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.
The lecture Nematicides – Anthelmintic Drugs by Pravin Shukle, MD is from the course Antimicrobial Pharmacology.
A young boy is brought by his parents to your office complaining of abdominal pain and swelling. The family lives on a farm. On barium X-ray, you see a large intraluminal mass of worm-like organisms obstructing the ileum. Which drug will be the best option of treatment for this patient?
Which drug is given in a single-dose regimen to treat cutaneous larva migrans?
A patient comes to you and complains of a sensation of something moving in their eye. On examination, you notice a worm in the subconjunctival tissue. Which drug will you prescribe him?
Which drug produces hematuria in toxic doses?
5 Stars |
|
5 |
4 Stars |
|
0 |
3 Stars |
|
0 |
2 Stars |
|
0 |
1 Star |
|
0 |