Anthelmintic Drugs

1. Anthelmintics
Prepared by,
Mr. Namdeo Shinde
M. Pharm
SATARA COLLEG OF PHARMACY, SATARA
.(Maharashtra) India-415004

2. Anthelmintics. (Anti = against, helminthes = worms)
Vermicides : Drugs that kill worms
Vermifuges :Drugs that expel the worms from the body by
1)
Peristaltic movement of intestine, or
2) Cathartic and purgative action.
Characters of ideal anthelmintics:
1) Orally active.
2) Effective in single dose.
3) Inexpensive.
4) Wide safety margin between toxicity to worm and toxicity to

3. :Classification of Helminthes
Phylum: Nemathelminthes. Class: Nematodes (true round worms)
I) Intestinal Nematodes: 1) Round worms as Ascaris. 2) Hookworms as
Ancylostoma. 3) Pinworms as Oxyuris. 4) Whipworms as Trichuris.
5) Thread worms as Strongyloids. 6) Enterobius Vermicularis.
II) Tissue Nematodes:Filaria.
Phylum: Platyhelminthes ( flatworms)
Class: Termatodes ( Flukes )
1) Liver flukes:
.2) Blood flukes:
3) Intestinal flukes:
Fasciola Hepatica.
Fasciola Gigantica
Schistosoma haematobium.
Heterophyes heterophyes.
Class: Cestodes ( Tapeworms )
Beef tapeworm:Taenia saginata.
Pork tapeworm:Taenia solium.
Dwarf tapeworm:Hymenolepis nana.
Schistosoma mansoni.

4. A] Drugs active on Nematodes:
I] Chlorinated compounds: CCl4 , tetrachloroethylene.
II] Piperazine derivatives: piperazine citrate,
diethylcarbamazine citrate.
III] Benzimidazole derivatives: Thiabendazole,
Mebendazole, Flubendazole, and Albendazole.
IV] Vinylpyrimidine derivatives: Pyrantel pamoate.
V] Dyes:( cyanine dyes ): Pyrivinium pamoate
VI] Imidazothiazoles: Levimasole.

5. I] Chlorinated compounds: CCl4 , tetrachloroethylene.
CCl4
Must be followed by purgative to remove dead worms and excess drug.
Its side effects are
1) liver necrosis.
2) not used during pregnancy, otherwise make liver and kidney damage to the
fetus
tetrachloroethylene.
MOA: Cause irritation to the worm tissue. Used in Treatment of roundworm
infestations. Less toxic than CCl4, but all halogenated hydrocarbons cause liver
and kidney degeneration
II] Piperazine derivatives:
piperazine citrate, diethylcarbamazine citrate

6. Mode of action:
1) Inhibition of certain enzyme: which is fumarate reductase
system of the worm thereby interfering with an important
energy source.
2) Inhibition of the cell division: inhibit nematode cell division
in the metaphase by interfering with the microtubule
assembly
3) They have high affinity for tubulin, the precursor protein,
necessary for microtubule synthesis.
4) They make irreversible blockade of glucose uptake by
susceptible helminthes, so depletion of glycogen stored
within the parasite leads to decrease in ATP, which is
responsible for survival and reproduction in helminthes.

7. No need for purgative use after oral administration
**all of them have broad spectrum anthelmintic activity
mainly against intestinal nematodes, but,
1) Thiabendazole also used in treatment of cutaneous
larva migrans.
2)Mebendazole , flubendazole and albendazole effective
in some cestode worms.
side effects of mebendazole and albendazole:
 GIT side effects in normal doses.
 Liver impairment, bone marrow depression in high
doses.
 Should not given in pregnancy as teratogenic can cross
the placenta

8. Imidazothiazoles.
Levamisole.
1) act as Depolarizing neuromuscular blocking agent and as above
in pyrantel pamoate.
2) potent stereospecific inhibitor of fumarate reductase in various
nematodes, such inhibition causes contraction in helminthes,
followed by tonic paralysis, subsequent elimination of the worm.
** used for treatment of round worm as Ascariasis, and hook worm
as ancylostomiasis.**
Cmpletely absorbed from the GIT,
The levo isomer is the only active one.

9. Niclosamide.
1)interfere with helminthes metabolism where it inhibits mitochondrial
oxidative phosphorylation, inhibit respiration, block glucose uptake by the
cestode.
2)2)after initial attack of the drug,helminthes ( taenia solium ) become highly
sensitive to the proteolytic enzymes of the host intestine, undergo partial
digestion.
** the drug of choice in treatment of most tapeworm infestations. (cestodes)
such as Taenia saginata, Taenia solium, Hymenolepis nana.
** very important note:
In case of Taenia solium, ( pork tapeworm):laxative should be given within
1-2 hours after drug use to expel the dead worms and to avoid cysticercosis [
as the drug is not active against the larval form (cystcerci)].This cysticerci
results from release of live ova from worm segments damaged by the drug
and migrate to the stomach

10. Niclosamide.
1)interfere with helminthes metabolism where it inhibits mitochondrial
oxidative phosphorylation, inhibit respiration, block glucose uptake by the
cestode.
2)2)after initial attack of the drug,helminthes ( taenia solium ) become highly
sensitive to the proteolytic enzymes of the host intestine, undergo partial
digestion.
** the drug of choice in treatment of most tapeworm infestations. (cestodes)
such as Taenia saginata, Taenia solium, Hymenolepis nana.
** very important note:
In case of Taenia solium, ( pork tapeworm):laxative should be given within
1-2 hours after drug use to expel the dead worms and to avoid cysticercosis [
as the drug is not active against the larval form (cystcerci)].This cysticerci
results from release of live ova from worm segments damaged by the drug
and migrate to the stomach