Pharmaceutics

Author: Chief Editor:
Publisher:
Publish Date: 2003-07-01
Features: This book is revised based on the first edition of "Pharmaceutics (Textbook for Secondary Vocational Schools)," incorporating the development of pharmaceutics in China, the current state of pharmaceutical production, and the teaching requirements of various programs in medical and pharmaceutical secondary vocational schools. The book consists of nineteen chapters, providing a comprehensive explanation of the theories, preparation processes, production techniques, quality requirements, quality inspection, and packaging and storage of various dosage forms. It briefly introduces the knowledge of biopharmaceutics and appropriately supplements the content of new dosage forms, new processes, and new excipients that have been developed or applied domestically and internationally. The book strives to integrate theory with practice, combining the teaching characteristics of secondary vocational schools with the modern of pharmaceutics development. It is written in an easy-to-understand manner, facilitating learning. This book is suitable for pharmaceutics teaching in various programs of medical and pharmaceutical secondary vocational schools and can also serve as a professional training textbook.
Excerpt: Due to the wide variety of drugs and their different properties, each drug must be processed for clinical use to achieve a form suitable for application, ensuring safety, efficacy, and stability. Therefore, the purposes of preparing dosage forms include:
1. Adapting to clinical needs for medical, preventive, and diagnostic treatment. Since diseases vary in severity and manifestation, and treatment should be tailored to the specific condition, different dosage forms are required. Ancient Chinese medical texts also mention: "Some diseases are suitable for pills, some for powders, some for decoctions, some for wine, and some for ointments." This highlights the importance of selecting appropriate dosage forms for different diseases to achieve better efficacy. Modern requirements for acute treatment drugs call for rapid onset and quick control of symptoms, such as injectables, aerosols, and sublingual tablets. For chronic diseases, drugs are expected to have a slow and sustained effect, making long-acting preparations like pills, sustained-release, and controlled-release formulations suitable. Thus, different dosage forms can regulate the speed of drug action. Additionally, special dosage forms can be provided for different affected areas, such as ointments and film coatings for skin and mucosal conditions.
2. Adapting to the properties of the drug itself. Drugs vary widely in their physicochemical properties, and different dosage forms and preparation processes can lead to different therapeutic effects and influence drug efficacy. For example, drugs like insulin and corticosteroids are not suitable for oral dosage forms due to the destructive effects of gastrointestinal fluids, so they are formulated as injectables or cavity-administration dosage forms. Drugs with strong gastric irritation should not be formulated as powders or capsules.
3. Facilitating transportation, storage, and application. Many drugs, especially traditional Chinese medicinal materials, can affect transportation, storage, and application if not processed due to their large volume and inconvenience. Formulating them into various dosage forms, such as extracts, granules, tablets, and pills, can reduce volume, enhance efficacy, and facilitate storage and transportation. At the same time, formulation techniques can adjust color, aroma, and taste, making them more suitable for different patients.
4. Improving the bioavailability and efficacy of certain drugs. Some drugs can increase bioavailability and efficacy by altering processing methods or changing dosage forms. For example, griseofulvin reduces daily dosage through micronization technology. Converting certain tablets or pills into capsules can accelerate release, enhance absorption, and improve utilization.
In summary, dosage forms play a role in regulating the intensity of drug action, extending the duration of action, controlling the speed of onset, and even altering therapeutic effects. There is a complementary relationship between drugs and dosage forms—drugs are the primary factor, while dosage forms ensure the efficacy of the drug and are the necessary application form of the drug.
III. Classification of Dosage Forms
There are many types of dosage forms, each with distinct properties, preparation methods, and uses. To facilitate learning, research, and application, dosage forms with different characteristics are classified. Currently, there are four widely used classification methods:
1. Classification by Morphology
- Liquid dosage forms (e.g., solutions, injectables)
- Solid dosage forms (e.g., tablets, powders, capsules)
- Semisolid dosage forms (e.g., ointments)
- Gaseous dosage forms (e.g., aerosols)
This classification method is meaningful in preparation, storage, and transportation because dosage forms with the same morphology often share similar preparation methods and administration routes.
2. Classification by Dispersive System
- True solutions
- Colloidal solutions
- Emulsions
- Suspensions
- Microparticulate systems
- Solid systems
- Gaseous systems
This classification method is based on the requirements of the dispersing system, facilitating the study of physical stability and preparation processes.
3. Classification by Preparation Method
- Extracted preparations (e.g., tinctures, extracts)
- Aseptic preparations (e.g., injectables, eye drops)
This classification is based on similar preparation methods but has limited practical significance and is rarely used.
4. Classification by Administration Route
- Gastrointestinal administration (e.g., tablets, syrups, capsules)
- Rectal administration (e.g., suppositories, enemas)
- Non-gastrointestinal administration (e.g., injectables)
- Respiratory administration (e.g., aerosols)
- Cutaneous administration (e.g., topical solutions, ointments)
- Mucosal administration (e.g., eye drops, nasal drops, oral adhesives)
This classification is closely related to clinical medication, specifically reflecting administration routes and clinical application methods, providing guidance for patient use.
The above four classification methods each have their advantages and disadvantages, and different medical workers use them in varying ways. This book follows long-standing conventions and covers these classification methods to varying degrees.
IV. Common Terminology in Pharmaceutics
(1) Drug refers to substances used to prevent, treat, and diagnose diseases.
(2) Medicinal product refers to substances used to prevent, treat, or diagnose human diseases, intentionally regulate human physiological functions, and are specified with indications, dosage, and administration methods, including traditional Chinese medicinal materials, pieces of traditional Chinese medicine, Chinese patent medicines, chemical raw materials and their preparations, antibiotics, biochemical products, radioactive drugs, sera, blood products, and diagnostic drugs.
(3) Active pharmaceutical ingredient (API) refers to the active components used in the production of various preparations and are the raw drugs for preparations.
(4) Semi-finished product refers to intermediate products in the production process of various preparations that require further processing.
(5) Finished product refers to the final qualified product after the completion of the entire manufacturing process.
(6) Finished medicine refers to special preparations made from components with significant efficacy and high stability. They are generally patented and can be purchased directly without a doctor's prescription.
(7) Label claim refers to the main drug content listed on the label of a medicinal product.
(8) Dose refers to the amount of drug suitable for one clinical application.
(9) Shelf life refers to the period under certain conditions during which the drug maintains its effective quality.
(10) Responsibility period refers to the period negotiated and established between production and sales units to clarify mutual responsibilities during storage and sales.