00:00
So let's move on to the
antihelminthic agents.
00:04
We'll start of with
the nematodes.
00:06
So the nematicidal agents
start off with albendazole.
00:11
It's probably first in alphabet
but it's also first in choices.
00:15
It's a very, very good agent.
00:17
It inhibits microtubule assembly
which is essential for
the structural stability
of the organism.
00:24
It kills the ova
or eggs in ascariasis
and these other agents.
00:30
It is also going to kill
the larva in ascariasis
and cysticercosis which is
also called the pork tapeworm.
00:39
It is larvicidal in hookworm.
00:41
And it is also larvicidal
in hydatid disease.
00:44
So we use this agent in a
number of different types
of infections that
are listed there.
00:51
In terms of toxicity from this
agent, because the agent is used
for such a short duration
or time,
toxicity is really quite rare.
01:00
Sometimes we'll see a reversible drop in white cell count.
01:03
And sometimes we'll see a short
time rise in liver enzymes
with prolonged used.
01:08
But the times that we actually
use this for prolonged usages
is really quite rare.
01:13
So becomes mostly a non issue.
01:18
Diethylcarbamazine is
quite an interesting drug.
01:23
We actually use it to immobilize
the microfilariae
by an unknown mechanism.
01:30
And it is used in eye worm.
01:31
So this is actually an
image of an eye worm.
01:34
So you can actually see
them in the square,
in the iris of a patient.
01:41
It looks like a white line
that actually moves around.
01:43
It's actually quite a horrific
thing to see if you've
ever seen it live.
01:48
Toxicity to this medication,
reactions to proteins of dying
filariae include fever,
rash and ocular damage.
01:55
So it's not so much the drug
itself that's causing the toxic
reaction.
02:00
It's a fact that when these
filariae are dying, those break
down proteins are causing
all kinds of reaction.
02:07
And that's where you
get run into trouble.
02:11
Ivermectin is another
well known agent.
02:15
It's a nematicidal.
02:17
This is cutaneous larva migrans
and you will see this
in your practice at some point
or another.
02:23
These are worms that are
actually under the skin.
02:25
It's one dose,
so ivermectin is one dose.
02:29
It intensifies the GABA
neurotransmission in
the nematodes.
02:33
And the nematodes become
spastic and immobilize.
02:36
And they can't feed.
02:38
They can't do anything
and they die.
02:39
We use it in cutaneous larva
migrans, strongylodiasis
and filariasis.
02:49
Toxicity to ivermectin
is quite rare.
02:52
Remember that the actual
toxicity to the drug is almost
non-existent because
it's just a single dose.
02:58
Where you get the toxicity
is from the dying worms.
03:01
And so the agents that are being
released from the dying worms
includes fever.
03:06
The side effects include fever,
rash and ocular damage
if it's in the eye.
03:11
Now this disgusting picture is
an infection of ascariasis.
03:19
This was removed from a 4 year
old child who ended up
having a bowel obstruction.
03:23
And they couldn't
figure out why.
03:25
And the found out that his
valve was full of these worms.
03:27
So mebendazole is the treatment
for this.
03:31
It's absorbed minimally.
03:34
So less than 10 percent of
this agent can be absorbed
from the bowel.
03:37
It inhibits
microtubule synthesis.
03:40
And it also inhibits the glucose
uptake in the nematodes
so they die very quickly.
03:45
It is the primary drug
for ascariasis,
pinworm and whipworm.
03:49
And it is the backup drug
for visceral
or tissue larva migrans.
03:58
Thiabendazole is another
nematicidal agent.
04:00
It's a structural
cogener of mebendazole.
04:03
In terms of how it is working,
it's absorb systemically
and it has much more systemic side effects
then the other agents.
04:13
It works through inhibiting
microtubule synthesis
and glucose uptake in nematodes.
04:18
It's an alternative for
systemic infections things like
strongyloides or trichinosis
which are the adult worms.
04:25
In terms of toxicity GI
irritation is quite common.
04:28
You can also get intrahepatic
cholestasis, liver failure.
04:33
And in terms of neurological
symptoms you can sometimes
get headache, dizziness
and drowsiness.
04:38
A drop in white count
leukopenia is common.
04:42
Hematuria is something that
we have to be aware of
and can occur.
04:46
And allergic reactions not
just to the dying organisms
but also to the drug itself
are also present.
04:52
You can also get a Stevens
Johnson syndrome
which can be fatal.
04:57
We're not entirely sure if this
is due to the drug itself
or if it's due to the dying
organisms, we haven't
quite figured that one out yet.
05:05
And any rate be quite aware
that this is a potential problem
with this agent.