This document defines anthelmintics as agents used to destroy or eliminate parasitic worms from the gastrointestinal tract. It classifies anthelmintics and discusses several common drugs used as anthelmintics including mebendazole, albendazole, thiabendazole, oxaminiquine, praziquantel, piperazine citrate, diethylcarbamazine citrate, pyrantel pamoate, oxentel, niclosamide, and ivermectin. The document provides details on the chemical structure, mechanism of action, and uses of many of these anthelmintic drugs.

1. ANTHELMINTICS
• DEFINITION
•CLASSIFICATION
•DRUGS
Mr. Naga Prashant Koppuravuri, M.Pharm (Ph.D), FAGE.,
Assistant Professor,
Department of Pharmaceutical Chemistry.

2. DEFINITION
Are the agents which are used to
destroy (or) eliminate parasitic
worms (HELMINTH) from the GIT.
act by killing (or) paralysing the
worms.
So that such worms could be easily
expelled out of gut.

3. REPRODUCTION
 These parasitic worms firmly hold the intestinal mucosa and
continue their reproduction by egg production.
 They harm the host by depriving them of
 Food
 Causing blood loss
 Injury to organs
 Intestinal & lymphatic
obstruction
 Secreting toxins

4. ■ Adult filariae live in the lymphatics,
connective tissue or mesentery of host and
produce live embryos or microfilariae,
which goes to blood stream.
■ They are ingested by mosquitoes or similar
insects, they develop to larvae in
secondary host and pass to mouth parts of
insect and
re-injected to humans

5. TYPES OFWORMS
■ Cestodes (tape worm)
■ Nematodes (round worm)
■ Trematodes (Flukes)

6. Ascaris lumbricoids ( common round worm)

7. filariasis

8. Hookworm

9. Pinworm male ,female

10. Tapeworm

11. whipworm

12. TYPES OF ANTHELMINTICS
■ Depending upon the action, anthelmintics can be categorised
into
■Vermifuges expel the worms
from the body
■Vermicides kill the worms in
the body

13. Chemical Classification
1. Benzimidazoles- mebendazole, albendazole thiabendazole.
2. Quinolines & isoquinolines- oxaminiquine praziquantel.
3. Pierazine derivatives- piperazine, diethylcarbamazine.
4. Vinyl pyrimidines- Pyrantel pamoate, oxantel
5. Amides- Niclosamide
6. Natural products- Ivermectin
7. Organo phosphorous compounds- Metrifonate
8. Imidazolothiazoles-Levimazole
9. Nitro derivatives-Niridazole

16. MEBENDAZOLE
■ Vermox
■ Methyl-5-benzoyl-2-benzimidazolyl carbamate.
■ MOA- It irreversibly blocks glucose uptake in susceptible
helminths, therby depleting glycogen stored in the parasite.
■ It does not affect glucose metabolism in the host.
N
H
N
NH COCH3
O
C

17. USES
■ Effective against
■ Whip worm (Trichuria )
■ Pin worm(Enterobius vermicularis)
■ Hook worm
■ Ascaris lumbricoides

18. SYNTHESIS
C
SCH3
H2N NH
ClCOOCH3
S-methyl thio urea
methyl chloro
formate
C
SCH3
H2N NCOOCH3
NaOH
PH 8
Methyl-s-methyl
thio urea carbamate
STEP 1
STEP 2
O
C
Cl
4-Chloro benzo
phenone
HNO3
O
C
Cl
NO2
NH3
O
C
NH2
H2-Pd-C
NO2
O
C
NH2
NH2
C
SCH3
H2N NCOOCH3
O
C
N
H
N
NHCOOCH3
-NH3
-CH3SH

19. ALBENDAZOLE
■Eskazole, Zentel
■Methyl 5-(propylthio)-2-benzimidazole carbamate
■Widely employed throughout the world for the treatment of intestinal
nematode function.
■Is effective as a single dose treatment for
Ascariasis
Hookworm infections
Trichuriasis
N
H
N
NH COOCH3
S

20. THIABENDAZOLE
 Mintezol
 2[4-thiazolyl]benzimidazole
N
H
N
S
N

21. MECHANISMOF ACTION
 bind with β-tubulin and inhibit microtubule polymerization.
 β-tubulin is the precursor of formation of microtubules.Thereby
arrest in cell division in nematodes.
■Biochemical Changes
■Inhibition of mitochondrial fumerate reductase
■Reduced glucose transport
■Uncoupling of oxidative phosphorylation

22. THIABENDAZOLE (cont)
■It has a broad spectrum anthelmintic activity.
■Used to treat
■Enterobiasis (thread worm)
■Ascariasis (round worm)
■Trichuriasis (whip worm)
■In addition to its use in human medicine, it is
widely employed in vertinary practice to control
helminths.

