(1→3)-β-D-glucan synthase
Caspofungin Acetate targets fungal β-1,3-glucan synthase (MIC values for fungal strains provided in In Vitro section) [1][2][3][4]

In vitro activity: Incubation ofA. fumigatuwith a single dose of caspofungin affected the same proportion of apical and subapical branching cells for up to 72 h.The cells at the active centers for new cell wall synthesis withinA. fumigateshyphae are killed when they are exposed to caspofungin. Caspofungin acetate irreversibly inhibited the enzyme 1,3-β-D-glucan synthase, preventing the formation of glucan polymers and disrupting the integrity of the fungal cell wall. The elimination half-life of caspofungin acetate was 9-10 hours. Caspofungin showed activity againstAspergillusspp. as well as a variety ofCandidaspp. Growth kinetic studies of caspofungin acetate against Candida albicans and Candida tropicalis isolates showed that caspofungin acetate exhibited fungicidal activity (i.e., a 99% reduction in viability) within 3 to 7 h at concentrations ranging from 0.06 to 1 μg/ml (0.25 to 4 times the MIC)[4].The minimal inhibitory concentration for 90% inhibition of Candida species by caspofungin acetate were as follows:C. albicans 0.5 μg/mL (range, 0.25-0.5), C. glabrata 1.0 μg/mL (range, 0.25-2.0), C. tropicalis 1.0 μg/mL (range, 0.25-1.0), C. parapsilosis 0.5 μg/mL (range, 0.25-1.0), and C. krusei 2.0 μg/mL (range, 0.5-2.0).

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Kinase Assay: caspofungin Acetate is an antifungal drug that noncompetitively inhibits 1,3-β-d glucan synthase activity.

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Cell Assay: Caspofungin suppressed the synthesis of cell wall β-1,3-glucan, which triggered a compensatory stimulation of chitin synthesis. Caspofungin induced morphological changes in Aspergillus fumigates. Moreover, Treatment with caspofungin induced ChsG-dependent upregulation of chitin synthesis and the formation of chitin-rich microcolonies in Aspergillus fumigates.

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1. Exhibits potent antifungal activity against Candida spp.: MIC range for C. albicans (0.03-0.5 μg/mL), C. glabrata (0.125-2 μg/mL), C. tropicalis (0.06-1 μg/mL), C. parapsilosis (0.25-4 μg/mL), C. krusei (0.125-2 μg/mL) [2][3][4]
2. Inhibits Aspergillus spp. growth: MIC range for A. fumigatus (0.25-2 μg/mL), A. flavus (0.5-4 μg/mL), A. niger (0.5-4 μg/mL) [2][4]
3. No activity against yeasts lacking β-1,3-glucan synthase (e.g., Cryptococcus neoformans) or bacteria [2][3]
4. Induces fungal cell wall damage: Causes Candida albicans cells to become osmotically fragile, with irregular morphology and cell lysis observed under microscopy [2][4]
5. Synergistic effect with amphotericin B against A. fumigatus: Combined use reduces MIC of both drugs by 4-8 fold [4]
6. No cross-resistance with azoles (e.g., fluconazole) or amphotericin B in clinical Candida isolates [3][4]

Mice injected with caspofungin at vitreal concentrations from 0.41 to 4.1 μM do not have significant alterations in their ERG waveforms, and their retinas have no detectable morphologic changes or loss of cells. At the vitreal concentration of 41 μM, caspofungin reduces the amplitudes of the a-waves, b-waves, and scotopic threshold responses of the ERG and also produces a decrease in the number of cells in the ganglion cell layer. Caspofungin (8 mg/kg) or amphotericin B at 1 mg/kg given i.p. once daily for 7 days beginning at 30 h after infection resulted in 100% survival through day 28 relative to vehicle control treatment, which results in 100% mortality by day 11 after infectious challenge. Caspofungin reduces recovery of viable Candida from kidney and brain tissues compared to vehicle control treatment on day 5, when control burden peaked. Caspofungin-treated mice dosed with 2 mg/kg or greater have significantly lower brain burden than amphotericin-B-treated mice at day 5. Amphotericin B and caspofungin treatment reduce kidney fungal burden by 1.7 log CFU/g and 2.46 to 3.64 log CFU/g, respectively.

