Antimicrobial agents Antimicrobial agent is a chemical substance derived from a biological source or produced by chemical synthesis that kills or inhibits the growth of microorganisms

Antibiotics Antibiotic is a chemical substance produced by a microorganism that inhibits the growth of or kills other microorganisms

Classification of AMAs Classified in many ways; 1. Based on chemical structure 2. Mechanism of action 3.Type of organism against which primarily active 4. Spectrum of activity 5. Type of action 6. Source of origin

Based on chemical structure Sulphonamides and related drugs: Drugs are:- Sulfadiazine Sulfones- Dapsone Paraaminosalicylic acid(PAS) Diaminopyrimidines:- Trimethoprim Pyrimethamine

Based on chemical structure Quiniolones:- Nalidixic acid Norfloxacin Ciprofloxacin Gatifloxacin etc Beta-lactam antibiotics:- Pencillins Cephalosporins Carbapenems Monobactams

Based on chemical structure Tetracyclines:- Oxyteracycline, Doxycycline etc. Nitrobenzene :- Chloramphenicol. Aminoglycosides:- Streptomycin, Gentamicin, Amikacin, Neomycin, Tobramycin etc.

Based on chemical structure Macrolide antibiotics:- Erythromycin, Clarithromycin, Azithromycin, Roxithromycin etc. Lincosamide antibiotics:- Lincomycin, Clindamycin etc.

Based on chemical structure Glycopeptide antibiotics :- Vancomycin, Teicoplanin. Oxazolidinone :- Linezolid Polypeptide antibiotics :- Polymyxin-B, Colistin, Bacitracin, Tyrothricin etc.

Based on chemical structure Nitrofuran derivatives:- Nitrofurantoin, Furazolidone etc. Nitroimidazole derivatives:- Metronidazole, Tinidazole etc. Nicotinic acid derivatives :- Isoniazid, Pyrazinamide, Ethionamide etc.

Based on chemical structure Polyene antibiotics :- Nystatin, Amphotericin-B, Azole derivatives:- Miconazole, Clotrimazole, Ketoconazole, Fluconozole etc.

Based on chemical structure Others :- Rifampicin, Cycloserine, Spectinomycin, Viomycin, Ethambutol, Griesofulvin, Clofazimine, Sodium fusidate, Thiacetazone etc.

Mechanism of action Inhibit cell wall synthesis :- Pencillins,Cephalosporines, Cycloserine, Vancomycin,Bacitracin etc. Cause leakage from cell membranes:- Polypeptide derivatives & Polyene derivatives Inhibit protein synthesis:- Tetracyclines,Chloramphenicol, Macrolides,Linezolid,Clindamycin etc

Mechanism of action Misreading of m-RNA code and affect permeability:- Aminoglycosides Inhibit DNA gyrase enzyme:- Quinolones Interefere with DNA function :- Rifampicin , Metronidazole etc.

Mechanism of action Interfere with DNA synthesis:- Acyclovir, Zidovudine etc Interfere with intermediary metabolism:- Sulfonamides, Sulfones, PAS, Trimethoprim, Pyrimethamine, Etham butol etc.

Type of Organisms against which will primarily active Antibacterial:- Pencillns, Aminoglycosides,Erythromycin etc Antifungal:- Griesofulvin, Amphotericin B, Ketoconazole, Flucanzole etc. Antiviral:- Acyclovir,Zidovudine, Amantadine etc. Antiprotozoal:- Chloroquine,Pyrimethamine, Metronidazole, Diloxnide etc. Anthelmintic:- Mebendazole, Albendazole Pyrantel, Niclosamide, DEC etc.

Spectrum of Activity Narrow-spectrum:- PencillinG Streptomycin Erythromycin Broad spectrum:- Tetracyclines Chloramphenicol

Type of Action Bacteriostatic:- Sulfonamides,Tetracyclines, Erythromycin, Chloramphenicol, Clindamycin, Linezolid etc. Bactericidal:- Pencillins, Cephalosporins Aminoglycosides, Polypeptides, Metronidazole, INH, Cotrimoxazole, Ciprofloxacin,Vancomycin etc.

Biological source of origin Fungi :- Pencillin, Cephalosporin, Griesofulvin etc. Bacteria:- Polymyxin B, Colistin, Bacitarcin Aztreonam, Tyrothricin etc. Actinomycetes:- Aminoglycosides, Macrolides, Tetracyclines, Polyenes, Chloramphenicol

AMAs-General problems on usage Toxicity Hypersensitivity reactions Drug resistance Mutation Superinfection Nutritional deficiency Masking of an infection

Choice of AMAs- Factors Patient factors:- Age, Renal and hepatic function, Drug allergies, Local factors, Pregnancy, Genetic factors. Drug factors:- Spectrum of activity, type of activity, Sensitivity of the organism, Relative toxicity, Pharmacokinetic profile, Route of administration, Evidence of clinical efficacy, and cost. Organism- related:- On bacteriological examination

Thank u Philip K Mathew Clinical instructor School of Pharmacy University of Nizwa