Phase 1 Studies evaluate the safety and metabolism of the drug in a small number (20-100) of healthy volunteers and subjects who have the disease studied. Many of these studies require overnight visits at the clinic.
Phase II studies evaluate the effectiveness of the drug and are usually carried out “blinded” with a placebo control group and utilizes several hundred patients. In these studies various doses of the drug are administered to decide the best dosage form to be used.
After the study is completed, a statistical analysis is conducted to determine the benefits and safety of the study drug. Depending on these results the sponsor can continue the process of evaluation through Phase III and apply for FDA approval or discontinue the study or compound.
On completion of these studies, if the safety and value of the drug is evident, Phase III studies are carried out in several hundred to several thousand patients, and on successful completion the pharmaceutical company can apply to the FDA for approval to market the drug.
After approval, Phase IV studies are conducted to further evaluate the drug against other similar marketed drugs and to monitor long term effectiveness and safety.
If you missed last week’s blog, you can read it here. Next week’s blog will focus on the next stage other aspects of the clinical trial process.