General introduction:
Antibiotics in the language of pharmacology is a class of drugs that possess their pharmacological action against microorganisms. in a more specific way, they are also called antimicrobial agents. there is a long list of harmful microbes against which antibiotics can be administered. conventionally, people refer antibiotics only to its sub-type "antibacterial", which is totally wrong in terms of proper pharmacological definition.
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antibiotics classification pdf
classification of antibiotics ppt
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antibiotics classification pdf
classification of antibiotics ppt
Classification Of Antibiotics:
classification of antibiotics is an extended topic. for convenience, classification is subdivided into the following main subdivisions.
- Classification based on Nature of organism
- Mechanism of action based classification
- classification based upon nature of the action
- chemical structure based classification
- Spectrum-based classification
- source based classification (the source from which the antibiotics are synthesized or isolated).
Nature Of Organism:
on basis of microbes nature, antibiotic may be used for any of the following therapies.
- antibacterial therapy
- antifungal therapy
- antiviral therapy
- antiprotozoal therapy- includes antimalarial and anti-amoebic drugs.
- antimycobacterial therapy - because of clinical significance, this is a separate class. includes anti t.b and antileprotic drugs.
Mechanism/mode of action based classification:
This classification classifies antibiotics keeping the mechanism in view under which they brought their pharmacological action. Following are the subclasses.
- cell wall synthesis inhibitors
- cell membrane disrupters
- protein synthesis inhibitors
- folic acid synthetase inhibitors
- Nucleic acid function inhibitors
Cell wall synthesis Inhibitors:
As the name indicates these antimicrobial prevent cell wall formation in the infectious microbes, thus leading to cell lysis and so on, the death of microbe.
antimicrobial included in this class are as follows;
- penicillin
- cephalosporin
- monobactam
- aztreonam
- bacitracin
- vancomycin
- echinocandins (Antifungal).
Cell membrane disrupters:
these antibiotics posses their pharmacological ability to disrupt the cell membrane of microorganisms.
Azoles, polyene (antifungals) and polymyxin-b are included in this class).
Action based classification:
action and mechanism of action are slightly different things.
this classification means that after interacting with antibiotics what lethal effects would result in microbes.
on this basis, antibiotics are classified in bacteriostatic and bactericidal. (both of them are antibacterials)
bacteriostatic:
these antibiotics are agents that prevent the bacterial population from increasing and not necessarily killing them. however, a bacteriostatic in high dose is essentially bactericidal.
Chloramphenicol, tetracycline, sulfonamide, and macrolide are included in bacteriostatic.
Bactericidal:
bactericidal are drugs that kill off the microbes by any mechanisms discussed earlier.
penicillin and other beta-lactams, fluoroquinolones, co-trimoxazole, aminoglycosides, metronidazole etc are included in bactericidal.
Chemical structure-based classification:
On the basis of chemical structure, we relate antibiotics on the basis of the same basic nucleus. Following sub-classes are included in this classification.
Beta lactames:
beta lactames includes pencillin, cephalosporin, monobactam, carbaphenem.
Tetracyclines:
they are 4 cyclic structures resembling benzene.examples are Doxycycline & tetracyclines.
Macrolides:
These include large cyclic ketone structures.Erythromycin and clarithromycin are included in this class.
chloramphenicol:
nitrobenzenes derivatives are included in this class.
quinolines:
ciprofloxacin is quinoline antibiotic.
Azoles:
Metronidazole, ketoconazole is structurally composed of a nitrogen-containing ring.
polyene (many double bonds):
nystatin and amphotericin-b are polyenes in structure.
polypeptides:
polymyxin-b and bacitracin are structurally polypeptides.
Glycopeptides:
vancomycin is structurally glycopeptide.
Spectrum-based classification:
This classification gives us an idea about the range of microorganisms against which the antibiotics are effective.
very narrow range antibiotics:
antistaphylococcal drugs and penicillin class are antibiotics of very narrow therapeutic range.
Narrow spectrum antibiotics:
isoniazid and penicillin G are narrow spectrum antibiotics.
Extended-spectrum antibiotics:
ampicillin is an extended spectrum antibiotic. means it is effective against a range of microbes broader than the former two.
Broad spectrum antibiotic:
their range is much larger than the classes discussed earlier. broad spectrum antibiotics are effective against a large number of microbes.
drugs included are;
- tetracycline
- chloramphenicol
- co-amoxiclav
- cotrimoxazole
- 3rd and 4th generation cephalosporins.
Source-Based Classification:
by the source, we generally refer to the source from which the antibiotic is obtained.
on the basis of source antibiotic maybe;
- Microbial source
- semi-synthetic source
- synthetic source
Antibiotics Of Microbial Source:
from microbes various antibiotics are isolated. the microorganisms from which antibiotics are isolated are bacteria, actinomycetes, and fungi.
bacitracin is obtained from bacteria.
tetracyclines, chloramphenicol, streptomycetes, aminoglycosides, and macrolides are obtained from actinomycetes.
penicillin, cephalosporin, and griseofulvin (antifungal) are obtained from Fungi.
Semi-synthetic Antibiotics:
semi-synthetic means that the starting material of them is a natural source which is chemically modified to form the product.
following are semisynthetic antibiotics.
- aminopenicillins
- amoxicillin
- ampicillin
Synthetic Antibiotics:
synthetic antibiotics do not have natural starting material. they are developed entirely in laboratories. Following are the examples;
- Sulfonamides
- most antimalarial
- isoniazid
- most antiviral (viruses are on the borderline between living and non-living here their living properties are kept in consideration).
- most anthelmintics
