Pediatrics pharmacology Antibiotics

1. Dr.Azad A Haleem AL.Brefkani
University Of Duhok
College of pharmacy
Pediatrics Department
azad82d@gmail.com
2016

2. ANTIBIOTICS
• Antibiotics can be defined as substances
capable of killing & inhibiting the growth of
micro organisms

3. Mechanism of action
• Inhibition of cell wall synthesis : Penicillins
Cephalosporins
Monobactams
Vancomycin
• Inhibition of DNA gyrase: Quinolones
• RNA polymerase Rifampicin
• Inhibition of protein synthesis: Aminoglycosides
Tetracyclines
Erythromycin
Chloramphenicol
• Inhibition of folic acid metabolism: Trimethoprim
Sulfonamides

4. Bacteriostatic vs. bactericidal drugs
• Bacteriostatic
– arrest the growth and replication of bacteria at
serum levels achievable in the patient.
– limit the spread of infection while the body's
immune system attacks, immobilizes, and
eliminates the pathogens.
– If the drug is removed before the immune system
has scavenged the organisms, enough viable
organisms may remain to begin a second cycle of
infection.

5. • Bactericidal
– kill bacteria at drug serum levels achievable in the
patient. - often drugs of choice in seriously ill
patients.
• It is possible for ATB to be bacteriostatic for
one organism and bactericidal for another.

6. Antimicrobial activity
• Antimicrobial activity: the ability that a drug
kills or suppresses the growth of
microorganisms.
• Minimum inhibitory concentration (MIC)
– the minimum amount of a drug required to
inhibit the growth of bacteria in vitro.
• Minimum bactericidal concentration (MBC)
– the minimum amount of a drug required to kill
bacteria in vitro

7. Classification of antibacterial agents
Bactericidal Bacteriostatic
β-lactam agents Erythromycin
Aminoglycosides Tetracyclines
Co-trimoxazole Chloramphenicol
Vancomycin Sulfonamides

8. Chemotherapeutic spectra
• Narrow spectrum
• only against a single or a limited group of
microorganisms,
• e.g. INH is active only against mycobacteria.
• Broad spectrum
• affect a wide variety of microbial species.
• e.g. tetracycline and chloramphenicol
• Alter the normal bacterial flora ????
• precipitate a superinfection of an organism, e.g.,
candida.

9. Drug resistance
• growth of bacteria is not halted by the maximal level of
that antibiotic that can be tolerated by the host.
• Primary
• Some organisms are inherently resistant to an antibiotic
• e.g., gram-negative organisms are inherently resistant to
vancomycin.
• Secondary
• spontaneous mutation or acquired resistance and selection.
• Cross-resistance
• resistant to more than one antibiotic.

10. Thanks