Managing uncertainty in antifungal dosing: antibiograms, therapeutic drug monitoring and drug-drug interactions

Therapeutic drug monitoring of antifungal therapies: do we really need it and what are the best practices?

INTRODUCTION

Despite advancements, invasive fungal infections (IFI) still carry high mortality rates, often exceeding 30%. The challenges in diagnosis, coupled with limited effective antifungal options, make managing IFIs complex. Antifungal drugs are essential for IFI management, but their efficacy can be diminished by drug-drug interactions and pharmacokinetic variability. Therapeutic Drug Monitoring (TDM), especially in the context of triazole use, has emerged as a valuable strategy to optimize antifungal therapy.

AREAS COVERED

This review provides current evidence regarding the potential benefits of TDM in IFI management. It discusses how TDM can enhance treatment response, safety, and address altered pharmacokinetics in specific patient populations.

EXPERT OPINION

TDM plays a crucial role in achieving optimal therapeutic outcomes in IFI management, particularly for certain antifungal agents. Preclinical studies consistently show a link between therapeutic drug levels and antifungal efficacy. However, clinical research in mycology faces challenges due to patient heterogeneity and the diversity of fungal infections. TDM's potential advantages in guiding Echinocandin therapy for critically ill patients warrant further investigation. Additionally, for drugs like Posaconazole, assessing whether serum levels or alternative markers like saliva offer the best measure of efficacy is an intriguing question.

Evaluation of the knowledge of hematologists about the management of infectious complications in hematologic patients

INTRODUCTION

Infection is a serious complication among patients with hematologic malignancies (HMs) and in hematopoietic cell transplant (HCT) recipients. In most centers, the management of these complications is provided by the hematologist in person, thus demanding a knowledge of basic aspects of infection.

METHODS

To evaluate the knowledge of the hematologist on infections, we invited clinicians to answer two questionnaires with 20 multiple-choice questions covering epidemiology, prophylaxis, diagnosis and treatment of infection in patients with HMs and HCT.

RESULTS

We obtained 289 answers: 223 in survey 1 (febrile neutropenia) and 66 in survey 2 (infection in HCT). The median score was 5.0 in both surveys (range 0.5 - 9.0). In survey 1, the questions with the lowest number of correct answers were Q3 (8%), concerning the cefepime dose, and Q1 (9%), which asked about the epidemiologic link between the use of high dose cytarabine and viridans streptococcal bacteremia. In survey 2, two questions about cytomegalovirus (CMV) infection had the lowest percentage of correct answers (Q4, 12% and Q11, 18%). Clinicians attending to HCT recipients had higher scores, compared to clinicians attending to patients with HM only (median score of 5.0 and 4.5, p = 0.03, in survey 1 and 6.0 and 4.5, p = 0.001, in survey 2). In both surveys staff clinicians, residents and professors had similar scores.

CONCLUSION

This is the first study in Brazil assessing the knowledge of hematologists on infectious complications. The low median score overall indicates an urgent need for continuous education. Such initiatives will eventually result in better patient care.

Management of Polypharmacy and Potential Drug-Drug Interactions in Patients with Pulmonary Aspergillosis: A 2-Year Study of a Multidisciplinary Outpatient Clinic

Pulmonary aspergillosis mainly affects elderly patients, patients with pulmonary complications, patients with hematological malignancies, organ transplant recipients, or critically ill patients. Co-morbidities may result in a high rate of polypharmacy and a high risk of potential drug-drug interaction (pDDI)-related antifungal azoles, which are perpetrators of several pharmacokinetic- and pharmacodynamic-driven pDDIs. Here, we report the results of the first 2-year study of an outpatient clinic focusing on the management of therapies in patients with pulmonary aspergillosis. All patients who underwent an outpatient visit from May 2021 to May 2023 were included in this retrospective analysis. A total of 34 patients who were given an azole as an antifungal treatment (53% voriconazole, 41% isavuconazole, and 6% itraconazole) were included. Overall, 172 pDDIs were identified and classified as red- (8%), orange- (74%), or yellow-flag (18%) combinations. We suggested handling polypharmacy in those patients using specific diagnostic and pharmacologic interventions. As expected, red-flag pDDIs involved mainly voriconazole as a perpetrator (71%). However, nearly 30% of red-flag pDDIs were not related to antifungal therapy. These findings highlight the importance of conducting an overall assessment of the pharmacologic burden and the key role played by a multidisciplinary team for the optimization of therapies in patients with pulmonary aspergillosis.

