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Pharmacology II - Exam 4 > Anti-Helminths > Flashcards

Flashcards in Anti-Helminths Deck (24)
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1
Q

Clinical Use of Praziquantel

A

Effective against adults and immature stages

Drug of choice for trematode and cestode infections but not nematodes

2
Q

Is Praziquantel contraindicated in pregnancy?

A

Yes

3
Q

The mechanism of action of Praziquantel…

A

Increases influx of calcium across tegument, leading to disruption of tegument and antigen exposure

Increase Ca influx in muscles cells –> increased muscle contraction –> spastic paralysis

4
Q

The other contraindication of Praziquantel

A

Intraocular Cysticerosis: parasite killing can lead to irreversible damage to the retina due to the inflammatory response

5
Q

What can happen with high doses of pyrantel pamoate?

A

Neuromuscular blockade

6
Q

Mechanism of Actions of Pyrantel Pamoate…

A

Depolarizing neuromuscular blockade

Stimulated nicotinic acetylcholine receptor at the neuromuscular junction –> release of acetylcholine –> inhibits acetylcholinesterase

All this causes spastic paralysis

7
Q

Anti-Helminthic actions of pyrantel pamoate

A

Not effective against migratory stages in tissues

Kills larvae and adults in intestines; not effective against eggs

8
Q

What causes the adverse reaction from DEC use?

A

The antigens released from dying microfilariae and/or adult worms

Steroids can decrease this reaction

9
Q

Clinical Uses of DEC

A

Loiasis caused by Loa Loa

Controls and treats lymphatic filariasis in combination with albendazole

10
Q

MOA of DEC??

A

Alters worm surface membrane resulting in enhanced killing by the host immune system

Stimulates platelet aggregation around membrane-damaged parasites

11
Q

Alkalinized urine does what to DEC?

A

DEC gets reabsorbed across the proximal tubules, leading to elevated plasma levels and prolonged half-life

12
Q

Ivermectin Resistance

A

Increased ATP-dependent PGP transporter activity on the surface of worm to mediate drug efflux

Mutations in ligand-gated Cl- channel leading to decreased drug binding

13
Q

What is a Mazzotti-like reaction?

A

Caused by Ivermectin

Itching, swollen tender lymph nodes
Headache, dizziness, somnolence, fever, tachy, hypotension, myalgia, arthralgia, diarrhea, facial/peripheral edema

14
Q

MOA of Ivermectin

A

Activates invertebrate specific glutamate gated Cl- channel –> hyperpolarization and muscle paralysis

Binds with high affinity to GABA-gated Cl- channels in nematodes

15
Q

Clinical Uses of Ivermectin

A

Nematode infections leading to…

Onchocerciasis (river blindness)
Lymphatic filariasis (combined with albendazole for adult worms)
16
Q

Benzimidazoles: Three drugs

A

Mebendazole
Albendazole
Thiabendazole

17
Q

MOA of benzimidazoles

A

Inhibits microtubule polymerization by binding to B-tubulin

Absence of microtubules causes:

  • Inhibition of mitosis
  • Cessation of cellular secretion
  • Inhibition of mitochondrial fumarate reductase
  • Uncoupling of oxidative phosphorylation
18
Q

Resistance to Benzimidazole…

A

Change in B-tubulin isotype usage

-Point mutation in B-tubulin isotype to tyrosine at position 200

19
Q

Clinical Uses of Benzimidazoles

A

GI lumen and systemic

  • Ascariasis
  • Enterobiasis
  • Trichuriasis
  • Necatoriasis
  • Lymphatic filariasis
20
Q

Dosage of Benzimidazole

A

Either a single dose or a 3-day regimen

21
Q

Mebendazole and Albendazole have very similar toxicities. But which one can cause liver abnormalities with long term use?

A

Albendazole

22
Q

What drug can increase the systemic drug levels of Mebendazole?

A

Cimetidine

23
Q

Which drug is the drug of choice for schistosomiasis?

A

Praziquantel

24
Q

Which drug is not useful for trematodes and cestodes?

A

Ivermectin