Idoxuridine (2-10 μM, 72 hours) possesses an IC50 value of 4.3 μM, making it an antiviral medication [1].

Idoxuridine stimulates C3HeB/FeJ female and male mice as well as A/J female mice when administered intraperitoneally three times, three hours apart, at a dose of 50–200 mg/kg [2].

Cell proliferation assay [1]
Cell Types: Crandell-Reese cat kidney (CRFK) Cell
Tested Concentrations: 2-10 μM
Incubation Duration: 72 hrs (hours)
Experimental Results: Shows IC50 value of 4.3μM.

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Cytotoxicity assay [1]
Cell Types: Crandell-Reese cat kidney (CRFK) cell
Tested Concentrations: 5-50 μM
Incubation Duration: 72 hrs (hours)
Experimental Results: 10.8% reduction relative to CRFK cells.

Animal/Disease Models: C3HeB/FeJ female and male mice and A/J male mice, 2 to 4 months old [2]
Doses: 50-200 mg/kg
Route of Administration: intraperitoneal (ip) injection, 3 times, 3 hrs (hrs (hours)) apart.
Experimental Results: The dose range for stimulating the production of red blood cells (SRBC) by sheep hemolysin plaque forming cells (HPFC) is 50-200 mg/kg.

Absorption, Distribution and Excretion
Systemic absorption is unlikely after ocular administration, even with swallowing nasolacrimal fluid, because vidarabine is rapidly deaminated in the gastrointestinal tract. Idoside has poor corneal penetration and is therefore ineffective for treating iritis or deep stromal infections. Idoside can cross the placenta. Human studies have not been conducted. It is currently unclear whether iodoside is distributed into breast milk. However, no adverse reactions have been documented in humans. This article describes a reproducible microbiological assay for detecting micrograms of iodoside (IDU) in serum, urine, or cerebrospinal fluid. This antiviral assay is not affected by type-specific antibodies or interferon. In patients with suspected human herpesvirus encephalitis, slow intravenous infusion of iodoside (4 mg/min) resulted in drug inactivation and/or clearance rates exceeding the administration rate. Significant concentrations of the drug were detected in serum, urine, and cerebrospinal fluid after multiple rapid infusions of iodoside (50 mg/min). Iodinosides have a low binding rate to serum proteins and do not undergo deiodination in fresh serum or urine to form inactive products (iodouracil, uracil, iodides). They are rapidly excreted in urine. Iodinosides are also inactivated in tissues. This antiviral detection method targeting iodinosides in body fluids should be applicable to other viruses and potential antiviral drugs.
Metabolism/Metabolites
Iodinosides are rapidly inactivated by deaminases or nucleotidases.
Iodinosides are rapidly inactivated by deaminases or nucleotidases.

Toxicity Data
Rat (intraperitoneal injection): LD50: 4000 mg/kg Mouse (intraperitoneal injection): LD50: 1000 mg/kg Interactions Concomitant use of boric acid and idoxuridine preparations is not recommended; boric acid may interact with inactive ingredients in some idoxuridine preparations, leading to precipitation; furthermore, boric acid may interact with preservatives in some idoxuridine preparations (especially higher concentrations of thimerosal), resulting in increased ocular toxicity. Non-human Toxicity Values Mouse intraperitoneal injection LD50: 2.5 g/kg

[1]. In vitro efficacy of ganciclovir, cidofovir, penciclovir, foscarnet, idoxuridine, and acyclovir against feline herpesvirus type-1. Am J Vet Res. 2004 Apr;65(4):399-403.

[2]. Stimulation of hemolysin plaque-forming cells by idoxuridine. Cancer Res. 1975 Jan;35(1):88-92.

[3]. Orthopoxvirus targets for the development of antiviral therapies. Curr Drug Targets Infect Disord.

