Drug Discovery
With few exceptions, the first part of developing a new drug occurs during basic research. Basic research defines scientific work (either done academically, for the government or for a private company) which aims to better understand how the human body works and/or how diseases develop. During the course of this research, scientists often discover new compounds that can either treat a disease or prevent it from developing. These compounds can be tested using cultures of cells or they may be analyzed by measuring their effects on proteins and/or DNA. According to the FDA, sometimes these drugs can also be developed using computer simulations.
Animal and Human Testing
Just because a potential drug works well in computer simulations or cultured cells does not mean that it will be effective in live animals. For this reason, potential medications are next tested in animal models. As the FDA notes, most drugs are tested in multiple animal models. Sometimes these animals are genetically modified so that their physiology mimics that of a human with a specific health problem. This is done to see if the drug can effectively treat a health condition in a more complex environment. It can also give clues as to potential side effects as well as the amount of the drug that is needed to be effective. If a drug is deemed to be safe in animal tests, the next step is to give it to human volunteers (also known as phase I clinical trials). These human volunteers are healthy; the purpose of this step in the drug development process is to measure the safety of the drug. Phase I clinical trials also allow for measurement of drug accumulation in the body as well as how it is metabolized and excreted.
Phase II and III Clinical Trials
The drug development tutorial from Pharmaceutical Product Development Incorporated explains that if a drug passes phase I clinical trials, it can then be tested in patients with the condition for which the drug would be used. Phase II testing involves taking a group of diseased patients and either giving them the new drug or a treatment that is currently in use for comparison. For some studies, this latter treatment is replaced by a placebo, which is a pill that contains no actual medication. This phase helps researchers determine how much of the drug is needed to treat diseased humans. Once a drug passes phase II trials, phase III clinical trials begin. Phase III trials work similarly to phase II trials, but with more patients involved. Phase III trials may also try different doses and administration routes to optimize how the drug is used. After these trials are successfully completed, a drug is approved or rejected by the FDA.
