Anthelminthic Drugs

1. Anthelminthic Drugs

2. • Anthelmintics:-
• Drug use to eradicate or reduce the numbers of helminthic parasites in the
intestinal tract or tissues of the body
• 3 major groups of helminths infecting humans
1. Nematodes (Round: hook, whip, thread, Pin, Filaria, guinea worms)
• Round worm-Ascaris lumbricoides
• Hook worm- Ancylostoma duodenale
• Whipworm- Trichuris trichiura
• Pinworm- Enterobius vermicularis
• Symptoms: nausea, abdominal pain and cough.
• Live worms are passed through stool or vomit.
• Transmission→ through the fecal – oral route, or by fingers contaminated by soil
seeded with the eggs of the round worm.

3. 2. Trematodes or Flat worms (Flukes: blood, lungs, GIT )
 Blood Flukes- schistosomia haematobium
 Biliary Flukes (Hepatic)-Clonorchis sinensis
 Intestinal Flukes
 Lung Flukes- Paragonimus westermani
• 3. Cestodes (Tape: beef, pork, fish, dwarf worm)
• Cestodes have a flat, segmented body and they attach to the host’s intestine.
• lack a mouth & digestive tract
• Infestation by tapeworms or cestodes is transmitted by ingestion of infected beef
or pork.
• Tenia solium-Pork tapeworm

4. • Tenia saginata- beef tapeworm
• Diphyllobothrium latum-Fish tapeworm
• So proper cooking required
• Vermicides→ Drug that kill worms
• Vermifuges→ Drug that expel the worms
• They are of huge importance for human tropical medicine & veterinary medicine
• Ideal anthelmintic drugs:-
• Broad spectrum of action
• Achieve a high percentage of cure with a single dose.
• Not get absorbed
• Free from toxic effects
• Palatable and cheap

5. ANTHELMINTIC DRUGS
For
Round worm,
Hookworm,
Pin worm
Albendazole
Mebendazole
Pyrantel
Pamoate
Piperazine
Levamisole
For
Threadworm
Ivermectin
Albendazole
For Whipworm,
Trichinella spiralis
Albendazole
Mebendazole
For Filariasis
 Diethylcarbamazine
 Ivermectin
 Albendazole
 Praziquantel
 Niclosamide
 Albendazole
For Tapeworms
 Albendazole
 Mebendazole
For Hydatid Disease

6. Drugs includes:-
•Mebendazole
•Albendazole
•Niclosamide
•Ivermectin
•Pyrantel pamoate
•Levamisole
•Praziquantel
•Piperazine
•Diethylcarbamazine citrate(DEC)

7. Mebendazole:-
• A broad spectrum Anthelmintic
• It is poorly absorbed when given orally
• MOA:-It acts by binding to β-tubulin and interfering with the synthesis of the
parasite’s microtubules
• Also inhibit glucose transport into the parasite
• Result→ intestinal parasites are immobilized/die slowly
• Affected parasites are expelled with faces.
• It is relatively free of toxic effects.
• Pharmacokinetics:-
• Absorption-poorly absorbed from GI tract
• Distribution-highly bound to plasma protein
• Metabolism-liver

8. • Excretion-faeces
• A/E:- Anorexia, nausea, vomiting, fever,
• Contraindication:- Pregnancy, because of its Embryotoxic and Teratogenic
effects.
• Below 1year
• USES:- DOC for intestinal nematodes-round worm, hookworm, whipworm, pin
worm
• Dose:-100mg BD for 3 days
• Albendazole:-
• It is effective against many common intestinal worms in a single dose.
• The drug is well tolerated
• Mechanism of action similar to Mebendazole
• Broad spectrum anthelmintic activity
• Pharmacokinetics:-Fatty food→↑absorption

9. • Produce metabolic product → Albendazole sulphoxide
Hydatid cyst hence preferred in the treatment of hydatid disease
• A/E:-Rare Adverse effect (well tolerated) Nausea, vomiting
• USES:-
• Nematodes- Round worm(Ascaris l) ,hook worm (Ancylostoma D)
• Neurocysticercosis-DOC
• Advantages:-
Cheaper
Duration of treatment is shorter
Reaches high concentration in brain& CSF
Less toxic & better tolerated
• Hydatid disease
• Filariasis-as a adjuvant 400mg with DEC
Widely distributed

