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Trade names | Fungizone, Mysteclin-F, AmBisome and other |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682643 |
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Routes of administration | Intravenous infusion |
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Bioavailability | 100% (IV) |
Metabolism | kidney |
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ECHA InfoCard | 100.014.311 |
Chemical and physical data | |
Formula | C47H73NO17 |
Molar mass | 924.091 g·mol−1 |
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Melting point | 170 °C (338 °F) |
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Amphotericin B is an antifungal medication used for serious fungal infections and leishmaniasis. [3] The fungal infections it is used to treat include mucormycosis, aspergillosis, blastomycosis, candidiasis, coccidioidomycosis, and cryptococcosis. [4] For certain infections it is given with flucytosine. [5] It is typically given intravenously (injection into a vein). [4]
Common side effects include a reaction with fever, chills, and headaches soon after the medication is given, as well as kidney problems. [4] Allergic symptoms including anaphylaxis may occur. [4] Other serious side effects include low blood potassium and myocarditis (inflammation of the heart). [3] It appears to be relatively safe in pregnancy. [4] There is a lipid formulation that has a lower risk of side effects. [4] It is in the polyene class of medications and works in part by interfering with the cell membrane of the fungus. [3] [4]
Amphotericin B was isolated from Streptomyces nodosus in 1955 at the Squibb For Medical Research Institute from cultures isolated from the streptomycete obtained from the river bed of Orinoco in that region of Venezuela [6] and came into medical use in 1958. [7] [8] It is on the World Health Organization's List of Essential Medicines. [9] It is available as a generic medication. [4] [10]
One of the main uses of amphotericin B is treating a wide range of systemic fungal infections. Due to its extensive side effects, it is often reserved for severe infections in critically ill, or immunocompromised patients. It is considered first line therapy for invasive mucormycosis infections, cryptococcal meningitis, and certain aspergillus and candidal infections. [11] [12] It has been a highly effective drug for over fifty years in large part because it has a low incidence of drug resistance in the pathogens it treats. This is because amphotericin B resistance requires sacrifices on the part of the pathogen that make it susceptible to the host environment, and too weak to cause infection. [13]
Amphotericin B is used for life-threatening protozoan infections such as visceral leishmaniasis [14] and primary amoebic meningoencephalitis. [15]
The following table shows the amphotericin B susceptibility for a selection of medically important fungi.
Species | Amphotericin B MIC breakpoint (mg/L) |
---|---|
Aspergillus fumigatus | 1 [16] |
Aspergillus terreus | Resistant [16] [17] |
Candida albicans | 1 [16] |
Candida glabrata | 1 [16] |
Candida krusei | 1 [16] |
Candida lusitaniae | Intrinsically resistant [17] |
Cryptococcus neoformans | 2 [18] |
Fusarium oxysporum | 2 [18] |
Amphotericin B alone is insoluble in normal saline at a pH of 7. Therefore, several formulations have been devised to improve its intravenous bioavailability. [19] Lipid-based formulations of amphotericin B are no more effective than conventional formulations, although there is some evidence that lipid-based formulations may be better tolerated by patients and may have fewer adverse effects. [20]
The original formulation uses sodium deoxycholate to improve solubility. [17] Amphotericin B deoxycholate (ABD) is administered intravenously. [21] As the original formulation of amphotericin, it is often referred to as "conventional" amphotericin. [22]
In order to improve the tolerability of amphotericin and reduce toxicity, several lipid formulations have been developed. [17] Liposomal formulations have been found to have less renal toxicity than deoxycholate, [23] [24] and fewer infusion-related reactions. [17] They are more expensive than amphotericin B deoxycholate. [25]
AmBisome (liposomal amphotericin B; LAMB) is a liposomal formulation of amphotericin B for injection and consists of a mixture of phosphatidylcholine, cholesterol and distearoyl phosphatidylglycerol that in aqueous media spontaneously arrange into unilamellar vesicles that contain amphotericin B. [17] [26] It was developed by NeXstar Pharmaceuticals (acquired by Gilead Sciences in 1999). It was approved by the FDA in 1997. [27] It is marketed by Gilead in Europe and licensed to Astellas Pharma (formerly Fujisawa Pharmaceuticals) for marketing in the US, and Sumitomo Pharmaceuticals in Japan.[ citation needed ]
