The echinocandins represent the third major class of antifungal agents and the first to enter clinical use with a genuinely new mechanism of action: inhibition of fungal cell wall synthesis rather than membrane targeting. This novel target site confers excellent tolerability, a favorable drug interaction profile compared to the azoles, and fungicidal activity against Candida species that gives the class a distinct therapeutic advantage in invasive candidiasis.
Cell Wall Target and Mechanism. Fungi, unlike mammalian cells, possess a rigid cell wall composed primarily of beta-1,3-d-glucan (beta-glucan), chitin, and mannoproteins. Beta-glucan is an essential structural polymer that provides tensile strength and maintains cell shape and osmotic integrity. Its synthesis is carried out by the enzyme complex beta-1,3-d-glucan synthase (GS), encoded by the FKS1 (glucan synthase subunit 1 gene) and FKS2 (glucan synthase subunit 2 gene) genes in Candida species and the fksA gene in Aspergillus fumigatus. The echinocandins are cyclic lipopeptides that act as non-competitive inhibitors of GS, binding to the Fks subunit of the enzyme at the inner leaflet of the plasma membrane and blocking glucan chain elongation. Because mammalian cells lack a cell wall and do not synthesize beta-1,3-d-glucan, the GS target is exquisitely fungal-specific, which accounts for the excellent tolerability profile of the echinocandin class.1
Fungicidal vs. Fungistatic Activity. Echinocandins are fungicidal against most Candida species, which is their principal pharmacodynamic advantage over the azoles in invasive candidiasis. Disruption of beta-1,3-d-glucan synthesis destabilizes the cell wall, leading to osmotic lysis and rapid cell death through a concentration-dependent mechanism. The pharmacodynamic index (PD index) driving echinocandin efficacy is the ratio of the area under the concentration-time curve to the minimum inhibitory concentration (AUC/MIC), indicating that total drug exposure over time is the key determinant of antifungal effect rather than the time the drug concentration remains above the minimum inhibitory concentration (MIC). Against Aspergillus species, echinocandins are fungistatic rather than fungicidal: they inhibit the synthesis of new glucan at the hyphal tips, producing a characteristic morphological abnormality of swollen, abnormally branched hyphae, but do not kill existing hyphae. This distinction explains why echinocandin monotherapy is not first-line for invasive aspergillosis.12
Class Pharmacokinetic Features. All three echinocandins share certain pharmacokinetic characteristics that follow from their lipopeptide structure. They are large molecules with molecular weights exceeding 1,000 daltons (Da) that are not absorbed from the gastrointestinal (GI) tract, requiring intravenous (IV) administration for all therapeutic indications. Once administered IV, they are highly protein-bound (greater than 97% for all three agents, primarily to albumin), have large volumes of distribution reflecting extensive tissue penetration, and achieve high concentrations in the liver, spleen, lung, and kidneys. Penetration into the central nervous system (CNS) and vitreous humor of the eye is poor, which is an important limitation for Candida endophthalmitis and CNS candidiasis, conditions that require alternative or adjunctive therapy. Of note, none of the three echinocandins is significantly metabolized by cytochrome P450 (CYP) enzymes, which largely eliminates the CYP-mediated drug-drug interaction burden that complicates azole use.2
Elimination Pathways. Despite their shared CYP-independence, the three echinocandins differ in their elimination pathways, which has clinical implications. Caspofungin undergoes slow chemical degradation and N-acetylation in plasma, with metabolites excreted in bile and urine; dose adjustment is required for moderate to severe hepatic impairment (Child-Pugh score 7 to 9 or above). Micafungin is metabolized by arylsulfatase and catechol-O-methyltransferase (COMT) in the liver, with biliary excretion of metabolites; dose adjustment is not required for renal or hepatic impairment at currently licensed doses. Anidulafungin undergoes slow chemical degradation to an open-ring peptide in plasma at physiological temperature and pH, with biliary excretion; it is not hepatically metabolized in a significant way, and dose adjustment is not required for either renal or hepatic impairment. This non-enzymatic degradation of anidulafungin is unique among the class and is the reason it does not require dose adjustment in any organ dysfunction state.3
Target: beta-1,3-d-glucan synthase (Fks subunit) — cell wall-specific, absent from mammalian cells. Activity: fungicidal against most Candida (AUC/MIC-driven); fungistatic against Aspergillus. Administration: IV only (all three). No CYP metabolism — low drug-drug interaction burden. Poor CNS and ocular penetration — limitation for CNS candidiasis and endophthalmitis. Dose adjustment: caspofungin requires reduction for hepatic impairment; micafungin and anidulafungin do not.
