00:00
And finally when we talk
about individual fungal diseases, we're going
to be talking about ways to cure them. And
we don't have vaccines against most of these
fungal diseases, but we do have drugs that
can be used to treat them, and some of them
work very well, some of them are somewhat
toxic, but it's all that we have.
00:20
So here's a table that lists all of the available
antifungal agents, let's zoom in on the top
part of this table so that we can discuss
them in a little detail. We have a number
of different classes of antifungal agents,
the first here is the polyenes. These are
rather large molecules whose mechanism of
action is to bind a component of the cell
membrane called ergosterol, and they disrupt
the membrane, and examples include amphotericin B,
nystatin which can be either given intravenously
or topical. Nystatin is a very common topical
antifungal which can be used to treat lots
of surface infections and you can see in the
last column labeled pathogen the various fungal
infections that are treated. You've got some
specific names like candida and Cryptococcus,
and then the endemic mycoses, which refers
to this category of infections that we acquire
from specific environments. We also have another
category called the allylamines, which block
synthesis of the same membrane component,
ergosterol, and an example of that is terbinafine
which is either topically or orally given
for dermatophytes. We have the azoles which
block ergosterol synthesis as well, so you
can see this is a common target. Ketoconazole
which is given orally for various infections.
01:38
and then let's zoom in on the bottom, we're
continuing with some of these azoles that
block ergosterol synthesis, itraconazole,
fluconazole and voriconazole, all IV or oral
administered for various infections and we
will refer to these specifically when we talk
about the diseases. The echinocandins inhibit
cell wall synthesis, caspofungin is an example
of a drug given intravenously for Candida
and Aspergillus infections. And finally there's
a pyrimidine inhibitor. This inhibits DNA
and protein synthesis called flucytosine,.
02:11
This is given all orally for Cryptococcal and
candida infections. And not all of these are
specific, so the ergosterol inhibition is
rather specific, but pyrimidine inhibitors
are not, so they often have side effects.