Anthelmintics are drugs that either kill (vermicide) or expel (vermifuge) infesting helminths. Helminthiasis is prevalent globally , but is more common in developing countries with poorer personal and environmental hygiene. Multiple infestations in the same individual are not infrequent. In the human body, g.i.t. is the abode of many helminths, but some also live in tissues, or their larvae migrate into tissues. They harm the host by depriving him of food, causing blood loss, injury to organs, intestinal or lymphatic obstruction and by secreting toxins. Helminthiasis is rarely fatal, but is a major cause of ill health. The choice of drug for each worm infestation is based not only on efficacy, but also on lack of side effects/toxicity, ease of administration (preferably single dose) and low cost. Development of resistance has not been a problem in the clinical use of anthelmintics.

1. Anthelmintic Drugs
Vinay Gupta
Dept. of Pharmacology
Uttar Pradesh University of Medical
Sciences
Saifai, Eatwah, India

2. Helmintic infections
 Human is the primary host for most
helminthic infections.
 Most worms produce eggs and larva
 These pass out of human body and
infect secondary host
 Immature forms invade humans via
skin or GIT
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3. Types of worms
HELMINTHS
Nemathelminths
(ROUND WORMS)
NEMATODES
Platyhelminths
(FLAT WORMS)
Trematodes
(FLUKES)
Cestodes
(TAPE WORM)
Segmented
Separate Sex
Un segmented
Un segmented
Separate Sex
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Hermaphroditic

4. NEMATODES -
 Round Worms –Ascaris lumbricoides
 Hook Worms – Necator americanus OR
Ancylostoma duodenale
 Thread Worms –Strongyloides stercoralis
 Pin Worms – Enterobius vermicularis
 Whip Worms – Trichuris trichiura
 Guinea Worms –Dracunculus medinensis
 Filarias - Wuchereria bancrofti
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RA HN TS PE WT GD FW

5. Ascaris lumbricoides (Round Worm)
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6. Necator americanus (Hook Worm)
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7. Trichuris trichiura (Whip Worm)
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8. Strongyloides stercoralis (Thread
Worm)
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9. Enterobius vermicularis (Pin Worm)
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10. Dracunculus medinensis (Guinea)
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11. Wuchereria bancrofti (Filarias)
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12. TREMATODES -
 Blood Flukes – Schistosomiasis/Bilharziasis
 Liver Flukes – Clonorchiasis
 Intestinal Flukes – Fasciolopsiasis
 Lung Flukes - Paragonimiasisi
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13. Schistosomiasis (Blood Flukes)
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14. Clonorchiasis (Liver Flukes)
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15. Fasciolopsiasis (Intestinal Flukes)
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16. Paragonimiasisi (Lung Flukes)
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17. CESTODES -
 Beef Tapeworm – Taenia saginata
 Pork Tapeworm – Taenia solium
 Fish Tapeworm – Diphyllobothrium latum
 Dwarf Tapeworm – Hymenolepis nana
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18. Taenia saginata (Beef Tapeworm)
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19. Taenia solium (Pork Tapeworm )
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20. Diphyllobothrium latum (Fish Tapeworm)
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21. Hymenolepis nana (Dwarf Tapeworm)
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22. ANTHELMINTIC DRUGS
 BENZIMIDAZOLE
 LEVAMISOLE & TRTRAMISOLE
 PIPRAZINE
 PYRANTEL PAMOATE
 IVERMECTIN
 BEPHENIUM
 DIETHYLCARBAMAZINE (DEC)
 PRAZIQUANTEL
 NICLOSAMIDEFeb 13, 2018 22

23. Anthelmintics Drugs MOA-
 Inhibition of Microtubule Polymerization & Blockage of
Glucose uptake – BENZIMIDAZOLES (M)
 Inhibition of Carbohydrate metabolism & Tonic
Paralysis- LIVAMISOLE & TETRAMISOLE (N)
 By Flaccid Paralysis – PIPRAZINE (CL)
 By Spastic Paralysis – PYRANTEL PAMOATE
 By Tonic Paralysis - IVERMECTIN (CL)
 By Muscle Contracture – BEPHENIUM
 By blocking Arachidonic acid metabolism – DEC (E)
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N M C - E

24. BENZIMIDAZOLES
 MOA –
 Act by combining with β – tubulin & inhibit
microtubule polymerization.
 In case of sensitive Nematodes they inhibit Glucose
Transport.
 ALBENDAZOLE
 THIABENDAZOLE
 TRICLABENDAZOLE
 MEBENDAZOLE
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BROAD
SPECTRUM