Caspofungin was the first echinocandin approved by the United States Food and Drug Administration (FDA), receiving approval in 2001, and has the longest track record of clinical use and the most extensive evidence base of the three agents. Its pharmacokinetic profile and interaction landscape are somewhat more complex than those of micafungin and anidulafungin, making it important to understand in detail.
Pharmacokinetics and Distribution. Caspofungin is administered intravenously and is highly protein-bound (approximately 97% to albumin). The volume of distribution at steady state is approximately 9.67 liters (L), which is smaller than that of the other echinocandins and reflects distribution primarily into well-perfused tissues. Plasma half-life following a single dose is approximately 9 to 11 hours, but the effective beta half-life during the terminal elimination phase is approximately 40 to 50 hours, reflecting slow release from tissue compartments. Steady-state plasma concentrations are reached after approximately 14 days of once-daily dosing without a loading dose, or within one to two days when a loading dose is administered. Caspofungin penetrates well into the lung, liver, spleen, and kidney, supporting its use in hepatosplenic candidiasis and pulmonary aspergillosis. CNS (central nervous system) and vitreous penetration is poor.4
Dosing Regimen. The standard adult dosing regimen for caspofungin is a 70 mg loading dose on Day 1 followed by 50 mg once daily for all indications. The loading dose is essential to rapidly achieve steady-state plasma concentrations given the long terminal half-life; omitting it delays therapeutic exposure by approximately two weeks. For patients weighing more than 80 kg, the maintenance dose may be increased to 70 mg once daily, as body weight significantly affects caspofungin pharmacokinetics. Dose adjustment is required for moderate hepatic impairment (Child-Pugh score 7 to 9): reduce the maintenance dose to 35 mg once daily (retain the 70 mg loading dose). For severe hepatic impairment (Child-Pugh score above 9), limited data exist and caspofungin is generally avoided if alternatives are available. No dose adjustment is needed for renal impairment because the drug and its metabolites are excreted in both urine and feces and renal elimination is not the dominant pathway.4
Hepatic Metabolism and Interactions. Caspofungin undergoes slow spontaneous chemical degradation and enzymatic N-acetylation in plasma; it is not a substrate of CYP3A4 (cytochrome P450 3A4), but it does interact with certain drugs through a mechanism involving induction of drug transporters. Rifampin (rifampicin), a potent inducer of CYP (cytochrome P450) enzymes and drug transporters, significantly reduces caspofungin trough concentrations (area under the concentration-time curve (AUC) reduction of approximately 30%); when co-administered with rifampin or other strong inducers (efavirenz, nevirapine, phenytoin, carbamazepine, dexamethasone), the caspofungin maintenance dose should be increased to 70 mg once daily. Tacrolimus plasma concentrations are reduced approximately 20% by caspofungin through an uncertain mechanism, requiring tacrolimus therapeutic drug monitoring (TDM) when this combination is used. Cyclosporine A increases caspofungin AUC by approximately 35% through inhibition of hepatic uptake transporters, and the co-administration is associated with transient elevations in alanine aminotransferase (ALT); many prescribers avoid this combination when alternatives exist, though it is not absolutely contraindicated.45
Loading dose: 70 mg IV on Day 1 (all indications; do not omit). Maintenance: 50 mg IV once daily (increase to 70 mg if weight above 80 kg). Hepatic impairment (Child-Pugh 7–9): reduce maintenance to 35 mg once daily, retain 70 mg loading dose. No renal adjustment required. Rifampin, phenytoin, carbamazepine co-administration: increase maintenance to 70 mg once daily. Cyclosporine combination: monitor ALT; consider alternatives.