Overview of therapeutic drug monitoring and clinical practice

With the rapid development of clinical pharmacy in China, therapeutic drug monitoring (TDM) has become an essential tool for guiding rational clinical drug use and is widely concerned. TDM is a tool that combines pharmacokinetic and pharmacodynamic knowledge to optimize personalized drug therapy, which can improve treatment outcomes, reduce drug-drug toxicity, and avoid the risk of developing drug resistance. To effectively implement TDM, accurate and sophisticated analytical methods are required. By researching the literature published in recent years, we summarize the types of commonly monitored drugs, therapeutic windows, and clinical assays and track the trends and hot spots of therapeutic drug monitoring. The purpose is to provide guidelines for clinical blood drug concentration monitoring, to implement individualized drug delivery programs better, to ensure the rational use of drugs for patients, and to provide a reference for the group to carry out related topics in the future.

Invasive candidiasis: current clinical challenges and unmet needs in adult populations

Invasive candidiasis (IC) is a serious infection caused by several Candida species, and the most common fungal disease in hospitals in high-income countries. Despite overall improvements in health systems and ICU care in the last few decades, as well as the development of different antifungals and microbiological techniques, mortality rates in IC have not substantially improved. The aim of this review is to summarize the main issues underlying the management of adults affected by IC, focusing on specific forms of the infection: IC developed by ICU patients, IC observed in haematological patients, breakthrough candidaemia, sanctuary site candidiasis, intra-abdominal infections and other challenging infections. Several key challenges need to be tackled to improve the clinical management and outcomes of IC patients. These include the lack of global epidemiological data for IC, the limitations of the diagnostic tests and risk scoring tools currently available, the absence of standardized effectiveness outcomes and long-term data for IC, the timing for the initiation of antifungal therapy and the limited recommendations on the optimal step-down therapy from echinocandins to azoles or the total duration of therapy. The availability of new compounds may overcome some of the challenges identified and increase the existing options for management of chronic Candida infections and ambulant patient treatments. However, early identification of patients that require antifungal therapy and treatment of sanctuary site infections remain a challenge and will require further innovations.

Postantifungal Effect of Antifungal Drugs against Candida: What Do We Know and How Can We Apply This Knowledge in the Clinical Setting?

The study of the pharmacological properties of an antifungal agent integrates the drug pharmacokinetics, the fungal growth inhibition, the fungicidal effect and the postantifungal activity, laying the basis to guide optimal dosing regimen selection. The current manuscript reviews concepts regarding the postantifungal effect (PAFE) of the main classes of drugs used to treat Candida infections or candidiasis. The existence of PAFE and its magnitude are highly dependent on both the fungal species and the class of the antifungal agent. Therefore, the aim of this article was to compile the information described in the literature concerning the PAFE of polyenes, azoles and echinocandins against the Candida species of medical interest. In addition, the mechanisms involved in these phenomena, methods of study, and finally, the clinical applicability of these studies relating to the design of dosing regimens were reviewed and discussed. Additionally, different factors that could determine the variability in the PAFE were described. Most PAFE studies were conducted in vitro, and a scarcity of PAFE studies in animal models was observed. It can be stated that the echinocandins cause the most prolonged PAFE, followed by polyenes and azoles. In the case of the triazoles, it is worth noting the inconsistency found between in vitro and in vivo studies.