bloodstream infections are associated with high attributable mortality, where early initiation of adequate antifungal therapy is important to increase survival in critically ill patients. The ...exposure variability of micafungin, a first-line agent used for the treatment of invasive candidiasis, in critically ill patients is significant, potentially resulting in underexposure in a substantial portion of these patients. The objective of this study was to develop a population pharmacokinetic model including appropriate sampling strategies for assessing micafungin drug exposure in critically ill patients to support adequate area under the concentration-time curve (AUC) determination. A two-compartment pharmacokinetic model was developed using data from intensive care unit (ICU) patients (
= 19), with the following parameters: total body clearance (CL), volume of distribution of the central compartment (V1), inter-compartmental clearance (CL12), and volume of distribution of the peripheral compartment (V2). The final model was evaluated with bootstrap analysis and the goodness-of-fit plots for the population and individual predicted micafungin plasma concentrations. Optimal sampling strategies (with sampling every hour, 24 h per day) were developed with 1- and 2-point sampling schemes. Final model parameters (±SD) were: CL = 1.03 (0.37) (L/h/1.85 m
), V1 = 0.17 (0.07) (L/kg LBMc), CL12 = 1.80 (4.07) (L/h/1.85 m
), and V2 = 0.12 (0.06) (L/kg LBMc). Sampling strategies with acceptable accuracy and precision were developed to determine the micafungin AUC. The developed model with optimal sampling procedures provides the opportunity to achieve quick optimization of the micafungin exposure from a single blood sample using Bayesian software and may be helpful in guiding early dose decision-making.
Aims
The pharmacokinetics (PK) of fluconazole and micafungin differ in neonates compared with children and adults. Dosing instructions in product labels appear to be inconsistent with the emerging ...scientific evidence. Limited information is available on the safety profile of these agents in neonates. Our objective was to study the population PK and safety of both drugs, randomly administered in neonates with suspected or confirmed systemic candidiasis.
Methods
Neonates were randomized 1:1 to fluconazole (loading dose 25 mg kg–1; maintenance dose 12 mg kg–1 day–1 or 20 mg kg–1 day–1, respectively, for infants <30 weeks or ≥30 weeks’ corrected gestational age) or micafungin (loading dose 15 mg kg–1 day–1; maintenance dose 10 mg kg–1 day–1). PK samples were taken on treatment days 1 and 5. Population parameters were determined using NONMEM and Monte Carlo simulations performed to reach predefined targets. Clinical and laboratory data, and adverse events were collected up to 36 weeks’ corrected gestational age or hospital discharge.
Results
Thirty‐six neonates were enrolled. The median (range) gestational age was 28.2 (24.1–40.1) and 26.8 (23.5–40.0) weeks for fluconazole and micafungin, respectively. Based on 163 PK samples, the median population clearance (l h–1 kg–1) and volume of distribution (l kg–1) for fluconazole were: 0.015 95% confidence interval (CI) 0.008, 0.039 and 0.913, and for micafungin were: 0.020 (95% CI 0.010, 0.023) and 0.354 (95% CI 0.225, 0.482), respectively. The loading dose was well tolerated. No adverse events associated with micafungin or fluconazole were reported.
Conclusion
Based on Monte Carlo simulations, a loading dose for fluconazole and dosing higher than recommended for both drugs are required to increase the area under the plasma drug concentration–time curve target attainment rate in neonates.
