BASIC CONCEPT OF PHARMACOLOGY

1. Chapter 2
Basic Concepts of
Pharmacology
By : Sanjay Kumar

2. Chapter 2 Topics
• Receptors
• Mechanisms of Drug Action
• Pharmacokinetics
• Drug Effects

3. Learning Objectives
• Understand receptors and their function in
mechanisms of drug actions.
• Be aware of the pharmacokinetics
involved in developing and testing drugs.
• Understand that some drug effects are
beneficial whereas others can be harmful.
• Be familiar with the common terms used to
describe drug interactions.

4. Receptors
• A receptor is a protein molecule on the
surface of or within a cell that recognizes
and binds with specific molecules, thereby
producing some effect within the cell.

5. Receptors
• A receptor is a protein molecule on the
surface of or within a cell that recognizes
and binds with specific molecules, thereby
producing some effect within the cell.
– receptor site may have specificity
– the affinity is the strength by which a particular
chemical messenger binds to its receptor site or
cell

6. Mechanisms of Drug Action
Agonist
An agonist is a drug that binds to a particular
receptor site and triggers the cell’s response in
a manner similar to the action of the body’s
own chemical messenger.

7. Mechanisms of Drug Action
Antagonist
An antagonist is a drug that binds to a
receptor site and blocks the action of the
endogenous messenger or other drugs.

8. Pharmacokinetics
• Activity of a drug within the body over a
period of time.
• Includes ADME

9. Pharmacokinetics
• Activity of a drug within the body over a
period of time
• Includes ADME
– absorption
– distribution
– metabolism
– elimination

10. Pharmacokinetics
Absorption
Process whereby the drug enters the circulatory
system

11. Pharmacokinetics
Distribution
Process by which a drug moves from the blood
into other body fluids and tissues and ultimately
to its sites of action
Blood flow is the rate-limiting factor.

12. Pharmacokinetics
Metabolism
Process by which drugs are chemically converted
to compounds and then excreted through
metabolic pathways.
Induction
Inhibition

13. Pharmacokinetics
Elimination
Clearance is the rate at which a drug is
eliminated from a specific volume of blood per
unit of time.

14. Discussion
What are the primary sites of
elimination in the body?

15. Discussion
What are the primary sites of
elimination in the body?
Answer: The kidney and the liver, but
can also be exhaled by the lungs or
excreted in perspiration.

16. Pharmacokinetics
Dose-Response Curve

17. Pharmacokinetics
Therapeutic Range

18. Pharmacokinetics
Duration of Action

19. Discussion
How is a drug’s volume of
distribution, clearance, and half-life
used in dosing drugs?

20. Discussion
How is a drug’s volume of distribution,
clearance, and half-life used in dosing
drugs?
Answer: Volume of distribution is
important for calculating the loading dose,
clearance for calculating the maintenance
dose, and half-life for determining the
dosing interval.

21. Pharmacokinetics
Pharmacokinetic Modeling
Method of describing the process of ADME of a
drug within the body

22. Drug Effects
Beneficial Responses

23. Drug Effects
Beneficial Responses
– Therapeutic Effect
The action for which the drug is prescribed

24. Drug Effects
Beneficial Responses
– Therapeutic Effect
The action for which the drug is prescribed
– Local Effect
Confined to a specific part of the body

25. Drug Effects
Beneficial Responses
– Therapeutic Effect
The action for which the drug is prescribed
– Local Effect
Confined to a specific part of the body
– Systemic Effect
Generalized, all-inclusive effect on entire body

26. Discussion
What are some of the issues a
healthcare practitioner considers
when selecting a drug for an
individual patient?

27. Drug Effects
When choosing a drug for a patient, a
healthcare practitioner considers:
Indications
The diseases, symptoms, and conditions for which the
drug is known to be of benefit
Contraindications
The diseases, symptoms, and conditions for which the
drug will not be beneficial and may do harm

28. Drug Effects
Side Effects
Secondary responses to a drug other than the
primary therapeutic effect for which the drug was
intended
• Allergic responses
• Drug dependence, addiction, abuse, and tolerance

29. Common Drug Relationships
Addition The combined effect of two drugs.
It is equal to the sum of the effects
of each drug taken alone.
Antagonism The action of one drug negates the
action of a second drug.

30. Common Drug Relationships
Potentiation An effect that occurs when a drug
increases or prolongs the action of
another drug, and the total effect is
greater than the sum of the effects
of each drug used alone.
Synergism Joint action of drugs in which their
combined effect is more intense or
longer in duration than the sum of
their individual effects.

31. Discussion
Name a common food-drug
interaction.

32. Discussion
Name a common drug-food
interaction.
Answer: Grapefruit juice can affect
drugs for up to a day following
ingestion.

33. Discussion
Why is it important for the pharmacy
to have a complete list of all of the
prescription drugs, OTC medications,
vitamins, and herbal remedies that a
patient is taking?

34. Discussion
Why is it important for the pharmacy to
have a complete list of all of the
prescription drugs, OTC medications,
vitamins, and herbal remedies that a patient
is taking?
Answer: Such a list will help healthcare
professionals identify potential drug
interactions.