Necessity for a System Implementing Therapeutic Drug Monitoring in Outpatient Settings Based on the Actual Use of Voriconazole Using the National Database of Health Insurance Claims and Specific Health Checkups of Japan: A Descriptive Epidemiological Study.

Voriconazole (VRCZ) is an antifungal drug that necessitates therapeutic monitoring (TDM). Typically, TDM is recommended for patients undergoing long-term outpatient treatment. However, in Japan, insurance reimbursement for TDM is only permitted for inpatients. There is a concern that VRCZ use is growing among outpatients, although information regarding this issue remains unavailable. Therefore, we aimed to clarify the use of VRCZ by utilizing data from the National Database of Health Insurance Claims and Specific Health Checkups in Japan. The use of branded and generic oral VRCZ from 2013 to 2019 was calculated using the defined daily doses/1000 inhabitants/d (DID) for each receipt type. Oral VRCZ was used more frequently in the outpatient setting than that in the inpatient setting, with use increasing over time. The use of generic drugs began in 2016 and accounted for 52.5% of the use in 2019 among outpatients. Considering outpatient prescriptions, 76.4-81.0% were dispensed at insurance pharmacies, indicating the need for community pharmacist involvement. Accordingly, the appropriate use of VRCZ in ambulatory care should be promoted in collaboration with community pharmacists, and a reimbursement system should be established to implement TDM in ambulatory care.