Hallucinations during voriconazole therapy: who is at higher risk and could benefit from therapeutic drug monitoring?

Safety of triazole antifungals: a pharmacovigilance study from 2004 to 2021 based on FAERS

Background

Triazole antifungals are widely used as broad-spectrum antifungal activity; however, there are many undetected and unreported adverse events (AEs).

Methods

Data from the Food and Drug Administration Adverse Event Reporting System (FAERS) from the first quarter (Q1) of 2004 to the third quarter (Q3) of 2021 were selected for disproportionality analysis to assess the connection between antifungal triazoles, and AEs and important medical events (IMEs).

Results

A total of 22,566 records associated with triazole antifungals were identified, with 9584 triazole antifungal-IME pairs. The following system organ classes (SOCs) appeared as significant signals: 'Endocrine disorders' [reported odds ratio (ROR) = 167.94], 'Metabolism and nutrition disorders' (ROR = 46.30), and 'Skin and subcutaneous tissue disorders' (ROR = 21.37). Strong signals were observed with respiratory failure, rash, hepatic function abnormal, and hypokalemia. Uncommon security signals included a change in the QT interval, neurotoxicity, pseudoaldosteronism, and hallucinations.

Conclusion

Various triazole antifungals cause AEs of different types and intensities of association. Our results are broadly consistent with prescribing information and previous studies; however, additional pharmacoepidemiological studies are required to verify AEs with modest incidence but high signal.

Plain Language Summary

A study on the adverse effects of triazole antifungals Introduction: The triazole antifungals we studied include fluconazole, itraconazole, voriconazole, posaconazole, and isavuconazole. Triazole antifungals are widely used as broad-spectrum antifungals; however, there are many undetected and unreported adverse events (AEs).Materials and Methods: The Food and Drug Administration Adverse Event Reporting System (FAERS) database contains AEs reported to the FDA by different countries regarding post-marketing drugs. Through the FAERS database, we retrieved a total of 22,566 AE reports related to triazole antifungals. We not only counted information about patients' gender, age, weight, reporting country, outcome indicators, and indications but also analyzed the system organ classes (SOCs) of AEs, and the number of reported drug-related AEs and the degree of relevance.Results: We found a total of 22,566 records related to triazole antifungal agents, of which 9584 reports made important medical events (IMEs) about triazole antifungal agents, which are serious AEs. The following SOCs appear as important signals: 'endocrine disorders', 'metabolic and nutritional disorders', and 'skin and subcutaneous tissue disorders'. Triazole antifungals produce AEs, such as respiratory failure, rash, hepatic function abnormal, and hypokalemia. They also produce uncommon AEs, including changes in the QT interval, neurotoxicity, pseudoaldosteronism, and hallucinations.Conclusion: By analyzing data from the FAERS database, we identified more AEs associated with these five triazole antifungals than were indicated in the instructions and our findings provide additional insight into triazole-related AEs to inform clinicians before and during treatment.

Voriconazole therapeutic drug monitoring: retrospective cohort study of the relationship to clinical outcomes and adverse events

BACKGROUND

Voriconazole is approved for treatment of invasive aspergillosis and other invasive fungal infections, but the role for therapeutic drug monitoring (TDM) is not clear.

METHODS

We performed a retrospective cohort study of patients at the University of Washington Medical Center and Fred Hutchinson Cancer Research Center from 2007-2009. We compared the effect of therapeutic levels on clinical outcomes and evaluated the relationship between drug levels and adverse events.