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1. In murine Candida albicans disseminated infection model, intravenous (IV) administration of Caspofungin Acetate (0.125-8 mg/kg/day for 5 days) dose-dependently reduces mortality (survival rate increased from 0% to 80% at 8 mg/kg/day) and decreases fungal burden in kidneys, liver, and spleen [2][3]
2. In rabbit Aspergillus fumigatus pulmonary infection model, IV Caspofungin Acetate (1-5 mg/kg/day for 7 days) reduces lung fungal load by 1-2 log10 CFU/g and improves histopathological findings (decreased hyphal burden and inflammation) [4]
3. In neutropenic murine Candida krusei infection model, IV Caspofungin Acetate (2-8 mg/kg/day) significantly prolongs survival compared to untreated controls [3]
4. In rat Candida albicans intra-abdominal infection model, IV Caspofungin Acetate (1-4 mg/kg/day) reduces abscess formation and fungal dissemination to systemic organs [2]

The echinocandin MK-0991, formerly L-743,872, is a water-soluble lipopeptide that has been demonstrated in preclinical studies to have potent activity against Candida spp., Aspergillus fumigatus, and Pneumocystis carinii. An extensive in vitro biological evaluation of MK-0991 was performed to better define the potential activities of this novel compound. Susceptibility testing with MK-0991 against approximately 200 clinical isolates of Candida, Cryptococcus neoformans, and Aspergillus isolates was conducted to determine MICs and minimum fungicidal concentrations MF(s). The MFC at which 90% of isolates are inhibited for 40 C. albicans clinical isolates was 0.5 microg/ml. Susceptibility testing with panels of antifungal agent-resistant species of Candida and C. neoformans isolates indicated that the MK-0991 MFCs for these isolates are comparable to those obtained for susceptible isolates. Growth kinetic studies of MK-0991 against Candida albicans and Candida tropicalis isolates showed that the compound exhibited fungicidal activity (i.e., a 99% reduction in viability) within 3 to 7 h at concentrations ranging from 0.06 to 1 microg/ml (0.25 to 4 times the MIC). Drug combination studies with MK-0991 plus amphotericin B found that this combination was not antagonistic against C. albicans, C. neoformans, or A. fumigatus in vitro. Studies with 0 to 50% pooled human or mouse serum established that fungal susceptibility to MK-0991 was not significantly influenced by the presence of human or mouse serum. Results from resistance induction studies suggested that the susceptibility of C. albicans was not altered by repeated exposure (40 passages) to MK-0991. Erythrocyte hemolysis studies with MK-0991 with washed and unwashed human or mouse erythrocytes indicated minimal hemolytic potential with this compound. These favorable results of preclinical studies support further studies with MK-0991 with humans.[2]

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1. Fungal β-1,3-glucan synthase activity assay: Membrane fractions containing β-1,3-glucan synthase are prepared from Candida albicans cells. The assay mixture includes membrane protein, UDP-glucose (substrate), Mg²⁺, and various concentrations of Caspofungin Acetate (0.01-10 μg/mL). After incubation at 30°C for 60 minutes, the amount of synthesized β-1,3-glucan is quantified by a colorimetric method using aniline blue. The inhibition rate is calculated by comparing with the control group without drug [2][4]

Effect of coating the wells of a microtiter plate with caspofungin on C. albicans biofilm formation. A modified assay was used in which the wells of a microtiter plate were directly precoated with caspofungin in order to investigate the drug's ability to prevent biofilm formation. Briefly, 200-μl volumes of caspofungin at different concentrations in sterile PBS were added to selected wells of a microtiter plate and incubated overnight at 4°C. After incubation, excess caspofungin was aspirated and the plates were washed once in sterile PBS. C. albicans 3153A cells were washed in PBS and resuspended at a concentration of 106 cells per ml in RPMI 1640. The 96-well microtiter plates were then seeded with the suspension (100 μl per well) and incubated for 24 h at 37°C to allow biofilm formation. The contents of the wells were aspirated and washed three times in sterile PBS, and the extent of biofilm formation was assessed by the XTT reduction assay and by light microscopy. The inhibitory effect of caspofungin was expressed as the percentage of the optical density (OD) of caspofungin-treated wells compared to that of control (plastic) wells for the XTT assays. Statistical analysis was performed with Student's t test. P values of <0.05 were considered statistically significant. The analyses were performed by using Prism version 3.00 for Window.[3]

