Anti helminthics

1. Anti-Helminthics
-Dr. Rahul Kumar Bhati

2. Classification of Helminths
• Nematodes (worms)- intestinal/blood/tissues
• Trematodes (flukes)
• Cestodes (tapeworms)

3. Broad spectrum anti-helmintic
• Benzimidazole: thiabendezole, mebendazole,
albendazole, triclabendazole
• Inhibits β tubulin polymerization
microtubule breakdownmetabolic pathways
disruptionparasitic death

4. Mebendazole
• A synthetic benzimidazole that has a wide spectrum
of anthelmintic activity and a low incidence of
adverse effects.
• Pharmacokinetics
– Oral absorption ＜10％
– First pass elimination is high.
– Protein-binding ＞90％
– Excreted mostly in the urine, a portion of absored drug
and its derivatives are excreted in the bile.
– Absorption is increased if the drug is ingested with a fatty
meal.

5. • Pharmacologic Effects
– Inhibits microtubule synthesis in nematodes, thus
irreversibly impairing glucose uptake. Intestinal parasites
are immobilized or die slowly.
– Kills hookworm, ascaris, and trichuris eggs.
• Clinical Uses:
– Pinworm infection
100 mg single dose repeated after 2 weeks
– Ascaris lumbricoides, Trichuris trichiura, Hookworm
100 mg BD for 3 days
– Other infections: intestinal capillariasis, trichinosis,
taeniasis, strongyloidiasis

6. • Adverse Effects and Cautions
– Low-dose: nearly free of adverse effects.
– Diarrhea, abdominal pain is infrequent.
– High-dose: pruritus, rash, eosinophilia, reversible
neutropenia, musculoskeletal pain, fever, transient
liver function abnormalities, alopecia,
glomerulonephritis, agranulocytosis, teratogenic.

7. Albendazole
• A benzimidazole carbamate
• A broad-spectrum oral anthelmintic for
treatment of hydatid disease and cysticercosis,
pinworm infection, ascariasis, trichuriasis,
strongyloidiasis, and infections with both
hookworm species.
• 400mg single oral dose; 3 days(for heavy
infestations); BD for 28 days(for visceral larva
migrans)

8. • Clinical Uses
– Administered on an empty stomach when used
against intraluminal parasites but with a fatty
meal when used against tissue parasites.
1. Ascariasis, Trichuriasis, and Hookworm and
Pinworm infections.
2. Strongyloidiasis
3. Hydatid Disease(with praziquental)
4. Neurocysticercosis (with steroids)
5. Other infections: cutaneous & visceral larva
migrans, gnathostomiasis

9. Anti-filariasis Drugs
– Wuchereria bancrofti, Brugia malayi, loa loa
– Parasitize in lymphatic system.
• DEC: Diethylcarbamazine
A synthetic piperazine derivative.
Rapidly absorbed from the gastrointestinal tract;
excreted rapidly in the presence of acidic urine.
• Pharmacologic Effects and Mechanisms
– Immobilizes microfilariae (which results in their
displacement in tissues) and alters their surface
structure, making them more susceptible to
destruction by host defense mechanisms.
– Adult parasites are killed more slowly.

10. • Clinical Uses
– The drug should be taken after meals
– Combined with albendazole for synergism.
1. Wuchereria bancrofti, Brugia malayi, Brugia timori, and
Loa loa
2. Tropical Eosinophilia
• Adverse Reactions
– Drug-induced Reactions: mild and transient, headache,
malaise, anorexia, nausea
– Reactions induced by Dying Parasites: release of foreign
proteins. Eosinophilia and leukocytosis. Papular rash,
muscle or joint pains.

