What is an Open-Label Clinical Trial?

Clinical trials are a central part of the drug and medical intervention development process. Different trial designs can be used by clinical researchers, with open-label trials one such design. This article will discuss what open-label trials are.

Image Credit: PopTika/Shutterstock.com

The Importance of Clinical Trials and Good Trial Design

Clinical trials are vital for the design and development of safe drugs, treatments, and medical interventions and bringing them to market. Often, the idea for a clinical trial starts in the laboratory. Researchers will test new drugs and treatments in animal models, with the most promising being considered for clinical trials.

There are four phases to clinical trials, each involving more participants and with different aims. Participants will be chosen to take part, typically based on specific criteria, and will be given either the treatment or a placebo if they are part of the control group. Trials are governed by specific protocols which set forth design elements such as who can take part, what they will be doing, what treatments will be applied, and what participants can expect from the clinical researchers.

If a clinical trial does not have adequately designed protocols and follows them there are ethical, financial, and safety ramifications. Clinical researchers must be mindful of recruitment and retention issues, design trials with enough transparency during recruitment, and listen to the concerns of patients throughout the trial. If a trial is badly designed, delays in bringing new treatments to market can occur, as well as the danger of erroneous data leading to bad conclusions on the effectiveness of drugs and treatments.

Read Here: A Guide to Understanding Clinical Trial Terminology

Blind Trials

Most studies performed today are what is known as “blind trials.” Blind trials anonymize the treatments and control groups to prevent bias from occurring and increase the validity of data gathered on the effectiveness of treatments. Patients are not told which group they will be assigned to.

There are different types of blind trials. If either the individual or the researcher does not know which treatment the participants receive and what group they are assigned to, the trial is known as a single-blind trial. When neither the trial participant nor the doctor treating them knows which treatment is being administered, the trial is termed a double-blind trial. Blinding is also referred to as masking.

Blind trials are fully randomized, controlled trials. Trials which test surgical interventions are typically more difficult to randomize than those which evaluate new medications.

Image Credit: Yeexin Richelle/Shutterstock.com

Open-Label Trials

There is a fundamental difference between open-label trials and traditional blinded trials. In an open-label trial, both investigators and trial participants are fully aware of which treatment group the participants are in and what treatments are assigned to them. Open-label trials are used to compare different treatments or gather further information on the long-term effects of new drugs and treatments.

In some instances, patients are eligible to continue in further open-label trials once they have completed one clinical trial. In recent years, there has been a significant increase in the number of open-label trials performed. Open-label trials can be used to gather additional safety and efficacious data on drugs on the market to increase the confidence of clinicians, patients, and clinical bodies. They can play a key and legitimate role in clinical research as long as they are well-designed and follow specific protocols of their own.

Refining the perception of the expected incidence of adverse effects which have been identified in blinded studies and preclinical studies is one of the main values of open-label clinical trials. However, the risk of unpredictable adverse reactions, which can lead to serious consequences facilitates the need for post-marketing safety surveillance systems. Open-label trials are insufficient for providing data on these reactions.

Open-label trials can increase the confidence about incidence rates, but as they are typically biased and uncontrolled, this data is not of great value to researchers. Random allocation of participants into treatment and control groups is still necessary even in open-label trials to produce valuable data on pharmacologically expected reactions to drugs and treatments.

Several benefits for open-label trials have been suggested by researchers, including the ongoing access to medicine by phase III pivotal trial volunteers which have been proven effective, but they otherwise may not be able to access. There are ethical issues, however, especially with allocating patients with unknown reactions to previous treatments, largely since the treatment data in previously randomized trials may not have been released when patients enter the open-label trial.

Moreover, open-label trials suffer from their use as marketing tools to build a treatment market and apply pressure for subsidized access to drugs from physicians and consumers. For open-label trials to be successful, multiple stakeholders including funding bodies must be convinced of their motives.

In Summary

Open-label trials have a legitimate place in the development of new medicines and treatments, albeit a limited one. Fundamentally different from randomized, blind trials, they still need some degree of random assignment of treatments and control groups to provide valuable information for clinicians. Whilst increased confidence in the safety of treatments is a rationale for open-label trials, this aim is currently being achieved by other means.


  • Day, R.O & Williams, K.M (2007) Open-label extension studies: do they provide meaningful information on the safety of new drugs? Drug Saf. 30(2) pp. 93-105 [online] Accessed online 16th March 2022. https://pubmed.ncbi.nlm.nih.gov/17253876/
  • Karanicolas, P.J et al. (2010) Blinding: Who, what, when, why, how? Can J Surg. 53(5) pp. 345-348 [online] Accessed online 16th March 2022. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947122/
  • Concert Pharmaceuticals Inc. (2019) Understanding Clinical Trial Terminology: What is an Open Label Clinical Trial? Conceptpharma.com [online] Accessed online 16th March 2022. https://www.concertpharma.com/understanding-clinical-trial-terminology-what-is-an-open-label-clinical-trial/

Further Reading

  • All Clinical Trial Content
  • What is a Phase 0 Clinical Trial?
  • What is a Phase 1 Clinical Trial?
  • What is a Phase 2 Clinical Trial?
  • What is a Phase 3 Clinical Trial?

Last Updated: Mar 31, 2022

Written by

Reginald Davey

Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for News Medical represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science.

Source: Read Full Article