Principle of chemotherapy

1. PRINCIPLES OF CHEMOTHERAPY

2. Chemotherapy----
Treatment of infectious diseases & cancer
Anti microbial & anti neoplastic pharmacology
Chemotherapeutic agents- are designed to
inhibit/ kill invading parasite
Kill malignant cell

3. Need of understanding principles & mechanisms
of Anti microbial & anti neoplastic
pharmacology
Microbes & cancer cells can evolve resistance to drug
therapies ----
How to overcome ??
1. effective use of existing drugs
2. Discovery of new drugs

4. Pharmacological strategy
Selective targeting ( selective toxicity )
Targeting selective differences between
 Microbes and host cell
 cancer cell and a normal cell

5. Realizing selectivity
1. Targets that are unique to pathogen –
eg: bacterial cell wall synthesis inhibitors
2. Selective inhibition of similar targets-
Protein synthesis inhibitors- select bacterial ribosomal
sub units ( 50s +30s)

6. MODE OF ACTION
• Cell wall synthesis inhibition
• Cell membrane function inhibition
• Nucleic acid synthesis inhibition
• Protein synthesis inhibition

7. Cell wall synthesis

9. NAM-NAG
A
DE
K
DA
DA
G G G G G
NAM-NAG
A
DE
K
DA
DA
G G G G G
NAM-NAG
A
DE
K
DA
DA
G G G G G
NAM-NAG
A
DE
K
DA
G G G G G
transpeptidase
ß-lactams
Cell wall synthesis inhibition
Eg: Penicillin

10. Cell membrane function
• Made up of phospholipid
bilayer
• Separates the internal
contents of the cell from the
external environment
• Regulate the transport of
materials entering and
exciting the cells.

11. Cell Membrane function inhibition
Eg: Polymyxin B
• The antibiotic binds to the
cell membrane, alter its
structure and makes it more
permeable.
• This disrupts osmotic balance
causing leakage of cellular
molecules, inhibition of
respiration and increased
water uptake leading to cell
death.

12. Protein synthesis

13. Protein synthesis inhibition
• Binds to 30S subunit and block the binding of amino acyl tRNA to the acceptor site on
the m-RNA ribosome complex.
• Eg: Tetracyclins

14. DNA Synthesis Inhibition
• The main quinolone target is the
topoisomerase which is responsible for
unwinding the DNA double helix during the
process of replication.
• Eg: Quinolones