Micafungin and anidulafungin are the second and third echinocandins approved by the FDA, in 2005 and 2006 respectively. Both share the class mechanism and fungicidal activity against Candida, but differ from caspofungin in their elimination pathways, interaction profiles, and dosing regimens in ways that are clinically meaningful in specific patient populations.
Micafungin: Pharmacokinetics. Micafungin has a volume of distribution of approximately 0.39 liters per kilogram (L/kg) and a plasma half-life of approximately 11 to 17 hours, allowing once-daily dosing without a formal loading dose requirement for most indications. Protein binding exceeds 99%, primarily to albumin. Micafungin is metabolized in the liver by arylsulfatase to M-1 (catechol form) and subsequently by catechol-O-methyltransferase (COMT) to M-2 (methoxy form), with minor contributions from CYP3A4 (cytochrome P450 3A4) to a hydroxylated metabolite (M-5); however, CYP3A4 accounts for a minor fraction of overall elimination and is not a primary metabolic route. Biliary excretion accounts for the majority of elimination; urinary excretion is minimal. Because renal elimination is negligible and hepatic metabolism does not depend significantly on CYP (cytochrome P450) enzymes, no dose adjustment is required for renal impairment or mild-to-moderate hepatic impairment. For severe hepatic impairment, micafungin has not been well studied and should be used with caution.3
Micafungin: Dosing and Indications. The standard adult dosing for micafungin is 100 mg IV once daily for candidemia and invasive candidiasis, and 150 mg IV once daily for esophageal candidiasis. For prophylaxis of Candida infections in hematopoietic stem cell transplant (HSCT) recipients, 50 mg IV once daily is the approved dose. Micafungin does not require a loading dose because its pharmacokinetic profile allows therapeutic trough concentrations to be achieved within one to two days of standard once-daily dosing. Body weight adjustment is not standard in adults, though population pharmacokinetic data suggest that patients at the extremes of body weight may benefit from weight-based dosing in selected circumstances. Micafungin achieved non-inferiority to liposomal amphotericin B (L-AmB) and to caspofungin in large randomized trials for invasive candidiasis, establishing its equivalence within the class.5
Micafungin: Interaction Profile. Micafungin is a weak inhibitor of CYP3A4 in vitro but has minimal clinically significant CYP-mediated interactions in vivo. The most notable interaction is a modest increase in sirolimus plasma concentrations (AUC (area under the concentration-time curve) increase of approximately 21%) through inhibition of intestinal CYP3A4 and possibly P-glycoprotein (P-gp). Nifedipine exposure is similarly modestly increased. These interactions are generally manageable with monitoring rather than dose adjustment or avoidance. Tacrolimus and cyclosporine concentrations are not significantly affected by micafungin, in contrast to the situation with caspofungin, which simplifies transplant management. A regulatory concern raised by animal studies showing hepatocellular tumors in rats with long-term high-dose micafungin has not been confirmed as clinically significant in human experience, but this finding has influenced labeling in some regulatory jurisdictions, recommending caution with extended courses.35
