01-Gen Prin Antibiotics

7/29/2019 01-Gen Prin Antibiotics

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Dr. Korawuth Punareewattana

Dept. of Vet Phar & Tox

Khon Kaen University

Topic 1 : General Principles of Antibiotics

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Contents

Terms

Classifications

Mechanisms of Action

Drug interactions

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Terms

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Terms with specific meanings

Antibacterial drugs

Antifungal drugs

Antiviral drugs

Antiprotozoal drugs

Terms with broad meanings or several meanings

Antibiotics Antibiotics and Synthetic antibacterials

Narrow and Broad senses

Antimicrobial drugs Broad and Narrow senses


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Antibiotic Classifications

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Based on Chemical structure

Based on Class of target microorganism

Based on Antibacterial activity

Based on Bacteriostatic or Bactericidal activity

Based on Time- or Concentration-dependent activity


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Classification based on Chemical Structure

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Beta-lactam antibiotics

Penicillins

Cephalosporins

Carbapenems

Monobactam

Peptide antibiotics

Lincosamides

Pleuromutilins

Streptogramins

Macrolides

Aminoglycosides

Tetracyclines

Chloramphenicol

Sulfonamides and

Diaminopyrimidine

Fluoroquinolones

Miscellaneous

Ionophores

Nitrofurans

Nitroimidazoles

Rifamycins

Oxazolidinones


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Sub-classified by clinical importance

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More commonly used

Beta-lactams

Sulfa-Trimethoprim

Fluoroquinolones

Aminoglycosides

Tetracyclines

Chloramphenicol

Less commonly used

Macrolides

Peptide antibiotics

Lincosamides

Pleuromutilins

Streptogramins

Miscellaneous

Nitroimidazole (Metronidazole)


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Classified byClass of Target Microorganisms

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Narrow-spectrum Bacteria only

Broad-spectrum Bacteria

And Other microorganisms

Mycoplasma

Rickettsia

Protozoa


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Classified by Class of Target Microorganisms

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Class of microorganisms

Drug Bacteria Fungi Mycoplasma Rickettsia Chlamydia Protozoa

Aminoglycosides + - + - - -

Beta-lactams + - - - - -

Chloramphenicol + - + + + -

Fluoroquinolones + - + + + -

Lincosamides + - + - - +/-

Macrolides + - + - + +/-

Oxazolidones + - + - - -

Pleuromutilins + - + - + -

Tetracyclines + - + + + +/-

Streptogramins + - + - + +/-

Sulfonamides + - + - + +

Trimethoprim + - - - - +


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Classified by Antibacterial activity

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Narrow-spectrum Gram-positive Bacteria only or

Gram-negative Bacteria only

Broad-spectrum Gram-positive andGram-negative Bacteria

This classification

is roughly classified

Is relatively compared


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Classified by Antibacterial activity

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Aerobic Bacteria Anaerobic Bacteria

Spectrum Gram + Gram - Gram + Gram - Examples

Very broad + + + + Carbapenems; chloramphenicol; Glycylcyclines

3rd-generation fluoroquinolones

Intermediately broad + + + (+) 3rd and 4thgeneration cephalosporins

+ (+) + (+) 2ndgeneration cephalosporins

(+) (+) (+) (+) Tetracyclines

Narrow + +/- + (+) Ampicillin; amoxicillin; 1st generation cephalosporins

+ - + (+) Penicillin; lincosamides; glycopeptides; streptogramins;

oxazolidones

+ +/- + (+) Macrolides

+/- + - - Monobactams; aminoglycosides

(+) + - - 2ndgeneration fluoroquinolones

(+) (+) - - Trimethoprim-sulfa

- - + + Nitroimidazoles

+ - (+) (+) Rifamycin


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Classification based on Bacteriostatic orBactericidal Activity

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Bacteriostatic drugs

Drugs that inhibit bacterial growth

MIC and MBCare much different i.e. > 10 times

Ex. - Chloramphenicol

- Tetracyclines

Bactericidal drugs

Drugs that kill bacteria

MIC and MBCare so close i.e 2-3 times

Ex. - Beta-lactams

- Aminoglycosides MIC minimum inhibition concentration

MBC - minimum bactericidal concentration


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Classification based onTimeorConcentration dependent activity

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Time-dependent antibiotics

Antibacterial action depends on time of drug exposure

Example drugs

Beta-lactams

Macrolides

Concentration-dependent antibiotics

Antibacterial action depends on drug concentration

Example drugs

Aminoglycosides

Fluoroquinolones


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Mechanisms of Action of Antibiotics

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Mechanisms can be classified into 5 groups

Inhibition of cell wall synthesis

Beta-lactam

Damage to cell membrane function

Polymyxins

Inhibition of nucleic acid synthesis or function

Nitroimidazoles

Fluoroquinolones

Inhibition of protein synthesis

Aminoglycosides, Chloramphenicol, Lincosamides etc.

Inhibition of folic acid synthetase

Sulfonamides


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Drug Interactions

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Antibiotic drug combinations that producesynergistic effectThese are possible mechanisms

Sequential inhibition of successive steps in metabolism

Sequential inhibition of cell wall synthesis

Facilitation of one antibiotics entry by another

Inhibition of inactivation enzymes

Prevention of emergence of resistance populations


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Drug Interactions

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Antibiotic drug combinations that produceantagonistic effectThese are possible mechanisms

Inhibition of bactericidal activity

Competition for drug-binding sites

Inhibition of cell permeability mechanisms

Induction of beta-lactamases by beta-lactam drugs

01-Gen Prin Antibiotics

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