Have you ever thought of why some drugs in particular anti-biotics
disappear after a brief stay. Though in majority of instances it's due to scrupulous
use of them by us leading to development of resistant strains against
them quickly there are also some structures that resist any
modification of structure. One such drug is Chloramphenicol. It has
existed as a bachelor from the day of its introduction till now. While
other anti - biotics ( Penicillin's and Cephalosporins ) have generated second and even some, third
generations our drug of interest has been as a bachelor without a
family of its own. We take a second look at it and analyze why it had
been a bachelor.
Replacement o the -NO2 group with a number of other substituents including CN, CONH2, NH2, OH results in loss of anti bacterial activity
The phenyl group has been replaced with other aromatic or alicyclic groups such as naphthyl, pyridyl, thienyl, cyclohexyl etc. Only the nitro thienyl compound has antibacterial activity and it was less potent.
Only the d - threo compounds of the 4 stereo isomers is anti bacterial activity.
The primary alcohol group seems to be imperative. Alteration of any kind leads to loss of activity.
The propanediol side chain too is non alterable.
Replacement of the di - chloro acetyl group with other halogens such as bromine resulted in loss of potency.
So what do you make of it? Simply vague ? The
structure is so sensitive that it results in loss of action on
alteration of any of its structural
parameters . What has this led to is the non availability of new
potent structures to combat the resistance generated against
Chloramphenicol by the ever mutating bacteria.
It took nearly 10 years to develope norfloxin from
naldixic acid which subsequently led to the now "At the Peak" family
of anti biotics FluroQuinolones. It just was that simple that
incorporation of an fluorine moiety at the C6 position resulted in
development of FluroQuinolones. So why not our bachelor may too
flourish in the years to come and make up for the present loss.
Hope so, for
the betterment of mankind.