25. ALBENDAZOLE
 Broad spectrum
 Its drug of choice for NCC & all Nematodes .
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26. Pharmacokinetics
 Used on empty stomach when used against
intraluminal parasites.
 Used with a fatty meal when used against tissue
parasites.
 Plasma half life 8-12 hours
 Metabolized in the liver to the active metabolite
albendazole sulfoxide
 sulfoxide is mostly protein bound distributes well to
tissues and enters bile, CSF & hydatid cysts.
 Metabolites are excreted in urineFeb 13, 2018 26

27. Albendazole -Therapeutic uses
 In severe cases – 3 days regimen
 Trichinella spiralis – 400 mg OD for 3 days
 NCC – 400 mg BD for 3 days to max period of 4 weeks
 Hydatid disease (Echinococcus granulosus)- 400 mg BD
for 4 weeks.
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Round worm
Hook Worm
Thread Worm
Whip Worm
400 mg
Single dose

28. Albendazole (con’)
 Used as Adjuvant-
 Other infections: Drug of choice in cutaneous
and visceral larva migrans ,
 intestinal capillariasis
 Lymphatic filariasis
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29. Albendazole - Adverse Effects
 In short term(1-3 days): No significant adverse
effects
 In long term use : Nausea, Diarrhoea, abdominal
pain, headache ,fever ,fatigue, alopecia.
 Rarely Hepatotoxicity – Reversible.
 Avoided in patients with Cirrhosis of Liver.
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NO to
Pregnancy
Neonates <2 yrs

30. MEBENDAZOLE
 Synthetic benzimidazole
 Wide spectrum and safer than albendazole
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31. Mebendazole - Pharmacokinetics
 Oral bioavailability - Poor
 Less than 10% of orally administered drug is
absorbed d/t hepatic First pass metabolism.
 Absorption increases with fatty meal.
 90-95 % plasma protein bound
 Half- life of 2-6 hours
 Excreted in urine .
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32. Mebendazole - Therapeutic Uses
 Trichuriasis – more effective than A.zole
 Guinea, Round, Whip, Thread & Hook worm
 in adults and children over 2 years cure rate is
90-100 % except hookworm it is less.
 DOSE –
 100 mg BD for 3 consecutive days OR
 500 mg as single dose
 Repeated after 21 days if no cure occurs.
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33. Mebendazole - Therapeutic Uses
 Its an alternative drug for Trichinosis (200mg
TDS for 3 days then 400 mg TDS for next 10
days).
 For Intestinal capillariasis – 200 mg BD for 21
Days.
 For Visceral larva migrans – 100 mg TDS for 5
days.
 Beef tapeworm (Taenia saginata) – 200 mg BD
for 4 Days
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34. Adverse Effects & Precautions
 Short term therapy- Mild GI disturbance.
 High dose : hypersensitivity reactions, alopecia
elevation of liver enzymes .
 Used with caution under 2ys of age may cause
convulsion.
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NO to
•Pregnancy
•Neonates <2 yrs
•Liver Cirrhosis

35. Thiabendazole
 Chelating agent and form stable complexes with metals
including iron, but not with calcium.
 Rapidly absorbed
 Half- life of 1-2 hrs
 Completely metabolized in liver and 90% is excreted in
urine.
 Should be given after meals .and tablets should be chewed
 Can also absorbed through skin.
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36. Clinical uses
 Strongyloidal infections.
 In cutaneous larva migrans .Thiabendazole cream
is applied topically or drug can be given orally for
2 days.
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37. Adverse Effects & Contraindications
 More toxic than other benzamidazoles
 GI disturbances
 Pruritus ,headache, drowsiness , psychoneurotic
symptoms.
 Irreversible liver failure.
 Fatal Stevens –Johnson syndrome
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NO to
•Pregnancy
•Young Childs
•Hepatic disease
•Renal Disease