A number of lipid complex preparations are also available. Abelcet was approved by the FDA in 1995. [28] It consists of amphotericin B and two lipids in a 1:1 ratio that form large ribbon-like structures. [17] Amphotec is a complex of amphotericin and sodium cholesteryl sulfate in a 1:1 ratio. Two molecules of each form a tetramer that aggregate into spiral arms on a disk-like complex. [26] It was approved by the FDA in 1996. [28]
An oral preparation exists but is not widely available. [29] The amphipathic nature of amphotericin along with its low solubility and permeability has posed major hurdles for oral administration given its low bioavailability. In the past it had been used for fungal infections of the surface of the GI tract such as thrush, but has been replaced by other antifungals such as nystatin and fluconazole. [30]
However, recently novel nanoparticulate drug delivery systems such as AmbiOnp, [31] nanosuspensions, lipid-based drug delivery systems including cochleates, self-emulsifying drug delivery systems, [32] solid lipid nanoparticles [31] and polymeric nanoparticles [33] —such as amphotericin B in pegylated polylactide coglycolide copolymer nanoparticles [34] —have demonstrated potential for oral formulation of amphotericin B. [35] The oral lipid nanocrystal amphotericin by Matinas Biopharma is furthest along having completed a successful phase 2 clinical trial in cryptococcal meningitis. [36]
Amphotericin B is well known for its severe and potentially lethal side effects, earning it the nickname "amphoterrible". [37] [38] Very often, it causes a serious reaction soon after infusion (within 1 to 3 hours), consisting of high fever, shaking chills, hypotension, anorexia, nausea, vomiting, headache, dyspnea and tachypnea, drowsiness, and generalized weakness. The violent chills and fevers have caused the drug to be nicknamed "shake and bake". [39] [40] The precise etiology of the reaction is unclear, although it may involve increased prostaglandin synthesis and the release of cytokines from macrophages. [41] [42] Deoxycholate formulations (ABD) may also stimulate the release of histamine from mast cells and basophils. [43] Reactions sometimes subside with later applications of the drug. This nearly universal febrile response necessitates a critical (and diagnostically difficult) professional determination as to whether the onset of high fever is a novel symptom of a fast-progressing disease, or merely the effect of the drug. To decrease the likelihood and severity of the symptoms, initial doses should be low, and increased slowly. Paracetamol, pethidine, diphenhydramine, and hydrocortisone have all been used to treat or prevent the syndrome, but the prophylactic use of these drugs is often limited by the patient's condition. [44]
Intravenously administered amphotericin B in therapeutic doses has also been associated with multiple organ damage. Kidney damage is a frequently reported side effect, and can be severe and/or irreversible. Less kidney toxicity has been reported with liposomal formulations (such as AmBisome) and it has become preferred in patients with preexisting renal injury. [45] [46] The integrity of the liposome is disrupted when it binds to the fungal cell wall, but is not affected by the mammalian cell membrane, [47] so the association with liposomes decreases the exposure of the kidneys to amphotericin B, which explains its less nephrotoxic effects. [48]
In addition, electrolyte imbalances such as hypokalemia and hypomagnesemia are also common. [49] In the liver, increased liver enzymes and hepatotoxicity (up to and including fulminant liver failure) are common. In the circulatory system, several forms of anemia and other blood dyscrasias (leukopenia, thrombopenia), serious cardiac arrhythmias (including ventricular fibrillation), and even frank cardiac failure have been reported. Skin reactions, including serious forms, are also possible.[ citation needed ]
Drug-drug interactions may occur when amphotericin B is coadministered with the following agents: [50]
Amphotericin B binds with ergosterol, a component of fungal cell membranes, forming pores that cause rapid leakage of monovalent ions (K+, Na+, H+ and Cl−) and subsequent fungal cell death. This is amphotericin B's primary effect as an antifungal agent. [51] [52] It has been found that the amphotericin B/ergosterol bimolecular complex that maintains these pores is stabilized by Van der Waals interactions. [53] Researchers have found evidence that amphotericin B also causes oxidative stress within the fungal cell, [54] but it remains unclear to what extent this oxidative damage contributes to the drug's effectiveness. [51] The addition of free radical scavengers or antioxidants can lead to amphotericin resistance in some species, such as Scedosporium prolificans , without affecting the cell wall.[ citation needed ]
Two amphotericins, amphotericin A and amphotericin B, are known, but only B is used clinically, because it is significantly more active in vivo . Amphotericin A is almost identical to amphotericin B (having a C=C double bond between the 27th and 28th carbons), but has little antifungal activity. [19]
