Intended for healthcare professionals

Education And Debate

Open label extension studies: research or marketing?

BMJ 2005; 331 doi: (Published 08 September 2005) Cite this as: BMJ 2005;331:572
  1. G J Taylor, senior medical statistician (,
  2. P Wainwright, professor of nursing2
  1. 1 Research and Development Support Unit, School for Health, University of Bath, Bath BA1 3NG
  2. 2 Faculty of Health and Social Care Sciences, Kingston University and St George's Hospital Medical School, London
  1. Correspondence to: G J Taylor
  • Accepted 19 June 2005

Open label extension studies allow continued prescribing of unlicensed drugs after a randomised trial, but it is unclear whether patients or drug companies are benefiting the most


Properly designed and conducted open label extension studies can provide rigorous information on long term safety and tolerability of potential new drugs. This in turn can benefit the licensing application for the drug by providing longer term data that would otherwise not be available until after the licence was approved. Nevertheless, the conduct of such studies raises several ethical and scientific concerns.1 2 As with any research method, there are good and bad examples. However, open label extension studies seem particularly prone to the pressures of marketing over good research methods and research ethics. We revisit some of these issues and argue that we need to change our approach to the ethical review of such studies.

Embedded Image

Participants in open label extension studies need more information


Open label extension studies

Open label extension studies typically follow a double blind randomised placebo controlled trial of a new drug. At the end of the double blind phase, participants are invited to enrol in an extension study. The study will normally be longer than the randomised trial (two years is not uncommon but they often continue until the drug is licensed). All participants in the extension study are given the study drug, and both they and the investigators know this. The objective is primarily to gather information about safety and tolerability of the new drug in long term, day to day use.

Use of open label studies after phase III trials is relatively common. In 2004, the multicentre research ethics committee for Wales reviewed three open label extension studies compared with 19 phase III studies of new drugs, a ratio of just over 6:1. However, a recent Medline …

View Full Text

Log in

Log in through your institution


* For online subscription