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Trifluridine (also called trifluorothymidine or TFT) is an anti-herpesvirusantiviral drug, used primarily on the eye. It was sold under the trade name Viroptic by Glaxo Wellcome, now merged into GlaxoSmithKline. The brand is now owned by Monarch Pharmaceuticals, which is wholly owned by King Pharmaceuticals.

Trifluridine was approved for medical use in 1980.^[1] It is also a component of the anti-cancer drug trifluridine/tipiracil, which is taken by mouth.

Medical uses[edit]

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Trifluridine eye drops are used for the treatment of keratitis and keratoconjunctivitis caused by the herpes simplex virus types 1 and 2, as well as for prevention and treatment of vaccinia virus infections of the eye.^[2]

A Cochrane Systematic Review showed that trifluridine and aciclovir were a more effective treatment than idoxuridine or vidarabine,^[3] significantly increasing the relative number of successfully healed eyes in one to two weeks.^[4]

For cancer treatment, the combination trifluridine/tipiracil is used.

Adverse effects[edit]

Common side effects of trifluridine eye drops include transient burning, stinging, local irritation, and edema of the eyelids.^[2]

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

Interactions[edit]

Only in vitro 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 concentrations of trifluridine. Being a thymidine phosphorylase inhibitor, trifluridine could also interact with substrates of this enzyme such as zidovudine.^[5]

For the eye drops, trifluridine absorption is negligible,^[2] rendering interactions basically irrelevant.

Pharmacology[edit]

Mechanism of action (eye drops)[edit]

H11f3

It is a nucleoside analogue, a modified form of deoxyuridine, similar enough to be incorporated into viral DNA replication, but the –CF₃ group added to the uracil component blocks base pairing, thus interfering with viral DNA replication.

Pharmacokinetics (eye drops)[edit]

Trifluridine passes the cornea and is found in the aqueous humour. Systemic absorption is negligible.^[2]

Pharmacokinetics (oral)[edit]

Pharmacokinetic data of oral trifluridine have only been evaluated in combination with tipiracil, which significantly affects biotransformation 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 to 5-trifluoromethyl-2,4(1H,3H)-pyrimidinedione (FTY), and also by glucuronidation. 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.^[5]

Tipiracil causes C_max (highest blood plasma concentrations) of trifluridine to increase 22-fold, and its area under the curve 37-fold, by inhibiting thymidine phosphorylase.^[5]

Chemistry[edit]

The substance is a white crystalline powder. It is freely soluble in methanol and acetone; soluble in water, ethanol, 0.01 M hydrochloric acid, and 0.01 M sodium hydroxide; sparingly soluble in isopropyl alcohol and acetonitrile; slightly soluble in diethyl ether; and very slightly soluble in isopropyl ether.^[6]

References[edit]

1. ^Long, Sarah S.; Pickering, Larry K.; Prober, Charles G. (2012). Principles and Practice of Pediatric Infectious Disease. Elsevier Health Sciences. p. 1502. ISBN978-1437727029.
2. ^ ^abcdDrugs.com: Monograph for Trifluridine.
3. ^Wilhelmus, Kirk R (2015-01-09). 'Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis'. Cochrane Database of Systematic Reviews. John Wiley & Sons, Ltd. 1: CD002898. doi:10.1002/14651858.cd002898.pub5. PMC4443501. PMID25879115.
4. ^Wilhelmus, Kirk R (2015-01-09). Cochrane Eyes and Vision Group (ed.). 'Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis'. Cochrane Database of Systematic Reviews. 1: CD002898. doi:10.1002/14651858.CD002898.pub5. PMC4443501. PMID25879115.
5. ^ ^abcHaberfeld, H, ed. (2015). Austria-Codex (in German). Vienna: Österreichischer Apothekerverlag.
6. ^FDA Professional Drug Information on Lonsurf.

