CYP (cytochrome P450); antifungal; Ergosterol biosynthesis pathway (by inhibiting 14 - alpha lanosterol demethylation) [1]; Gastric H,K - ATPase (IC50 = 5.2 μM) [2]

Clotrimazole (brand names Canesten and Lotrimin) is an antifungal medication used to treat fungal diseases in humans and animals, including vaginal yeast infections, oral thrush, and ringworm. It is also used to relieve athlete's foot and jock itch. It is frequently available over the counter in a variety of dose forms, including creams and combo medications. It is also available as lozenges or lozenges (prescription required). Ear infections are typically treated with liquids such as ear drops. Clotrimazole, an antifungal medication, affects the action of gastric H,K-ATPase in the same way as Na,K-ATPase does. Because of its high hydrophobicity, clotrimazole interacts with the ion pump at the membrane domain in the membrane's nonpolar core. A half-saturating concentration of 5.2 microM reduces enzyme activity. Various pump cycle partial reactions were investigated using the electrochromic styrene-based dye RH421, which has been widely utilized to examine P-type ATPase transport mechanism.

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- Clotrimazole is highly active against Candida spp., Trichophyton spp., Microsporum spp. and Malazzesia furfur in vitro. It also has some activity against certain gram - positive bacteria, and at very high concentrations, it can act on Trichomonas spp. [1]
- Clotrimazole can inhibit the gastric H,K - ATPase in a manner similar to that of Na,K - ATPase inhibition. It interacts with the ion pump at the membrane domain in the apolar core of the membrane. The inhibition can be reversed by a decreased pH or increased K+ concentrations [2]
- A 100 - mg clotrimazole neutral vaginal tablet has a partial bactericidal effect on gram - positive bacteria. A new formula containing 500 mg clotrimazole and lactic acid shows improved bactericidal activity against gram - positive bacteria and has a broad bactericidal effect on gram - negative species due to the lactic acid content [3]

In the treatment of vaginal candidiasis, clotrimazole vaginal tablets have produced cure rates comparable with those of conventional nystatin vaginal tablets. There have been no published comparisons with nystatin vaginal cream or foaming vaginal tablets - nystatin dosage forms preferred by some clinicians. Cootrimazole has also been successful in patients who had failed to respond to other antifungal agents such as nystatin and amphotericin B. Results in trichomonal vaginitis are not impressive. Skin infections caused by Candida or dermatophytes have been effectively treated with topical application of clotrimazole. In comparative trials, clotrimazole cream has been as effective as Whitfield's ointment and tolnaftate in the treatment of dermatophytoses, and as effective as nystatin in cutaneous candidiasis. Clotrimazole topical preparations are generally well tolerated, but local irritation has necessitated withdrawal of therapy in a few cases. Candidal septicemia and urinary and pulmonary candidiasis have been cured with oral clotrimazole therapy. Results in other types of serious fungal infections, including pulmonary aspergillosis, have been disappointing. A limiting factor in oral clotrimazole therapy is the high incidence of gastro-intestinal disturbances and neurological reactions[1].

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- Clotrimazole vaginal tablets can be used to treat vaginal candidiasis, with cure rates comparable to those of conventional nystatin vaginal tablets. Oral clotrimazole can cure candidal septicemia, urinary and pulmonary candidiasis, but has poor curative effect on pulmonary aspergillosis. A limiting factor in oral therapy is the high incidence of gastrointestinal disturbances and neurological reactions [1]
- Enzyme Assay： - Gastric H,K - ATPase activity assay: Use the electrochromic styryl dye RH421, which is widely used to study the transport mechanism of P - type ATPases. Analyze various partial reactions of the pump cycle. Measure the enzymatic activity change of gastric H,K - ATPase in the presence of different concentrations of clotrimazole, and determine that the half - saturating concentration of its inhibition is 5.2 μM. It is found that the interaction of clotrimazole with the H,K - ATPase introduces a single “dead - end” branch added to the post - albers scheme in the E1 state of the pump, and in this inhibiting state, the ion binding sites have a significantly enhanced affinity for protons and can bind up to two protons even at pH 8.5 [2]

