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Pharmacology for Anesthesia I

Pharmacology for Anesthesia I. Introduction. What is a Drug?. Pharmacokinetics (PK). What the body does to the drug Absorption Distribution Metabolism Excretion. Absorption. The process of diffusion or transport of a drug from the site of administration to the plasma.

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Pharmacology for Anesthesia I

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  1. Pharmacology for Anesthesia I Introduction

  2. What is a Drug?

  3. Pharmacokinetics (PK) What the body does to the drug • Absorption • Distribution • Metabolism • Excretion

  4. Absorption The process of diffusion or transport of a drug from the site of administration to the plasma Skipped by administering drugs parenterally Inhaled agents require special considerations

  5. Fick’s Law concentration gradient x surface area x diffusion coefficient membrane thickness Rate of Diffusion = Permeability Size Diffusion coefficient =

  6. Ionization State Henderson – Hasselbalch Equation concentration (protonated) concentration (unprotonated) log = pKa - pH

  7. Trapping

  8. Distribution The process of diffusion of a drug throughout the body Generally governed by the same characteristics as absorption Vd = volume of distribution Protein Binding

  9. Metabolism • The enzymatic modification of the drug molecule by the body • Often occurs in liver • May occur elsewhere

  10. Hepatic Metabolism

  11. Example of Phase II prior to Phase I

  12. CYP Enzymes

  13. Pharmacogenetics of Drug Metabolism

  14. Examples of Drug-Drug Interactions

  15. Elimination • The removal of the drug from the body • Renal • Hepatic • Respiratory • Cutaneous

  16. Clearance • Used to describe our ability to eliminate the active ingredient • Combination of metabolism and excretion Example of Zero order kinetics

  17. Distribution and Clearance • First Order Kinetics • Single compartment model • Double compartment model • Three compartment model • Etc.

  18. Absorption and Clearance

  19. Effect Not Always Governed by Plasma Concentration

  20. Dosing Regimens

  21. Can speed accumulation time by administering a loading dose

  22. Routes of Administration

  23. Pharmacodynamics • What the drug does to the body • Typically receptor mediated

  24. What factors affect the ability of a drug to interact with a receptor? • Drug size • Large enough to be specific • Not so large as to be unable to interact with the receptor • Drug Shape

  25. Some drugs do not appear to fit into these categories • Osmotic agents • Transport regulators

  26. Agonists Antagonists Competitive Noncompetitive Allosteric Activators Potentiators

  27. Partial agonists Inverse agonists

  28. Antagonists

  29. Noncompetitive Antagonist and Spare Receptors

  30. Full and Partial Agonists

  31. Cellular Receptors

  32. Different Drugs Similar Effects Potency vs. Efficacy

  33. Population Variation and Therapeutic Window

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