Each new drug- before it becomes available for sale – has to undergo several phases of comprehensive, specialized research and be approved by the regulatory authorities. The first steps in the drug development process consist of basic and preclinical research (including, amongst others, animal testing). The average total duration of such studies is about 4-5 years. If the results of this research indicate that a new drug is safe, the product goes through a series of clinical trials on humans. They are usually carried out in four phases, beginning with small scale testing aimed at assessing safety, thereafter broader studies focusing on the effectiveness of the new product.
Phase I. During Phase I a new product is tested on a limited number of healthy people (typically about 20 - 80 subjects) to determine the basic safety requirements and to collect pharmacological data. On average, the phase lasts from six months up to one year.
Phase II. During Phase II a new drug is tested on a small group of patients - volunteers (typically 100 - 200 subjects) with the disease or disorder against which the product is directed. The aim of this phase is to determine the product’s efficacy and therapeutic dose. Trials are normally conducted over a period of one to two years.
Phase IIIa-b. Phase IIIa studies include a significant number of patients (usually from several hundred to several thousand subjects), in order to verify the efficacy and safety of the studied medication on a larger scale. Phase IIIa studies are conducted in relation to formal registration requirements and they are run in many clinical centers, usually for two to three years.
After the completion of Phase IIIa with positive results, the sponsor submits a registration dossier to appropriate regulatory authorities. It contains full details of the preclinical results, pharmacological profile, efficacy and safety of the drug, information about product composition, and also plans for production, packaging and labeling of the new product. The registration review process may take 30 months or longer, depending on a country, product type and many other factors.
Trials of Phase IIIb. Usually begin after submission of the registration dossier, and before the formal approval of a new product for use and distribution. These studies, also involving a substantial number of patients, usually focus on matters such as cost-performance relations, effectiveness of a new drug in comparison to parameters of already-approved medications in the same therapeutic class or medicines to treat the same disease.
Phase IV. Phase IV studies begin after formal registration of a drug and usually serve to confirm its safety and efficacy for new indications (therapeutic use). They also assess the new dose and forms of the drug (e.g., capsules with prolonged release of the active substances to the body or flavored syrups for children). This phase serves to confirm certain non-clinical benefits, such as cost and quality of life assessment. It also provides an analysis of safety in patients treated with a new drug in the course of outpatient or inpatient treatment in a long-term perspective.