Medical Degree Program in China - Pharmacokinetics

1. Introduction

Pharmacokinetics is a new frontier science between pharmacy and mathematics, and it is a new field of pharmacy that develop rapidly in recent years. Pharmacokinetics is a science that studies the change of the content of the drug in animals with time.

Pharmacokinetics uses the principle of dynamics and mathematical model, quantitatively describes and summarizes drug absorption through various channels (such as intravenous injection, intravenous injection, oral administration, etc.) into the body, distribution, metabolism and excretion, absorption, distribution, metabolism and excretion (ADME) "dosage-time" or "blood drug concentration - time” variation dynamic rules. Pharmacokinetics studies the process of the relationship between the level of metabolites in different kinds of body fluid, tissue and secretion, and the mathematical relationship between the model and the model is put forward. Pharmacokinetics has become the main and most closely foundation of biological pharmacy, pharmacology, toxicology, and other disciplines, to promote the vigorous development of these disciplines. It also has a close relationship with basic disciplines such as mathematics, chemistry, and analytic chemistry. The results of the research have played an important role in guiding the design of new drug, optimizing the drug delivery plan, improving the drug dosage form, providing effective, quick acting, long acting, low toxic and side effects.

2. Clinical Significance

1) Pharmacokinetics as a science uses mathematical analysis methods to deal with drug in vivo dynamic process of , has great theoretical value, is an important part of mathematical medicine, its basic analysis method has seeped into the biological pharmacy, clinical pharmacy, therapeutics, clinical pharmacology, molecular pharmacology, biochemistry. Analysis in chemistry, pharmacy, pharmacology and toxicology a wide variety of scientific areas, has become these disciplines of the main and most closely related to the foundation, to promote the vigorous development of these disciplines.

2) Pharmacokinetics has a wide range of practical significance, and its development will be an objective evaluation of existing drugs, new drug active design and improvement of drug formulations, to provide efficient and medicament available, effective and low toxic and side effects, especially for guiding the clinical rational use of drugs, through the study of pharmacokinetics, understand clinical treatment required for effective blood drug concentration to select the most suitable dose, dosing cycle, loading dose calculation, and continuous medication would occur in vivo accumulation, design optimal dosage regimen and so has great practical value.

3) Pharmacokinetics has become a new and useful tool, has been widely used in the field of pharmacy and various disciplines, to become a pharmaceutical researchers and pharmaceutical workers need to understand and master the subject.

3. Research Content

1). the guiding significance of pharmacokinetics in the process of drug development

2). the significance of pharmacokinetics in the study of active ingredients of Chinese herbal medicine

3). the important role of pharmacokinetics in the study of pharmacology.

4). the guiding significance of pharmacokinetics in clinical medicine

5). the important status of pharmacokinetics in pharmaceutics, biopharmaceutics and other disciplines

4. Related Mechanisms

Pharmacokinetics studies the role of drugs in the body. After drugs by oral taken, injection or skin absorption, the vast majority of drugs go into the blood circulation throughout the body and interact with the target organ. However, the nature of the drug itself or route of taking drugs determines the the drug only acting on a particular part of the body, the interaction with target organ can produce the desired effect, and interaction with other cells, tissues or organs may adverse reactions.

Drugs are discovered through experiments or in animals and humans. The development of new drugs is designed according to the biochemical or molecular changes caused by diseases, which can specifically block or repair the abnormal conditions of these compounds. After determining the design of a new compound, but also has been revised many times to achieve optimal results, such as should also consider the drug selectivity, titer, affinity, efficacy and in vivo absorption and stability. The ideal drug is oral, can be well absorbed from the gastrointestinal tract (in order to facilitate medication), a stable in vivo, once daily medication enough to reach effective concentration, drug on the target site with high selectivity, and almost no side effects. In addition, the potency and efficacy of the drug should be high, the small dose is to be effective.

5. Scheme Design

1) The basic tasks of clinical pharmacokinetics and pharmacists

2) Individualized and blood concentration monitoring of drug delivery system

3) The status of blood drug concentration monitoring in the individualized treatment program

4) Need blood drug concentration monitoring

6. Guiding Roles

Research of pharmacokinetics has been widely carried out in the study of drug action, that is, using mathematical models and formulas for the absorption, distribution, transformation and elimination of drug, and so on. In preclinical pharmacological research, antibiotics, also more and more use pharmaceutic principles and antibiotics to regimen formulation and reasonable application to provide reference data, so that the application of antibiotics reaches to a new level. Therefore, drug dynamics has become a subject of increasing concern for clinical workers.

According to the principle of drug dynamics, numbers can be used to describe the drug's in vivo process. From blood drug concentration by calculating parameters obtained more information, so that we can have a more detailed understanding of the pharmacological characteristics of drugs, and can make a quantitative comparison, helping to formulate the reasonable dosage regimen, according to adjust body dosing regimens and for the prediction of toxicity occurred. But also should see, because of the complexity of the human body, whether through how delicate and complex calculation method, the pharmacokinetics studies can only draw a rough estimate; on this basis if supplemented by careful clinical observation and other testing methods, you can make some study better for clinical services, to maximize the play effect of drug treatment, and promote the rational use of drugs.

7. Compartment Model

Drug in vivo process generally includes absorption, distribution, metabolism (biological conversion) and excretion process. In order to study the change of the drug in the course of the above process, the mathematical model, which is used to simulate the process of drug in vivo, is established.

Drug transport in the body can be seen as a drug in the compartment of the transfer, this theory is called compartment model theory.

The concept of compartment is abstract, and its significance is not in physiology and anatomy. The compartment is determined according to the organization, organ, blood supply and the speed of drug distribution.

1) Single compartment model

2) Two compartment model

3) Multi compartment model

8. Parameter

1) Eliminate velocity constant

2) Biological half life

3) Clearance rate

4) First dose and maintenance dose

9. Selective

Certain drugs are relatively non selective, and they can act on many different tissues or organs. Other drugs are highly selective and have a major effect on a single organ and system.

1) Receptor

2) Enzyme

10. Efficacy and Potency

Potency, namely potency intensity, refers to the dose required to achieve a certain effect, such as an analgesic effect, or a reduction in blood pressure. The greater the potency intensity does not indicate that the drug is superior to other drugs. Many factors should be considered in clinical application, such as side effects, toxicity, duration and price.

Efficacy is the ability of the drug to produce the greatest effect. As well as potency, efficacy is just one of the factors that are considered in the clinical use of drugs.

11. Tolerance

Repeated or persistent use of some drugs can lead to tolerance, drug effect is reduced, and tolerance is the body's adaptability to the existence of drugs. There are two mechanisms of tolerance: (1) drug metabolism is accelerated, the vast majority are due to increased liver drug enzyme activity; (2) decreased number of receptors or the affinity of drugs to reduce. Tolerance refers to the individual to antibiotics, antiviral drugs, anti-cancer drugs, such as chemotherapy is not sensitive after the tolerance of the drug can be considered to increase the dose or other alternative medicine.

12. Equations

1) Urine drug data method to carry on the medicine dynamics analysis

2) Pharmacokinetics equation established by the blood drug concentration method

3) Pharmacokinetics method established by blood drug concentration method

13. Statistical Moment Method

1) Nonlinear pharmacokinetics

2) Discrimination methods of bioavailability and pharmacokinetics model

3) The design and principle of bioavailability and biological equivalence test