10. -:Levamisole:-
• Effective against round-worm & hookworm infestations (Ascaris &
Ancylostoma )
• MOA:-Drug causing spastic paralysis in worms by acting as Agonist on Nn
receptor (stimulation of ganglia)
• Also inhibit carbohydrate metabolism in parasitic worms
• Immunomodulator-↑T-cell number in Hodgkin disease
• In Colorectal cancer:- 5-FU+levamisole
• Adult dose-150mg
• A/E:-headache, dizziness, insomnia, Nausea
-:Niclosamide:-
• Vermicidal drug for all varieties of Taeniasis.
• MOA:- Inhibits oxidative Phosphorylation in the mitochondria of the parasite
• Poorly absorbed from GIT
• Given orally in the form of chewable tablets

11. -:Ivermectin:-
Ivermectin is a Macrocyclic lactone(16 membrane lactones ).
MOA:-
Ivermectin
Binds to glutamate-activated Cl- channels found in
nematode nerve or muscle cells
↑intracellular cl- concentration
causes hyperpolarization by,
resulting in paralysis

12. Pharmacokinetic:-
Absorption:-Well orally
T1/2-57hr.
PPB-high (90%)
Metabolism:-Liver (CYP3A4)
USES:-
Onchocerciasis- DOC
Cutaneous larva migrans:- DOC
Filariasis:-200mg ivermectin + Albendazole400mg
Lymphatic filariasis:-Ivermectin 400mg+ DEC 6mg/kg as single oral dose
every 6-12 month(regimens)
A/E:- Itching, rashes, headache, fever

13. Praziquantel:-
• Effective-Trematodes (Flukes) & Tapeworms & Not effective → Nematodes
• MOA:- Causes Ca2+ influx and spastic paralysis of adult worms
• Absorption:- well orally→↑ with Food (80% BA)
• First pass metabolism
• Adverse effects :-
Anorexia, drowsiness and allergic reactions
• USES:-
• Tapeworm infection-DOC
• Flukes(schistosomiasis)
• Neurocysticercosis-as second choice to Albendazole
• Contraindication:- ocular cysticercosis-blindness

14. Pyrantel pamoate:-
• Depolarizing neuromuscular blocking agent→ by persistent activation of nicotinic
receptors → resulted spastic paralysis in worms
• Also inhibits cholinesterase's
• Highly effective for roundworm, pinworm & hookworm infections
• Given orally but poor absorption
• USE:-
• Treatment of Ascariasis:- alternative to albendazole
• SE:-Rare nausea, vomiting , Diarrhoea, Headache

15. -:Diethylcarbamazine (DEC):-
• Most effective drug used in the treatment of Wuchereria bancrofti (Adult worm
of filariasis)
• MOA:- it damage the microfilarial membrane structure
• Also ↑ cell mediated immunity of human hosts & prevent resistance
• Pharmacokinetics:-
• Absorption:- rapidly via gastrointestinal tract
• Widely distributed in the body & metabolized by liver
• Excretion-urine ↑by Acidic pH
• Safe in pregnancy
• A/E:- Fever, lymphadenopathy, muscular pain, tachycardia and skin rashes,
allergic reactions( Mazzotti reaction)
• Caution:- start therapy with a small dose and then increase it gradually

16. • USES:-
1. Filariasis-DOC
• DEC 6mg/kg + 400mg Albendazole or 400mg Ivermectin (every 6-12 month)
• Dose-orally 100mg TDS for 3 weeks
• Combination therapy (Triple-drug therapy-IDA) → single dose for 3year
• (Ivermectin, Diethylcarbamazine, and Albendazole )→ 95% parasite cleared was
as safe and well tolerated
• ↓Transmission of filariasis
2. Topical pulmonary eosinophilia→ DEC-100mg TDS
3. Subcutaneous & ocular filariasis
4.Dermal filariasis- high dose 8-10mg/kg for 3-6weeks

17. Pharmacotherapy of Neurocysticercosis/Cysticercosis
• Cysticercus → larval form of tape worm
• Occurs larval form migrates from gut to brain through blood
• Larvae converted to cysts & deposited at various site resulted in
• Dermal cysticercosis , Visceral Cysticercosis, ocular & neuro- Cysticercosis
• Symptoms of neuro- Cysticercosis:-
• Convulsion, & other neurological manifestation
• RX:-
1. Anthelmintic drug:- Albendazole (800mg BD for 8-15 days) & Praziquantel
(15-30 days)
Albendazole is preferred over Praziquantel
• Advantages:-
High cure rate & shorter duration treatment

18. 2. Other drugs:-
A. Prednisolone – 40-60mg daily
• Steroid therapy:- start 2 days before the anthelminthic drug & cont. 1-2 week
after
• Advantages:-
Use to prevent exaggerated host inflammatory response to dying parasites
↑Absorption of Albendazole
B. Anti-epileptic Drugs:- Carbamazepine
Precaution:-
↑Dose of Anthelminthic drug due to Enzyme inducer effect of Carbamazepine
Should be given with food (↑Absorption)

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