The primary target of isoconazole is the fungal cytochrome P450 enzyme lanosterol 14alpha-demethylase (CYP51, also known as Erg11). By binding to the heme iron of CYP51, isoconazole prevents the demethylation of lanosterol to ergosterol. This leads to the accumulation of toxic 14alpha-methylated sterols and depletion of ergosterol, disrupting membrane integrity and function. It has a higher affinity for fungal CYP51 than for human CYP enzymes, providing selectivity.

In vitro, isoconazole shows potent antifungal activity against a broad range of dermatophytes (e.g., Trichophyton rubrum, MIC 0.1-1 ug/mL), yeasts (e.g., Candida albicans, MIC 0.5-2 ug/mL), and Malassezia species. It also has antibacterial activity against some Gram-positive bacteria (MIC 4-16 ug/mL). The IC50 for ergosterol biosynthesis inhibition in C. albicans is approximately 0.1-0.5 uM. It is more potent than clotrimazole against some strains. In addition, it has anti-inflammatory properties via inhibition of leukotriene synthesis.

In vivo, topical application of isoconazole nitrate in animal models (e.g., guinea pig dermatophytosis) shows high efficacy with once-daily application for 7-14 days, achieving mycological cure rates >90% at concentrations of 1-2%. It has low systemic absorption after topical administration (<1% of applied dose), minimizing systemic side effects. In a mouse model of vaginal candidiasis, isoconazole (0.5% cream) reduced fungal burden by >99% after 5 days of treatment.

An in vitro enzyme inhibition assay for CYP51: Recombinant C. albicans CYP51 (1 uM) is incubated with 10 uM of a fluorescent substrate (e.g., dibenzylfluorescein) and varying concentrations of isoconazole (0.1 nM-10 uM) in 100 mM potassium phosphate buffer (pH 7.4) containing 0.1 mM DTT and 0.5 uM NADPH-P450 reductase. The reaction is initiated by adding 1 mM NADPH. Fluorescence (ex 485/em 535) is monitored for 30 min at 37degC. IC50 is calculated. The IC50 for isoconazole is typically 10-50 nM.

A cell-based antifungal susceptibility assay: Candida albicans ATCC 90028 (1×10^3 CFU/well) is incubated in RPMI-1640 medium in 96-well plates with serial dilutions of isoconazole (0.001-100 ug/mL). After 48 h at 35degC, the MIC (minimum inhibitory concentration) is determined visually or by OD600. The MIC for isoconazole against C. albicans is typically 0.25-2 ug/mL. A cell viability assay using mammalian cells (e.g., HaCaT keratinocytes) shows low toxicity (IC50 >100 uM).

An in vivo animal protocol for topical efficacy: Female Hartley guinea pigs (n=10 per group) are infected with Trichophyton mentagrophytes on shaved dorsal skin. On day 7 post-infection, isoconazole nitrate 1% cream is applied once daily for 14 days. Clinical scores (erythema, scaling) are recorded daily. On day 21, skin scrapings are cultured for fungal growth. The treated group shows a significant reduction in clinical score (≥80%) and negative cultures in >90% of animals. The vehicle control shows persistent infection. An oral toxicity study in rats (for systemic exposure) is not relevant as the drug is topical.

PK of isoconazole after topical application: The compound is highly lipophilic (logP ~5.5). After topical application to human skin (1% cream, 5 g), plasma concentrations are very low (Cmax <10 ng/mL), and the elimination half-life from plasma is approximately 24-48 h. It accumulates in the stratum corneum, where it persists for several days after treatment cessation. After oral administration (not used clinically), it is well absorbed but extensively metabolized by CYP3A4; half-life is ~8 h. The volume of distribution is large (>5 L/kg). Oral bioavailability is >50% but not used due to toxicity.