Procedures such as solid-organ transplants and cancer treatments can leave many patients in an immunocompromised state. This leads to their increased susceptibility to opportunistic diseases such as ...fungal infections. Mucormycosis infections are continually emerging and pose a serious threat to immunocompromised patients. Recently there has been a sharp increase in mucormycosis cases as a secondary infection in patients battling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Mucorales fungi are notorious for presenting resistance to most antifungal drugs. The absence of effective means to treat these infections results in mortality rates approaching 100% in cases of disseminated infection. One of the most effective antifungal drug classes currently available is the echinocandins. Echinocandins seem to be efficacious in the treatment of many other fungal infections. Unfortunately, susceptibility testing has found that echinocandins have little to no effect on Mucorales fungi. In this study, we found that the model Mucorales Mucor circinelloides genome carries three copies of the genes encoding the echinocandin target protein β-(1,3)-d-glucan synthase (
,
, and
). Interestingly, we found that exposing M. circinelloides to micafungin significantly increased the expression of the
and
genes, resulting in an increased accumulation of β-(1,3)-d-glucan on the cell walls. However, this overexpression of the
genes is not directly connected to the intrinsic resistance. Subsequent investigation discovered that the serine/threonine phosphatase calcineurin regulates the expression of
and
, and the deletion of calcineurin results in a decrease in expression of all three
genes. Deletion of calcineurin also results in a lower minimum effective concentration (MEC) of micafungin. In addition, we found that duplication of the
gene is also responsible for the intrinsic resistance, in which lack of either
or
led a lower MEC of micafungin. Together, these findings demonstrate that calcineurin and
gene duplication contribute to the intrinsic resistance to micafungin we observe in
.
.
What is known and objective
Anidulafungin, caspofungin and micafungin are three widely used echinocandin drugs licensed for the treatment of invasive fungal infections, and their clinical use is ...widespread. To evaluate pharmacokinetic/pharmacodynamics variability of echinocandins in critically ill patients by comparing the differences in pharmacokinetic parameters between critically ill patients and healthy volunteers or general patients.
Methods
MEDLINE, EMBASE, The Cochrane Library and Pubmed were searched from inception until 6 September 2018. Studies investigating the pharmacokinetic parameters of echinocandins in critically ill patients, healthy volunteers or general patients were included. Our primary outcomes included AUC0‐24 h, Cmax and Cmin (24 hours). Two reviewers independently reviewed all titles, s and text, and extracted data. We applied R software (R 2017) to conduct meta‐analysis.
Results and discussion
Of 3235 articles screened, 17 studies were included in the data synthesis. Descriptive data from single‐arm studies show that critically ill patients who received caspofungin had more stable AUC0‐24 h than those who received anidulafungin and micafungin. The Cmax of critically ill patients who received caspofungin and micafungin was similar to healthy volunteers. However, the Cmax in critically ill patients who received anidulafungin was lower than in healthy volunteers. The Cmin and T1/2 of critically ill patients who received caspofungin were larger than in healthy volunteers. The Vd and CL of critically ill patients receiving anidulafungin and micafungin were larger than in healthy volunteers.
What is new and conclusion
This systematic review provides an analysis of the pharmacokinetic/pharmacodynamics variability of echinocandins in critically ill patients. Based on the limited data available, caspofungin has less pharmacokinetic/pharmacodynamics variability than anidulafungin and micafungin.
This systematic review included 17 studies. Descriptive data from single‐arm studies showed that in critical ill patients who received caspofungin has more stable AUC0‐24 h than those who received anidulafungin and micafungin. However, the Cmax in critical ill patients who received anidulafungin was lower than in healthy volunteers.
Micafungin is a selective inhibitor of the synthesis of fungal 1,3-β-
d
-glucan, an essential component of the fungal cell wall. It is available as a powder for infusion only and is registered for ...the treatment of invasive and esophageal candidiasis in addition to prophylaxis of
Candida
infections in both adults and children. Average exposure after a single intravenous 100 mg dose in healthy adults is 133 mg h/L. Both exposure and maximum plasma concentration show linear dose proportional pharmacokinetics (PK) over a 0.15–8 mg/kg dose range. In healthy adults, the clearance (CL) is 10.4 mL/h/kg and volume of distribution is 0.2 L/kg; both are independent of the dose. Micafungin is metabolized by arylsulfatase, catechol-
O
-methyltransferase, and several cytochrome P450 (CYP) isoenzymes (3A4, 1A2, 2B6 and 2C), but no dose adjustments are necessary in patients with (severe) hepatic dysfunction. Exposure to micafungin is lower in hematology patients, and is even further lowered in critically ill patients (including burn patients) compared with healthy volunteers, which might have consequences for treatment efficacy. In children, an increased CL has been reported: 40–80 mL/h/kg in premature neonates and 20 mL/h/kg in children >4 months of age. Therefore, relatively higher doses of 4–10 mg/kg in premature neonates and 2–4 mg/kg in children with invasive candidiasis are used. However, these higher CLs may also be explained by the eightfold higher free fraction of unbound micafungin in premature neonates, meaning that an augmented dose might not be required.