Clotrimazole 2, a synthetic imidazole derivative, is primarily used locally in the treatment of vaginal and skin infections due to yeasts and dermatophytes. In vitro, it is most active against Candida spp., Trichophyton spp., Microsporum spp. and Malazzesia fuffur (Pityrosporon orbiculare). In addition, it has some in vitro activity against certain Gram-positive bacteria, and at very high concentrations has activity against Trichomonas spp.[1]

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The antimycotic drug clotrimazole inhibits the function of the gastric H,K-ATPase in a manner similar to that observed for the Na,K-ATPase. Because of the high hydrophobicity of the compound, the interaction between clotrimazole and the ion pump occurs at the membrane domain in the apolar core of the membrane. The enzymatic activity was inhibited with a half-saturating concentration of 5.2 microM. Various partial reactions of the pump cycle were analyzed with the electrochromic styryl dye RH421 that has been widely used to study the transport mechanism of P-type ATPases. We discovered that the interaction of clotrimazole with the H,K-ATPase introduces a single "dead-end" branch added to the Post-Albers scheme in the E(1) state of the pump. In this inhibiting state, the ion binding sites have a significantly enhanced affinity for protons and bind up to two protons even at pH 8.5. Inhibition of the pump can be reversed by a decreased pH or increased K(+) concentrations. The mechanistic proposal that allows an explanation of all experiments presented is similar to that published for the Na,K-ATPase[2].

Absorption, Distribution and Excretion
Since clotrimazole is generally poorly absorbed, drug interactions are not a major concern for its use. It is primarily metabolized in the liver. Topical formulations show minimal absorption in serum and tissues. Clotrimazole is a lipophilic drug; animal studies have shown it can be secreted into breast milk. Limited data exist regarding the volume of distribution after oral tablet administration. After oral or intravenous administration, absorption, distribution, and excretion are rapid. It is primarily excreted via bile as inactive metabolites, with a small amount excreted in urine. The absorption rate of clotrimazole after application to intact skin is less than 0.5%; vaginal absorption is 3% to 10%. After application, bactericidal concentrations in the vagina can persist for up to 3 days. A small amount of absorbed drug is metabolized in the liver and excreted via bile. In adults, an oral dose of 200 mg daily results in plasma concentrations of 0.2 to 0.35 μg/mL. Only a very small amount of clotrimazole is absorbed systemically after topical application. After topical application, clotrimazole reaches its highest concentration in the stratum corneum; lower concentrations are observed in the stratum spinosum, papillary stratum, and reticular dermis. When administered intravaginally, a small amount of clotrimazole is absorbed systemically. In patients with normal or inflamed vaginal mucosa, the peak serum clotrimazole concentration 24 hours after a single 100 mg tablet insertion was 0.03 μg/mL, and the peak serum clotrimazole concentration 24 hours after administration of a cream containing 50 mg was 0.01 μg/mL. Approximately 3–10% of the intravaginally administered dose enters the systemic circulation, primarily as metabolites. Clotrimazole is absorbed via the gastrointestinal tract and excreted in feces and urine. With topical application, clotrimazole can penetrate the epidermis, but systemic absorption is minimal. A small amount of absorption has been reported after vaginal tablet administration. Metabolism/Metabolites Hepatic metabolism (to inactive metabolites). Clotrimazole…is metabolized in the liver to inactive compounds… This study investigated the effects of the antifungal imidazole compound clotrimazole on benzo[a]pyrene metabolism in keratinocytes cultured from the epidermis of BALB/c mice. Adding different concentrations of clotrimazole to the cultured keratinocytes resulted in dose-dependent inhibition of the activities of microsomal cytochrome P450-dependent monooxygenases aryl hydroxylase and 7-ethoxycoumarin O-deethylase. The main organic solvent-soluble metabolites of benzo[a]pyrene identified in the cultured cells were trans-7,8-dihydro-7,8-dihydroxybenzo[a]pyrene, 9-hydroxybenzo[a]pyrene, and 3-hydroxybenzo[a]pyrene. Small amounts of trans-4,5-dihydro-4,5-dihydroxybenzo[a]pyrene, benzo[a]pyrene quinones, and trans-9,10-dihydroxybenzo[a]pyrene were also present. The main organic solvent-extractable metabolites of benzo[a]pyrene found in extracellular culture media are primarily diols, with small amounts of phenols and quinones. The main water-soluble metabolites of benzo[a]pyrene are present both intracellularly and extracellularly, including glucuronide conjugates of 3-hydroxybenzo[a]pyrene, 9-hydroxybenzo[a]pyrene, and benzo[a]pyrene-3,6-dione, as well as small amounts of sulfate conjugates (primarily sulfate conjugates of trans-7,8-dihydro-7,8-dihydroxybenzo[a]pyrene). Clotrimazole inhibits the formation of both organic solvent-soluble and water-soluble conjugates in a dose-dependent manner. Clotrimazole also inhibits the in vitro metabolism of benzo[a]pyrene by microsomes prepared from benzo[a]anthracene-induced cultured keratinocytes, particularly showing stronger inhibition in benzo[a]anthracene-induced keratinocytes, especially in the formation of diols and quinones. Clotrimazole significantly reduced the enzyme-mediated covalent binding of benzo[a]pyrene to mouse keratinocyte DNA and proteins in a dose-dependent manner. These results indicate that clotrimazole (a widely used drug for treating various superficial fungal infections of the skin) is a potent inhibitor of polycyclic aromatic hydrocarbon (PAH) cytochrome P450-dependent conversion in cultured mouse keratinocytes. This system provides a convenient method for studying inhibitors of epidermal carcinogen metabolism.
Hepatic (metabolized to inactive metabolites)
Half-life: 2 hours