Mammalian and fungal membranes both contain sterols, a primary membrane target for amphotericin B. Because mammalian and fungal membranes are similar in structure and composition, this is one mechanism by which amphotericin B causes cellular toxicity. Amphotericin B molecules can form pores in the host membrane as well as the fungal membrane. This impairment in membrane barrier function can have lethal effects. [54] [55] [56] Ergosterol, the fungal sterol, is more sensitive to amphotericin B than cholesterol, the common mammalian sterol. Reactivity with the membrane is also sterol concentration dependent. [57] Bacteria are not affected as their cell membranes do not usually contain sterols.[ citation needed ]
Amphotericin B administration is limited by infusion-related toxicity. This is thought to result from innate immune production of proinflammatory cytokines. [55] [58]
The natural route to synthesis includes polyketide synthase components. [59] The carbon chains of amphotericin B are assembled from sixteen 'C2' acetate and three 'C3'propionate units by polyketide syntheses (PKSs). [60] Polyketide biosynthesis begins with the decarboxylative condensation of a dicarboxylic acid extender unit with a starter acyl unit to form a β-ketoacyl intermediate. The growing chain is constructed by a series of Claisen reactions. Within each module, the extender units are loaded onto the current ACP domain by acetyl transferase (AT). The ACP-bound elongation group reacts in a Claisen condensation with the KS-bound polyketide chain. Ketoreductase (KR), dehydratase (DH) and enoyl reductase (ER) enzymes may also be present to form alcohol, double bonds or single bonds. [61] After cyclisation, the macrolactone core undergoes further modification by hydroxylation, methylation and glycosylation. The order of these three post-cyclization processes is unknown. [61]
It was originally extracted from Streptomyces nodosus , a filamentous bacterium, in 1955, at the Squibb Institute for Medical Research from cultures of an undescribed streptomycete isolated from the soil collected in the Orinoco River region of Venezuela. [19] [62] Two antifungal substances were isolated from the soil culture, amphotericin A and amphotericin B, but B had better antifungal activity. For decades it remained the only effective therapy for invasive fungal disease until the development of the azole antifungals in the early 1980s. [21]
Its complete stereo structure was determined in 1970 by an X-ray structure of the N-iodoacetyl derivative. [60] The first synthesis of the compound's naturally occurring enantiomeric form was achieved in 1987 by K. C. Nicolaou. [63]
Amphotericin B was used to treat a patient with disseminated coccidioidomycosis who was admitted to the U.S. Public Health Service Hospital, Seattle, Washington on January 16, 1957. "The course was rapidly downhill with a grim prognosis as manifested by positive blood cultures, rising complement fixation titers, and failure of the skin to react to intradermal coccidioidin. Amphotericin B was started eight weeks following the onset of his illness. Following this there was remarkable improvement both objectively and subjectively. A fourteen-month follow-up following discontinuance of the drug revealed stabilization of all laboratory studies except for a re-elevation of the complement fixation titer from 1 to 16 to 1 to 32. The patient was completely asymptomatic except for the production of sputum containing a few spherules. The clinical effect of this drug in this patient has been most encouraging and is in agreement with results obtained by others. The lasting effect of the drug seems suggested by the patient's complete well-being after fourteen months of cessation of treatment. It is reasonable to assume that this drug will play a major part in the specific treatment of this disease." [64]
It is a subgroup of the macrolide antibiotics, and exhibits similar structural elements. [65] Currently, the drug is available in many forms. Either "conventionally" complexed with sodium deoxycholate (ABD), as a cholesteryl sulfate complex (ABCD), as a lipid complex (ABLC), and as a liposomal formulation (LAMB). The latter formulations have been developed to improve tolerability and decrease toxicity, but may show considerably different pharmacokinetic characteristics compared to conventional amphotericin B. [17]
Amphotericin's name originates from the chemical's amphoteric properties. [66]
It is commercially known as Fungilin, Fungizone, Abelcet, AmBisome, Fungisome, Amphocil, Amphotec, and Halizon. [67]
Coccidioidomycosis, is a mammalian fungal disease caused by Coccidioides immitis or Coccidioides posadasii. It is commonly known as cocci, Valley fever, as well as California fever, desert rheumatism, or San Joaquin Valley fever. Coccidioidomycosis is endemic in certain parts of the United States in Arizona, California, Nevada, New Mexico, Texas, Utah, and northern Mexico.
