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Antimicrobials
- 1. ANTIMICROBIALS MECHANISM OF ACTION Dr.ElzaJoy Munjely JR-I Depmt. Of Pharmacology Govt. Medical College,Kottayam.
- 2. CHEMOTHERAPY –treatment of systemic or topical infection with drugs that have selective toxicity for an invading pathogen without harming the host cells. Takes advantage of the biochemical & physiological differences that exist between microorganism & human beings.
- 3. Antimicrobials Drugs thatinhibit microbial growth & multiplication Antibacterial Antiviral Antifungal Antiprotozoal Antihelminthics Cidal/static Narrow/Extended/Broad spectrum
- 4. BACTERIOSTATICArrest thegrowth & replication & limit the spread of infection. Macrolides -Oxazolidones Chloramphinicol -Tetracyclines Sulphonamides -Trimethoprim Clindamycin -Nitrofurantoin Ethambutol -Linezolid Erythromycin
- 5. BACTERICIDALKill orirreversibly damage the multiplying bacteria. Betalactam -Vancomycin Polymixin -Bacitracin Isoniazid -Pyrazinamide Rifampicin -Aminoglycosides Nalidixic acid -Ciprofloxacin Metronidazole -Cotrimoxazole Chloramphenicol - static against gram –ve rods & cidal against pneumococci Sulphonamides/trimethoprim-static when used alone ,cidal when used in combination. Cidal is preferred when host defences are impaired & for complicated infections.
- 6. BROAD SPECTRUM effective against a wide range of infectious microorganisms which includes gram positive, gram negative & atypical bacteria Can be used emperically in case of serious infections may give rise to drug resistance. Example Tetracycline Chloramphenicol
- 7. NARROW SPECTRUM active against a selected group of bacterial types.Either gram negative or gram positive. used for the specific infection when the causative organism is known. cause less resistance of the bacteria as it will deal with only specific bacteria. Examples: Azithromycin Clarithromycin Clindamycin Erythromycin Vancomycin Streptomycin
- 8. EXTENDED-SPECTRUM ANTIBIOTIC As a result of chemical modification, affects additional types of bacteria ie, gram-negative + one or two gram positive & vice versa. Examples- carboxypenicillins & urideopenicillins.
- 9. Targets of antimicrobials Cell wall Cell membrane Protein synthesis Intermediary metabolism Intracellular organelles Nucleic acid metabolism Muscle fibres
- 10. Cell wall synthesisinhibitors Bacteria – peptidoglycan Inhibitors of peptidoglycan synthesisBetalactam,Vancomycin,Bacitracin,Cy closerin & Phosphomycin. Mycobacteria – mycolic acid & arabinoglycans INH, Ethambutol, Pyrazinamide Fungi – chitin Echinocandins
- 11. Cell membrane Cellmembrane disrupting drugs Anti-bacterial - polymixins Antifungal – polyene antibiotics Inhibitors of cell membrane synthesis Azoles Terbinafine
- 12. Protein Synthesis rRNA •30s •Aminoglycosides, Tetracyclines,Spectinomycin •50s •Macrolides, Choramphenicol, Lincosamides, • Streptogramins, linezolid tRNA •Mupirocin
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- 14. Intracellular organelles Mitoticspindle Griseofulvin Benzimidazoles Food vacuole Chloroquine, Quinine, Halofantrine, Mefloquine Mitochondrial electron transport chain Atovoquone
- 15. Muscle fibre Ivermectin, Pyrantel pamoate, Piperazine
- 16. Nucleic acid RNAsynthesis RNA polymerase Rifampicin DNA synthesis DNA gyrase Quinolones DNA polymerase inhibitors Acyclovir, Ganciclovir Reverse transcriptase Anti HIV RT inhibitors DNA damage - metronidazole
- 17. PP DHFA PABA THFA DNA m-RNA INHIBITION OF DNA SYNTHESIS InhibitsDNA gyrase Fluroquinolones DNA-directed RNA polymerase. Inhibits RNA synthesis Rifampicin INHIBITION OF FOLIC ACID SYTHESIS Trimethoprim Pyrimethamine Proguanil Trimetrexate Sulphonamides Dapsone PAS , Inhibition of 50 S Chloramphenic ol Macrolides Clindamycin Telithromycin Linezolid StreptograminsInhibition of 30 S Aminoglycosid es Tetracyclines Spectinomycin INHIBITION OF CELL WALL SYNTHESIS Betalactams,Bacitracin,cycloserin e Vancomycin,Teicoplanin Monobactams,Carbopenems, INH,Ethanbutol,Pyrazinamide Alteration of cell membrane integrity Polymixins Amphotericin B Azoles
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