1. ANTIBIOTICS Antibiotics are obtained from Fungi penicillins,cephalosporin,griseofulvin Bacteria polymyxin B,Tyrothricin colistin,aztreonam,bacitracin Actinomycetes aminoglycosides,macrolides,tetracyclines polyenes,chloramphenicol

2. CLASSIFICATION- A) Chemical structure Β -lactam antibiotics- penicillins,cephalosporins,monobactams,carbapenems Tetracyclins Oxytetracycline,doxytetracycline Nitrobenzene derivative- chloramphenicol Aminoglycosides Streptomycin,gentamycin,amikacin,neomycin

3. Macrolide antibiotics Erythromycin,clarithromycin,azithromycin Glycopeptide antibiotics Vancomycin,teicoplanin Lincosamide antibiotics Lincomycin,clindamycin Oxazolidinone- linezolid

4. Polypeptide antibiotics Polymyxin-B, colistin,bacitracin Polyene antibiotics Nystatin,amphotericin-B B. Mechanism of action 1. Inhibit cell wall synthesis penicillins,cephalosporins,cycloserines vancomycin,bacitracin

5. 2 . Causes leakage from cell wall membrane Polypeptide-polymyxins,colistin,bacitracin Polyenes- amphotericin B,nystatin 3. Inhibit protein syntheis tetracyclins,chloramphenicol,erythromycin, clindamycin 4. Cause misreading of m-RNA code and affect permeability Aminoglycosides-streptomycin,gentamycin

6. SPECTRUM OF ACTIVITY Narrow spectrum penicillin G streptomycin erythromycin Broad spectrum tetracyclines chloramphenicol

7. PENICILLINS First antibiotic to be used clinically in 1941 Originally obtained from fungus Penicillium notatum Present source is a high yeilding mutant of P. chrysogenum

8. CHEMISTRY AND PROPERTIES 1- Thiazolidine ring 2- β -lactam ring CH C CH 3 CH 3 CH S C NH COOH C N O O R 1 2 Benzyl side chain PENICILLINS Amide linkage

10. Lytic effect of these antibiotics may also be due to derepression of some bacterial autolysins which normally function during cell division Penicillin G Spectrum - narrow active only against gram +ve bacteria Cocci: Streptococci,Pneumococci gram –ve cocci- Neisseria gonorrhoeae N.meningitidis

13. PHARMACOKINETICS A - PnG is acid labile-destroyed by gastric acid absorption from i.m route is rapid & complete D – Reaches most of the body fluids Penetration in CSF is poor M- Little metabolised because of rapid excretion E - Very rapid renal excretion

15. USES 1.Streptococcal infections 2. Pneumococcal infections 3.Meningococcal infections 4.Gonorrhoea 5.Syphilis 6. Diphtheria 7.Tetanus

17. CLASSIFICATION 1.Acid resistant alternative to PnG phenoxymethyl penicillin(Penicillin V) 2.Penicillinase-resistant penicillins methicillin,cloxacillin 3.Extended spectrum penicillins a) aminopenicillins: ampicillin.bacampicillin,amoxicillin b) carboxypenicillins: carbenicillin,ticarcillin c) ureidopenicillins: piperacillin,mezlocillin β -lactamase inhibitors Clavulanic acid,sulbactum,tazobactum

18. 1.Acid resistant alternative to PnG - acid stable -oral absorption better -antibacterial spectrum identical to PnG -but it is1/5 as active against Neisseria 2.Penicillinase-resistant penicillins - these have side chains that protect the β -lactam ring from attack by staphylococcal penicillinase Methecillin - penicillinase resistant but not acid resistant

19. Cloxacillin- Highly penicillinase resistant as well as acid resistant 3. Extended spectrum penicillins Effective against gram-ve bacilli 1. Aminopenicillins -These have amino group in side chain -prodrugs -none is resistant to penicillinase

20. AMPICILLIN Uses -UTI -RTI -Meningitis -Gonorrhoea BACAMPICILLIN Ester prodrug of ampicillin Completely absorbed from g.i.t AMOXICILLIN Close congener of ampicillin Not a prodrug Oral absorption is better

21. 2. CARBOXYPENICILLINS - active against pseudomonas aeruginosa & proteus - Carbenicillin is neither penicillinase resistant nor acid resistant -inactive orally 3. UREDOPENICILLINS Piperacillin - 8 times more active than carbenicillin -used mainly in immunocompromised patients having serious gram-ve infections

22. BETA-LACTAMASE INHIBITORS Clavulanic acid Obtained from streptomyces clavuligerus Has β lactam ring but no antibacterial activity