Helminth Infections

Question 1

Mebendazole

Answer 1

Benzimidazole (Anthelmintic Drugs)

Characteristics:
- Pinworms, Roundworms, Whipworms, Hookworms
- Only kills worms not eggs

MOA:
- Impairment of polymerization of helminth beta-tubulin
–> Interferes with microtubule-dependent functions (glucose uptake)

AE:
- GI Disturbances

Question 2

Tiabendazole

Answer 2

Benzimidazole (Anthelmintic Drugs)

Characteristics:
- Pinworms, Roundworms, Whipworms, Hookworms
- Only kills worms not eggs

MOA:
- Impairment of polymerization of helminth beta-tubulin
–> Interferes with microtubule-dependent functions (glucose uptake)

AE:
- GI Disturbances

Question 3

Albendazole

Answer 3

Benzimidazole (Anthelmintic Drugs)

Characteristics:
- Pinworms, Roundworms, Whipworms, Hookworms
- Only kills worms not eggs

MOA:
- Impairment of polymerization of helminth beta-tubulin
–> Interferes with microtubule-dependent functions (glucose uptake)

AE:
- GI Disturbances

Question 4

Nitazoxanide

Answer 4

Anthelmintic
Characteristics:
- Oral Antiparasitic
- Targets Giardiasis and Cryptosporidiosis
- Forms active metabolite tizoxanide

MOA:
- Interferes with pyruvate:ferredoxin oxidoreductase (PFOR) enzyme dependent electron transfer reaction
–> Parasite can not make anaerobic energy and dies

Question 5

Praziquantel

Answer 5

Anthelmintic
Characteristics:
- Works on Flukes and Onchocerciasis

MOA:
- Binds consensus protein kinase C in beta-subunit of the flukes voltage-gated calcium channel
–> Induces Ca2+ influx causing prolonged contraction, paralysis, and eventually death

AE:
- Dizziness
- Abdominal Distress

Question 6

Piperazine

Answer 6

Anthelmintic
Characteristics:
- Targets roundworm and threadworm

MOA:
- GABA receptor agonist leading to nerve ending hyperpolarization
–> Induces paralysis of worms allowing for intestinal lumen to eliminate the worm alive

AE:
- Urticaria
- Seizures (Especially young children)

PK:
- Single dose for ringworm
- 7 days course for threadworm

Question 7

Pyrvinium

Answer 7

Anthelmintic
Characteristics:
- Pinworms only

MOA:
- Impairs glucose uptake
- Inhibition of mitochondrial complex 1

PK:
- Single dose repeated for 2-3 weeks

Question 8

Diethylcarbamazine

Answer 8

Anthelmintic
Characteristics:
- Derivative of Piperazine
- Used for elephantiasis

MOA:
- Alters helminth surface membrane such that it becomes susceptible to host’s immune system
- Interfering with helminth arachidonate metabolism

AE:
- Allergic side effects related to products of dying filariae

PK:
- Single dose for roundworm
- 7-day course for threadworm

Question 9

Niclosamide

Answer 9

Anthelmintic
Characteristics:
- Works for tapeworms
- No activity for roundworms, pinworms, hookworms

MOA:
- Uncouples oxidative phosphorylation by reducing potential of inner mitochondria membrane
–> Inhibits ATP production
- For T. solium give a purgative to release any ova from tapeworm segments

AE:
- Pruritus

Question 10

Levamisole

Answer 10

Anthelmintic
Characteristics:
- Targets Roundworm

MOA:
- Nicotinic acetylcholine receptor agonist that blocks neuromuscular junction causing paralysis
–> Worms expelled in feces

AE:
- Agranulocytosis
- Not used anymore

Question 11

Ivermectin

Answer 11

Anthelmintic
Characteristics:
- First line for filarial infection
- Treats onchocerciasis
- Targets roundworms, but, not hookworms

MOA:
- Binds to and opens glutamate gated chloride channels
- Binds GABA receptors
- Binds allosteric sites on acetylcholine nicotinic receptor
–> Increased transmission resulting in muscle paralysis

AE:
- Skin rash/itching
- Post-treatment encephalopathy