Anthelmintic drugs-Seminar .pptx

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Pharmaceutical Seminar I 1
Anthelmintic Drugs
Sandesh Sharma
Pharmacy Program, Gandaki University
Gyankunja, Pokhara-32, Kaski, Nepal
9/17/2022

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Presentation sections
• Introduction
• Types of infectious Agent
• Choice of Anthelmintic drugs (Mebendazole, Albendazole,
Thiabendazole, Pyrantel Pamoate, Nicolasamine, Praziquantel)
• Conclusion
• References
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Introduction
Anthelmintic Drugs= Drugs that either kill or expel helminths
 Vermicidal= kill worm
 Vermifuge= Promotes expulsion of worm
Note: Infection is more common in under developed and developing
countries.
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They harm the host by-
1. Depriving him of food
2. Causing blood loss
3. Injury to organ
4. Intestinal or lymphatic obstruction by secreting toxins.
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Introduction

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Types of infectious Agent
Fig. 1. Roundworm
Ref. URL 2
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Fig. 2. Whipworm
Ref. URL 2

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Fig. 3. Tapeworm
Ref. URL 2
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Fig. 4. Threadworm
Ref. URL 2

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Fig. 5. Filariasis
Ref. URL 2
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Fig. 6. Hydatid tapeworm
Ref. URL 2

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Choice of Anthelmintic drugs
It depends upon:
• Types of infection
• Efficacy
• Side effect/Toxicity
• Dose regimen
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Mebendazole
Mechanism of action
 The site of action of mebendazole appears to
be the micro tubular protein 'B-tubulin' of the
parasite.
 It binds to B-tubulin of susceptible worms
with high affinity and inhibits its
polymerization.
 Decrease glucose uptake, mitochondrial
enzyme and deplete glucogen store
 Hatching of nematode eggs and their larvae
are also inhibited, ascaris ova are killed.
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Fig:MOA of Mebendazole (Ref: URL 3)

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Contd..
Adverse effects
 Diarrhoea, Nausea, headache, Abdominal Pain.
 Incidence of expulsion of Ascaris from nose and mouth have occurred
probably due to starvation of the parasite and their slow death.
 Allergic reactions, loss of hair is reported at high dose.
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Contd..
Uses and administration
 Mebendazole is available as chewable tablets.
 Roundworm, Hookworm, Whipworm: 100 mg BD
for 3 consecutive days.
No fasting, purging or any other preparation of
the patients is needed.
 Pin worm (Thread worm): 100 mg single dose,
repeated after 2-3 wks
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Fig: Menbendazole tab. (Ref: URL 4)

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 Strict hygienic measures are needed simultaneous treatment of all
children.
 Trichinosis: 200 mg BD for 4 days; less effective than Albendazole.
 Hydatid disease : 200-400mg BD or TDS for 3-4wks; less effective than
Albendazole.
 It has also been used for mass treatment, but need for multiple doses
is a drawback.
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Albendazole
Mechanism of action
Inhibits polymerisation of beta tubulin.
Uses
 Ascaris, hookworm, and Trichuris : a single dose of 400
mg.
 Tapeworms and strongyloidosis: 400 mg daily for 3
consecutive days.
 Trichinosis: 3 day treatment.
 Neurocysticercosis - anthelmintic of choice: 400 mg BD for
8-15 days.
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Fig: Albendazole Tab.(Ref : URL 5)

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 Hydatid disease: 400 mg BD for 4 wks, repeat after 2 wks up to 3 courses.
 Absorption of Albendazole enhanced when the drug is taken with fatty
meal.
ADR
 Albendazole is well tolerated; only G.I side effects have been noted.
 Few patients have felt dizziness.
 Prolonged use, as in hydatid or in cysticercosis, has caused headache, fever,
alopecia, jaundice and neutropenia.
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 No preparation or postdrug fasting/ purging is required.
 For intestinal worms it should be given on empty stomach, while for
cysticercosis, hydatid and cutaneous larva migrans it should be given
with a fatty meal.
 It should be given with caution to patients with hepatic or renal
disease.
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Thiabendazole
Mechanism of action
Same
Uses
 Strongyloidosis
 Cutaneous larva migrans
 Trichinosis –intestinal infestation and larva in
muscles.
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Fig: Thiabendazole (Ref: URL 6)

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Pyrantel Pamoate
Mechanism of action
 Pyrantel causes activation of nicotinic
cholinergic receptors in the worms
resulting in persistent depolarization →
slowly developing contracture and spastic
paralysis.
 Worms are then expelled.
 An anticholinesterase action has also been
demonstrated.
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Fig: MOA of Pyrantel pamoate (Ref : URL 7)

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Contd.
ADR
 Occasional g.i.t symptoms , headache and dizziness is reported.
 It is tasteless, non irritant; abnormal migration of worms is not
provoked(raised).
 Its safety in pregnant women and in children below 2 years has not
been established.
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Contd.
Use and administration
 Ascaris : single dose 10mg/kg.
 Strongyloidosis: 3 day course.
 No fasting, purging or other preparation of the patient is needed.
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Nicolasamine
Mechanism of action
 The drug appears to act by inhibiting oxidative phosphorylation
in mitochondria and interfering with anaerobic generation of
ATP by the tapeworm.
 Injured by niclosamide, the tapeworms are partly digested in
the intestine.
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Contd.
Uses
 Taenia saginata, T.solium, and H. nana, as well as pinworm.
ADR
 Malaise, pruritus and light headedness are rare.
 Minor abdominal symptoms are produced occasionally.
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Praziquantel
Mechanism of action
 It is rapidly taken up by susceptible worms and
appears to act by causing leakage of
intracellular calcium from the membranes
→contracture and paralysis.
 The tapeworms lose grip of the intestinal
mucosa and are expelled.
 Flukes and schistosomes are also dislodged in
tissues and veins.
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Fig : MOA of Praziquantel (Ref :URL 8)

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Contd.
Adverse effects
 It tastes bitter: can produce nausea and abdominal pain.
 Headache and dizziness
 When used for schistosomes and visceral flukes, symptoms like
itching, rashes, fever and bodyache occur as a reaction to the
destroyed parasites.
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Contd.
Uses
 Tapeworms
 T. saginata,T.solium, H.nana
 Neurocysticercosis
 Schistosomes( Blood Fluke)
 Other flukes: Fasciola hepatica
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Fig: Praziquantel tab (Ref:URL 9)

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Conclusion
Parasitic nematodes infect almost all forms of life. In the human context,
parasites are one of the major causative factors for physical and
intellectual growth retardation in the developing world.
Therefore, development of new anthelmintics with different modes of
action is critical for sustainable parasitic control in the future.
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References
 Tripathi K.D. (2013). Essentials of Medical Pharmacology, Jaypee
Brothers Medical Publishers.
 URL 1 : https://pubmed.ncbi.nlm.nih.gov/9265850/
 URL 2: https://en.m.wikipedia.org/wiki/List_of_parasites_of_humans
 URL 3: mechanism of albendazole – Bing
 URL 4: Mebendazole - Bing
 URL 5: albendazole 400 mg - Bing images
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References
Contd:
 URL 6: Thiabendazole anthelmintic - Bing images
 URL 7: Pyrantel causes activation of nicotinic cholinergic receptors -
Bing images
 URL 8: Pharmacology Animation Book
 URL 9: praziquantel - Bing images
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