External links[edit]

• Costin D, Dogaru M, Popa A, Cijevschi I (2004). 'Trifluridine therapy in herpetic in keratitis'. Rev Med Chir Soc Med Nat Iasi. 108 (2): 409–12. PMID15688823.
• Kuster P, Taravella M, Gelinas M, Stepp P (1998). 'Delivery of trifluridine to human cornea and aqueous using collagen shields'. CLAO J. 24 (2): 122–4. PMID9571274.
• O'Brien W, Taylor J (1991). 'Therapeutic response of herpes simplex virus-induced corneal edema to trifluridine in combination with immunosuppressive agents'. Invest Ophthalmol Vis Sci. 32 (9): 2455–61. PMID1907950.
• 'Trifluridine Ophthalmic Solution, 1%'(PDF). Retrieved 2007-03-24.CS1 maint: discouraged parameter (link)

3/19/03

Page 6 of 10

© 2003 Fairchild Semiconductor Corporation

PHOTO FET OPTOCOUPLERS

H11F1 H11F2 H11F3

TYPICAL APPLICATIONS

AS A VARIABLE RESISTOR

AS AN ANALOG SIGNAL SWITCH

ISOLATED VARIABLE ATTENUATORS

Distortion free attenuation of low level A.C. signals is accom-
plished by varying the IRED current, I

F

Note the wide dynamic

range and absence of coupling capacitors; D.C. level shifting or
parasitic feedback to the controlling function.

ISOLATED SAMPLE AND HOLD CIRCUIT

Accuracy and range are improved over conventional FET
switches because the H11F has no charge injection from the
control signal. The H11F also provides switching of either
polarity input signal up to 30V magnitude.

AUTOMATIC GAIN CONTROL

This simple circuit provides over 70db of stable gain control for
an AGC signal range of from 0 to 30mA. This basic circuit can
be used to provide programmable fade and attack for electronic
music.

MULTIPLEXED, OPTICALLY-ISOLATED A/D CONVERSION

The optical isolation, linearity and low offset voltage of the
H11F allows the remote multiplexing of low level analog signals
from such transducers as thermocouplers, Hall effect devices,
strain gauges, etc. to a single A/D converter.

ACTIVE FILTER FINE TUNING/BAND SWITCHING

The linearity of resistance and the low offset voltage of the
H11F allows the remote tuning or band-switching of active
filters without switching glitches or distortion. This schematic
illustrates the concept, with current to the H11F1 IRED’s
controlling the filter’s transfer characteristic.

TEST EQUIPMENT - KELVIN CONTACT POLARITY

In many test equipment designs the auto polarity function uses
reed relay contacts to switch the Kelvin Contact polarity. These
reeds are normally one of the highest maintenance cost items
due to sticking contacts and mechanical problems. The totally
solid-State H11F eliminates these troubles while providing
faster switching.

500K

H11f3m

V

IN

V

OUT

V

IN

V

OUT

500K

50

Ω

I

F

H11F1

I

F

H11F1

LOW FREQUENCY

HIGH FREQUENCY

DYNAMIC RANGE

≈ 70db

FOR 0

≤ I

F

≤ 30mA

@10KHz

DYNAMIC RANGE

≈ 50db

FOR 0

≤ I

H11f3 Datasheet

F

≤ 30mA

@1MHz

V

IN

V

OUT

I

F

V

IN

V

OUT

I

F

t

H11F1

C

+

-

V

IN

V

OUT

I

F

H11F1

AGC

SIGNAL

500K

+

-

V

1

CALL V1

V

2

V

n

H11F1

MSB

MSB

CALL

V

n

D

ATA

INPUT

H11F1

LSB

LSB

H74A1

H74A1

A/D

CONVERTER

PROCESS
CONTROL

LOGIC

SYSTEM

DATA

ACQUISITION

I

F1

ADJUSTS f

1

, I

F2

ADJUSTS f

2

I

F1

A2

A3

A1

H11F1

I

F2

H11F1

I

F

A

C

H11F1

I

F

H11F1

I

F

I

TEST

B

D

H11F1

I

Ge H11f3

F

H11F1

DEVICE

UNDER

TEST

PARAMETER

SENSING

BOARD

I

F

TO

A & B FOR

POLARITY 1

C & D FOR

POLARITY 2