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Biological half-life
After oral administration of 1.5 g clotrimazole to 7 healthy subjects and 47 patients, peak plasma concentrations were detected at 2 or 4 hours using microbiological methods, reaching up to 1 μg/mL. The half-life ranged from 3.5 to 5.5 hours.
Clotrimazole is absorbed via the gastrointestinal tract, with a biological half-life of approximately 4 hours. Hepatic and renal dysfunction had minimal effect on serum concentrations or half-life.

Toxicity Summary
Clotrimazole interacts with yeast 14α-demethylase, a cytochrome P-450 enzyme that converts lanosterol to ergosterol, an essential component of the cell membrane. Clotrimazole inhibits ergosterol synthesis in this manner, leading to increased cell permeability. Clotrimazole may also inhibit endogenous respiration, interact with membrane phospholipids, inhibit yeast conversion to mycelium and purine uptake, impair triglyceride and/or phospholipid biosynthesis, and inhibit the transmembrane transport of calcium and potassium ions by blocking an ion transport pathway called Gardos channels. Interactions Clotrimazole has been shown to have synergistic effects with certain anionic surfactants against Candida albicans strains. Apparent partition coefficient determinations indicate the formation of lipophilic ion pairs between clotrimazole and anionic surfactants. This suggests that the synergistic effect may be attributed to the formation of these ion pairs.

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Non-human toxicity values
LD50: Male rat, oral administration 708 mg/kg
LD50: Male mouse, oral administration 923 mg/kg

[1]. Clotrimazole: a review of its antifungal activity and therapeutic efficacy. Drugs. 1975;9(6):424-47.

[2]. Inhibition of the gastric H,K-ATPase by clotrimazole. Biochemistry. 2010 Jun 1;49(21):4524-32.

[3]. In vitro antibacterial activity of different clotrimazole formulations. Chemotherapy. 1982;28 Suppl 1:32-6.

