We need your help now

Support from readers like you keeps The Journal open.

You are visiting us because we have something you value. Independent, unbiased news that tells the truth. Advertising revenue goes some way to support our mission, but this year it has not been enough.

If you've seen value in our reporting, please contribute what you can, so we can continue to produce accurate and meaningful journalism. For everyone who needs it.

Matt Rourke/AP/Press Association Images
Clinical trials

What happens during a clinical trial?

Medicines available in Ireland are required to undergo clinical trials before being granted a license – but just what is involved in a clinical trial?

ALL MEDICINES AVAILABLE in Ireland are required to undergo several stages of clinical trials before being granted a license – but just what is involved in a clinical trial?

What happens during a clinical trial?

The aim of a clinical trial is to establish several factors about a drug, including its effectiveness and potential side effects.

Once a trial has been conducted, any data collected is sent to a regulatory body such as the Irish Medicines Board (IMB) for a benefit/risk assessment, which examines whether the advantages offered by a treatment outweigh any potential drawbacks.

A clinical trial is a study of the “pharmacological or clinical impact of a medicinal product on human subjects” according to the IMB. During a trial, pharmacokinetic effects are studied (ie what changes a human body makes on a drug) as well as its safety and effectiveness.

Trials can take many years to complete.

What kinds of clinical trials are there?

There are several types of clinical trials, including; controlled trials, blind and double-blind trials, randomisation and placebo trials.

Controlled trials require a trial group and control group of patients, who receive new and standard treatments, respectively. This is to allows researchers to compare treatments.

In a randomised trial, patients are randomly selected into groups by a computer – ensuring there is no bias. During a blind trial, a patient is not told whether they are receiving a new or standard treatment.

During a double-blind trial, the medical team will be unaware of which treatment which subject is getting, although – don’t worry – the information is available when needed.

Placebos appear to be drugs but have no actual effect on the body. Subjects are informed if a trial involves a placebo before taking part.

All kinds of investigational medicinal products can be studied during a clinical trial – including:

  • Chemical entities
  • Biotechnology products
  • Cell therapy products
  • Gene therapy products
  • Plasma derived products
  • Immunological medicinal products (eg vaccines
  • Herbal medicinal products
  • Radiopharmaceutical products
  • Homeopathic products


The stages of clinical trials – known as phases – involve either healthy volunteers or ill patients. The Irish medicines board outlines four categories of clinical trials:

Phase I: This is the first stage in which a new treatment is used on people; before this, laboratory trials would have been conducted. Phase I typically involves a small number of people – usually under 50 – and seeks to establish safe dosage, administration methods and effects.

Phase II: A small group is also used for phase II trials, which aims to narrow-down the usefulness of a treatment for particular manifestations of a disease, and also establishes whether trials can progress to a larger group of people.

Phase III: This phase includes a much larger group and aims to establish more information regarding possible side-effects, as well as to compare the new treatment with standard treatment.

Phase VI: Thousands of patients are needed for this phase, which ultimately proves whether a treatment is effective.

Advantages and disadvantages

People have different reasons for taking part in clinical trials; many choose to become involved in order to help in the development of treatments for particular diseases, possibly because they themselves suffer from it.

On the plus side, subjects will find that a great deal of attention in given to their condition and and they might also be given access to a promising new treatment. They could also contribute to the improvement of care for others down the line.

On the other hand, unexpected side-effects may exist, or the treatment may turn out not to be as effective as others. The Irish Cancer Society warns that some health insurance companies do not cover the costs associated with a trial – so those considering taking part should check with their provider first.

A patient’s doctor will go through all the pros and cons of taking part in a trial. The Irish Cancer Society suggests that, when speaking with their GP, patients ask the following questions:

  • What is the purpose of the trial?
  • What is the trial called?
  • What treatment will I be receiving?
  • What is the difference between the trial treatment and standard treatment?
  • What are the side effects of the trial treatment?
  • What are the benefits of taking part in the trial?
  • What are the risks of taking part in the trial?
  • How many patients are taking part in this trial?
  • How long will my treatment take?
  • Will the trial cost me money?
  • Will I be in the same hospital and have the same doctors?
  • What treatment will I have if I do not want to take part in the trial?
  • What will happen if I want to discontinue the trial treatment?
  • When will the trial results be available?

Before a subject begins participating in a clinical trial they must undergo medical tests. This helps researchers to establish a person’s health before taking part, and to draw conclusions about the effectiveness of the treatment.

What regulations are in place?

Since 2004, clinical trials in Ireland involving medicinal products for human use have been covered by the European Communities (Clinical Trials on Medicinal Products for Human Use) Regulations. All trials are also closely overseen by the IMB and take place in hospitals, medical clinics and surgeries.

Your Voice
Readers Comments
    Submit a report
    Please help us understand how this comment violates our community guidelines.
    Thank you for the feedback
    Your feedback has been sent to our team for review.