What are the various stages of a clinical trial?

Have you ever considered volunteering for a clinical trial? It’s a worthy cause and a chance to help advances in medicine. If you’ve been hesitant, it might be because of a lack of information about the process. Not many of us understand what happens when a drug, vaccine or device goes through the various trials that it must go through before being brought to market. Here are the different phases of a clinical trial:

Phase 0

Trials that take place normally start at phase 1 but a doctor might ask a patient to take part in a phase 0 part of a trial. This stage is for researchers to examine if a drug behaves in the same way that it behaved in the laboratory and how the researchers expect the drug to react. This phase only includes a very small number of participants and a very low dose of the drug.

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Phase I

This is the normal start point for all trials and begins rather small with a few healthy participants. The aim of this part of the trial is to see what dosage can be administered safely, what possible side effects might be experienced and how the drug moves through and is metabolised by the human body. This stage is also referred to as the escalation stage. The first cohort is given a very small quantity and if all goes well, the following cohort will receive a slightly higher dose and so on. If no problems are experienced when the maximum dosage is administered, phase 2 trials can commence.

Phase 2

This important stage of the trial is to investigate the effectiveness of the drug. The cohort is larger in phase 2 and some participants with the particular disease or condition involved are also included. Sometimes the drug will be compared with another similar treatment or compared with a placebo. Side effects are monitored, as well as dosage amounts.

Phase 3

The main goal of a phase 3 trial is to compare a current top treatment with the new one unless the drug or vaccine is entirely new. This stage recruits many more participants, sometimes hundreds or thousands. Some will have a disease or condition, some will be taking medication for conditions and the cohort should be diverse to represent society. This helps to monitor any new side effects and also any medication contraindications. If you want to find out more about Bridging Studies, visit a site like https://www.richmondpharmacology.com/specialist-services/bridging-studies

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Phase 4

This phase will take place once a drug has been submitted for approval by health authorities and a licence for marketing has been approved. This group of volunteers will be larger and will help researchers to monitor the efficacy in a wider population. Also examined will be side effects, risk-benefit analysis and long term considerations regarding efficacy and safety.

Some trials only have phase 1 and some other adaptive trials might include two phases run at the same time with an overlap in the stages.

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