Acute toxicity: Isoconazole nitrate has low acute toxicity after topical application (LD50 >2000 mg/kg in rats). Oral LD50 in rats is approximately 1000 mg/kg. It is not a skin sensitizer. In reproductive toxicity studies, it is not teratogenic in animals at topical doses. However, it is potentially hepatotoxic if absorbed systemically at high doses. It is not a carcinogen. Topical application may cause mild local irritation (burning, itching) in some patients. Avoid contact with eyes. It is contraindicated in patients with known hypersensitivity.

[1]. Frenzel, U. H., & Gutekunst, A. (1983). Contact dermatitis to isoconazole nitrate. Contact dermatitis, 9(1), 74.

[2]. Veraldi S. (2013). Isoconazole nitrate: a unique broad-spectrum antimicrobial azole effective in the treatment of dermatomycoses, both as monotherapy and in combination with corticosteroids. Mycoses, 56 Suppl 1, 3–15.

Isoconazole is an imidazole compound with a 2-[(2,6-dichlorobenzyl)oxy]-2-(2,4-dichlorophenyl)ethyl group at the 1 position. It is a dichlorobenzene, belonging to the imidazole class of compounds, and is also an ether. Isoconazole is an azole antifungal drug with similar efficacy to clotrimazole in treating foot and vaginal infections. See also: Isoconazole nitrate (active portion).

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Isoconazole (CAS: 27523-40-6) is marketed as isoconazole nitrate (CAS: 24168-96-5) under brand names such as Travogen, Travazol, and Iodozol. It is a broad-spectrum imidazole antifungal, structurally related to miconazole and econazole. It has been used clinically since the 1970s, primarily in Europe and Asia, for the treatment of athlete's foot (tinea pedis), ringworm, jock itch, and vaginal candidiasis. The typical formulation is 1% cream or ointment, applied once or twice daily. It is also available in combination with diflucortolone valerate (a corticosteroid) to reduce inflammation (e.g., Travogen). The mechanism of action is similar to other azole antifungals: inhibition of ergosterol synthesis. Isoconazole has shown some activity against certain azole-resistant Candida strains, possibly due to its high lipophilicity and ability to accumulate in the fungal membrane. In addition to its antifungal activity, it exhibits anti-inflammatory effects by inhibiting 5-lipoxygenase and cyclooxygenase, reducing leukotriene and prostaglandin synthesis. This dual action is beneficial for treating inflamed lesions. The drug is generally well-tolerated with a low incidence of side effects (2-5% of patients report mild local reactions). It is not recommended for use during pregnancy due to insufficient safety data (FDA pregnancy category C). The compound is a racemic mixture; the enantiomers have similar activity. Its synthesis involves the reaction of 1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethanol with 2,6-dichlorobenzyl chloride. The nitrate salt improves water solubility and stability. Isoconazole is included on the World Health Organization's List of Essential Medicines as an antifungal. It is available over-the-counter in some countries. Due to its broad spectrum and low cost, it remains a popular topical antifungal agent. However, resistance has been reported in some Candida species after prolonged use. The compound is stable at room temperature when stored in a tightly sealed container, protected from light. Its purity is typically >98% by HPLC. It is not a controlled substance. In research, it is used as a positive control in antifungal susceptibility testing and in studies of ergosterol biosynthesis.

C18H14CL4N2O

416.13

415.983

27523-40-6

Isoconazole nitrate; 24168-96-5

3760

Typically exists as solids at room temperature

0

6

25

407

0

C1=CC(=C(C(=C1)Cl)COC(CN2C=CN=C2)C3=C(C=C(C=C3)Cl)Cl)Cl

MPIPASJGOJYODL-UHFFFAOYSA-N

InChI=1S/C18H14Cl4N2O/c19-12-4-5-13(17(22)8-12)18(9-24-7-6-23-11-24)25-10-14-15(20)2-1-3-16(14)21/h1-8,11,18H,9-10H2

1-[2-(2,4-dichlorophenyl)-2-[(2,6-dichlorophenyl)methoxy]ethyl]imidazole

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*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.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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