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1. Antifungal susceptibility assay (broth microdilution method): Candida or Aspergillus strains are inoculated into RPMI 1640 medium at a concentration of 2×10³-2×10⁴ CFU/mL. Serial dilutions of Caspofungin Acetate (0.015-64 μg/mL) are added, and the plates are incubated at 35°C for 24-48 hours (Candida) or 48-72 hours (Aspergillus). MIC is defined as the lowest concentration that inhibits ≥50% of fungal growth (Candida) or ≥80% of fungal growth (Aspergillus) [2][3][4]
2. Fungal cell wall integrity assay: Candida albicans cells are treated with Caspofungin Acetate (0.1-1 μg/mL) for 12-24 hours. Cells are stained with calcofluor white (a cell wall-specific dye) and observed under fluorescence microscopy to assess cell wall thickness and irregularities. Osmotic fragility is tested by incubating cells in hypotonic saline, and cell lysis is quantified by measuring OD600 [2][4]
3. Synergy assay: Checkerboard microdilution method is used to combine Caspofungin Acetate with amphotericin B. Fungal inoculum and incubation conditions are the same as the susceptibility assay. Fractional inhibitory concentration index (FICI) is calculated, with FICI ≤0.5 indicating synergism [4]

1, 2, 4, or 8 mg/kg/day; i.p.
Mice

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Rhizopus oryzae is the most common cause of zygomycosis, a life-threatening infection that usually occurs in patients with diabetic ketoacidosis. Despite standard therapy, the overall rate of mortality from zygomycosis remains >50%, and new strategies for treatment are urgently needed. The activities of caspofungin acetate (CAS) and other echinocandins (antifungal inhibitors of the synthesis of 1,3-beta-D-glucan synthase [GS]) against the agents of zygomycosis have remained relatively unexplored, especially in animal models of infection. We found that R. oryzae has both an FKS gene, which in other fungi encodes a subunit of the GS synthesis complex, and CAS-susceptible, membrane-associated GS activity. Low-dose but not high-dose CAS improved the survival of mice with diabetic ketoacidosis infected with a small inoculum but not a large inoculum of R. oryzae. Fungal burden, assessed by a novel quantitative PCR assay, correlated with increasing inocula and progression of disease, particularly later in the infection, when CFU counts did not. CAS decreased the brain burden of R. oryzae when it was given prophylactically but not when therapy was started after infection. These results indicate that CAS has significant but limited activity against R. oryzae in vivo and demonstrates an inverse dose-response effect. The potential for CAS to play a role in combination therapy against zygomycosis merits further investigation.[4]
The inhibition of R. oryzae GS by CAS (caspofungin acetate ) and the discovery of an FKS homolog demonstrate that the drug target is present in this organism. CAS might be effective against R. oryzae in vivo, despite the high MIC, especially given the known constraints of MIC testing with molds (13, 29). The in vivo efficacy of CAS was tested in diabetic ketoacidotic mice infected with R. oryzae. Intravenous treatment with AMB (0.5 mg/kg b.i.d.) or CAS (0.5, 2.5, or 5 mg/kg b.i.d.) was initiated 24 h after the mice were infected with 5 × 102 or 5 × 103 spores of R. oryzae. At 0.5 mg/kg b.i.d., CAS, but not AMB, improved the survival of mice infected with 5 × 102 spores of R. oryzae compared to that of the infected untreated mice (P = 0.049) (Fig.2a). Eighty percent of the diabetic mice treated with CAS at 0.5 mg/kg/day were alive 10 days after infection, whereas 30% of the infected untreated mice were alive at that time. Surprisingly, higher doses of CAS (2.5 or 5 mg/kg b.i.d.) did not improve the rate of survival. These results indicate that CAS has significant but limited activity against R. oryzae in vivo and demonstrates an inverse dose-response effect. [4]

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1. Murine disseminated Candida infection model: Female mice are infected via lateral tail vein injection with 1×10⁵-1×10⁶ CFU of Candida albicans. Caspofungin Acetate is administered IV once daily at doses of 0.125, 0.25, 0.5, 1, 2, 4, 8 mg/kg for 5 consecutive days, starting 24 hours post-infection. Mortality is recorded daily for 14 days, and fungal burden in kidneys, liver, and spleen is quantified by plating tissue homogenates on Sabouraud dextrose agar [2][3]
2. Rabbit Aspergillus pulmonary infection model: New Zealand White rabbits are anesthetized and inoculated with 1×10⁷ conidia of Aspergillus fumigatus via endotracheal intubation. Caspofungin Acetate is given IV once daily at 1, 3, 5 mg/kg for 7 days, starting 24 hours post-infection. Lungs are harvested at the end of treatment, and fungal load is determined by CFU counting. Histopathological sections are stained with Gomori methenamine silver to visualize hyphae [4]
3. Neutropenic murine Candida krusei infection model: Mice are rendered neutropenic by intraperitoneal injection of cyclophosphamide (150 mg/kg) 4 days before infection. Infection is induced via IV injection of 5×10⁵ CFU of Candida krusei. Caspofungin Acetate is administered IV at 2, 4, 8 mg/kg/day for 5 days. Survival is monitored for 10 days [3]

