美國食品藥品管理局（FDA）于2018年5月發(fā)布了“考慮列入OTC專論的外用藥活性成分的最大用量試驗：研究要點和考慮的因素供企業(yè)用的指導原則”。最大用量試驗（MUsT）是評估外用藥體內(nèi)生物利用度的標準方法，該指導原則對MUsT許多研究要點提出了具體的建議。詳細介紹該指導原則的主要內(nèi)容，期待對我國這方面的研究和監(jiān)管有益。

FDA issued Maximal Usage Trialsfor Topical Active Ingredients Being Considered for Inclusion in an Over-The-Counter Monograph:Study Elements and Considerations Guidance for Industry in May 2018. Maximal usage trial (MUsT) is a standard approach to assess the in vivo bioavailability of topical drug products.The guidance provides specific suggestions for many study elements of MUsT. This paper introduces the main contents of the guidance in detail, and expects to be beneficial to the research and supervision of this aspect in China.