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis, and others. Such drugs are usually obtained by a doctor's prescription, but a few are available over the counter (OTC). The evolution of antifungal resistance is a growing threat to health globally.
Nystatin, sold under the brand name Mycostatin among others, is an antifungal medication. It is used to treat Candida infections of the skin including diaper rash, thrush, esophageal candidiasis, and vaginal yeast infections. It may also be used to prevent candidiasis in those who are at high risk. Nystatin may be used by mouth, in the vagina, or applied to the skin.
Ketoconazole, sold under the brand name Nizoral among others, is an antiandrogen, antifungal, and antiglucocorticoid medication used to treat a number of fungal infections. Applied to the skin it is used for fungal skin infections such as tinea, cutaneous candidiasis, pityriasis versicolor, dandruff, and seborrheic dermatitis. Taken by mouth it is a less preferred option and only recommended for severe infections when other agents cannot be used. Other uses include treatment of excessive male-patterned hair growth in women and Cushing's syndrome.
Fluconazole is an antifungal medication used for a number of fungal infections. This includes candidiasis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, dermatophytosis, and tinea versicolor. It is also used to prevent candidiasis in those who are at high risk such as following organ transplantation, low birth weight babies, and those with low blood neutrophil counts. It is given either by mouth or by injection into a vein.
Coccidioides immitis is a pathogenic fungus that resides in the soil in certain parts of the southwestern United States, northern Mexico, and a few other areas in the Western Hemisphere.
Caspofungin is a lipopeptide antifungal drug from Merck & Co., Inc.. It is a member of a class of antifungals termed the echinocandins. It works by inhibiting the enzyme (1→3)-β-D-glucan synthase and thereby disturbing the integrity of the fungal cell wall.
Terconazole is an antifungal drug used to treat vaginal yeast infection. It comes as a lotion or a suppository and disrupts the biosynthesis of fats in a yeast cell. It has a relatively broad spectrum compared to azole compounds but not triazole compounds. Testing shows that it is a suitable compound for prophylaxis for those that suffer from chronic vulvovaginal candidiasis.
Polyene antimycotics, sometimes referred to as polyene antibiotics, are a class of antimicrobial polyene compounds that target fungi. These polyene antimycotics are typically obtained from certain species of Streptomyces bacteria. Previously, polyenes were thought to bind to ergosterol in the fungal cell membrane, weakening it and causing leakage of K+ and Na+ ions, which could contribute to fungal cell death. However, more detailed studies of polyene molecular properties have challenged this model suggesting that polyenes instead bind and extract ergosterol directly from the cellular membrane thus disrupting the many cellular functions ergosterols perform. Amphotericin B, nystatin, and natamycin are examples of polyene antimycotics. They are a subgroup of macrolides.
Sporotrichosis, also known as rose handler's disease, is a fungal infection that may be localised to skin, lungs, bone and joint, or become systemic. It presents with firm painless nodules that later ulcerate. Following initial exposure to Sporothrix schenckii, the disease typically progresses over a period of a week to several months. Serious complications may develop in people who have a weakened immune system.