Anidulafungin: Pharmacokinetics and Elimination. Anidulafungin is distinguished within the echinocandin class by its unique elimination mechanism: it undergoes slow chemical degradation at physiological temperature and pH to an open-ring peptide product, which is then excreted in bile. This non-enzymatic, non-hepatic degradation means that anidulafungin pharmacokinetics are unaffected by hepatic function, renal function, or CYP enzyme activity, making it the echinocandin with the fewest potential drug interactions and the most straightforward dosing across all levels of organ dysfunction. The plasma half-life is approximately 24 to 27 hours, somewhat longer than caspofungin or micafungin. Protein binding exceeds 99%. Volume of distribution is approximately 30 to 50 L. Tissue penetration follows the class pattern: good in liver, lung, spleen, and kidney; poor in CNS (central nervous system) and vitreous.6
Anidulafungin: Dosing and Indications. Anidulafungin is administered as a 200 mg loading dose on Day 1 followed by 100 mg IV once daily for candidemia and invasive candidiasis. For esophageal candidiasis the loading dose is 100 mg followed by 50 mg once daily. The loading dose is larger relative to the maintenance dose than with caspofungin (2:1 ratio vs. 70:50 mg), reflecting the longer half-life and the need to achieve therapeutic exposure promptly. Unlike caspofungin, no dose adjustment is required for any degree of hepatic or renal impairment. In the pivotal ANIDACAS (Anidulafungin vs. Fluconazole for Invasive Candidiasis) trial, anidulafungin demonstrated superiority to fluconazole for global success in invasive candidiasis at the end of intravenous therapy, though the difference was not maintained at follow-up when step-down to oral fluconazole occurred in both arms. The drug has no approved indication for prophylaxis.6
Micafungin: Invasive candidiasis: 100 mg IV once daily (no loading dose). Esophageal candidiasis: 150 mg IV once daily. HSCT prophylaxis: 50 mg IV once daily. No renal or hepatic dose adjustment (mild-moderate). Anidulafungin: Invasive candidiasis: 200 mg loading dose Day 1, then 100 mg IV once daily. Esophageal candidiasis: 100 mg loading dose, then 50 mg once daily. No dose adjustment for any organ impairment.
The echinocandin spectrum is defined by excellent activity against most Candida species and fungistatic activity against Aspergillus, with important gaps for Cryptococcus, the Mucorales, and several less common but clinically significant pathogens. Resistance mediated by mutations in the FKS (Fks glucan synthase subunit) hot spot regions of the glucan synthase gene has emerged as a clinical problem, particularly in Candida glabrata, and requires systematic awareness in the management of invasive candidiasis.
Candida Spectrum. Echinocandins are active and fungicidal against the major clinically important Candida species: C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, C. krusei, and C. dubliniensis. A critical advantage over fluconazole is retained activity against fluconazole-resistant C. glabrata and intrinsically fluconazole-resistant C. krusei. Against Candida parapsilosis and Candida guilliermondii, MICs are naturally higher than against other Candida species, reflecting intrinsically reduced glucan synthase inhibitor susceptibility; while clinical outcomes with echinocandin therapy are generally acceptable, this observation has led some guidelines to recommend fluconazole as a preferred agent for C. parapsilosis infections when the isolate is fluconazole-susceptible. Candida auris, the multidrug-resistant emerging pathogen, is typically echinocandin-susceptible and echinocandins are the preferred agents for C. auris infections pending susceptibility results.7
