What's In a Phase?
We often hear of a clinical trial described as being a 'Phase I' (or 'Phase II or III') study. What does this numbering system mean?
First of all, the Phase nomenclature is only used in clinical trials -- research involving human participants designed to test a drug or device that is to be marketed for use in people. And clinical research doesn't usually begin until tests in the laboratory and tests using animals, known as 'pre-clinical' research, have generated promising results.
The Phases are really just steps along the way from early and scarce information to more complete and plentiful information about how a drug or device can be expected to affect patients. In order...
Phase I studies involve few participants and are primarily designed to test the safety of the product. They answer questions such as "Will the product make people sick? If so, how sick?" and "How much of the product can people take before they get sick from it?" Remember, there is already some evidence from pre-clinical studies to suggest that the product will work. The issue for the Phase I study is what doses are relatively safe to use in people.
Phase II studies involve larger numbers of participants. They continue to look at safety -- for effects that didn't show up in the relatively small number of participants in the Phase I trial. But they also are designed to demonstrate how well the drug works at various dosages. Sometimes referred to as 'Efficacy' studies, Phase II clinical trials show how effective the drug is in different doses.
Phase III studies usually include very large numbers of participants. Conditions such as dosages and drug formulation (what form the drug is in, such as a pill or capsule or liquid) are tested in lots of people. This gives a fairly good idea of how well the product will work, what the usual side effects will be (that's what the gazillion things listed on the warning label are), and sometimes longer term observations are made.
Next time: What happens following Phase III...
-Joe
Related Topics: FDA Approves New Angina Drug, FDA Approves Rotavirus Vaccine
Technorati Tags: clinical trials, phases
First of all, the Phase nomenclature is only used in clinical trials -- research involving human participants designed to test a drug or device that is to be marketed for use in people. And clinical research doesn't usually begin until tests in the laboratory and tests using animals, known as 'pre-clinical' research, have generated promising results.
The Phases are really just steps along the way from early and scarce information to more complete and plentiful information about how a drug or device can be expected to affect patients. In order...
Phase I studies involve few participants and are primarily designed to test the safety of the product. They answer questions such as "Will the product make people sick? If so, how sick?" and "How much of the product can people take before they get sick from it?" Remember, there is already some evidence from pre-clinical studies to suggest that the product will work. The issue for the Phase I study is what doses are relatively safe to use in people.
Phase II studies involve larger numbers of participants. They continue to look at safety -- for effects that didn't show up in the relatively small number of participants in the Phase I trial. But they also are designed to demonstrate how well the drug works at various dosages. Sometimes referred to as 'Efficacy' studies, Phase II clinical trials show how effective the drug is in different doses.
Phase III studies usually include very large numbers of participants. Conditions such as dosages and drug formulation (what form the drug is in, such as a pill or capsule or liquid) are tested in lots of people. This gives a fairly good idea of how well the product will work, what the usual side effects will be (that's what the gazillion things listed on the warning label are), and sometimes longer term observations are made.
Next time: What happens following Phase III...
-Joe
Related Topics: FDA Approves New Angina Drug, FDA Approves Rotavirus Vaccine
Technorati Tags: clinical trials, phases
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