吉林大学：《药理学》课程PPT教学课件（七年制）Introduction to Pharmacology

Introduction to Pharmacology

Introduction to Pharmacology

Overview The aim of drug therapy ■Drug target tissue Absorption Distribution Metabolism Elimination The route of administration is determined by the properties of the drug and by the therapeutic objectives.Enteral and parenteral

Overview ◼ The aim of drug therapy ◼ Drug target tissue ◼ Absorption Distribution Metabolism Elimination ◼ The route of administration is determined by the properties of the drug and by the therapeutic objectives. Enteral and parenteral

Drug at site of administration Absorption (input) Drug in plasma 2Distribution Drug in tissues Metabolism Metabollte(s)in tissues ④Elimination (output) Drug and/or metabolite(s) in urine,feces,bile Figure 1.1 Schematic representation of drug absorption,distribution,metabolism and elimination

enteral Oral:the most common route Sublingual:allows the drug to diffuse into the capillary network ■ Rectal:Fifty percent of the drainage of the rectal region bypasses portal circulation

enteral ◼ Oral: the most common route ◼ Sublingual: allows the drug to diffuse into the capillary network ◼ Rectal: Fifty percent of the drainage of the rectal region bypasses portal circulation

parenteral Intravascular:IV injection is the most common route used for drugs that are not absorbed orally. Intramuscular:can be aqueous solutions or specialized depot preparations Subcutaneous:slower than the IV route and minimizes the risks associated with IV

parenteral ◼ Intravascular: IV injection is the most common route used for drugs that are not absorbed orally. ◼ Intramuscular: can be aqueous solutions or specialized depot preparations ◼ Subcutaneous: slower than the IV route and minimizes the risks associated with IV

Other Inhalation:provides the rapid delivery across the surface area of the mucous membranes of the respiratory tract Intranasal:desmopressin in the treatment of diabetes insipidus. Intrathecal/intraventricular:to introduce drugs directly into the CSF. Topical:the application is used when a local effect of the drug is desired

Other ◼ Inhalation: provides the rapid delivery across the surface area of the mucous membranes of the respiratory tract. ◼ Intranasal: desmopressin in the treatment of diabetes insipidus. ◼ Intrathecal/intraventricular: to introduce drugs directly into the CSF. ◼ Topical: the application is used when a local effect of the drug is desired

Sublingual Inhalation Oral patch Topica Rectal Figure 1.2 Commonly used routes of drug administration.(IV=intravenous; IM=intramuscular;SC= subcutaneous)

Absorption of drugs Absorption is the transfer of a drug from its site of administration to the blood stream. The rate and efficiency of absorption depend on the route of administration

Absorption of drugs ◼ Absorption is the transfer of a drug from its site of administration to the blood stream. The rate and efficiency of absorption depend on the route of administration

Transport of drug from the GI tract Passive diffusion:moves from a region of high concentration to one of lower concentration. Active transport:involves specific carrier proteins.Energy-dependent.Against a concentration gradient

Transport of drug from the GI tract ◼ Passive diffusion: moves from a region of high concentration to one of lower concentration. ◼ Active transport: involves specific carrier proteins. Energy-dependent. Against a concentration gradient

Effect of pH on drug absorption Weak acids or weak bases HAH++A+ BH B+H+ the effective concentration of the permeable form of each drug at its absorption site is determined by the relative concentrations of the charged and uncharged forms

Effect of pH on drug absorption ◼ Weak acids or weak bases HA H++A + BH B+H+ the effective concentration of the permeable form of each drug at its absorption site is determined by the relative concentrations of the charged and uncharged forms