Evaluation of Sulfobutylether-β-Cyclodextrin Exposure in a Critically Ill Patient Receiving Intravenous Posaconazole While Undergoing Continuous Venovenous Hemofiltration

Extrapolating Antifungal Animal Data to Humans - Is it reliable?

PURPOSE OF REVIEW

This article aimed to review animal models of antifungals and identifies human literature to assess if the extrapolation of results is reliable.

RECENT FINDINGS

Animal studies have helped identify AUC/MIC targets for new drugs and formulations such as isavuconazole and delayed release posaconazole that have translated to successful outcomes in humans. Models have also been influential in the identification of possible combination therapies for the treatment of aspergillosis, such as voriconazole and echinocandins. However, challenges are endured with animal models when it comes to replicating the pharmacokinetics of humans which has been exemplified with the newest itraconazole formulation. Additionally, animal models have displayed a survival benefit with the use of iron chelators and amphotericin for mucormycosis which was not demonstrated in humans.

SUMMARY

Animal models have been a staple in the development and optimization of antifungal agents. They afford the ability to investigate uncommon diseases, such as invasive fungal infections, that would otherwise take years and many resources to complete. Although there are many benefits of animal models there are also shortcomings. This is why the reliability of extrapolating data from animal models to humans is often scrutinized.

Clinical Pharmacokinetics of Second-Generation Triazoles for the Treatment of Invasive Aspergillosis and Candidiasis

Second-generation triazoles were developed in response to the quest for more efficacious and safer therapeutic options for the treatment of severe systemic aspergillosis and candidiasis. These agents include voriconazole, posaconazole, isavuconazole, and ravuconazole. The aim of this review was to present and compare the pharmacokinetic characteristics of second-generation triazoles for the treatment of invasive aspergillosis and candidiasis, emphasizing their clinical implications. The MEDLINE, Scopus, EBSCO, Google Scholar, and SCIndeks databases were searched using advanced search options, including the names of second-generation triazoles and pharmacokinetic terms as keywords. The intravenous administration of voriconazole, posaconazole, and isavuconazole results in stable pharmacokinetics of these drugs, with mostly predictable variations influenced by common and usually known factors in routine clinical settings. The high oral bioavailability of isavuconazole and, to some extent, voriconazole makes them suitable for intravenous-to-oral switch strategies. Except for intravenous voriconazole (due to the accumulation of the toxic vehicle hydroxypropyl betadex), dose reduction of second-generation triazoles is not needed in patients with renal failure; patients with hepatic insufficiency require dose reduction only in advanced disease stages. The introduction of therapeutic drug monitoring could aid attempts to optimize the blood concentrations of triazoles and other drugs that are known to or that possibly interact, thus increasing treatment efficacy and safety. There is a need for new studies that are designed to provide useful data on second-generation triazole pharmacokinetics, particularly in special circumstances such as central nervous system and ocular infections, infections in newborns and infants, and in subjects with genetic polymorphisms of metabolizing enzymes.

Comparative evaluation of isavuconazonium sulfate, voriconazole, and posaconazole for the management of invasive fungal infections in an academic medical center

Background

Invasive fungal infections are a major cause of morbidity and mortality. Newer antifungals may provide similar efficacy with improved safety compared to older more established treatments. This study aimed to compare clinically relevant safety and efficacy outcomes in real world patients treated with isavuconazole, voriconazole, or posaconazole.

Methods

This single center retrospective matched cohort study evaluated adults between January 2015 and December 2017. The primary outcome was a composite safety analysis of antifungal related QTc prolongation, elevated liver function tests (> 5 times ULN), or any documented adverse drug event. Key secondary outcomes included: individual safety events, 30-day readmissions, magnitude of drug interactions with immunosuppressive therapy, and overall cost.

Results

A total of 100 patients were included: 34 patients in the voriconazole group and 33 patients within each of the isavuconazole and posaconazole groups. The composite safety outcome occurred in 40% of the total cohort and was different between isavuconazole (24.2%), voriconazole (55.9%), and posaconazole (39.4%; p = 0.028). Change in QTc (p < 0.01) and magnitude of immunosuppression dose reduction (p = 0.029) were different between the three groups. No differences in mortality, length of stay, readmission, or infection recurrence were observed between groups (p > 0.05 for all). The overall medication cost, when including therapeutic drug monitoring, was not different between treatments (p = 0.36).

Conclusions

Patients treated with isavuconazole resulted in fewer composite safety outcomes, driven by decreased incidence of QTc prolongation, compared to patients treated with voriconazole or posaconazole. Overall drug cost was not significantly different between the treatment therapy options.

A pharmacokinetic case study of intravenous posaconazole in a critically ill patient with hypoalbuminaemia receiving continuous venovenous haemodiafiltration

This article reports a pharmacokinetic case study of intravenous posaconazole in a 49-year-old male patient with intra-abdominal sepsis and hypoalbuminaemia receiving continuous venovenous haemodiafiltration. Concentration-time data following 300 mg intravenous posaconazole was analysed using a population pharmacokinetics approach. The 300-mg intravenous dose appears to be adequate for the treatment of yeast infections; however, for the treatment of invasive aspergillosis in isolated cases of critically ill patients with hypoalbuminaemia, the current dosing may not achieve desired exposure, although steady state exposure data are needed.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

Scedosporium apiospermum and S. prolificans mixed disseminated infection in a lung transplant recipient: An unusual case of long-term survival with combined systemic and local antifungal therapy in intensive care unit

Infections due Scedosporium spp. in lung transplant recipients are associated with disseminated disease with high mortality rates. The adjunctive local antifungal therapy may be a useful option when systemic treatment is insufficient and/or surgery is not feasible. We present a case of mixed disseminated infection due Scedosporium apiospermum and S. prolificans in a lung transplant recipient. Combined local and systemic antifungal therapy provided an unusual long-term survival in the intensive care unit.