The different phases of a clinical trial

Have you ever wondered what the different phases of a clinical trial are? Trials that take place for the testing of a new drug are normally broken down into four phases. If a treatment is successful in phase I, it will then pass to phase II, phase III and then phase IV consists of studies that take place after regulatory approval.

Pre-clinical phases involve the testing of a drug or device on non-human cells which provides information about how effective it is, any toxicity issues and how the organism impacts the drug or device itself.

Phase I involves the testing of the drug on healthy human volunteers in a clinical trial, with small doses initially and then increasing doses further on but still on a lower than therapeutic dosage. This stage used to be called ‘first-in-man studies’ but was replaced by ‘first-in-humans’ for better gender neutrality. This phase is for examining how much of a drug can be given to a person before any adverse effects become evident. For more information on Adaptive Phase 1 Studies, visit Richmond Pharmacology

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A small group of healthy volunteers will be invited to a clinical trial clinic, so they can be observed around the clock. There will be a range of doses, with some escalation to determine the safest dose. The dosage will still remain low to minimize risk.

Phase II involves testing the drug or device on patients for whom the compound could benefit to assess its efficacy and any possible side effects. These patients will receive what is known as a therapeutic dosage. Once phase I has established dosage levels, phase it to discover if the drug has any real effect and how well it works. Some trials will involve phases I and II being combined for toxicity and efficacy.

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Phase III involves testing on patients to gauge how effective it is and its safety. This phase involves a much larger random patient group to gauge how useful the drug is in daily clinical practice. Due to the size of this part of a trial, the length and design are the most expensive of all the phases. In most, but not all cases, there will be two phase III trials to show a drug’s effectiveness and safety before regulatory boards issue approval.

Phase IV is the stage after a drug or device has received approval by the necessary regulatory boards but continues to be monitored in the public. It is also known as the post marketing surveillance stage.  This stage might be a requirement of the regulation approval. The monitoring is essential for detecting any long-term problems over a much wider population.

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