38. TRICLABENDAZOLE
 Narrow spectrum.
 used primarily in Veterinary.
 reported recently as Drug of choice for human
facioliasis (10mg/kg) – repeated after a week.
 also reported to be efficacious for Lung Fluke
with a dose of 10 mg/kg for 3 days.
 The drug is well tolerated & no significant S/E
have been reported.
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39. PRAZIQUANTEL
 Synthetic Isoquinolone- pyrazine derivative.
 Causes influx of Ca2+
- results in intense
contraction & expulsion of worms from GIT.
 PK-
 Readily absorbed Orally (80%)
 First pass metabolism in Liver – converted in
to inactivated hydroxylated metabolites.
 Plasma C/n Increases with high Carbohydrate
diet.
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40. PRAZIQUANTEL...Therapeutic uses
 Blood Flukes (Schistosomiasis)- both M/F.
 Dose: 20 mg/kg BD/TDS - Orally
 For other Flukes –
 Dose: 75 mg/kg OD/BD for 1-2 days – Orally
 Also effective for Cestodes (Tape Worm) like –
 T. solium, T. saginata – Dose: 10mg/kg - am
 NCC – 50mg/kg in 3 divided dose for 15 days.
 Corticosteroids reduces bioavailability.
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41. PRAZIQUANTEL... S/E
 N, V, D, Dizzziness, Drowsiness, Urticaria with
Eosinophilia (d/t release of proteins from dying
worms)
 C/I in Pregnancy, Children below 5 yrs.
 C/I in Ocular Cysticercosis
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No to
•Pregnancy
•Child < 5
•Ocular CC

42. PYRANTEL PAMOATE
Broad spectrum
Pharmacokinetics:
 Poorly absorbed orally thus produces selective
effect on Intestinal worms.
 Major of the drug is excreted unchanged in the
feces.
 Minor of the drug is excreted unchanged in the
urine.
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43. PYRANTEL PAMOATE...
Mechanism of action:
 Neuromuscular blocking drug leads to paralyses of
worms (Spastic Paralysis).
Effective
 against luminal organisms( mature or immature
forms).
 Not effective against migratory stages in the tissues
or against ova
Feb 13, 2018 43

44. Therapeutic uses & S/E
Used as alternative of M.zole for treatment of-
Ascariasis – 11mg/kg – single dose
Hook worm (Ankylostomiasis) – 11mg/kg for 3 days
Treatment may be repeated after 3 weeks if required for
Hook worm.
Not effective against Trichuriasis.
 Its preferred over Benzimidazoles d/t lack of toxicity.
S/E are mild & transient – N, V, D, Anorexia, fever etc.
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NO to
•Pregnancy
•Neonates <2 yrs

45. PIPERAZINE
 Only recommended for the treatment of
Ascariasis & Pin Worm - cure rate 90% with 2
days treatment.
 Not used for other helminth infestations.
 Readily absorbed orally and excreted mostly
unchanged in urine
 Mechanism of action: (Flaccid Paralysis)
 Causes paralysis of ascaris by blocking
acetylcholine at myoneural junction , the live
worms expelled by normal peristalsis.
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46. PIPERAZINE...
 DOSE –
 5 gm hs, followed by a purgative in next morning.
 For Pin worm – 2gm/day for 7 days- both for Adult *
kids > 12 yrs.
 Kids < 2 yrs – 50mg/ kg/ day
 Kids 2-4 yrs – 750mg/ day
 Kids 5-12 yrs – 1.5 g/ day
 Treatment repeated after 2-3 week in case of heavy
infections.
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47. Adverse Effects
 Mild – N, V, D, GI disturbance
 Neurotoxicity , allergic reactions .
Contraindications
 Epilepsy
 Impaired liver or kidney functions
 pregnancy
Feb 13, 2018 47
No to
•Pregnancy
•Epilepsy

48. NICLOSAMIDE
 Second-line drug for treatment of Cestodes - tape worm
infections.
 The drug is not an ovicidal.
 D/t availability of better drugs like Benzimidazole &
Praziquantel, the use at present is declined.
Mechanism of action:
 Adult worm is rapidly killed by inhibition of oxidative
phosphorylation .
Pharmacokinetics:
 Poorly absorbed from gut & excreted in urine.
Feb 13, 2018 48

49. Clinical Uses & S/E
 Treatment of most forms of tapeworms.
 Not effective against NCC or hydatic disease.
 Given in the morning on empty stomach.
 Purgative is necessary to purge all dead segments& prevent
liberation of ova.
 DOSE – 2g OD / Orally
 Mild ,infrequent and transitory GI disturbance.
Feb 13, 2018 49
NO to
•Pregnancy
•Neonates <2 yrs