11. Ivermectin
• Act on nematode specific glutamate gated
chloride channel (inhibitory)
• Broad spectrum;
• DOC for onchocerciasis as it reduces the
microfilarial load without the toxicity seen with
DEC
• Also very useful in strongyloides(thread worm);
cutaneous larva migrans; pediculosis
• S/E: fever, pruritis, arthralgia, edema,
lymphadenopathy

12. Levamisole
• A synthetic imidazothiazole derivative and the L
isomer of D,L-tetramisole
• Highly effective in eradicating ascaris and
moderately effective against both species of
hookworm.
• NN agonist- depolarizing N-M junction
block→paralysis-affected helmints unable to
maintain their attachment to intestinal lumen-
expelled in feces
• Immunomodulating effect; vitiligo, mouth ulcer;
anticancer

13. Piperazine
• Treatment of ascariasis
• No longer recommended for treatment of pinworm
infection, because a 7-day course of treatment is
required.
• GABA agonist at the myoneural junction-Causes
paralysis of ascaris-due to chloride dependent
hyperpolarisation-paralysed worms are expelled alive
• Neurotoxic adverse effects; teratogenic

14. Pyrantel
• A tetrahydropyrimidine derivative.
• A broad-spectrum anthelmintic
• Highly effective for the treatment of pinworm,
ascaris, and Trichostrongylus orientalis infections.
• Moderately effective against both species of
hookworm but less so against N. americanus.
• Not effective in trichuriasis or strongyloidiasis.
• Oxantel, an analog of pyrantel, is effective against
trichuriasis; the two drugs have been combined for
their broad-spectrum anthelmintic activity.

15. • Effective against mature and immature forms of
helminths within the intestinal tract but not against
migratory stages in the tissues or against ova.
• NN receptor agonist and also causes inhibition of
acetylcholinesterase-a depolarizing neuromuscular
blocking agent → paralysis-expulsion
• Used with caution in patients with liver dysfunction.
• No combination with piperazine because of
antagonistic action.

16. Anti flukes
• Praziquental:
• Metrifonate: Organophosphorus compound;
depolarisimg block of bloodfluke
• Oxamniquine: block nucleic acid & protein
synthesis
• Bithionol: uncouples oxidative
phosphorylation

17. Praziquantel
• A synthetic isoquinoline-pyrazine derivative.
• Pharmacological Effects
– Effective in the treatment of schistosome infections of all
species and most other trematode and cestode infections,
including cysticercosis.
– Against adult worms and immature stages.
• Mechanisms
– Increases cell membrane permeability to calcium →
vacuolization, marked contraction, paralysis, dislodgement,
death.

18. • Clinical Uses
– Schistosomiasis
– Clonorchiasis and Opisthorchiasis
– Paragonimiasis
– Taeniasis and Diphyllobothriasis
– Neurocysticercosis (not ocular cysticercosis)
– Hydatid disease
– Other parasites: fasciolopsiasis, metagonimiasis,
heterophyiasis

19. • Adverse Reactions
– Mild and trainsient.
– Headache, dizziness, drowsiness, lassitude
– low-grade fever, pruritus, and skin rashes
(macular and urticarial)—due to the release of
foreign protein from dying worms.

20. Anti cestodes
• Niclosamide: A salicylamide derivative
• Treatment of most tapeworm infection.
• Pharmacologic Effects
– Not absorbed in git--Scoleces and segments of
cestodes—but not ova — are rapidly killed on
contact with nicolsamide due to the drug’s
inhibition of oxidative phosphorylation or to its
ATPase-stimulating property.
– With the death of the parasite, digestion of
scoleces and segments begins.
– Disulfiram reaction

21. • Clinical Uses
– Given in the morning on an empty stomach.
– The tablets must be chewed thoroughly and are then
swallowed with water.
Niclosamide can be used as an alternative drug for the
treatment of intestinal fluke infections.
• Adverse Effects and Cautions
– Infrequent, mild and transitory.
– Nausea, vomiting, diarrhea, and abdominal discomfort.

24. • Worms: Albendazole
– Strongyloide, Onchocerca: Ivermectin
– Filarial: DEC
– Pin-worm: Mebendazole
– Dracanculosis: metronidazole
• Flukes/Cestodes: Praziquental
– Liver fluke: bithionol
– Cysticercosis/Hydatid: Albendazole

25. Thank you..