Classification of antimicrobial drugs

Based on the different criteria the anti microbials are classified....

1. CLASSIFICATION OF Antimicrobial drugs
Ameena Kadar K A
Grace College Of Pharmacy
Palakkad

2. Drugs in this class differ from all others in that they are designed to inhibit/kill the
infecting organism and to have no/minimal effect on the recipient.

This type of therapy is generally called chemotherapy which has come to mean
treatment of systemic infections with specific drugs that selectively suppress/kill the
infecting microorganism.

 Antibiotics : These are substances produced by microorganisms, which selectively
suppress the growth of or kill other microorganisms at very low concentrations.
This definition excludes other natural substances which also inhibit microorganisms
but are produced by higher forms (e.g. antibodies) or even those produced by
microbes but are needed in high concentrations.

Chemotherapeutic agent : Initially this term was restricted to synthetic compounds,
but since many antibiotics and their analogues have now been synthesized, this
criterion has become irrelevant; both synthetic and microbiologically produced drugs
need to be included together.
 It would be more meaningful to use the term Antimicrobial agent (AMA) to designate
synthetic as well as naturally obtained drugs that attenuate microorganisms.

3. CLASSIFICATION
Antimicrobial drugs can be classified on the basis of many characteristics:

A.Chemical structure :
a) Sulfonamides and related drugs:
oSulfadiazine and others
o Sulfones - Dapsone (DDS)
oParaaminosalicylic acid (PAS)
b) Diaminopyrimidines:
oTrimethoprim
oPyrimethamine
c) Quinolones:
oNalidixic acid
oOfloxacin
oCiprofloxacin
oPrulifloxacin
oGatifloxacin
oMoxifloxacin
d) β-Lactam antibiotics:
oPenicillins
oCephalosporins
o Monobactams
o Carbapenems

4. e) Tetracyclines:
oOxytetracycline
o Doxycycline
f) Nitrobenzene derivative:
oChloramphenicol
g)Aminoglycosides:
o Streptomycin
o Gentamicin
oAmikacin
o Neomycin
h)Macrolide antibiotics:
oErythromycin
oClarithromycin
oAzithromycin
oRoxithromycin
i) Lincosamide antibiotics:
o Lincomycin
oClindamycin
j) Glycopeptide antibiotics:
oVancomycin
o Teicoplanin.
k) Oxazolidinone:
oLinezolid

5. l) Polypeptide antibiotics:
oPolymyxin-B
oColistin
oBacitracin
oTyrothricin.
m) Nitrofuran derivatives:
oNitrofurantoin
o Furazolidone
n) Nitroimidazoles:
o Metronidazole
oTinidazole
o) Nicotinic acid derivatives:
o Isoniazid
oPyrazinamide
o Ethionamide
p) Polyene antibiotics:
o Nystatin
o Amphotericin-8
oHamycin
q) Azole derivatives:
o Miconazole
o Clotrimazole
o Ketoconazole
o Fluconazole

6. r) Others:
oRifampin
oSpectinomycin
oSod. Fusidate
oCycloserine
oViomycin
oEthambutol
oClofazimine
oGriseofulvin
oThiacetazone.

B. Type of organisms against which primarily active:

 Antibacterial:
oPenicillins
oAminoglycosides
o Erythromycin
o Fluoroquinolones.

 Antifungal:
oGriseofulvin
oAmphotericin B
oKetoconazole

7. Antiviral:
oAcyclovir
oAmantadine
o Zidovudine

 Antiprotozoal:
oChloroquine
oPyrimethamine
oMetronidazole
oDiloxanide

 Anthelmintic:
oMebendazole
o Pyrantel
o Niclosamide
o Diethyl carbamazine.

C. Spectrum of activity :

a.Narrow-spectrum (Which are active against Gram +ve bacteria) :
oNatural pencillins
oSemi-synthetic pencillins
Methicillin
Oxacillin

8. oCephalosporins
oLincomycin
oMacrolides

b. Broad-spectrum :
oSemi synthetic pencillins
Ampicillin
Amoxicillin
oTetracyclines
o Chloramphenicol
oAminoglycosides
oPolymixins
oFluoroquinolones
oCephalosporins of 2
nd
& 4
th
generation.

Drugs with all ranges of intermediate band width, e.g. extended spectrum penicillins:
oNewer cephalosporins,
oAminoglycosides
oFluoroquinolones, etc.

9. D. Type of action :

Primarily bacteriostatic :
oSulfonamides
oErythromycin
oTetracyclines
oClindamycin
o Chloramphenicol
oLinezolid
oEthambutol

 Primarily bactericidal :
oPenicillins
oCephalosporins
oAminoglycosides
oVancomycin
oPolypeptides
oFluoroquinolones
oRifampin
oMetronidazole
oLsoniazid
o Cotrimoxazole
oPyrazinamide

10. Some primarily static drugs may become cidal at higher concentrations (as attained in the
urinary tract), e.g. erythromycin, nitrofurantoin.
On the other hand, some cidal drugs, e.g. cotrimoxazole, streptomycin may just be static
under certain circumstances.

E. Natural sources of antibiotics :

Fungi :
oPenicillin
oCephalosporin
Bacteria :
oPolymyxin B
o Colistin
o Bacitracin
oTyrothricin
oAztreonam
 Actinomycetes :
oAminoglycosicles
oTetracyclines
oChloramphenicol
o Griseofulvin
oMacroildes
oPolyenes

11. F. Based on Mechanism Of Action :

13. REFERENCES:

Essentials of Medical Pharmacology by K D Tripathi , 8
th
edition, Page no: 739-741.