5-Iodo-2'-deoxyuridine is a pyrimidine-2'-deoxynucleoside compound with 5-iodouracil as its nucleobase, used as an antiviral drug. It is both an antiviral drug and a DNA synthesis inhibitor. It is a pyrimidine-2'-deoxynucleoside and also an organic iodine compound. It is an analogue of deoxyuridine and inhibits viral DNA synthesis. This drug is used as an antiviral drug. Iodidine is a nucleoside analogue antiviral drug. Iodidine is an iodinated analogue of deoxyuridine, possessing activity against herpes simplex virus (HSV) and potentially exhibiting radiosensitizing effects. After ocular administration, iodidine (IUdR) is converted to monophosphate, diphosphate, and triphosphate forms, which are incorporated into DNA, thereby disrupting viral replication. After oral administration of the iodidine prodrug ropiridine, it is converted to iodidine by hepatic aldehyde oxidase. This drug can be incorporated into DNA and increases cellular sensitivity to ionizing radiation by increasing DNA strand breaks. Iodidine is an analogue of deoxyuridine and inhibits viral DNA synthesis. This drug is used as an antiviral agent. Indications: For the treatment of keratoconjunctivitis and keratitis caused by herpes simplex virus. Mechanism of Action: Iodidine exerts its antiviral effect by inhibiting viral replication by replacing thymidine in viral DNA. This, in turn, inhibits the normal function of thymidine phosphorylase and viral DNA polymerase. The mechanism of action of iodidine is to prevent viral replication or infection/destruction of tissues. Iodidine is structurally very similar to thymidine and inhibits thymidine phosphorylase and specific DNA polymerases, which are essential for incorporating thymidine into viral DNA. Iodidine replaces thymidine incorporation into viral DNA, causing DNA defects that prevent the virus from infecting or destroying tissues and from replicating. Iodidine can also be incorporated into mammalian DNA. Therapeutic Uses: Antiviral Drug: Iodidine is indicated for the treatment of keratitis caused by herpes simplex virus (HSV). (This information is included on the US product label.) Iodidine is indicated for the treatment of keratitis caused by vaccinia virus. /Not included in the US product label/
Iodinoside is used to treat keratoconjunctivitis caused by herpes simplex virus (HSV). /Not included in the US product label/
Iodinoside is ineffective against scarring, vascularization, or progressive vision loss that may result from infection. It is also ineffective against post-viral HSV keratoconjunctivitis and adenoviral keratoconjunctivitis. /Not included in the US product label/

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Drug Warnings
Patients with a hypersensitivity to iodine or iodine-containing preparations may also be hypersensitive to this drug.
The following side effects/adverse reactions were selected based on their potential clinical significance: Less common side effects include: allergic reactions (itching, redness, swelling, pain, or other irritation not present prior to treatment), or increased light sensitivity of the eyes; less common side effects include: corneal opacity (blurred, dim, or hazy vision).
FDA Pregnancy Risk Classification: C/Risk cannot be ruled out. There are insufficient, well-controlled human studies, and animal studies have not shown any risk to the fetus or lack relevant data. Use of this drug during pregnancy may harm the fetus; however, the potential benefits may outweigh the potential risks. This study compared the toxicity of topical application of 30% idoxuridine dimethyl sulfoxide solution, dimethyl sulfoxide solution alone, or saline in 96 patients with recurrent genital herpes simplex virus (HSV) infection and 39 patients with primary HSV infection. Complications experienced by patients using idoxuridine dimethyl sulfoxide solution included local burning sensation, systemic contact dermatitis, and vulvar carcinoma in situ. Iodoxuridine in 30% dimethyl sulfoxide was clinically ineffective against genital HSV infection and may be dangerous.

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Pharmacodynamics
The chemical structure of idoxuridine is very close to that of thymidine (one of the four building blocks of DNA, the genetic material of herpesviruses). Therefore, idoxuridine can replace thymidine in viral replication or “growth.” The resulting defective DNA forms a pseudostructure that cannot infect or destroy tissue. In short, Herplex-D topical solution disrupts the infectivity and destructive capabilities of the herpes simplex virus by pre-interfering with key components of its genetic material. Virus-infected cells can only be attacked during the active DNA synthesis phase. This occurs early in the development of herpes simplex lesions, but at different times in different cells. Therefore, ideally, the affected area should be kept saturated with antiviral agents.

C9H11IN2O5

354.0985

353.971

54-42-2

Idoxuridine hydrate;17140-71-5

5905

White to off-white solid powder

2.1±0.1 g/cm3

194 °C(lit.)

1.715

-0.52

3

5

2

17

386

3

C1[C@@H]([C@H](O[C@H]1N2C=C(C(=O)NC2=O)I)CO)O

XQFRJNBWHJMXHO-RRKCRQDMSA-N

InChI=1S/C9H11IN2O5/c10-4-2-12(9(16)11-8(4)15)7-1-5(14)6(3-13)17-7/h2,5-7,13-14H,1,3H2,(H,11,15,16)/t5-,6+,7+/m0/s1

1-[(2R,4S,5R)-4-hydroxy-5-(hydroxymethyl)oxolan-2-yl]-5-iodopyrimidine-2,4-dione

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~125 mg/mL (~353.01 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (5.87 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (5.87 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (5.87 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)