Therapeutic Uses
Topical anti-infective; antifungal; growth inhibitor Clotrimazole is a clomilide derivative used to treat topical fungal, dermatophyte, and yeast infections. While clotrimazole exhibits significant in vitro activity against a variety of fungi, its value in treating systemic fungal infections is limited. Vaginal Administration: Insert one 100 mg tablet daily for one week to treat candidal vaginitis. Topical Application: Apply an adequate amount of cream or solution twice daily to the skin infected with Candida albicans, Trichophyton, or Microsporum. A two-week course of treatment is usually sufficient. Clotrimazole has been used in investigational oral administration for the treatment of mucocutaneous candidiasis. For more complete data on the therapeutic uses of clotrimazole (12 types), please visit the HSDB record page. Drug Warnings Clotrimazole preparations are not suitable for use around the eyes; avoid the eye area when using. Clotrimazole tablets should not be used to treat systemic candidiasis. Clotrimazole vaginal tablets…single-dose treatment is not recommended for severe vaginal candidiasis. To achieve the maximum therapeutic effect of clotrimazole, it should be administered according to the prescribed dosage. When taking clotrimazole tablets orally, the tablets must dissolve slowly in the mouth. Therefore, patients taking clotrimazole tablets must be of appropriate age and in good physical and/or mental condition, able to understand and follow the instructions for use. Liver function tests should be performed regularly during treatment with oral clotrimazole tablets, especially in patients with impaired liver function. Clotrimazole cream, lotion, and solution should only be used in early pregnancy if the medication is deemed essential to the patient's health. Because it is unclear whether clotrimazole is excreted into breast milk, breastfeeding women should use this medication with caution.

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Pharmacodynamics
Clotrimazole is a broad-spectrum antifungal drug that inhibits the growth of pathogenic yeasts by altering cell membrane permeability. Clotrimazole has antifungal activity at concentrations up to 20 μg/mL and may have bactericidal activity against Candida albicans and other Candida species at higher concentrations in vitro. Unfortunately, clotrimazole resistance, which was rare in the past, is now common in various patient populations. Clotrimazole is generally considered a bacteriostatic rather than a bactericidal agent, although this distinction is not absolute, as clotrimazole also exhibits bactericidal properties at high concentrations. Clotrimazole is a synthetic imidazole derivative primarily used for the topical treatment of vaginal and skin infections caused by yeasts and dermatophytes. It can also be used to treat patients who do not respond to other antifungal drugs such as nystatin and amphotericin B [1]. The main mechanism of clotrimazole's antifungal action is the concentration-dependent inhibition of 14α-lanosterol demethylation, thereby inhibiting ergosterol synthesis, which in turn disrupts the permeability barrier of the fungal cell membrane and inhibits fungal growth. In addition, it can also inhibit sarcoplasmic reticulum Ca2+ ATPase, reduce intracellular calcium ion levels, and block calcium-dependent potassium channels and voltage-dependent calcium channels [6].

C22H17CLN2

344.84

344.108

C, 76.63; H, 4.97; Cl, 10.28; N, 8.12

23593-75-1

Clotrimazole-d5;1185076-41-8

2812

White to off-white solid powder

1.1±0.1 g/cm3

482.3±40.0 °C at 760 mmHg

147-149ºC

245.5±27.3 °C

0.0±1.2 mmHg at 25°C

1.617

5.44

0

1

4

25

396

0

C1=CC=C(C=C1)C(C2=CC=CC=C2)(C3=CC=CC=C3Cl)N4C=CN=C4

VNFPBHJOKIVQEB-UHFFFAOYSA-N

InChI=1S/C22H17ClN2/c23-21-14-8-7-13-20(21)22(25-16-15-24-17-25,18-9-3-1-4-10-18)19-11-5-2-6-12-19/h1-17H

1-[(2-chlorophenyl)-diphenylmethyl]imidazole

Canesten; Lotrimin; 23593-75-1; Lotrimin; Canesten; Mycelex; Mycosporin; Clotrimazol; Empecid; Clotrimazole

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 : ~50 mg/mL (~144.99 mM)
H2O : ~0.1 mg/mL (~0.29 mM)

Solubility in Formulation 1: ≥ 2.5 mg/mL (7.25 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 25.0 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: ≥ 2.5 mg/mL (7.25 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 25.0 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: ≥ 2.5 mg/mL (7.25 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 25.0 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.)