7 - Anthelminthics

Question 1

Classification of Anthelminthics

Answer 1

Vermicide (kill) and Vermifige (expel)

Question 2

Complete elimination of parasites (helminthic infections) can be challenging because….

Answer 2

limited drug efficacy and frequent reinfection after therapy

Question 3

Strongyloides and Echinococcus are..

Answer 3

The only helminths that can complete their life cycle and unable to replicate themselves in the human host

Question 4

The major soil-transmitted helminth infections are..

Answer 4

Ascariasis, trichuriasis, and hookworm (Ancylostoma duodenale)

Question 5

General MoA of anthhelmintics

Answer 5

Inhibiting energy production and targeting neuromuscular system

Question 6

Anthelmintics may result in..

Answer 6

Spastic paralysis (e.g. metrifonate, praziquantel, and pyrantel pamoate) and flaccid paralysis (e.g. ivermectin and piperazine)

Question 7

Benzimidazoles have excellent safety profiles, except for…

Answer 7

Thiabendazole, because it has more side and adverse effects

Question 8

Primary MoA of Benzimidazoles

Answer 8

Inhibit microtubule polymerization by binding to beta-tubulin –> Interfere cell division of helminths (selective toxicity due to higher binding affinity than humans)

Question 9

Albendazole is clinically used for..

Answer 9

Local infection (intraluminal parasites), systemic infection (tissue parasite), neurocysticercosis (lead to helminth seizure), hydatid disease, ascariasis, trichuriasis, and hookworm infections

Question 10

Mebendazole should be administered..

Answer 10

With a fatty meal to increase absorption and tablets should be chewed before swallowing

Question 11

Thiabendazole is an alternative to..

Answer 11

Ivermectin and Albendazole

Question 12

Bithionol is used as..

Answer 12

Alternative treatment for fascioliasis & pulmonary paragonimiasis through uncoupling of oxidative phosphorylation

Question 13

Bithionol is used as..

Answer 13

Alternative treatment for fascioliasis & pulmonary paragonimiasis through uncoupling of oxidative phosphorylation

Question 14

Diethylcarbamazine citrate is a drug of choice in the treatment of..

Answer 14

Filariasis, loiasis, and topical eosinophilia

Question 15

MoA of diethylcarbamazine citrate

Answer 15

Immobilizes microfilariae + alter surface structure –> tissue displacement –> increased destruction susceptibility

Question 16

To reduce the prevalence of W. Bancrofti infection, diethylcarbamazine citrate is combined with..

Answer 16

Ivermectin / Albendazole

Question 17

Indication of Ivermectin

Answer 17

Drug of choice in strongylodiasis and onchocerciasis and alternative drug for several helminthiasis

Question 18

MoA of Ivermectin

Answer 18

Intensifying GABA-mediated transcription of signals in peripheral nerves –> flaccid paralysis –> blocks microfilariae release (not kill adult worms)

Question 19

Metrifonate (Trichlorfon) indication

Answer 19

Alternative drug for schistosoma haematobium infections

Question 20

Metrifonate MoA

Answer 20

Inhibit cholinesterase –> accumulation of ACh –> Continuous spasm –> spastic paralysis in adult worms –> move to small arterioles of lungs –> killed by immune system

Question 21

For mixed infections with S. haematobium and S. mansoni, metrifonate is combined with..

Answer 21

Oxamniquine

Question 22

Niclosamide indication

Answer 22

Second-line treatment for most tapeworm infections

Question 23

Niclosamide MoA

Answer 23

Inhibition of oxidative phosphorylation/Stmulation of ATPase activity –> rapid helminth death

Question 24

Niclosamide is taken..

Answer 24

In the morning on an empty stomach and must be chewed thoroughly

Question 25

Oxamniquine indication

Answer 25

Alternative to praziquantel for treating S. mansoni

Question 26

MoA of Oxamniquine

Answer 26

Contraction and paralysis of the worms --> Detachment from terminal venules in the mesentery and transit to the liver

Question 27

Piperazine indication

Answer 27

Alternative treatment to ascariasis, cure rates over 90%

Question 28

MoA of piperazine

Answer 28

Block acetylcholine at myoneural junction --> causes paralysis of ascarsis --> worms expelled by peristalsis

Question 29

Praziquantel indication

Answer 29

Treatment of schistosome infections + trematode and cestode infections

Question 30

Praziquantel plasma concentration increases when

Answer 30

Taken with high-carb meal or with cimetidine

Question 31

MoA of Praziquantel

Answer 31

Increase permeability of trematode and cestode cell membranes to calcium --> parasite contraction (spastic paralysis) --> worm loses grip in GIT and expelled

Question 32

Praziquantel tablets are taken..

Answer 32

After a meal and swallowed without chewing because of bitter taste (induce retching and vomiting)

Question 33

Pyrantel pamoate indication

Answer 33

Pinworm, ascarsis, and Trichostrongylus orientalism infections, and both hookworm species (moderate effectiveness)

Question 34

Pyrantel pamoate

Answer 34

Disturb nerve function junction --> inducing activation of nicotinic receptor --> release of acetylcholine / cholinesterase inhibition --> acetylcholine accumulation --> spastic paralysis --> paralyzed worms expelled

Question 35

Doxycycline indication

Answer 35

Onchocerciasis and macrofilaricidal activity against W. bancrofti