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40 Cards in this Set

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The general rule about antihelminthics
Don't kill the parasite they incapacitate it and let the body do the work
Can worms reproduce in humans
Aside from a few exceptions- No
Drugs used to treat Nematode infections
Benzimadozoles: mebendazole, albendazole, and thiabendazole
Pyrantel Pamoate
Primary MOA of Benzimadozoles
(-) of microtubule polymerization by binding to B-tubulin
Explain the selectivity of Benzimadozoles
B-tubulin binding occurs at much decreased [] in parasite than in mammals
Use of Mebendazole
Whipworm- Trichuris trichiria
Mixed infections of T. trichiuria w/Ascaris and/or Enterobius
Hookworm
Preoperative sterilization of hyadatid cysts
Special things about Mebendzaole (3 things)
1. Broad spectrum, virtual atoxicity
2. Toxic to nematode eggs
3. Cure rates >90% w/all 3 parasites
PK of Mebendazole
Poorly absorbed from intestinal tract
SE of Mebendazole
Few side effects, abdominal pain and diarrhea associated w/expulsion or worms
Contraindication for Mebendazole
Pregnancy
Albendazole
Primary drug of choice for almost all helminth infections
Absorption of Albendazole
4X greater when taken w/fatty meals
SE of Albendazole
Increase in AST
Jaundice
Chemical chlestasis
Contraindication for Albendazole
Cirrhosis
Pregnancy
Infants
Use of Thiabendazole
Strongyloides stercoralis
Cutaneous larva migrans
*active against nematode eggs and larvae
SE of Thiavendazole
Nausea, vomiting, anorexia, and dizziness
Malodorous urine and sweat
*Because of these restrict use to treatment of Strongyloides
Use of Pyrantel Palmoate
Ascaris
Enterobius
Hookworm
PK of PP
poorly absorbed so parasite exposed to increase []
MOA of PP
Depolarizing neuromuscular blocker--> release of Ach and persistent nicotinic stimulation of ganglion receptors of helminth--> paralizes worm
SE of PP
Headache
Dizziness
Drowsiness
Antifilarial agents
Diethylcarbamazine (DEC)
Ivermectin
Use of DEC
W. bancrofti and Loa loa (active againt both forms)
O. volvulus (only microfilarial form)*
Why is DEC usually not used for O. volvulus treament?
Only active against one form and severe adverse rxns
PK of DEC
Readily absorbed from GI
SE of DEC
Caused by worm destruction and drug
Headache
Nausea and vomiting
Anorexia
Cough
Joint and muscle pain
SE caused from worm destruction by DEC. How do we treat this?
Can result in shock from an allergy to the destroyed parasite

Treat w/Corticosteroids
Use of Ivermectin
(7 things)
O. volvulus
W. bancrofti
B. malayi
Strongyloides
Ascaris
Enterobiasis
Trichuris
Ivermectin vs. DEC
Single dose of ivermectin as effective as daily DEC in reducing skin microfilaria
MOA of Ivermectin
Causes influx of negatively charged Cl- --> hyperpolarization --> muscle paralysis
Most common SE of Ivermectin
Headache
Contraindications of Ivermectin
Impaired BBB b.c. of its actions on GABA receptors
Drugs used to treat Schistosomiasis and tapeworm infection
Praziquantel
Niclosamide
Use of Praziquantel
S. mansoni, haematobium, japonicum ~ 90% cure rate
Clonorchis
Fasciolopsis
Paragonimus
Neurocysticerousis
Praziquantel and double infection
Useful in pts w/hepatosplenic dz, so can be used in pts w/double infection of S. haematobium and mansoni
Praziquantel is effective against which parasite stages? What doesn't it work on?
Immature and Adult forms
Fasciola hepatica
MOA of Praziquantel
Increases helminth's permeability to Ca2+ ions -> vacuolization, contraction, paralysis -> exposure of parasite antigens to host
SE of Praziquantel
Mild and transient: Colicky abdominal pain, dizziness, and headache
Use of Niclosamide
2nd choice of tapeworm infections
MOA of Niclosamide
Inhibitor of helminth specific fumarate reductase -> blocks ATP production
Does Niclosamide kill eggs too?
No-treatment of T. solium infections should be followed by a purge to remove gravid segments