RESULTS

A total of 108 patients had voriconazole TDM performed, of whom 84 (77.8%) had a hematologic malignancy and 47 (43.5%) had undergone hematopoietic stem cell transplantation. The primary reasons for treatment were presumed pulmonary aspergillosis (n = 83, 76.8%), other invasive mould infections (n = 13, 12.0%) and candidiasis (n = 9, 8.3%). There was a high degree of variability in voriconazole drug levels among patients (r2 = 0.01; range, <0.10 - 20 mg/L). Of the 46 patients with proven or probable invasive fungal disease, 25 (54.3%) achieved partial or complete response to therapy. There was no significant relationship between therapeutic drug levels and achievement of complete or partial response at 12 weeks (OR 0.29, 95% CI: 0.05-1.34) or radiologic response (OR 1.46, 95% CI: 0.32-7.83). Overall, 45 (41.7%) patients experienced adverse events. Voriconazole levels > 5.5 mg/L were not associated with increased incidence of encephalopathy (OR 3.08, 95% CI 0.79-11.0) or hepatotoxicity (OR 2.45, 95% CI 0.49-10.1).

CONCLUSIONS

Voriconazole therapeutic drug levels were not associated with improvement in clinical outcomes among patients with proven or probable invasive fungal disease. We also did not find an association between supratherapeutic drug levels and hepatoxicity or encephalopathy. It is possible that the utility of voriconazole therapeutic drug monitoring to improve clinical efficacy or decrease adverse events may be limited to a subset of high-risk patients.

Voriconazole drug monitoring in the management of invasive fungal infection in immunocompromised children: a prospective study

OBJECTIVES

To evaluate voriconazole plasma level monitoring in immunocompromised children and determine the relationship of plasma levels with dose, safety and efficacy.

METHODS

We used a prospective study including all consecutive children with invasive fungal infection (IFI) treated with voriconazole between August 2008 and May 2010. IFI diagnosis and clinical outcome evaluation were based on European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group ('EORTC/MSG') definitions.

RESULTS

A total of 196 voriconazole plasma trough measurements from 30 patients (median age 10 years) obtained during 2135 days of voriconazole therapy were analysed. Nineteen patients (63%) presented with proven or probable IFI. Voriconazole plasma levels varied widely and 73% of patients required dose adjustment. The median voriconazole dose was 20 mg/kg/day and the median duration of therapy was 6 weeks. Age 5 was the smallest value defining two groups on which the correlation between dose and plasma levels had a different behaviour, and this relationship was especially significant for patients <5 years old (Spearman's rank correlation coefficient=0.38213, P=0.008). For patients <5 years old the median dose to achieve therapeutic levels was 38.0 mg/kg/day (12-40.0) and for those ≥5 years old it was 15 mg/kg (4-52). Voriconazole plasma levels showed a significant relationship with early outcome (P=0.0268), but not late outcome (P=0.2015). Overall mortality was 42% and a significant relationship with voriconazole therapeutic plasma levels was not demonstrated. A significant relationship was established between plasma levels above normal range and skin and neurological toxicity (P=0.0001), but this could not be demonstrated for liver toxicity.

CONCLUSIONS

Our study confirms the large variability in voriconazole trough plasma levels in children and a trend to non-linear pharmacokinetics in older patients. In addition, doses significantly higher than those recommended in younger children seem warranted and a significant relationship between plasma voriconazole above the normal range and some adverse events is confirmed.

[Level of evidence for therapeutic drug monitoring of voriconazole]

Voriconazole is a major antifungal drug with activity against endemic fungi, Candida and Aspergillus species in immunocompromised patients. Voriconazole has a good bioavailability, an high protein binding percentage in plasma and is metabolized in liver via CYP2C19. It presents important neuro- and hepatotoxicities. Some studies determined trough concentrations of voriconazole in plasma using liquid chromatography coupled with UV or tandem mass detection. These studies showed a relationship between trough concentrations of voriconazole and efficacy or toxicity. Indeed, some studies reported a relationship between a lack of clinical response and concentrations below 1 or 2 μg/mL according to the localization of infection, while toxicities are frequently observed at concentrations above 5 μg/mL. Some particular populations will have to be taken into account such as children, patients with hemodialysis-dependent renal deficiency or hepatic insufficiency, cystic fibrosis patients or those treated concomitantly with interfering drugs. According to our survey, therapeutic drug monitoring of voriconazole appears recommended. However, controlled studies are still necessary to validate it prospectively and to evaluate pharmacokinetically-based methods proposed for individual dose adjustment.