Anthelmintic Agent.pptx by Mrs. Manjushri P. Dabhade

Anthelmintic
 The parasitic worms (elongated, soft-bodied invertibrates) are
termed as helminths & the condition resulting from infection
with worms is called helminthiasis.
 Almost 350 species of helminths have been found in humans,
and most colonise the gastrointestinal tract (G.I.T).
 Humans are primary host for helminthic infections, in the
sense that they harbour the sexually mature form that
reproduces.
 Mature helminthes lay eggs, that pass out of the body and
develop into larvae in the external environment, typically
aquatic, where they are ready to infect the new host.

 Stages: Egg Larva worm (adult)
 Worms live in hosts alimentary canal, muscles, viscera,
meninges, lungs, liver & subcutaneous tissues.
 Helminthiasis is more common in developing countries.
 They harm the host by depriving him of nutrients,
causing blood loss, injury to organs by secreting toxins.
 Helminthiasis is rarely fatal, but is a major cause of
health issue as Malnutrition, Anemia, protein deficiency,
Elephantiasis (swelling of limbs), Liver damage, blood in
urine.

Sources of infection caused by helminths
(parasitic worms): based on their mode of
transmission
1. Contaminated food and water
2. Direct skin penetration
 Contact of barefoot with contaminated soil or
water
3. Vector-borne Transmission
 Mosquito bites
 Fly/ Bugs bites
4. Person-to-Person Contact
 Hand-to-mouth
 Overcrowded conditions

Classification: based on their morphology
1. Platyhelminthes (Flatworms): Phylum
 Class: Trematoda (Flukes- Leaf-like, unsegmented, few
mm to 8 cm) – Example: Schistosoma
 Class: Cestodes (Tapeworms- Long, ribbon-like,
segmented, 2 mm to 10 m) – Example: Taenia solium
2. Nematoda (Roundworms- 2 mm to 9 m): Phylum
 Intestinal Nematodes:
 Tissue & Blood Nematodes (Filarial Worms): Live in
blood, lymph, skin, or connective tissues

 Anthelmintics are drugs used to destroy or expel
the parasitic worms from the body.
 vermicide (kill)
 vermifuge (expel)

Classification of Anthelmintics based on
worms:
1. Intestinal Nematode Infection
 Benzimidazole derivatives- Thiabendazole,
Mebendazole & Albendazole
2. Cestode Infection (Tapeworm)
 salicylanilide derivative- Niclosamide
3. Trematode Infection (Flukes)
 Quinololine methanol- Oxamniquine
 isoquinoline-pyrazine- Praziquantal
4. Anti-Filarial agents
Piperazine- Diethylcarbamazepine
Natural- Ivermectin

Benzimidazole derivatives
 It is a basic compound with a pka of 4.7 that forms
complexes with metal ions.
 used against nematodes (roundworm- hookworm &
whipworm) cutaneous larva, visceral larva.
Thiabendazole (TBZ)
4-(1H-1,3-Benzodiazol-2-yl)-1,3-thiazole

MOA:
1. It inhibits the helminth-specific mitochondrial
fumarate reductase enzyme.
2. It also arrest nematode cell division in metaphase
by interfering with microtuble assembly (spindal
formation). They exhibit high affinity for tubulin, the
precursor protein for microtubule synthesis.
Fumarate Succinate
Fumarate
reductase
reduction
Anarobic respiration (ETC)

Mebendazole
 Methyl (5-benzoyl-1H-benzimidazol-2-yl)carbamate
 Used against nematodes ( pinworm, whipworm, common
roundworm, common hookworm, American hookworm in single
or mixed infections.
 Adverse Effect: abdominal discomfort.
 It is teratogenic, so should not be given during pregnancy.

MOA:
1. Irreversibly block the glucose uptake in helminths, thereby
depleting glycogen stored in the parasite, leads to energy crisis
& paralysis of the Parasite.
2. It also arrest nematode cell division in metaphase by
interfering with microtuble assembly (spindal formation). They
exhibit high affinity for tubulin, the precursor protein for
microtubule synthesis.

Albendazole
 Methyl [5-(propylthio)-1H-benzoimidazol-2-yl]carbamate
 Used against dog tapeworm, for the treatment of cystic hydatid
disease of the liver, lung, and peritoneum, caused by the larval
form of the dog tapeworm.
 ADR-prolonged use causes headache, jaundice, bone marrow
depression, & neutropenia.
 MOA: same as mebendazole
 It is insoluble in water. The oral absorption of albendazole is
enhanced by a fatty meal.
 The drug undergoes rapid & extensive first-pass metabolism to
the sulforide, which is active form in plasma.

treatment of Cestode Infection
(Tapeworm)

Niclosamide
Used for the treatment of tapeworm (Beef Tapeworm, Pork
Tapeworm, Fish Tapeworm) and intestinal fluke infections:
MOA: oxidative phosphorylation or stimulation of ATPase
activity. Niclosamide may work as a molluscicide by binding to
and damaging DNA.
5-Chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenzamide

treatment of Trematode Infection
(flukes)

Quinoline Methanol Derivative
MOA: Oxamniquine may associate with an irreversible
inhibition of the nucleic acid metabolism of the
parasites.
Oxamniquine
(RS)-1,2,3,4-Tetrahydro-2-isopropylaminomethyl-7-nitro-6-quinolylmethanol

MOA: Praziquantel works by causing severe spasms and
paralysis of the worms' muscles. This paralysis is
accompanied - and probably caused - by a rapid Ca 2+
influx inside the schistosome. Morphological alterations are
another early effect of praziquantel.
Praziquantel
(RS)-2-(Cyclohexylcarbonyl)-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-
one

Piperazine derivative
Diethylcarbamazine
N,N-diethyl-4-methylpiperazine-1-carboxamide
Used to treat filarial infections like bancroft’s, onchocerciasis,
laviasis.
MOA: diethylcarbamazine is thought to block the response of
the ascaris muscle to acetylcholine, leads to paralysis in the
worm which dislodged from the intestinal wall and expelled out
in the faeces.

Ivermectin
 It is a class of highly-active broad-spectrum semi-
synthetic antiparasitic medication isolated from the
fermentation products of Streptomyces avermitilis.

Used in the treatment of onchocerciasis (river blindness), but
may also be effective against other worm as hookworm,
whipworm.
MOA:
 Destroy the microfilariae immature form of nematode)
 Inhibit the release of microfilariae by the adult worms
 It blocks interneuron-motor neuron transmission by
stimulating the release of the inhibitory neurotransmitter
GABA.

Anthelmintic Agent.pptx by Mrs. Manjushri P. Dabhade

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Anthelmintic Agent.pptx by Mrs. Manjushri P. Dabhade