Aspergillus and Other Mold Coverage. Against Aspergillus fumigatus and other Aspergillus species, echinocandins produce fungistatic rather than fungicidal activity by inhibiting glucan synthesis at hyphal tips, resulting in characteristic morphological changes. This fungistatic activity supports the use of echinocandins as salvage or combination therapy in invasive aspergillosis (IPA) but not as first-line monotherapy. The combination of an echinocandin with a triazole (most commonly voriconazole plus anidulafungin or caspofungin) has been evaluated in clinical trials and observational studies. The COMBISTRAT (Combination Antifungal Therapy for Invasive Aspergillosis) trial and a large multicenter study by Marr et al. suggested potential outcome benefit with combination therapy in patients with IPA who have active galactomannan antigenemia, though the benefit was not uniformly confirmed across all subgroups. Echinocandins lack activity against Cryptococcus neoformans (which lacks significant beta-1,3-d-glucan in its cell wall), the Mucorales, Fusarium species, and most hyalohyphomycetes other than Aspergillus.78
FKS Hot Spot Mutations and Resistance Mechanisms. The primary mechanism of acquired echinocandin resistance is mutation in the hot spot (HS) regions of the FKS1 (glucan synthase subunit 1 gene) or FKS2 (glucan synthase subunit 2 gene) genes encoding the Fks glucan synthase subunit. Two hot spot regions have been characterized: hot spot 1 (HS1) spanning amino acids 641 to 649 and hot spot 2 (HS2) spanning amino acids 1345 to 1365. Mutations at specific positions within these hot spots, most commonly serine to leucine or serine to phenylalanine substitutions at position 645 in C. albicans and equivalent positions in other species, reduce the binding affinity of echinocandins for the Fks enzyme by several orders of magnitude. In C. glabrata, FKS2 mutations confer high-level resistance, and C. glabrata is the Candida species most frequently associated with acquired echinocandin resistance in clinical settings, particularly in patients who have received prolonged prior echinocandin therapy. Resistance rates in C. glabrata of 5 to 13% have been reported in some centers following widespread echinocandin use. Acquired FKS resistance in C. albicans, C. tropicalis, and C. parapsilosis remains less frequent but has been documented, particularly after extended therapy.8
Clinical Epidemiology of Resistance. FKS mutations should be suspected in patients who have breakthrough candidemia while receiving echinocandin therapy or who have a history of prolonged echinocandin exposure. Minimum inhibitory concentrations for echinocandin-resistant isolates typically fall above the susceptibility breakpoints established by the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST); however, some FKS mutants retain MICs within or near the susceptibility range, so molecular FKS mutation testing is more sensitive than MIC (minimum inhibitory concentration) testing alone for detecting resistant isolates. For patients with suspected echinocandin resistance, liposomal amphotericin B (L-AmB) is the standard alternative, as azole resistance may co-exist with echinocandin resistance in some C. glabrata isolates. Cross-resistance among the three echinocandins for FKS-mediated resistance is expected because all three target the same Fks hot spot regions.89
Suspect FKS resistance in: breakthrough candidemia on echinocandin therapy; prior prolonged echinocandin exposure (especially in C. glabrata); isolates with rising MICs on repeat testing. Action: send isolate for formal susceptibility testing; consider FKS hot spot molecular testing if available; switch to L-AmB empirically if clinical deterioration. Cross-resistance among all three echinocandins: expected. Do not switch within class for suspected FKS resistance.
The echinocandin class has a favorable tolerability profile compared to both the polyenes and the azoles, which is a major reason for its preferred status in invasive candidiasis. Understanding the modest but clinically important interaction differences among the three agents, and establishing appropriate monitoring practices, completes the pharmacological framework for their clinical use.
