Clinical Pharmacology 01.09.2021 for mbbspptx

Clinical Pharmacology 01.09.2021 for mbbs

1. Clinical Pharmacology

2. CHART -1 Semi log plasma concentration- time plot of a drug eliminated by First order kinetics after intravenous injection. 16 8 4 2 1 β t ½ - 2 4 6 8 10 Time (Hours) α Log Plasma conc

3. Questions :- 1.What is plasma half life of a drug? 2.What is ά and β phase? 3.Mention two drugs having long plasma half life? 4. What is the difference between plasma t ½ and biological t ½ ? 5.What is the relationship between plasma half life and plasma protein binding?

4. 1.What is plasma half life of a drug? Ans :- Plasma half life (t ½) of a drug is the time taken for its plasma concentration to be reduced to half of its original value.

5. 2. What is α and β phase? α – Initial rapidly declining phase due to distribution of the drug. β - Later less declining phase due to elimination of the drug.

6. 3. Mention two drugs having long plasma half life? Digoxin – 40 hrs Phenobarbitone – 90 hrs

7. 4. What is the difference between plasma t ½ and biological t ½ ? PLASMA HALF LIFE – Concentration of the drug reduced to half of its original value. BIOLOGICAL HALF LIFE - Effect of the drug reduced to half of its original pharmacological effect.

8. 5. What is the relation between plasma half life and plasma protein binding? Drugs with high degree of plasma protein binding will have a long plasma half life. Because the bound fraction is not available for metabolism and excretion and is slowly released into the systemic circulation. Plasma proteins act as temporary storage sites.

9. CHART -2 Kinetics of Elimination Drug A Drug B TIME TIME Log Plasma conc Log Plasma conc

10. QUESTIONS :- 1. What is the kinetics of elimination followed by Drug A and Drug B? 2. What is First order Kinetics? 3. What is Zero order kinetics? 4.What is Michaelis menten kinetics? Give one example? 5.What is Clearance of a drug?

11. 1.What is the Kinetics of elimination followed by drug A and drug B:- * Drug A  First order kinetics * Drug B  Zero order kinetics

12. 2.What is first order kinetics?  A constant fraction of the drug present in the body is eliminated in unit time.  The rate of elimination is directly proportional to the drug concentration.  Clearance remains constant.

13. 3 . What is Zero order Kinetics?  A constant amount of the drug present in the body is eliminated in unit time.  The rate of elimination remains constant irrespective of drug concentration.  Clearance decreases with increase in drug concentration.

14. 4.What is Michaelis menten kinetics? Give one example ? It is a dose dependent kinetics where smaller doses are handled by First order kinetics but as the plasma concentration reaches higher values, the rate of drug elimination becomes zero order kinetics. Eg :- Phenytoin, (Digoxin, Warfarin, Dicoumarol , Tolbutamide, Aspirin)

15. 5.What is clearance of a drug? Clearance of a drug is the theoretical volume of plasma from which the drug is completely removed in unit time. CL = Rate of elimination Plasma concentration (C)

16. Chart no 3

17. Chart no 3 - Questions Define Therapeutic Window? Define therapeutic index of a drug? Mention 2 drugs having wide therapeutic index ? What is Therapeutic drug monitoring (TDM)? Mention 2 drugs which may require TDM?

18. Answers A) It is the range between the dose which produces minimal therapeutic effect and the dose which produces maximal acceptable adverse effect. Also called Therapeutic range. B) It is the ratio of median lethal dose with the median effective dose. Therapeutic index = LD50 ED50

19. C) Diazepam, Paracetamol D) TDM is the clinical practice of measuring specific drugs at designated intervals to maintain a constant concentration in a patient’s bloodstream, thereby optimizing individual dosage regimens. E) Drugs with narrow therapeutic window require TDM. Ex: Digoxin, Lithium

20. Chart no 4

21. Chart no 4 Define Dose Response Curve. Mention the advantages of log DRC. Define potency of a drug. Define efficacy of a drug. Which is more important in selecting a drug- Potency or Efficacy?

22. Answers A) DRC is a graphical representation of the relationship between the dose of the drug and the effect it achieves. B) Wide range of drug doses can be easily displayed on a graph. Comparison between agonists and study of antagonists become easier. C ) Potency refers to the amount of drug needed to produce a certain response

23. D) Efficacy refers to the maximum response that can be elicited by a drug E) Drug Efficacy

24. Chart – 5

25. Questions A) Define Drug-Drug interaction? B) Define Drug Synergism? C) What are the types of Drug synergism? D) Define Drug Antagonism? E) What are the types of Drug Antagonism?

26. Answers A) When 2 or more drugs are given together, one drug may affect the action of another drug. B) When the action of one drug is facilitated or increased by the other, they are said to be synergistic. C) Additive and Supra-additive

27. D) When one drug decreases or abolishes the action of another, they are said to be antagonistic. E) Physical, Chemical, Physiological, Receptor