23. SYNTHESIS
NH2
S
N
C
N
Aniline cyano thiazole
NaOCl
N
H
C
N
Cl
S
N
N
H
N
S
N
NH4OH

24. OXAMNIQUINE
■ Vansil
■ 1,2,3,4-tetrahydro-2-[isopropyl-amino) methyl]-7-nitro-6-
quinoline methanol.
■ It inhibits DNA, RNA & protein synthesis.
■ SAR- OH group is essential for activity.
■ For the treatment of intestinal schistosomiasis.
N
H
O2N
HOH2C
CH2NHCH

25. PRAZIQUANTEL
■ Biltricide
■ 2-(cyclohexyl carbonyl)-1,2,3,6,7,11b-hexahydro-4H-
pyrazino[2,1-a]isoquinolin-4-one.
■ It increases cell membrane permeability of susceptible worms,
resulting in loss of intracellular calcium and loss of extracellular
sodium.
N
N
C
O

26. ■ Massive contractions & ultimate
paralysis of the fluke musculature occurs.
■ The worms lose grip of intestinal mucosa
and are expelled.
■ USE- It has become the agent of choice
for the treatment of infections caused by
fluke infections

27. PIPERAZINE CITRATE
 Artheriticine, Dispermin
 MOA: It blocks the response of the ascaris muscle to acetyl
choline, causing the flaccid paralysis in the worm, which is
dislodged from the intestinal wall and expelled in the feces.
 Highly effective againstAscaris lumbricoides & Enterobius
vermicularis.(Round worm & thread worm)
N
H
H
N

28. SYNTHESIS
HO
NH2
H2N
OH
-2H20
HEAT
HN
NH

29. DIETHYL CARBAZINE
CITRATE
 HETRAZAN
 N,N-diethyl-4-methyl-1-piperazine carboxamide
N
N
H3C
CO N
C2H5
C2H5

30. Mechanism Of Action
■Immobilizes microfilariae and alters their surface structure,displacing them from
tissues & making them susceptible to destruction by host defense mechanism
■ It has immunosuppressive effects
■Filariasis and ascariasis

32. Pyrantel Pamoate Pin-X

34. Oxentel
Oxantel pamoate is an agonist of the acetylcholine receptors in the
muscle of nematodes and causes paralysis.

35. NICLOSAMIDE
■ Cestocide, Mansonil,Yomesan
■ 5-chloro-N-(2-chloro
-4 nitrophenyl)-2-hydroxy
benzamide
■ MOA:The drug inhibits anerobic phosphorylation ofADP
by the mitochondria of the parasite, and interfering with
anerobic generation of ATP by theTape worm.
■ So it inhibits seperation and blocking glucose absorption
by the intestinal nematode function.
OH
Cl
C
O
NH NO2
Cl

36. ■ SAR- For the activity, the OH group of benzoic acid moiety had
to be in 2 nd position.
■ Uses-Agent for choice for the treatment ofTaenia solium and
Taenia saginata.
■ A saline purge 1-2 hr after the ingestion of this drug is
recommended to remove the damaged scolex & worm
infections.
■ Quinacrine can aid for this purpose.

37. IVERMECTIN
O
CH3
O
HO
H
H
OH
O
O
CH3
CH3
H3C
CH3
H3C
H
H
O
H
CH3
O
CH3
O
O
OH
OH3C
CH3
H

38. ■ Are a mixture of 22,23dihydro derivatives of avermectins B1a
&B1b prepared by catalytic reduction.
■ Are members of a family of structurually complex antibiotics
produced by a strain of Sterptomyces avermilitis.
■ The structures of avermectins were established by a
combination of spectroscopic and X-ray crystallographic
techniques to contain pentacyclic aglycone glycosidically linked
at 13 th position to a disaccharide that comprises two
oleandrose sugar residues.
■ MOA- It blocks interneuron transmission in nematodes by
stimulating the release of inhibitory neurotransmitter γ-amino
butyric acid-GABA.
■ Uses- widespread use in veterinary practice in the treatment of
Onchocerciasis caused by Oncocerca volvulus.

39. Levimazole
Metrifonate
Niridazole