Bioequivalence is the comparison of the bioavailability of two drugs. The bioavailability of pharmaceutically equivalent products (similar pharmaceutical forms bearing the same molar amounts of the same active substance) is similar. In other words, the amount and rate of active substance in the bio-phase are similar. These kinds of studies are carried out on completely healthy volunteers.

     Therapeutic equivalence tests whether two different drugs (not two different products of the same drug, as in bioequivalence) give the same clinical result. It is not necessary that the two drugs be exactly the same here. Over the last 40 years, the use of generic drugs has increased in order to reduce health spending. Bioequivalence studies are the works carried out after the patent rights of the products, which are the products of innovation, expire. These studies have led to the introduction of cheaper but therapeutically equivalent products. Licensing of generic drug products in various countries of the world has been facilitated and encouraged. The first Good Clinical Practice (ICU) guide was designated in 1977-1978 in the United States (USA) by the Food and Drug Administration (FDA). Since 1992, the FDA has begun to work to set the standards of bioequivalence studies with the regulations it has made. The IKU guide was published in 1991 in the European Union and entered into force. The predominant part of pharmaceutical production in our country is generic products. In our country, bioequivalence studies have become more important as a result of the most recent regulations. According to the Pharmaceutical Manufacturers Association (IEIS), about 50% of the medicines currently prescribed in our country are equivalent drugs. Drug development and studies conducted prior to the use of developed drugs in humans are carried out as regulated in the Helsinki Declaration. In these researches, an international consensus on the necessary rules has been developed. National health institutions have begun to implement these regulations more effectively. In accordance with the relevant legislation, both clinical units and bio-analytical units apply to the Ministry of Health after completing the necessary infrastructure. The Ministry of Health monitors these units on the basis of their relevant legislation and international good clinical practices and good laboratory practices and delivers a positive or negative opinion or requests the correction of certain issues. These units may begin to work after they have obtained the required certificate of conformity.

In the center;

    - Sponsors

    - CROs (contact research organizations)

     - Investigators

     - Ethics Committees

     - Monitors

     - Auditors all work as a whole. Basic tasks of the center are as follows:

     - Protection of patients and volunteers

     - The reliability of stored data

     - The aim is not the treatment of the patient, but to respond to the scientific questions. The basic principles of the center are as follows;

    - Clinical trials must be carried out in accordance with the Helsinki declaration and approved by the ethics committee.

    - The main objectives and risks in the study should be assessed, and trials should be carried out when it is decided that they are beneficial to the society,

     - The rights, safety, and well-being of volunteers prioritize above anything else.

     - Every detail of the clinical trial should be specified in the protocol. The study should be conducted according to this protocol or protocol amendments.

     - The studies should be carried out by specialist physicians.

     - Every individual who will take part in the study should be qualified.

    - Each of the volunteers must read and sign the 'informed volunteer consent form' before the study.

     - The confidentiality of the data obtained as a result of the study should be protected and stored.

     - Investigational products must be produced according to the GMP (Good Manufacturing Practices) rules and should be administered as described in the protocol.

     - The quality of every research/trial should be checked.

Selection of Volunteers

Inclusion Criteria

    - Both genders can be included.

    - Usually, he/she should be between 18 and 45 years of age; however, he/she may be older depending on the design of the study, but it is not possible to accept those under the age of 18.

    - He/she should have a body mass index at normal limits.

    - He/she should be healthy according to the clinical examination and laboratory criteria.

Exclusion Criteria

The volunteer cannot participate in the study under following conditions:

     - If there is an allergy history

     - If he/she uses another medication    

     - If he/she has undergone major GIS surgery

     - If he/she has given blood in the last three months

     - If he/she is alcohol or drug addict

     - If he/she consumes excessive tea/coffee

     - If he/she oversmokes

     - If he/she drinks grapefruit

After the volunteer is included in the study, he/she has to read and sign the informed consent form.

Informed consent form in Bioequivalence Studies 

    It is a form which is filled in by the volunteer, who will participate in the clinical trial, and includes the content, benefits and side-effects of the reference or test drug, which will be applied to the volunteer, and the rules that must be followed during the study. The volunteer has to read and sign this form with his/her free will.

In general, in the informed consent form, the following should be indicated:

     - Objective, method and methodology of the study, for which consent is requested,

     - The number of people participating in the study,duration of the study and the telephone numbers list of people to be contacted,   

     -Payments to be made for the volunteers and the amount of compensation to be covered in case of damage.

Standardization of the study

     -Diet: All volunteers have to be given a standard diet as long as they stay in the clinic.

     - Fluid intake: How long after the medicament intake water can be drunk on the day of study and the amount of daily consumption must be adjusted.

     - Physical activity: Volunteers should avoid heavy physical activity.

     - Time of medication administration: It must be the same in all periods.

     - Way of medication administration: It should be standard in all volunteers as hungry or satiated.    

     - Food and beverages, which may disturb the circulation, digestion, liver and kidney functions, should not be given.

After the blood samples collected from the volunteers are evaluated in the laboratory, a statistical analysis of the obtained data is performed. Here, the dose-response curves of both drugs are compared and the area under the curve and the maximum concentration values are compared. If these values are within the appropriate range, two drugs are considered equivalent.