1 / 31

Understanding Pharmacological Actions: Effects, Risks & Reactions

Explore the diverse aspects of pharmacological actions, including dosage effects, drug mechanisms, and adverse reactions. Learn about therapeutic benefits, toxic effects, allergic reactions, and drug-induced diseases. Gain insights into drug dependence and withdrawal symptoms.

lelaf
Download Presentation

Understanding Pharmacological Actions: Effects, Risks & Reactions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 2Pharmacodynamics药物效应动力学 • Pharmacological action - Overview • Dose-effect relationship • Mechanisms of drug actions • Drug receptors

  2. 1-Pharmacological Action - Overview • 1.1 Action and effect of drug • Action • Specifically primary action between drug and cells or molecules • Effect • Apparent functional and morphological changes induced by drug directly and/or indirectly

  3. 1-Pharmacological Action - Overview • 1.2 Direct and indirect effects of drugs • Direct effects: • Effects resulted from the action of drug on the target organ(s) or tissue(s) • Indirect effects: • Effects resulted from functional integration of target system(s) and modulation system(s)

  4. BP ↑ direct Action on vascular 1receptors HR ↓ indirect Neuroendocrine modulation Action Effect

  5. 1-Pharmacological Action - Overview • 1.3 Selectivity of drug effect • Selectivity: Organs / Tissues • Specificity: Biomolecules • Reasons of selectivity • Drug distribution • Biological properties of tissues or organs

  6. bronchodilation Salbutamol heart rate↑ BP ↑ bronchodilation Epinephrine Selective effects ofβreceptor agonists on the treatment of bronchial asthma

  7. 1-Pharmacological Action - Overview 1.4 Therapeutic effect and adverse reaction (desirable and undesirable effects)

  8. Balance the ratio of benefits / risk !!

  9. 1-Pharmacological Action - Overview • 1) Therapeutic effects (Efficacy) • (1) Etiological treatment • (2) Symptomatic treatment • (3) Supplement therapy

  10. 1-Pharmacological Action - Overview • 2) Adverse drug reactions (Adverse effects) • 不符合用药目的，并对病人带来不适或痛苦的反应（广义） Box 1 现在，我国将不良反应定义为上市药品在正常用法用量情况下出现的与用药目的无关的有害反应。以区别于药物过量（overdose），在本课程中将两者合称为“不良反应”。

  11. 1-Pharmacological Action - Overview • (1) Side effectundesirable effects of that drug for that therapeutic indication at usual doses, usually are non-deleterious. （治疗剂量时出现的与治疗目的无关的药物作用） GI ↓ Constipation Gland ↓ Dry mouth Atropine Mydriasis Blurring vision Bladder↓ Urine retention HR ↑ Palpitation

  12. 1-Pharmacological Action - Overview • (2) Toxic effectFunctional or morphological damages produced by larger doses of longer terms of drug uses. （剂量过大或用药时间过长体内蓄积过多时发生的危害性反应） • Local & system toxicity • Reversible & irreversible toxic reactions • Acute & delayed/chronic toxicity • Teratogenic / carcinogenic effects

  13. 1-Pharmacological Action - Overview • Box 2药源性疾病(drug-induced diseases) • 严重的不良反应可以引起疾病，这种由药物不良反应引起的疾病称为药源性疾病，它主要是不合理用药造成的。药源性疾病实际上是药物不良反应在一定条件下产生的后果，一般来说，药源性疾病不包括因使用药物超过极量所引起的急性中毒。

  14. 1-Pharmacological Action - Overview • (3) After effect • Effects after drug concentration in the body is lower than threshold level. • (停药后血药浓度已降至阈浓度之下时残存的药理效应) • Short-lasting：e.g.Barbiturates • Long-lasting：e.g.Glucocorticoids

  15. 1-Pharmacological Action - Overview • (4) Allergic reaction ( Hypersensitivity ) • Abnormal immunological reactions induced by drugs. • ( 接触药物后发生的异常免疫反应) • Types I, II, III, IV • Skin, fever, blood-forming organs, anaphylactic shock