Flucytosine, also known as 5-fluorocytosine (5-FC), is an antifungal medication. It is specifically used, together with amphotericin B, for serious Candida infections and cryptococcosis. It may be used by itself or with other antifungals for chromomycosis. Flucytosine is used by mouth and by injection into a vein.
Miltefosine, sold under the trade name Impavido among others, is a medication mainly used to treat leishmaniasis and free-living amoeba infections such as Naegleria fowleri and Balamuthia mandrillaris. This includes the three forms of leishmaniasis: cutaneous, visceral and mucosal. It may be used with liposomal amphotericin B or paromomycin. It is taken by mouth.
Echinocandins are a class of antifungal drugs that inhibit the synthesis of β-glucan in the fungal cell wall via noncompetitive inhibition of the enzyme 1,3-β glucan synthase. The class has been dubbed the "penicillin of antifungals," along with the related papulacandins, as their mechanism of action resembles that of penicillin in bacteria. β-glucans are carbohydrate polymers that are cross-linked with other fungal cell wall components, the fungal equivalent to bacterial peptidoglycan. Caspofungin, micafungin, and anidulafungin are semisynthetic echinocandin derivatives with limited clinical use due to their solubility, antifungal spectrum, and pharmacokinetic properties.
Clotrimazole, sold under the brand name Lotrimin, among others, is an antifungal medication. It is used to treat vaginal yeast infections, oral thrush, diaper rash, tinea versicolor, and types of ringworm including athlete's foot and jock itch. It can be taken by mouth or applied as a cream to the skin or in the vagina.
Isavuconazonium, sold under the brand name Cresemba, is a systemic antifungal medication of the triazole class which is used to treat invasive aspergillosis and mucormycosis. It is used as the sulfate. It is taken by mouth or given via injection into a vein.
Apophysomyces variabilis is an emerging fungal pathogen that can cause serious and sometimes fatal infection in humans. This fungus is a soil-dwelling saprobe with tropical to subtropical distribution. It is a zygomycete that causes mucormycosis, an infection in humans brought about by fungi in the order Mucorales. Infectious cases have been reported globally in locations including the Americas, Southeast Asia, India, and Australia. Apophysomyces variabilis infections are not transmissible from person to person.
Nilima Arun Kshirsagar is an Indian clinical pharmacologist who developed and patented liposomal amphotericin B and its drug delivery system in 1993. She is the former dean of King Edward Memorial Hospital and Seth Gordhandas Sunderdas Medical College. She is the national chairperson in clinical pharmacology at Indian Council of Medical Research (ICMR) and president of the South Asian chapter of the American college of clinical pharmacology. She is a Member of the WHO Committees on Product development and Drug statistics Methodology.
Topical antifungaldrugs are used to treat fungal infections on the skin, scalp, nails, vagina or inside the mouth. These medications come as creams, gels, lotions, ointments, powders, shampoos, tinctures and sprays. Most antifungal drugs induce fungal cell death by destroying the cell wall of the fungus. These drugs inhibit the production of ergosterol, which is a fundamental component of the fungal cell membrane and wall.
Oteseconazole, a novel tetrazole containing orally bioavailable and selective inhibitor of fungal lanosterol 14α-demethylase (CYP51), has shown promising efficacy in the treatment of recurrent vulvovaginal candidiasis (RVVC).
AM-2-19 is an experimental antifungal drug based on amphotericin B (AmB) that is engineered to be less toxic to the kidneys. Amphotericin B, a polyene group of molecule targets fungal ergosterol as well as human cholesterol, results in kidney damage. While AM-2-19 or SF001, initially developed by Sfunga Therapeutics, and now being developed by Elion Therapeutics, not only selective to fungal ergosterol but also draws out fungal ergosterol more effectively. The investigational new drug (IND) application was filed in May 2023. SF001 received Qualified Infectious Disease Product (QIDP) for invasive aspergillosis and Fast Track designations from the FDA in 2023. It is now under phase I trial. An oral formulation is currently in the feasibility phase.