50. DIETHYL CARBAMAZINE
 Drug of choice for the treatment of filariasis and tropical
eosinophilia.
Pharmacokinetics:
 Rapidly absorbed from gut
 Half- life is 2-3 hours
 The drug should be given after meals
 It is excreted in urine as unchanged or metabolite.
 Dosage is reduced in urinary alkalosis and renal impairment.
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51. Mechanism of Action
 Immobilizes microfilariae and alters their
surface structure ,displacing them from
tissues & making them susceptible to
destruction by host defense mechanism
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52. Adverse Effects
 Fever , malaise, papular rash, headache, GI
disturbance,cough. Chest,muscle,joint pain
 Leucocytosis
 Retinal hemorrhage
 Encephalopathy
 lymphangitis and lymphadenopathy.
 *It is not teratogenic
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53. Contraindications & Cautions
 *Hypertension
 * Renal disease
*patient with lymphangitis
Patients suspected of malaria
Feb 13, 2018 53

54. IVERMECTIN
 Drug of choice for treatment of filaria &
strongyloidiasis (Round worm)
 It is a macrocyclic lactone ring
 Given only orally
 Rapidly absorbed
 Does not cross BBB.
 Half- life is 16 hrs
 Excretion in urine & feces.
Feb 13, 2018 54

55. Mechanism of Action
 Paralyze nematodes by intensifying
GABA- mediated transmission of
signals in peripheral nerves.
 Tonic paralysis.
Feb 13, 2018 55

56. Clinical uses
 Drug of choice for cutaneous larva
migrans & strongyloidiasis.
 Onchocerciasis
 It is also used for scabies , lice .
 Filariasis ( it is microfilaricidal ).
Feb 13, 2018 56

57. Adverse Effects
 Fatigue ,dizziness, GI disturbance
 Killing of microfilaria result in a Mazotti
reaction ( fever, headache, dizziness,
somnolence, hypotension , tachycardia,
peripheral edema……).
 Corneal opacities & other eye lesions.
Feb 13, 2018 57

58. Contraindications & Cautions
 Concomitant use with other drugs that enhance
GABA
e.g Barbiturates, bnzodiazepines, valproic acid.
 pregnancy
 Meningitis
 Children under 5 years of age.
Feb 13, 2018 58

59. BITHIONOL
 Drug of choice for the treatment of fascioliasis
( sheep liver fluke)
 Pharmacokinetics:
 It is orally administered and excreted in urine.
Feb 13, 2018 59

60. Adverse Effects
 GI disturbance, Dizziness, headache, Skin rashes ,
urticaria, Leucopenia.
 Contraindications and precautions:
 Hepatitis , leucopenia
 Used with caution in children under 8 years of age.
Feb 13, 2018 60

61. Feb 13, 2018 61

62. LIFE CYCLES OF HELMINTHS
Feb 13, 2018 62

63. Intestinal nematodesIntestinal nematodesIntestinal nematodesIntestinal nematodes
Larvae pass
through lungs
Larvae penetrate
through intact skin
strongyloides
hookworm
Eggs ingested
trichiuris
enterobius
Larvae enter
bloodstream
ascaris
Adult worms in the
the intestine
Eggs
Larvae hatch
from eggs
Feb 13, 2018 63

64. Strongyloides life cycleStrongyloides life cycle
Adult worms in the
the intestine
Eggs
1st stage
larvae hatch
from eggs
Larvae penetrate
through intact skin
Larvae enter
bloodstream
Larvae pass
through lungs
Larvae molt
twice to form
filariform larvae
(infectious)
Autoinfection
Feb 13, 2018 64

65. Generalized life cycle of
intestinal nematodes.
Feb 13, 2018 65

66. Feb 13, 2018 66

67. The life cycle of blood fluke, Schistosoma japonicum. This organism causes
chistosomiasis. Unlikesome flukes, S. japonicum does not have a redia stage, nor does it enter
an arthropod host.
Feb 13, 2018 67

68. Feb 13, 2018 68

69. Cystic Hydatid Disease
contact
with
dogs
ingestion of
entrails
ingestion of
eggs in
pasturesEchinococcosis
Feb 13, 2018 69

70. Feb 13, 2018 70

71.  Generalized
life cycle of
tapeworms
Feb 13, 2018 71

72.  Image showing life cycle inside and
outside of the human body of one
fairly typical and well described
helminth: Ascaris lumbricoidesFeb 13, 2018 72

73. Thanks...
Feb 13, 2018 73