2_Pharmacokinetics.pdf nursing student lecture

Pharmacology nursing student lecture

1. Date : 16 / 2 /2025Dr : ( M. Habib)
Field of Nursing
Nursing Program
Pharmacology Lecture : General Pharmacology-1

2. 1.Describe different aspects of pharmacokinetics including absorption,
distribution, metabolism, and elimination
2.Apply knowledge gained in the basics of pharmacokinetics to
different examples of drugs

3. Drug
A chemical substance that alters body functions
It can be used for treatment, prevention or diagnosis
of disease

4. Generic Name
Acetylsalicylic AcidAspirin Aspocid
Rivo
Trade NameChemical Name
Drug nomenclature

5. Pharmacology is divided into 2 branches:
Pharmacodynamics Pharmacokinetics

6. Pharmacokinetics
Absorption
Distribution
Metabolism
Excretion

7. Drug absorption
The passage of the drug from the site of administration to the blood
Factors affecting drug absorption
1. Drug properties:
A. Molecular Weight:
↓ MW drugs →↑rate of absorption
B. Solubility:
Lipid soluble (Unionized) →↑rate of absorption
C. Drug Formulation
Different formulations have different rates of absorption

8. 2. Conditions at site of administration:
Blood flow:
↓ blood flow in subcutaneous tissue →↓ the rate of drug
absorption
Addition of epinephrine to local anesthetics →prolongs their
action
GIT motility:
GIT content:

9. Bioavailability
The fraction of drugs reaching systemic circulation
unchanged after any route of administration
Intravenous bioavailability = 100%
Factors Affecting Bioavailability
•Amount of drug absorbed (see before)
•First-Pass Metabolism
Metabolism of the drug in gut wall or liver before reaching blood
e.g.Nitroglycerin undergoes extensive 1
st
pass metabolism in
liver

10. Routes Bypassing the First-pass Effect
Parenteral
Sublingual
Rectal (to some extent)

11. Drug Distribution
After a drug is absorbed, it is distributed in the body

12. Drug in blood exists in 2 forms:
•Free fraction → active
•Bound fraction → inactive
➢The two forms exist in equilibrium.
➢When the free form is metabolized and/or excreted, another
part is released from plasma proteins.
Binding to plasma proteins

13. Drug Metabolism (Biotransformation)
Sites of drug metabolism:
•The Liver (main site)
•Other sites:
oKidney
oLung
oGIT
oSkin

14. Factors affecting drug metabolism:
1.Age
2.Sex
3.Diseases: Liver diseases → ↓ drug metabolism →
Reduce the dose

15. Factors affecting drug metabolism:
4. Drugs: act on cytochrome P450 affecting of drug metabolism
Enzyme inducers
•They stimulate drug metabolism
•Example: Rifampicin → ↑metabolism of warfarin → ↓ its effect
So, ↑dose of warfarin
Enzyme inhibitors
•They inhibit drug metabolism
•Example: Erythromycin → ↓ metabolism of theophylline → toxicity
So, ↓ dose of theophylline