Tolerability and Common Adverse Effects. Echinocandins are generally well tolerated. The most common adverse effects across the class are infusion-related reactions (fever, rash, flushing, pruritus), which occur in approximately 2 to 5% of patients and are thought to be related to histamine release rather than IgE-mediated allergy; slowing the infusion rate typically resolves or prevents these reactions. Liver enzyme elevations, particularly alanine aminotransferase (ALT) and aspartate aminotransferase (AST), occur in 5 to 15% of patients, are usually mild and reversible, and uncommonly require drug discontinuation. Hypokalemia occurs with sufficient frequency to warrant monitoring, particularly in seriously ill patients receiving concurrent diuretics or amphotericin B. Headache, nausea, diarrhea, and phlebitis at the infusion site are reported. Echinocandins lack the nephrotoxicity of amphotericin B and the CYP (cytochrome P450)-mediated toxicities of the azoles, making them particularly suitable for patients with renal impairment or complex polypharmacy.5
Infusion Rate and Preparation. All three echinocandins require careful attention to infusion rate to minimize infusion-related histamine-like reactions. Caspofungin should be infused over approximately 60 minutes. Micafungin is infused over 60 minutes at a concentration not exceeding 0.5 mg/mL. Anidulafungin must be infused at a rate not exceeding 1.1 mg/min, which for the standard 100 mg maintenance dose translates to a minimum infusion duration of approximately 90 minutes. Exceeding these rates increases the risk of histamine-mediated infusion reactions. Caspofungin and micafungin should not be mixed or co-infused with dextrose-containing solutions; saline-based diluents are used. Anidulafungin is reconstituted in 20% dehydrated alcohol (ethanol) solution before further dilution, and the ethanol content of the final solution is modest but should be noted in patients where ethanol exposure is a concern.46
Drug Interaction Summary by Agent. Caspofungin has the most complex interaction profile of the three. Strong CYP inducers (rifampin, efavirenz, nevirapine, phenytoin, carbamazepine, dexamethasone) reduce caspofungin AUC (area under the concentration-time curve) by approximately 30%, requiring maintenance dose escalation to 70 mg once daily. Cyclosporine increases caspofungin AUC by approximately 35% with associated ALT elevations; this combination should be avoided unless no alternative exists. Tacrolimus concentrations are modestly reduced by caspofungin (approximately 20%), requiring TDM (therapeutic drug monitoring). Micafungin has the most favorable interaction profile: no dose adjustments are required for most common combinations, with only modest effects on sirolimus and nifedipine through weak CYP3A4 (cytochrome P450 3A4) inhibition. Anidulafungin has essentially no pharmacokinetic drug interactions by virtue of its non-enzymatic degradation; no dose adjustments are required with any co-administered drug on a pharmacokinetic basis.456
Laboratory Monitoring. Baseline and periodic monitoring of liver function tests (LFTs) including ALT, AST, alkaline phosphatase, and total bilirubin is recommended for all patients on echinocandin therapy, with the frequency determined by clinical context (typically baseline and at one to two week intervals for stable outpatient or prolonged inpatient courses). Serum potassium and magnesium should be monitored, particularly in severely ill patients or those on concurrent medications that cause electrolyte wasting. Renal function monitoring is not driven by echinocandin nephrotoxicity concerns (the class is non-nephrotoxic) but by the underlying condition or co-administered nephrotoxins. Therapeutic drug monitoring of echinocandin plasma concentrations is not routinely performed in clinical practice; population pharmacokinetic data support standard dosing achieving adequate exposure in most adult patients, though selected scenarios (extremes of body weight, pharmacokinetic drug interactions, refractory infection) may warrant consideration of TDM in specialized centers.59
Caspofungin: adjust dose up with strong CYP inducers; adjust down for Child-Pugh 7–9; avoid with cyclosporine if possible; monitor tacrolimus. Micafungin: check sirolimus concentration; no other routine adjustments; caution in severe hepatic impairment. Anidulafungin: no pharmacokinetic interactions; no dose adjustment for any organ impairment — simplest profile of the three; note ethanol content in vehicle. When drug interactions or hepatic impairment are the primary concern, anidulafungin or micafungin is preferred over caspofungin.
Echinocandins occupy the first-line position for invasive candidiasis in most current guidelines, displacing fluconazole from that role except in specific low-risk scenarios. Translating the pharmacological differences among the three agents into individual patient prescribing decisions requires integrating indication, interaction burden, organ function, and the clinical trajectory of the infection.
