Differences in Approved Doses and Drug Lag in Drugs Approved between 2012 and 2021: A Comparison between Japan and the U.S.

Abstract

In recent years, multinational clinical trials (MCTs) have become a cornerstone of drug development. MCTs involve the participation of multiple regions in a single trial, with regulatory submissions based on the same trial results across all participating regions. While it is generally assumed that approved doses will align across regions, few studies have specifically analyzed the differences in approved doses between Japan and the U.S. in recent years. MCTs have been shown to reduce drug approval timing differences (drug lag) between Japan and the U.S. in certain therapeutic areas. However, data on drug lag for recently developed drugs remain limited. This study investigates differences in approved doses and drug lag between Japan and the U.S. for drugs approved in Japan between 2012 and 2021. The study analyzed 579 drugs with comparable dose information in Japan and the U.S., and confirmed that MCTs play a role in minimizing dose differences between Japan and the U.S. Additionally, the study confirmed that drug development through MCTs significantly shortens drug lag in these drugs, similar to previous studies with different target drugs. Overall, the findings highlight that drug development through international clinical trials not only reduces drug lag but also minimizes differences in approved doses between Japan and the U.S.