872. Voriconazole Therapeutic Drug Monitoring (TDM): How Common is Autoinduction?

Abstract Background Therapeutic drug monitor (TDM) guided optimized dosing of Voriconazole allows optimal exposure in the management mold infection (MI). In addition to already known nuances pharmacokinetics such as CYP2C19 genetic polymorphism and role interactions both necessitating TDM, case reports have suggested that auto-induction may occur after initially achieving a therapeutic level. We assessed whether levels can change over time become subtherapeutic due auto-induction. Methods prospectively enrolled, adults ≥ 18 y.o age, on for treatment MI at University Of Alberta Hospital. After an initial margin, (1–5.5mg/l), we monitored twice month, using high-performance liquid chromatography, until discontinuation or 12 weeks therapy. calculated incidence sub-therapeutic concentrations (auto-induction) defined drop level below one, with previous between margins 1–5.5 mg/L. Adjustment was discretion treating physician. The excess dose adjustment patients where increased. Results Between January 2021 April 2022, enrolled patients. Median age (IQR) 62 (52–73), 25 % were female. Patient characteristics are table 1. Auto-induction observed 6/10 (60%) who completed follow up blood work. 46 days (39–55). increased 4/6 four adjustment, cumulative 13% higher than expected, which correspond 5,300 mg per patient maintain levels. Conclusion is common treated Voriconazole. Future studies needed assess if undetected affects outcomes. Funding: AVIR Pharma. Disclosures Carlos Cervera, Associate Professor, Astra-Zeneca: Advisor/Consultant|AVIR Pharma: Grant/Research Support|AVIR Honoraria|Lilly: Advisor/Consultant|Merck: Support|Merck: Honoraria|Sunovion: Advisor/Consultant|Takeda: Honoraria|VerityPharma: Advisor/Consultant Dima Kabbani, MD, MSc, Honoraria|GSK: Honoraria|Merck: Support.