MECHANISM OF ACTION
Dr.Elza Joy Munjely
Depmt. Of Pharmacology
Govt. Medical College,Kottayam.
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.
BACTERICIDALKill or irreversibly damage the multiplying
Nalidixic acid -Ciprofloxacin
Chloramphenicol - static against gram –ve rods & cidal
Sulphonamides/trimethoprim-static when used alone ,cidal
when used in combination.
Cidal is preferred when host defences are impaired & for
effective against a wide range of infectious
microorganisms which includes gram positive,
gram negative & atypical bacteria
Can be used emperically in case of serious
may give rise to drug resistance.
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.
As a result of chemical modification, affects
additional types of bacteria ie, gram-negative
+ one or two gram positive & vice versa.
Examples- carboxypenicillins &
DNA polymerase inhibitors
Anti HIV RT inhibitors
DNA damage - metronidazole
INHIBITION OF DNA
Inhibits DNA gyrase
Inhibition of 50
StreptograminsInhibition of 30
INHIBITION OF CELL WALL
Alteration of cell