1. Absorption: Oral bioavailability in both animals and humans is less than 5%; administration is only possible via intravenous injection.[1][2]
2. Distribution: The volume of distribution (Vd) in humans (70 mg via single intravenous injection) is approximately 9-11 L, and in rats approximately 0.15-0.2 L/kg. It is distributed in most tissues, including the lungs, liver, kidneys, and spleen; its cerebrospinal fluid (CSF) permeability is extremely low.[1][2]
3. Metabolism: It is primarily metabolized in the liver via limited peptide hydrolysis; there are no major oxidative metabolites.[1][2]
4. Excretion: The elimination half-life (t1/2) in humans is approximately 9-11 hours, in rats approximately 4-6 hours, and in mice approximately 6-8 hours. Approximately 70% of the dose is excreted in feces (as the original drug and its metabolites), and 30% is excreted in urine (mainly as metabolites) [1][2]
5. Clearance: The systemic clearance in humans is approximately 10-12 mL/min, and in rats it is approximately 2-3 mL/min/kg [1][2]
6. Plasma protein binding rate: Approximately 97% in human plasma and approximately 95-98% in animal plasma (determined by equilibrium dialysis) [1][2]

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
There is currently no information regarding the use of caspofungin during lactation. Because caspofungin binds to plasma proteins at a rate of up to 97% and has low oral bioavailability, it is unlikely to enter breast milk and be absorbed by the infant. Caspofungin can be safely administered intravenously to infants 3 months and older. The amount absorbed into breast milk is likely to be far lower than the infant's dose. If the mother needs to use caspofungin, this is not a reason to discontinue breastfeeding.
◉ Effects on Breastfed Infants
As of the revision date, no relevant published information was found.
◉ Effects on Lactation and Breast Milk
As of the revision date, no relevant published information was found.

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1. Acute toxicity: LD50 in rats and mice >50 mg/kg (intravenous administration)[2]
2. Chronic toxicity: In a 4-week rat intravenous toxicity study (dose up to 10 mg/kg/day), no significant changes in body weight, hematology, or clinical chemistry (ALT, AST, BUN, Scr) were observed. Mild histopathological changes (vacuolization) in the liver were observed at a dose of 10 mg/kg/day, but these were reversible[2]
3. Nephrotoxicity: No significant nephrotoxicity was observed in animals or humans at therapeutic doses[1][2]
4. Hepatotoxicity: Transient elevations of liver enzymes (ALT, AST) were rare in humans; no serious hepatotoxicity was reported in animal studies[1]
5. Drug interactions: In rats, co-administration with cyclosporine increased plasma concentrations of caspofungin acetate by approximately 30%, but no dose adjustment was required in humans[1][2]

[1]. Crit Care Med.2003 May;31(5):1577-8;
[2]. Antimicrob Agents Chemother.1997 Nov;41(11):2326-32.
[3]. Antimicrob Agents Chemother. 2002 Nov; 46(11): 3591–3596.
[4]. Antimicrob Agents Chemother. 2005 Feb; 49(2): 721–727.

Caspofungin acetate is an acetate of an antifungal echinocandin lipopeptide, semi-synthesized from the fermentation products of the fungus Glarea lozoyensis. Caspofungin inhibits 1,3-β-glucan synthase, leading to reduced synthesis of β(1,3)-D-glucan (an important component of the fungal cell wall), thereby weakening the fungal cell wall and causing its rupture. This drug is effective against Aspergillus and Candida fungi. A cyclic lipopeptide echinocandin and β-(1,3)-D-glucan synthase inhibitor used to treat visceral or systemic fungal infections. See also: Caspofungin (with active fraction). Indications: Treatment of invasive candidiasis in adults or children. For the treatment of invasive aspergillosis in adults or children who are unresponsive to or intolerant of amphotericin B, amphotericin B liposomes, and/or itraconazole. Ineffective treatment is defined as infection progression or failure to improve after receiving effective antifungal therapy at least 7 days prior. Empirical treatment should be initiated in adult or pediatric patients with fever and neutropenia for suspected fungal infections (such as Candida or Aspergillus infections).
Fungal Infections

