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How to do pre-clinical research on chemical drugs and biological drugs? (2)

2021-06-23
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Biological medicine refers to a class of medicines used for prevention, treatment and diagnosis that are manufactured using biological, biological tissue, cells, body fluids, etc., using the research results of biology, medicine, and biochemistry.

Biological drugs, especially antibody drugs, have the advantages of high targeting and good selectivity, so the curative effect is accurate and side effects are small; the disadvantages are poor membrane permeability (difficult to enter cells and difficult to break through the blood-brain barrier), and some are immunogenic.

Registration classification of therapeutic biological products

Category 1: Innovative biological products: therapeutic biological products that have not been marketed at home or abroad.

Category 2: Improved biological products: the improvement of domestic or overseas marketed products to improve the safety, effectiveness, and quality controllability of new products, and has obvious advantages for therapeutic biological products.

2.1 Biological products that optimize their dosage form and route of administration on the basis of products already on the market, and have obvious clinical advantages.

2.2 Add new indications that have not been approved at home or abroad and/or change the medication population.

2.3 Biological products with similar products on the market constitute a new compound product.

2.4 On the basis of marketed products, biological products with major technological improvements, such as recombinant technology to replace biological tissue extraction technology, have obvious clinical advantages after changing amino acid sites or expression systems and host cells compared with marketed products.

Category 3: Biological products listed domestically or overseas:

3.1 Biological products produced overseas that have been listed overseas and not listed in the domestic market shall be declared for listing.

3.2 Biological products that have been listed overseas but not listed in China shall be declared for domestic production and marketing.

3.3 Biological analogues.

3.4 Other biological products.

Discovery of Leading Compounds for Biological Drugs

As the preliminary structure type and clue substance of the drug, the discovery of lead compounds and structural transformation and modification can obtain drugs with excellent pharmacological effects. The choice of the type of lead compound has a greater impact on the success rate of drug development.

Biopharmaceutical production process

The development process of biopharmaceutical production process generally requires the construction of engineering cell bank, shake flask process development, small-scale process development, pilot scale-up, production purification and preparation steps.

The peculiarities of preclinical evaluation of biological drugs

Compared with conventional small molecule chemical drugs, biotechnology drugs are different in physical and chemical properties, immunological and toxicological properties, metabolic processes, and formulations. Since the target of biopharmaceuticals is mainly receptors or epitopes, it has the characteristics of species specificity, immunogenicity, incomplete structural confirmation, and versatility. Therefore, the evaluation of biotech drugs is similar to traditional preclinical evaluation. The method is different.

Many biological drugs are immunogenic in animals, and antibodies are produced after single or multiple administrations, which limits long-term toxicological evaluation, but can be used to determine the relative immunogenicity of different animals. Generally, it is highly immunogenic to animals and also immunogenic to humans; the frequency of administration, individual differences in patients, concurrent other diseases and the combined use of other drugs also affect the immunogenicity of the human body.

Most biological drugs are excreted from the body through biodegradation. Therefore, except for some drugs whose formulations are specifically improved in order to prolong the effective time, it is not necessary to conduct conventional in vivo and in vitro drug metabolism studies. Biological drugs generally have a longer action time, such as human-derived monoclonal antibodies and modified proteins that can act for several days to several weeks. Therefore, the frequency of administration of biotechnology drugs is generally 2-4 times a week, once a week or once a month.

The toxicity of biological drugs is often related to the expansion of pharmacological effects, and the shape of the dose response curve cannot be predicted. For immunomodulators, when the dose or concentration is increased, the physiological effects are often reversed. Therefore, it is difficult to extrapolate the results of animal experiments to humans. Although most biopharmaceuticals are designed to act on specific target receptors, target receptors often have regulatory effects on a variety of cellular functions.

The formulation of biotechnology drugs is relatively simple, and the route of administration is often parenteral or topical administration. In recent years, with the continuous application of new drug delivery technologies, it is also possible to administer inhalation or oral administration.

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