Invasive Candidiasis and Candidemia. The 2016 Infectious Diseases Society of America (IDSA) guidelines for candidiasis recommend an echinocandin as the preferred initial therapy for most patients with candidemia and invasive candidiasis, regardless of species. The shift from fluconazole to echinocandins as empirical first-line therapy reflects the increasing prevalence of fluconazole-resistant C. glabrata, the superior fungicidal activity of echinocandins, and evidence of lower mortality with echinocandin initial therapy in meta-analyses and randomized trials. Fluconazole remains an acceptable alternative for less severely ill patients with no prior azole exposure in settings where C. glabrata or C. krusei is an unlikely pathogen; it is also the preferred step-down agent for oral de-escalation once susceptibility is confirmed and clinical stability is achieved. The recommended duration of therapy for uncomplicated candidemia is 14 days from the last positive blood culture in a patient with no evidence of deep-seated infection and documented removal of the intravascular catheter.710
Oral Step-Down Strategy. A critical element of echinocandin management in candidiasis is the transition to oral fluconazole once clinical stability is achieved and susceptibility data are available. This step-down strategy (IV echinocandin induction followed by oral fluconazole consolidation) is supported by the IDSA guidelines and by clinical evidence showing equivalent outcomes to prolonged IV therapy in eligible patients. Criteria for step-down include: clinical improvement (defervescence, hemodynamic stability, tolerating oral medications), documented fluconazole-susceptible species, negative follow-up blood cultures, resolution of neutropenia if present, and absence of deep-seated infection requiring prolonged IV therapy (endocarditis, osteomyelitis, CNS infection). Patients with C. glabrata infection and confirmed fluconazole susceptibility can step down to fluconazole; if azole resistance is documented, echinocandin therapy must be continued for the full treatment course. Oral voriconazole is an alternative step-down option for C. krusei or azole-resistant isolates where susceptibility permits.10
Aspergillosis: Salvage and Combination Roles. Echinocandins are not first-line monotherapy for invasive aspergillosis (IPA), where voriconazole or isavuconazole is preferred. They have an established role in salvage therapy for refractory IPA and have been investigated as components of combination regimens. The rationale for combination therapy with a triazole and an echinocandin rests on the complementary mechanisms (cell membrane ergosterol depletion plus cell wall glucan inhibition) and some preclinical synergy data. The most frequently studied combination is voriconazole plus anidulafungin; the Marr et al. multicenter study found improved 6-week survival with this combination compared to voriconazole monotherapy in patients with galactomannan-positive IPA, though the finding was limited to a subgroup analysis and the overall primary endpoint was not significant. Current IDSA guidelines consider combination therapy an option in selected patients with severe or refractory IPA, but it is not a universal recommendation.78
Special Populations: Hepatic Impairment and Transplant Patients. Among patients with significant hepatic impairment, anidulafungin or micafungin is preferred over caspofungin because neither requires dose adjustment for hepatic dysfunction. In solid organ transplant recipients receiving calcineurin inhibitors, micafungin or anidulafungin is preferred over caspofungin to avoid the caspofungin-cyclosporine ALT (alanine aminotransferase) elevation interaction and the caspofungin-tacrolimus pharmacokinetic interaction. In patients on rifampin-based tuberculosis (TB) regimens, caspofungin dose escalation to 70 mg once daily is required, or alternatively micafungin or anidulafungin can be used without adjustment. For severely ill patients in the intensive care unit (ICU) where polypharmacy interactions are high and organ dysfunction is common, anidulafungin is an attractive choice because of its uniquely simple pharmacokinetic profile and absence of any drug interactions or organ-based dose adjustments.456
Mechanism: beta-1,3-d-glucan synthase inhibition; fungicidal against Candida, fungistatic against Aspergillus. No CYP metabolism — low interaction burden vs. azoles. IV only; poor CNS/ocular penetration. First-line for invasive candidiasis; step down to oral fluconazole when stable and susceptible. FKS hot spot mutations: primary resistance mechanism; C. glabrata highest risk; cross-resistance within class. Caspofungin: adjust for hepatic impairment, CYP inducers, cyclosporine. Micafungin: no routine adjustments; minor sirolimus interaction. Anidulafungin: no interactions; no organ-based adjustments — preferred in polypharmacy and ICU settings. Combination with voriconazole considered for severe or refractory IPA.
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