Objectives
To study the population pharmacokinetics of micafungin in critically ill patients, evaluate and optimize dosage regimens.
Methods
An HPLC–fluorescence bioassay for micafungin was ...developed, fully validated and applied to a pharmacokinetic study conducted in 14 ICU patients. Dense blood sampling was performed from days 1 to 7. A population pharmacokinetic model accounting for interindividual (IIV) and interoccasion variability (IOV) of the PK parameters was developed. Simulations were performed to estimate the probability of target attainment (PTA) for several dosing regimens.
Key findings
A two‐compartment pharmacokinetic model best described the data, with population clearance CL = 1.31 L/h and central volume V1 = 14.2 L. The relatively high IOV observed (45% for CL, 27% for V1) sets limits for the dose individualization in this population. The low PTA on the first day of treatment suggests the need of a loading dose. PTA and CFR estimates show that the current micafungin dosage may be insufficient for the treatment of borderline susceptible Candida strains.
Conclusions
A loading dose of up to 300 mg of micafungin is needed for the treatment of invasive candidiasis in ICU patients while a maintenance dose of up to 200 mg can be considered in empirical antifungal treatment.
Candida glabrata readily develops resistance to echinocandins. Identification, antifungal susceptibility testing (AST) and resistance mechanism to echinocandins among C. glabrata was determined in ...Kuwait. C. glabrata isolates (n = 75) were tested by Vitek2, multiplex PCR and/or PCR-sequencing of rDNA. AST to fluconazole, caspofungin, micafungin and amphotericin B was determined by Etest and to micafungin by broth microdilution (BMD). Mutations in hotspot-1/hotspot-2 of FKS1/FKS2 and ERG11 were detected by PCR-sequencing. All isolates were identified as C. glabrata sensu stricto. Seventy isolates were susceptible and five were resistant to micafungin by Etest and BMD (essential agreement, 93%; categorical agreement, 100%). Three micafungin-resistant isolates were resistant and two were susceptible dose-dependent to caspofungin. Four and one micafungin-resistant isolate contained S663P and ∆659 F mutation, respectively, in hotspot-1 of FKS2. Micafungin-resistant isolates were genotypically distinct strains. Only one of 36 fluconazole-resistant isolate contained nonsynonymous ERG11 mutations. Thirty-four of 36 fluconazole-resistant isolates were genotypically distinct strains. Our data show that micafungin susceptibility reliably identifies echinocandin-resistant isolates and may serve as a surrogate marker for predicting susceptibility/resistance of C. glabrata to caspofungin. All micafungin-resistant isolates also harbored a nonsynonymous/deletion mutation in hotspot-1 of FKS2. Fingerprinting data showed that echinocandin/fluconazole resistance development in C. glabrata is not clonal.
Neonatal candidiasis causes significant morbidity and mortality in high risk infants. The micafungin dosage regimen of 10 mg/kg established for the treatment of neonatal candidiasis is based on a ...laboratory animal model of neonatal hematogenous Candida meningoencephalitis and pharmacokinetic (PK)-pharmacodynamic (PD) bridging studies. However, little is known about the how these PK-PD data translate clinically.
