anti bacterials

1. Pharmacology
Antibacterial agents
Slide-21

2. Introduction
• Antibiotics : term used to describe any
substance produced by living organisms which
inhibit the growth of or kill another organism,
usually a bacterial or fungal infections.

3. How antibiotics exert their effects?
• Bacteriostatic : agents prevent bacteria from
replicating, but don’t kill them, like tetracyclin,
chloramphenicol, sulphonamines.
• Bactericidal : which kill bacteria rapidly like
aminoglycoside.
• Bactericidal can become bacteriostatic under
certain conditions like concentration of the drug,
the number and type of bacteria.

4. Informations
• Antibacterial agent power also depend on the
patient himself, individual resistance play an
important role.
• Bacteria classified into gram-positive and gram-
negative according to the staining technique in
the lab.
• Anaerobes : bacteria that can live or multiply in
the absence or present of oxygen.

5. Factors determine which antibiotic to
use?
• 1- the infecting organism, maybe suspected from
the nature of the disease, also the nature of
organism should be confirmed by culture of
blood, sputum, urine.
• 2- the correct antibiotic to eradicate the
infection,
• 3- the ability of antibiotic to penetrate the site of
action.

6. Factors determine which antibiotic to
use?
• 4-the route of administration.
• 5- the drug history of the patient.
• 6-Possible complications factors EX: (
pregnancy, renal, or hepatic failure).
• 7- the cost of drug

7. The Sulphonamides
• 1- Sulfadimide and sulfasalazide
• Sulfadimide is used in treatment of urinary tract
infection.
• Sulfasalazide used in long term treatment of
ulcerative colitis and crohn’s disease and also in
rheumatoid arthritis.
• Side effects: nausea, rashes, urinary tract
obstruction so patient should be given 2-3 L of
water daily to maintain good urinary flow.

8. The Sulphonamides
• 2- Trimethoprim :
• Used for urinary infections and bronchitis.
• shouldn’t be used in the first 3 monthes of
pregnancy.
• Side effects: nausea, rashes.

9. The Sulphonamides
• 3- Co-trimoxazole:
• Balkatrin®
• Is a mixture between trimethorphin and
sulfamethoxazole.
• Affect bacteria by Interfering with their use of
paraaminobenzoic acid (PABA), which is
precursur of folic acid were the folic acid is a
essential I cell division.

10. The Sulphonamides
• Used for the treatment of chronic bronchitis ,
UTI, and the treatment of severe salmonella and
other tract infections.

11. Nitrofurans
• Only drug which is still used is nitrofurantoin;
used to treat UTI or as a prophylactic.

12. Quinolones
• Interfere with enzyme which is important for cell
division in bacteria.
• 1- Ciprofloxacin (Cipro®),(Ciprodar®),
(Ciprolon®)
• Used in typhoid, UTI, and gonorrhea.
• Preferable in adults as a prophylactic for close
contact with meningococcal meningitis.
• Given orally or infusion
• Avoided in children and with epileptic patients.

13. Quinolones
• 2- Norfloxacin (Noracin®) and Nalidixic acid
(Negram®)
• For uncomplicated UTI.
• 3-4 days course.
• Other examples: Levofloxacin , ofloxacin

14. β-Lactam antibiotics
• All beta-lactams contain β-lactam ring in their
chemical structure and this ring is important for
the activity.
• Divided into:
• 1- penicillins
• 2- cephalosporins
• 3- other lactams.

15. Beta-lactam ring

16. β-Lactam antibiotics
• 1- Penicillins:
• First and most widely used AB’s.
• Benzyl-penicillin:
• (penicillin G®), first penicillin to be used.
• Usually given as deep I.M injection.
• Entre the circulation rapidly, can’t cross CSF.
• Bacteriostatic , at high doses become bactericidal
• Given 4 times a day (short half life)
• If given orally it get broken down by gastric acids.

17. β-Lactam antibiotics
• Procaine benzyl-penicillin:
• Successful method to prolong the duration of
action of benzyl-penicillin.
• Combine benzyl-penicillin with procaine.
• Given 2 times a day.
• Several concentrations most importantly
400.000 I.U or 1.200.000 I.U. given orally.

18. β-Lactam antibiotics
• Other penicillins :
• Phenoxymethyl penicillin (Ospen®)
important to be given 30-min before meals.
• Flucloxacillin: used for staphelococcal
infections.

19. Broad spectrum penicillins
• Broad- spectrum penicillins:
• 1- Ampicillin (Ultracillin®)
• Used for chronic bronchitis, UTI, and typhoid.
• Given orally or by injection.
• Given 3-4 times a day.
• 2-Amoxicillin (Ultramox®)
• Absorbed by GI better than Ampicillin, so we
need smaller doses.

20. Broad spectrum penicillins
• 3- Pivampicillin:
• ampicillin linked with other molecule for better
absorption.
• 4- moxiclav (Augmentin®)
• Amoxicillin with clavulanic acid which prevent the
breaking down of amoxicillin, so prevent the
bacteria from breaking the drug.
• Children dose(457/5 ml syrup) 2.5-5 ml BID for 5
days
• Adult dose 1g tablet, 1 tab BID for 5-days

21. Extended release penicillins
• Include :
• 1- Azolacillin
• 2- Piperacillin
• 3- Ticarcillin
• Has same action of ampicillin but also active
against pesudomonas aeruginosa and
proteus morganii.
• Given only I.V.
• In worse situations is combined with
aminoglycosides.

22. Side effects of penicillins
• Pain at site of injection
• Sensetivity
• Diarrhea
• Anaphylactic reactions with collapse which could
be fatal.
• Co-amoxiclav can cause jaundice.

23. Cephalosporins
• Related to penicillins in the structure.
• Contain beta-lactam ring.
• Some can given orally but mostly by injection.
Older cephalosporins:
• Cefazolin, Cefradine, Cefadroxil (Duricef®).

24. Cephalosporins
Recently introduce cephalosporins:
• Beta-lactamase resistant.
• Used in:
• - severe infections such as septicemia.
• - meningococcal meningitis; cefotaxime and
ceftraiaxone can enter CSF.
• - hepatobiliary or abdominal sepsis.
• Cefuroxime very effective for chest infections.

25. Cephalosporins
• Examples :
• Cefuroxime (Zincef®)
• Cefamandole (Mandole®)
• Cefotaxime (Claforan®)
• Cefoxitin (Mefoxin®)
• Ceftizoxime (Cefizox®)
• Ceftazidime (Fortum®)
• Ceftriaxone (Rocephin®)

26. Cephalosporins
Oral cephalosporins:
• Cefadroxil (Duricef®)
• UTI and respiratory infection.
• Twice daily.
• Cefixime :
• Effective for H.influenza
• Cefuroxime axetil (Zinnat®)
• Cefpodoxime (Cefobid®)

27. Other β-lactams
• 1- Aztrenam (Azactam®):
• Given by injection.
• For gonorrhea and influenza .
• 2-Imipenem with cilastatin (Tienam®)
• Has the wildest anti-bacterial range include
pesudomonas and anaerobes.
• I.V infusion or deep I.M
• Used when other AB’s are conraindicated or
ineffective.