  16. 1-Pharmacological Action - Overview • (5) Idiosyncratic reactions • A genetically determined abnormal reactivity to a chemical. • (少数特异质病人对某些药物特别敏感，反应性质也可能与常人不同) • Genetic abnormality • Examples: • Deficiency of erythrocytic glucose-6-phosphate dehydrogenase • Hypersensitivity to scoline

  17. 1-Pharmacological Action - Overview • (6) Others • Secondary reaction • Adverse reactions resulting from primary therapeutic effects of drugs. • (继发于药物治疗作用之后的不良反应) • Example: • Broad-spectrum antibiotics induce overgrowth of resistant bacteria (superinfection)

  18. 1-Pharmacological Action - Overview • Withdrawal symptoms • Clinical syndrome appeared or worsened when the drug is terminated. • ( 突然停药后原有疾病复发或加剧) • Examples: • Propranolol－ CHD • Clonidine－ hypertension • Anti-epileptic drugs－ epilepsy

  19. 1-Pharmacological Action - Overview • Dependence • An adaptive state that develops in response to repeated drug administration. • Psychologic dependenceis manifested by compulsive drug-seeking behavior. • Physiologic dependenceis present when withdrawal of drug produces symptoms and signs. • Drug addictionis defined as the compulsive, out-of-control drug use, despite negative consequences. • Drug abuse: any use of a drug for non-medical purposes. • (a maladaptive pattern of drug use leading to clinically significant impairment or distress)

  20. 1-Pharmacological Action - Overview • Box 3药物不良反应的分型 • 剂量关系密切型(甲型)：是药物固有药理作用的延续和增强，包括的副作用、毒性反应。具有剂量依赖性和可预测性的特点。 • 剂量关系不密切型(乙型)：与药物固有药理作用无关的异常反应，与变态反应或高敏体质有关。具有与剂量无关和难以预测的特点。 • 特殊型（丙型）：药物引起的癌症、畸胎、染色体畸变等。

  21. 2-Dose-Effect Relationship • The observed effect of a drug as a function of its dose in the living system, usually drug results in a greater magnitude of effect as the dose increased. • 药理效应与剂量在一定范围内成比例，称为剂量-效应关系（量效关系） • In vitro studies:concentration-effect relationship

  22. 2-Dose-Effect Relationship 2.1 Dose（concentration） Clinical：Threshold doses(阈剂量) Therapeutic (usual) doses(治疗量，常用量) Maximal doses(极量) Toxic doses(中毒量) Lethal doses(致死量) MIC and other concentrations Experimental： in vivo - ED50, TD50, LD50 , …… in vitro-IC50, EC50, ……

  23. 2-Dose-Effect Relationship • 2.2 Responses (Effects) • （1）Graded responses （量反应）： • Response changes quantitatively • Measurable responses in an individual • （2）Quantal responses（质反应）： • All-or-none • Percentage of the population

  24. 2-Dose-Effect Relationship • 2.3 Dose-effect curve or dose-response curve • ( 量效曲线) • （1）logD-E (logC-E):S-shaped curve • Gradedin vitro：pD2 , EC50 , IC50 , MIC …… • in vivo：PD100, ID30 , …… • Quantalmedian doses: ED50 , LD50 , ID50 …… • （用药个体的一半出现某种效应所需剂量，半数效量）

  25. Concentration-effect curve (graded response)

  26. Dose-effect curve (quantal response)

  27. Individual variability ofdose-effect curve

  28. 2-Dose-Effect Relationship • （2）Maximal effect and potency • Maximal effect (最大效应) or efficacy (效能):different maximal magnitudes of effects • Potency (效价强度):difference in doses that produce an effect at same level（等效剂量） • 药物作用强弱及敏感程度的比较

  29. Potency:B > A > C > D Efficacy:A = C = D > B Slope:D > A, B, C Efficacy:loop diuretics > thiazide diuretics;morphine > aspirin Potency:difference in the effective doses of same type drugs

  30. 2-Dose-Effect Relationship • 1.4 Risk and its assessment (安全性评价) • （1）Therapeutic index（治疗指数, TI） • TI＝LD50/ED50， • （2）Safety margin:LD5～ED95 • or LD1～ED99

  31. Therapeutic index Therapeutic index Safety margin

More Related