Clinical trials are a part of the Food and Drug Administration’s (FDA) process for drug approval. The intent behind the process is to screen drugs for two things before allowing the public access to the drugs: safety and efficacy. At each trial stage a drug can ‘fail’ and the research program for it will be terminated or go back to the pretrial stage. The trial process also gives the FDA data it needs to schedule the drugs if they are approved.

There are four phases to clinical trials; each has a specific area of focus for a drug. Phase one may actually have several years’ worth of research invested into the drug before it can begin. This is because phase one of human testing cannot occur until the company is relatively certain that the drug is both safe for human consumption and stands a reasonable chance of treating the condition it is intended to address. In a phase one trial, the drug is administered to healthy adults who do not have the condition the drug seeks to treat. This phase is creates a draft of possible side effects for the drug, and gives the researchers a base point to tinker with the formula and dosage to minimize the occurrence and severity of side effects.

If a drug that successfully makes it through the first test, it will move to phase two. In the second phase, the main purpose is to test the efficacy of the drug in the treatment plan or its symptoms. A larger group of adults with diagnosed correctly will receive a controlled drug in the event to assess how it works, also known as efficacy.

If the drug is shown to be effective, it will move on to phase three, which tests for drug interactions. In this phase of the study, the test subject pool is broadened to include patients that have other health problems than the one the drug is intended to treat. It also includes patients on other medications. This allows researchers to see how the drug interacts with other medications and conditions before it is released.

When a drug has passed a phase three trial, it is ready to be approved by the FDA, but more a test phase: stage four. This is a later stage market, where companies keep tabs on possible problems that slip through the cracks in previous trials, side effects such as low frequency but only when medication is used by hundreds of thousands of people.