Mechanisms of drug action in medical microbiology

1. Mechanisms of drug action
Seemati

2. Introduction
study of actions of the drugs on the body and their
mechanism of action
Principles of drug action
1. Stimulation 3. Irritation
4 . replacement 5. Cytotoxic actions 6. Modification of
immunestatus
2. Depression

3. Stimulation
. Adrenaline stimulates heart
. Pilocarpine stimulates salivary glands
Depression
. Barbiturate depress the CNS
. omeparzole depresses gastric acid secretion
Irritation
..mild - castor oil, severe Leads to inflammation

4. Replaceme
nt
. Insulin in diabetic mellitus
.Iron in anaemia
Cytotoxic
actions
. Penicillin , chloroquine
. Anti-cancer drugs
Modification of
immunestatus
. Vaccines and sera
. Carlicosterioids

5. Mechanisms of drug
action

6. 1. Inhibition of bacterial cell wall synthesis
Gram positive bacterial cell wall contains
peptidoglycan and biochoic acid and the bacterium
may or may not be surrounded by a protein
polysaccharides envelope
✓ Gram negative bacterial cell wall contains
peptidoglycan,lipopolysaccharides , lipoprotein,and
protein .
Ex : penicillin G , vancomycin
✓ peptidoglycan Layer NAG and NAM
arrangement

7. 2. Protein synthesis
This drug acts to inhibit bacterial protein and DNA
synthesis
✓ puromycin is an antibiotic that prevents bacterial
protein translation.
Eg : Erythromycin , tetracycline

8. 3. inhibition of nucleic acid synthesis
nucleic acid in 2
✓ DNA
✓ RNA
DNA synthesis in replication
process
RNA synthesis in transcription and
translation process

9. ✓ antimicrobial agents can interfere with nucleic acid
synthesis at different levels
✓ They can inhibit nucleotides synthesis and they can
interfere with the polymerase involved in the replication
and transcription of DNA
Ex: metramidazole

10. 4. Cell membrane
Cell membrane made up of LIPIDS and PROTEIN
Eg : polymycin drug
✓ polymyxin denature the lipids and proteins
In this drugs contains lipass and
protase so denature the cell
membrane

11. 5. Metabolic pathway
✓ Some organisms present on
metabolic pathway contain folic acid
and synthesis .
✓stopping of folic acid synthesis use the
drugs of sulfonamide .
✓ Stoping of folic acid synthesis use the drugs of
Trimethoprin
✓ stopping of folic acid synthesis use the
drugs of Trimethoprin

12. 6. ATP synthesis
ATP synthesis on 2 ways
° Krebs cycle
° Glucose cycle
With the help of co-factor
✓✓ Co- factor COA, acyl .CoA
Give the cofactor and stop the
action so , ATP don't synthesis

14. Thank you