2. 3 Steps of Clinical Trials
A small number of healthy adults → a small number of patients → a large number of patients All trial results are used to turn a "drug candidate" into a "drug
Clinical trials usually proceed in three steps (phases).
At the end of the three steps, the pharmaceutical company developing the drug compiles all the data and applies to the Ministry of Health, Labour and Welfare to have it approved as a drug.
Only after passing the MHLW's rigorous review and approval does the "drug candidate" become a "drug.
(1) "Phase I studies" (clinical pharmacology studies)
First, the drug candidate is administered to a small group of healthy adults, starting with a very small dose and gradually increasing the dosage, to determine whether it is safe. We also measure the amount of the drug candidate present in blood and urine to determine how quickly it is absorbed into the body and how long it takes to be excreted from the body.
Column: "Whether physical changes are caused by clinical trials or not
In order to determine whether changes in the body are side effects of a "drug candidate," a placebo (which does not contain an active ingredient and is indistinguishable from the "drug candidate" in terms of appearance, taste, etc.) may be used at the same time for comparison. Depending on the type of drug candidate, it may be more appropriate to start the trial with patients who are expected to respond to the drug, and in this case, preliminary efficacy studies can usually be conducted.
(2) "Phase II studies" (exploratory studies)
Next, for a relatively small number of patients who are expected to respond to the drug candidate, we examine how the drug will work (efficacy), what side effects it will have (safety), and how it should be used (dosage, interval, duration, etc.), depending on the severity of the disease.
In order to investigate efficacy and usage, several dosages are usually used for comparison, and a placebo* is usually added. If there is a standard drug currently in use, it may be compared to that drug.
(3) "Phase III trials" (validation trials)
Finally, the efficacy, safety, and usage of the "drug candidate" obtained from the results of Phase II trials on a large number of patients are finally confirmed. The method of confirmation is mainly a comparison with the standard drug currently in use, if any, or with a placebo if no standard drug is available.
Apart from this, the safety and security of the drug when used over a long period of time are also examined.
Column: "To conduct clinical trials fairly and without bias
Comparative trials should be conducted in an unbiased and impartial manner, and it is not uncommon to use a lottery-like method to determine which patients are assigned to which treatment (randomized assignment), and to ensure that neither the investigators nor the patients are aware of which treatment they are assigned (double-blind In many cases, a double-blind method (double-blind method) is used. All procedures are tested at the same time.