Biomedical Engineering Reference
In-Depth Information
INH
Mycolic acid
ETB
Arabinogalactan
PYZ
Short chain fatty acid
precursors
RNA polymerase
(beta subunit)
RIF
Systematic diagram for the site of action of principle anti-TB drugs
Figure 14.4
Site of action of principal anti-tuberculosis drugs against M. tuberculosis H
37
Rv.
Pyrazinamide (PYZ)
- It gets converted into pyrazanoic acid, which
lowers the pH of the surroundings of
M. tuberculosis
and thus organism
unable to grow. It is also antimetabolite of nictoniamide and interferes with
the synthesis of NAD, thus inhibiting synthesis of short chain fatty acid
precursors [45, 47].
Ethambutol (ETH)
- It inhibits mycobacterial arabinosyl transferases
involved in the polymerization of D-arabinofuranose to arbinoglycan, an
essential cell wall component of mycobacterium [45, 47].
INH, ETB along with streptomycin helps in eradicating most of the
rapidly replicating bacilli in i rst 2 weeks of treatment. RIF and PYZ are
two drugs which play an important role in sterilisation of lesions by eradi-
cating organisms, and are crucial for 6 months treatment regimens. RIF
is responsible for killing non-replicating organisms and high sterilising
ef ect of PYZ act on semi-dormant bacilli and not af ected by any other
TB agents, in sites hostile to the penetration and action of the other drugs
[48, 49].
Despite of having availability of highly ef ective treatments of TB, cure
rates remain low. Patients have to consume large amount of drugs, the
major cause of patient's non-compliance. h ese short course regimens
results in decrease of the therapeutic potential of patient resulted in escala-
tion in the mortality rate and increased risk of developing acquired drug
