known as Pyrimidine 2'-deoxyribonucleosides and closely resembles the chemical composition of uridine but without the presence of the 2' hydroxyl group. Idoxuridine ...

, similar enough to be incorporated into viral

DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...

, but the –CF₃ group added to the

uracil Uracil () (symbol U or Ura) is one of the four nucleobases in the nucleic acid RNA. The others are adenine (A), cytosine (C), and guanine (G). In RNA, uracil binds to adenine via two hydrogen bonds. In DNA, the uracil nucleobase is replaced by ...

component blocks

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

ing, thus interfering with viral DNA replication.

Pharmacokinetics (eye drops)

Trifluridine passes the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...

and is found in the

aqueous humour The aqueous humour is a transparent water-like fluid similar to plasma, but containing low protein concentrations. It is secreted from the ciliary body, a structure supporting the lens of the eyeball. It fills both the anterior and the posterio ...

. Systemic absorption is negligible.

Pharmacokinetics (oral)

Pharmacokinetic data of oral trifluridine have only been evaluated in combination with tipiracil, which significantly affects

biotransformation Biotransformation is the biochemical modification of one chemical compound or a mixture of chemical compounds. Biotransformations can be conducted with whole cells, their lysates, or purified enzymes. Increasingly, biotransformations are effected w ...

of the former. At least 57% of trifluridine are absorbed from the gut, and highest blood plasma concentrations are reached after two hours in cancer patients. The substance has no tendency to accumulate in the body. Plasma protein binding is over 96%. Trifluridine is metabolised by the enzyme

thymidine phosphorylase Thymidine phosphorylase () is an enzyme that is encoded by the TYMP (gene), TYMP gene and catalyzes the reaction: :thymidine + phosphate \rightleftharpoons thymine + 2-deoxy-alpha-D-ribose 1-phosphate Thymidine phosphorylase is involved in purin ...

to 5-trifluoromethyl-2,4(1''H'',3''H'')-pyrimidinedione (FTY), and also by

glucuronidation Glucuronidation is often involved in drug metabolism of substances such as drugs, pollutants, bilirubin, androgens, estrogens, mineralocorticoids, glucocorticoids, fatty acid derivatives, retinoids, and bile acids. These linkages involve glycosid ...

. Elimination half-life is 1.4 hours on the first day and increases to 2.1 hours on the twelfth day. It is mainly excreted via the kidneys. Tipiracil causes C_max (highest blood plasma concentrations) of trifluridine to increase 22-fold, and its

area under the curve In mathematics, an integral assigns numbers to functions in a way that describes displacement, area, volume, and other concepts that arise by combining infinitesimal data. The process of finding integrals is called integration. Along with ...

37-fold, by inhibiting thymidine phosphorylase.

Chemistry

The substance is a white crystalline powder. It is freely soluble in

methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...

and

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

; soluble in water,

ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...

, 0.01 M hydrochloric acid, and 0.01 M sodium hydroxide; sparingly soluble in

isopropyl alcohol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group (chemical formula ) it is the simple ...

and

acetonitrile Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula and structure . This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not clas ...

; slightly soluble in

diethyl ether Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable liq ...

; and very slightly soluble in isopropyl ether. on Lonsurf.

References

External links

* * * * {{Antivirals Anti-herpes virus drugs Antineoplastic drugs Trifluoromethyl compounds GSK plc brands Pfizer brands Pyrimidinediones