Micafungin plasma concentrations from infants were used to construct a population PK model using Pmetrics software. Bayesian posterior estimates for infants with invasive candidiasis were used to evaluate the relationship between drug exposure and mycologic response using logistic regression.
Sixty-four infants 3-119 days of age were included, of which 29 (45%) infants had invasive candidiasis. A 2-compartment PK model fits the data well. Allometric scaling was applied to clearance and volume normalized to the mean population weight (kg). The mean (standard deviation) estimates for clearance and volume in the central compartment were 0.07 (0.05) L/h/1.8 kg and 0.61 (0.53) L/1.8 kg, respectively. No relationship between average daily area under concentration-time curve or average daily area under concentration-time curve:minimum inhibitory concentration ratio and mycologic response was demonstrated (P > 0.05). Although not statistically significant, mycologic response was numerically higher when area under concentration-time curves were at or above the PD target.
While a significant exposure-response relationship was not found, PK-PD experiments support higher exposures of micafungin in infants with invasive candidiasis. More patients would clarify this relationship; however, low incidence deters the feasibility of these studies.
To compare the effectiveness and tolerability of micafungin versus posaconazole during chemotherapy-induced neutropenia in acute leukemia (AL) and myelodysplastic syndrome (MDS).
Patients with AL or ...MDS undergoing chemotherapy were randomized to open-label micafungin 100 mg intravenously daily or posaconazole suspension 400 mg orally twice daily until neutrophil recovery, up to 28 days. Patients were followed for 12 weeks. The primary endpoint was prophylaxis failure (premature discontinuation due to infection, intolerance, adverse event, or death). Time to failure and survival were calculated by Kaplan–Meier analysis.
From March 2011 to May 2016, 113 patients who received at least 2 doses of prophylaxis were analyzed (58 patients randomized to micafungin and 55 to posaconazole). Prophylaxis failure occurred in 34.5% and 52.7% of patients on micafungin and posaconazole, respectively (P = 0.0118). The median number of days on prophylaxis was 16 interquartile range (IQR) 12–20 for micafungin and 13 IQR 6–16 for posaconazole (P = 0.01). Micafungin failures were largely due to antifungal treatment; posaconazole failures were mostly due to gastrointestinal intolerance or adverse effects. IFI incidence and survival were similar between study arms.
Our data support micafungin as alternative antifungal prophylaxis in patients with AL and MDS.
Breast cancer and osteosarcoma are common cancers in women and children, respectively, but ideal drugs for treating patients with breast cancer or osteosarcoma remain to be found. Micafungin is an ...antifungal drug with antitumor activity on leukemia. Based on the notion of drug repurposing, this study aims to evaluate the antitumor effects of micafungin on breast cancer and osteosarcoma in vitro and in vivo, and to elucidate the underlying mechanisms. Five breast cancer cell lines (MDA-MB-231, BT-549, SK-BR-3, MCF-7, and 4T1) and one osteosarcoma cell line (143B) were chosen for the in vitro studies. Micafungin exerted an inhibitory effect on the viability of all cell lines, and MCF-7 cells were most sensitive to micafungin among the breast cancer cell lines. In addition, micafungin showed an inhibitory effect on the proliferation, clone formation, and migration in MCF7 and 143B cells. The inhibitory effect of micafungin on the growth of breast cancer and osteosarcoma was further confirmed with xenograft tumor mouse models. To explore the underlying mechanisms, the effect of micafungin on epithelial-mesenchymal transition (EMT) was examined. As expected, the levels of matrix metalloproteinase 9 and vimentin in MCF-7 and 143B cells were notably reduced in the presence of micafungin, concomitant with the decreased levels of ubiquitin-specific protease 7 (USP7), p-AKT, and p-GSK-3β. Based on these observations, we conclude that micafungin exerts antitumor effect on breast cancer and osteosarcoma through preventing EMT in an USP7/AKT/GSK-3β pathway-dependent manner.
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