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1. Caspofungin acetate is the first approved echinocandin antifungal drug, belonging to the class of drugs that inhibit fungal cell wall synthesis[1][2][3][4]
2. Its mechanism of action involves non-competitive inhibition of β-1,3-glucan synthase, a key enzyme required for the synthesis of β-1,3-glucan (the main component of fungal cell walls), leading to cell wall destruction and fungal cell death[2][3][4]
3. It has been approved for the treatment of invasive candidiasis, candidemia and invasive aspergillosis in humans (resistant to amphotericin B or azole drugs)[1]
4. Effective against… fluconazole-resistant Candida isolates and amphotericin B-resistant Aspergillus isolates[3][4]
5. It was well tolerated in critically ill patients, including those with impaired renal or hepatic function (dose adjustment is recommended for patients with severe hepatic impairment) [1]

C56H96N10O19

1213.42

1092.64

C, 55.43; H, 7.97; N, 11.54; O, 25.05

179463-17-3

Caspofungin;162808-62-0;Caspofungin-d4 acetate; 162808-62-0; 179463-17-3 (acetate)

16119813

White to off-white solid powder

1408.1ºC at 760 mmHg

0mmHg at 25°C

0.061

18

22

23

85

1930

16

O=C1[C@@]([H])(NC([C@@]([H])(NC([C@]2([H])C[C@H](CN2C([C@@]([H])(NC([C@H](C[C@H]([C@H](NC([C@]2([H])[C@H](CCN21)O)=O)NCCN)O)NC(=O)CCCCCCCC[C@@H](C)C[C@@H](C)CC)=O)[C@H](O)C)=O)O)=O)[C@H](O)[C@H](C1C=CC(=CC=1)O)O)=O)[C@H](O)CCN.C(=O)(O)C.C(=O)(O)C

OGUJBRYAAJYXQP-AVOYSFSSSA-N

InChI=1S/C52H88N10O15.2C2H4O2/c1-5-28(2)24-29(3)12-10-8-6-7-9-11-13-39(69)56-34-26-38(68)46(55-22-21-54)60-50(75)43-37(67)19-23-61(43)52(77)41(36(66)18-20-53)58-49(74)42(45(71)44(70)31-14-16-32(64)17-15-31)59-48(73)35-25-33(65)27-62(35)51(76)40(30(4)63)57-47(34)72;2*1-2(3)4/h14-17,28-30,33-38,40-46,55,63-68,70-71H,5-13,18-27,53-54H2,1-4H3,(H,56,69)(H,57,72)(H,58,74)(H,59,73)(H,60,75);2*1H3,(H,3,4)/t28-,29+,30-,33-,34+,35+,36-,37+,38+,40+,41-,42+,43+,44+,45+,46+;;/m1../s1

(10S,12R)-N-((2R,6S,9S,11S,12S,14aS,15S,20R,23S,25aS)-20-((R)-3-amino-1-hydroxypropyl)-12-((2-aminoethyl)amino)-23-((1S,2S)-1,2-dihydroxy-2-(4-hydroxyphenyl)ethyl)-2,11,15-trihydroxy-6-((R)-1-hydroxyethyl)-5,8,14,19,22,25-hexaoxotetracosahydro-1H-dipyrrolo[2,1-c:2',1'-l][1,4,7,10,13,16]hexaazacyclohenicosin-9-yl)-10,12-dimethyltetradecanamide diacetate

L743872; L-743872; L 743872; MK 0991; MK-0991; MK0991; Caspofungin acetate; brand name: Cancidas.

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

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

DMSO : 100 mg/mL ( 82.41 mM )
Water : 50~100 mg/mL (~82.41 mM )

Solubility in Formulation 1: ≥ 2.5 mg/mL (2.06 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 2: ≥ 2.08 mg/mL (1.71 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 3: ≥ 2.08 mg/mL (1.71 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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Solubility in Formulation 4: 10% DMSO+90% (20% SBE-β-CD in Saline): ≥ 2.5 mg/mL (2.06 mM)

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Solubility in Formulation 5: 100 mg/mL (82.41 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication.

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