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Based on their source, drugs can be classified into three categories: chemically synthesized drugs, biological products, and drugs of natural origin. According to statistics, chemically synthesized drugs remain the main source of candidate drugs, accounting for over 50% of such drugs over the years. Active ingredients extracted from natural minerals, animals, and plants, as well as drugs produced through chemical or biological synthesis, are collectively referred to as chemical drugs. Chemical drugs have well-defined structures, and they serve to prevent and treat diseases, diagnose illnesses, or regulate bodily functions, improve quality of life, and maintain good health. From the 19th century to the 1930s, many natural products were isolated, purified, and identified from plants and animals, such as organic acids (such as salicylic acid) and alkaloids (such as **, atropine, quinine, caffeine), etc. These natural products possess certain physiological or pharmacological activities and can be used directly as drugs. Their separation and identification demonstrate that the chemical substances contained in natural medicines are the basis for their therapeutic effects. These natural medicine molecules not only provide drugs that can be accurately applied in clinical settings, but also lay a solid foundation for the development of pharmacology. After the mid-19th century, the development of the chemical industry, particularly in areas such as dye chemistry and coal chemistry, provided more chemical substances and raw materials. As a result, pharmacological studies were conducted on numerous intermediates and products derived from organic synthesis chemistry. At the same time, the development of organic synthesis techniques has made it possible to synthesize drugs from simple chemical raw materials. The successful use of substances such as chloroform and ether as general anesthetics, and chloral hydrate as a sedative for sleeping, contributed to the development of the pharmaceutical industry. At the end of the 19th century and the beginning of the 20th century, the pharmaceutical industry began to synthesize and produce chemical drugs on a large scale. People started to synthesize simple chemical drugs such as salicylic acid and aspirin, benzocaine, aminopyrine, phenacetin, etc., and to manufacture them in large quantities. Research in medicinal chemistry began to shift from the study of natural products to that of synthetic compounds. Meanwhile, certain natural and synthetic organic dye intermediates such as leukodoric acid are used in the treatment of infections caused by pathogenic bacteria, and it has been found that certain synthetic compounds possess chemotherapeutic effects and are thus used clinically. The synthetic organic dye intermediates used in the treatment of pathogenic bacterial infections during this stage were the earliest forms of chemical drugs, laying a solid foundation for the vigorous development of the pharmaceutical industry. However, at this stage, the focus was limited to the study of existing substances, as well as the search for and identification of their potential medicinal values; it was an isolated approach that failed to conduct in-depth research on the relationship between the chemical structure of natural or synthetic substances and their biological activity. Chemical drugs are based on compounds as their fundamental substance, and their therapeutic effects (biological effects) serve as the basis for their use. Medici provides services such as optimization of chemical drug synthesis processes and optimization of formulation processes. It was roughly from the 1930s to the 1960s. It is characterized by the large-scale emergence of synthetic drugs, the isolation, determination, and assessment of endogenous bioactive substances, as well as the clinical use of enzyme inhibitors; it can be regarded as the \"golden age\" of drug development. Dornagk first used prontosil in the clinical treatment of bacterial infections, marking the beginning of modern chemotherapy and paving the way for dozens of sulfonamide drugs with clinical applications. In the 1940s, the antibacterial activity of penicillin was further confirmed, and it was used in clinical settings for the first time, becoming the first antibiotic to be applied clinically. Due to its unique structure and strong antibacterial activity, penicillin brought about a revolution in therapeutics. The emergence of penicillin prompted people to begin isolating and searching for other antibiotics from fungi and other microorganisms. At the same time, building on the clinical use of penicillin, research on semisynthetic antibiotics was carried out, and several categories of semisynthetic penicillins that were resistant to acid and enzymes as well as having broad-spectrum activity were successfully developed. During this period, not only were many natural substances with proven medicinal value synthesized, thereby alleviating the shortage of natural resources to some extent, but also steroid hormones, semi-synthetic antibiotics, drugs for the nervous system, medications for cardiovascular diseases, and chemotherapeutic agents for malignant tumors were synthesized using organic synthesis techniques and other methods. As a result, chemical drugs made great progress during this stage. To date, humans have developed and utilized thousands of different chemical drugs. Based on their area of action, they can be classified into drugs for the central nervous system, drugs for the peripheral nervous system, drugs for the circulatory system, drugs for the digestive system, and so on ； Based on their functions, they can be classified into antipyretic and analgesic drugs, anti-tumor drugs, antibacterial drugs, antiviral drugs, etc ； Based on their chemical structural characteristics, they can be further divided into peptide drugs, hormonal drugs, barbiturate drugs, etc. Biosynthetic drugs utilize biologically active molecules such as enzymes as carriers to synthesize drugs, thereby improving reaction selectivity and reaction rate. Drug biosynthesis refers to the application of biosynthesis in drug production, as well as the stereoselectivity in drug biosynthesis and the production of customized drugs. Drug biosynthesis primarily makes use of bioactive molecules, such as various enzymes that act as catalysts in the synthesis process. This enhances reaction selectivity, allows for milder reaction conditions, and increases the reaction rate. Moreover, synthesis involving microorganisms is more convenient; for example, chromosomes have been used in drug synthesis – all that is needed is a culture medium containing artificially synthesized raw materials along with an appropriate temperature, and the various enzymes present in E. coli can then use these materials to synthesize drugs. Drug biosynthesis involves the production of specific drugs through the metabolism of organisms; it represents an extension of modern fermentation engineering and genetic engineering. This method causes less environmental pollution and is suitable for the large-scale production of drugs. Drugs mainly originate from the primary and secondary metabolic products of organisms. In short, it is the process of using microorganisms to convert drug precursors into drugs. It is a future trend in the development of modern medicine, as well as a guiding direction for medicine in the years to come. There is actually no clear distinction between chemically synthesized drugs and biosynthetically produced drugs. If a distinction must be made, traditional chemical synthesis methods do not involve biologically active macromolecules such as proteins or nucleic acids, nor do they rely on microorganisms; instead, they use artificially designed synthetic routes and classical organic reactions for synthesis. The introduction of biotechnology is reflected in the involvement of biologically active molecules, such as various enzymes, in the synthesis process. The greatest advantage of biosynthetic drugs is the increased selectivity of the reactions, milder reaction conditions, and a higher reaction rate. Moreover, synthesis involving microorganisms is more convenient; for example, E. coli with modified chromosomes has been used for drug synthesis – all that is needed is a culture medium containing artificially synthesized raw materials, and the various enzymes in E. coli can use these materials to synthesize the drugs