Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 Introduction to Pharmacology Pawitra Pulbutr B.Pharm (Hon.), M.Sc in Pharm (Pharmacology) B.Pharm (Hon.), M.Sc in Pharm

Similar presentations


Presentation on theme: "1 Introduction to Pharmacology Pawitra Pulbutr B.Pharm (Hon.), M.Sc in Pharm (Pharmacology) B.Pharm (Hon.), M.Sc in Pharm"— Presentation transcript:

1

2 1 Introduction to Pharmacology Pawitra Pulbutr B.Pharm (Hon.), M.Sc in Pharm (Pharmacology) B.Pharm (Hon.), M.Sc in Pharm อ. ภญ. ปวิตรา พูลบุตร

3 2 Objectives เข้าใจความหมายของเภสัชวิทยา อธิบายความหมายของเภสัชจลนศาสตร์และ เภสัชพลศาสตร์ เข้าใจถึงการออกฤทธิ์ของยาโดยการจับกับ Receptor, ความหมายของ Affinity และ Efficacy เข้าใจความหมายของ Agonist, Partial agonist และ Antagonist พร้อมทั้งแยก ความแตกต่างได้ อธิบายการเกิด Antagonism และ Enhancement of drug effects ในรูปแบบ ต่างๆ เข้าใจ Quantal dose-response curve และ Graded dose response relations

4 3 What is Pharmacology? functions of the living systems chemical agent Pharmacology can be defined as the study of the manner in which the functions of the living systems is affected by chemical agent

5 4 Chemical agents DRUGS Living System Pharmacologic effect Physiological Biochemical Mechanism of drug action Drug fate in the body Absorption Distribution Metabolism Elimination Desired Treatment Prophylaxis Undesired Side effect Toxicity Interaction

6 5 Chemicals Alters biological functions Do not create new functions Interact with “ specific “ specific molecule ” molecule ” (target) (target) in the body Intrinsic substance OR Xenobiotics What is drug? MedicineMedicine

7 6 Drug - Body Interactions Pharmacodynamics เภสัชพลศาสตร์ What drug does to the body Pharmacokinetics เภสัชจลนศาสตร์ What body does to the drug

8 7 Pharmacodynamics What drug does to the body How do drugs act ? … Mechanism of action Drug-Target Interactions Dose response relationship Desired effects (Clinical response) Undesired effects (Adverse drug reaction; ADRs) Mechanism of action

9 8 Target for drug action Protein ReceptorsReceptors Ion channelsIon channels EnzymesEnzymes Carrier moleculesCarrier molecules Other eg. DNA RNA, Tubulin

10 9 Pharmacokinetics What body does to the drug Drug fate in the body Absorption Distribution Metabolism Excretion Drug concentration at sites of actions Drug action Drug action Onset & Duration of action Onset & Duration of action Elimination

11 Figure 1.1 Schematic representation of the pharmacokinetic and pharmacodynamic processes that link the administration of drugs to its effects Dose of drug administered Drug concentration In systemic circulation Drug in tissues or distribution Drug concentration at site of action Drug metabolized or excreted Pharmacokinetics Pharmacologic effect Clinical response ToxicityEfficacy Pharmacodynamics absorption distribution Elimination distribution

12 11 Drug acts at receptor Drug or Ligand Receptor Ligand can either stimulate or block receptor Stimulate … “ Agonist ” Block … “ Antagonist ”

13 12 KA KA = drug concentration which have 50% occupancy at equilibrium KA KA indicates Affinity; ความชอบจับของยากับ receptors 50 % occupancy High K A ; Low Affinity Low K A ; High Affinity MODELMODEL

14 Theoretical relationship between occupancy and ligand concentration K A indicate affinity K A = drug concentration which have 50% occupancy at equilibrium

15 14

16 Concentration Effect Curve is not equal Concentration effect curve is not equal to occupancy concentration curve response is not related to affinity Can not indicate the affinity … response is not related to affinity

17 16 Agonists VS Antagonists Agonists Bind receptorPhysiological response Maximal response “ Full agonist ” Submaximal response “ Partial agonist ” Drugs act at receptor (one type of drug target) Ligand = Agents that bind to receptor

18 Figure 1.4 Theoretical occupancy and response curve for full and partial agonist Response full agonist Response partial agonist Response Concentration Occupancy Response Occupancy A= Full agonist B= Partial agonist

19 18 A & C = Full agonist A & C = Full agonist B & D = Partial agonist B & D = Partial agonist A & C = Full agonist A & C = Full agonist B & D = Partial agonist B & D = Partial agonist

20 19 Antagonist Bind receptorNo physiological response Block receptor Prevent endogenous ligand or agonist binding Agonist has both “ Affinity & Efficacy ” Antagonist has only “ Affinity ” Agonist + AntagonistPharmacologic antagonism

21 20 Drug antagonism Pharmacologic antagonism Physiologic antagonism Chemical antagonism

22 21 Competitive reversible Agonist + Competitive reversible antagonist

23 22 Irreversible Agonist + Irreversible antagonist

24 23 Enhancement of drug effect Additive effect1+1 = 2 Paracetamol + Ibuprofen Synergism1+1 > 2 Sulfamethoxazole + Trimethoprim Potentiation0+1 > 1 Penicillin + Probenecid

25 24 Dose response curve Quantal response = All or none response Count the number of subjects who response Quantal dose response curve

26 Figure 1.6 Quantal dose effect curves Median effective dose = ED 50 Median lethal dose = LD 50 Therapeutic index (T.I.)= LD 50 / ED 50Therapeutic index (T.I.)= LD 50 / ED 50 More safety … High therapeutic index

27 26 Graded dose response relations Different response when increasing the dose Figure 1.7 Graded dose-response comparison of 2 sedative-hypnotic drugs Efficacy ประสิทธิภาพ … Maximum effect (E max ) Efficacy ประสิทธิภาพ … Maximum effect (E max ) Potency ความแรง...Dose to give the same response (Lower dose; Higher potency) Potency ความแรง...Dose to give the same response (Lower dose; Higher potency) sedatio n Anesthes ia Respiratory arrest Drug A Drug B dose Efficacy … A = B Efficacy … A = B Potency … A > B Potency … A > B

28 27 Key words of the day Pharmacology Pharmacokinetics Pharmacodynamics Affinity … K A Concentration – Occupancy curve Concentration response curve Ligand … Agonist-Antagonist Antagonism Enhancement Quantal dose response relationship Therapeutic index/ Standard margin of safety Efficacy VS Potency

29 28


Download ppt "1 Introduction to Pharmacology Pawitra Pulbutr B.Pharm (Hon.), M.Sc in Pharm (Pharmacology) B.Pharm (Hon.), M.Sc in Pharm"

Similar presentations


Ads by Google