{"id":6767,"date":"2026-05-12T12:17:12","date_gmt":"2026-05-12T10:17:12","guid":{"rendered":"https:\/\/mediconomics.com\/glossar\/phase-0-study\/"},"modified":"2026-05-12T12:17:12","modified_gmt":"2026-05-12T10:17:12","slug":"phase-0-study","status":"publish","type":"glossary","link":"https:\/\/mediconomics.com\/en\/glossar\/phase-0-study\/","title":{"rendered":"Phase 0 study"},"content":{"rendered":"

A Phase 0 study<\/strong> (also known as an exploratory IND study<\/em> or microdosing study<\/em>) is a very early clinical study in humans that can be conducted before conventional Phase I studies.<\/p>\n

The aim is to obtain initial information on pharmacokinetics<\/strong>, distribution<\/strong>, or target binding<\/strong> with minimal risk\u2014often using very low doses and without therapeutic intent.<\/p>\n

What distinguishes Phase 0 from Phase I?<\/h2>\n

While Phase I studies primarily investigate safety, tolerability, and dose finding, Phase 0 focuses on early, exploratory data<\/strong> to support decision-making within the development program.<\/p>\n

Typical differences:<\/p>\n

    \n
  • Very low dose<\/strong> (often a microdose, e.g., 1\/100 of the expected pharmacologically active dose)<\/li>\n
  • Small number of participants<\/strong> and short study duration<\/li>\n
  • No intention to achieve a therapeutic effect<\/li>\n
  • Strongly analytics-driven (e.g., sensitive bioanalysis, PET tracer approaches)<\/li>\n<\/ul>\n

    What are Phase 0 studies used for?<\/h2>\n

    Phase 0 studies can help make an early decision on whether a drug candidate should be further developed. They are used, among other things, to: <\/p>\n

      \n
    • collect initial human PK<\/strong> data and assess animal-to-human extrapolation<\/li>\n
    • investigate target engagement<\/strong> or tissue distribution<\/li>\n
    • prioritize candidates within a compound class<\/li>\n<\/ul>\n

      Regulatory framework and limitations<\/h2>\n

      From a regulatory perspective, Phase 0 studies are possible, but they still require a robust study protocol, ethics approval, and appropriate quality standards for the investigational product approach. The data are generally not sufficient<\/strong> to infer safety for higher doses. <\/p>\n

      Positioning in project management<\/h2>\n

      From an economic perspective, Phase 0 can make development more efficient because early \u201cgo\/no-go\u201d decisions are based on human data. At the same time, it creates additional effort and is only meaningful if the results are truly decision-relevant. <\/p>\n

      FAQ<\/h2>\n

      Is a Phase 0 study mandatory?<\/h3>\n

      No. It is optional and is only conducted if it provides clear additional insight. <\/p>\n

      Who participates in Phase 0 studies?<\/h3>\n

      Mostly healthy volunteers; in some cases, patients may also be included if this is scientifically or ethically appropriate.<\/p>\n

      Why is a microdose often used?<\/h3>\n

      A microdose reduces risk, while still allowing measurement of PK parameters or distribution if sufficiently sensitive analytical methods are available.<\/p>\n","protected":false},"excerpt":{"rendered":"

      A Phase 0 study (also known as an exploratory IND study or microdosing study) is a very early clinical study in humans that can be conducted before conventional Phase I studies. The aim is to obtain initial information on pharmacokinetics, distribution, or target binding with minimal risk\u2014often using very low doses and without therapeutic intent. […]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"glossary-cat":[],"class_list":["post-6767","glossary","type-glossary","status-publish","hentry"],"acf":[],"related_terms":"","external_url":"","internal_reference_id":"","_links":{"self":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6767","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":0,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/6767\/revisions"}],"wp:attachment":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/media?parent=6767"}],"wp:term":[{"taxonomy":"glossary-cat","embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary-cat?post=6767"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}