Anthelmintic drugs are an important topic for the undergraduate students.

1. Anthelmintic Drugs
Dr Bikash Meher
Dr Bikash Ranjan Meher
Assistant Professor
AIIMS, Bhubaneswar

2. Case Study
A 34-year-old female, who immigrated to US few years ago, presented
to your clinic, complaining of dizziness and mild seizures that have
been going on for the past 12 years. Her family noticed an increase in
the frequency of her intermittent atypical near-syncopal attacks within
the past two months and decided to seek medical attention. She also
suffers from dyspepsia, nausea with scanty non bilious vomiting.
During the initial conversation with the patient for obtaining her
medical history, the patient started complaining of dizziness, which
eventually led to generalized convulsions that lasted for about one
minute. The patient was urgently transported to a near by hospital in
the emergency department. At the hospital, computed tomography
(CT) of the brain showed multilobulated cystic mass in the
posteromedial left temporal/occipital region with surrounding
oedema. Furthermore, the magnetic resonance imaging (MRI) of the
head without contrast revealed a nodular focus of enhancement within
the multilobulated cystic mass in the brain.

3. Introduction
Individual drugs
M.O.A
Therapeutic Uses
Adverse Effects
Outline of lecture

4. Helminthiasis is infestation with one or more intestinal
parasitic worms(helminth)
Infected people excrete helminth eggs in their faeces, which
then contaminate the soil in areas with inadequate sanitation.
Other people can then be infected by ingesting eggs or larvae
in contaminated food, or through penetration of the skin by
infective larvae in the soil
Lead to chronic illness,malnutrition,anemia
Introduction

5. Helminths
Nematodes Trematodes
Cestodes

7. Prevalence of Worm infestations

8. Drug treatment Health education Improved sanitation

9. Goals of drug therapy
• To control infection1
• To eliminate the parasites2
• To reduce transmission of
infection3

10. Anthelminthic drugs
Benzimidazole
Thiabendazole
Albendazole
Mebendazole
Piperazines
DEC
Piperazine
Heterocyclics
Paziquantel
Oxamiquine
Amide
Niclosamide
Nitroderivatives
Niridazoles
Imidazothiazole
Levamisole

11. Albendazole
Benzimidazoles
Share common mechanism of action
Mebendazole ,Thiabendazole, Triclabendazole

12. Inhibits microtubule polymerization
Inhibits glucose uptake
Uncouple oxidative phosphorylation
Mechanism of action

14. Pharmacokinetics
Variable Oral absorption
Increased with a fatty meal
Metabolized Albendazole sulfoxide
Wide distribution
Elimination T1/2 8-12hrs

15. • 400mg single doseA. duodenale
N. americanus
A. lumbricoides
• 400mg OD for 3 days
T. trichura
• 400mg BD for 1 month
Hydatid disease
• 400mg BD for 4 weeks
Neurocycsticercosis
Clinical Uses

16. Other Uses
Visceral larva migrans( 400mg BD for 30days)
Cutaneous larva migrans( 400mg daily for 3 days)
Microsporidiasis(400mg BD for 2wks)
Intestinal capiliariasis(400mg daily for 10days)
Strongyloidiasis(400mg OD for 3days)
Clonorchis sinensis(400mg BD for 7days)
Lymphatic filariasis

17. Adverse effects
Epigastric distress, Diarrhea, Dizziness, Insomnia
Headache ,Alopecia, Fatigue
↑Aminotransferase enzyme

18. Precaution
No prior preparation, no fasting after the drug and no laxatives
required
Administered on an empty stomach for intra luminal worms
but with fatty meals for tissue parasites
CI
Pregnancy, Children< 2yrs
Drug Interaction
Glucocorticoids and Praziquantel ↑albendazole sulfoxide

19. Points to remember
Albendazole is the drug of choice for neurocysticercosis and
all nematodes EXCEPT
 Trichuriasis
 Strongyloidiasis
 Filariasis
 Dracunculiasis

20. Mebendazole
Synthetic benzimidazole
Wide spectrum
 Mechanism of action
Same as albendazole

21. Pharmacokinetics
Very less oral absorption(10%) but ↑ with fatty meal
90 % protein bound
Converted to inactive metabolites
Half- life of 2-6 hours

22. • 100mg BD for 3 daysHook worm
Round worm
Whip worm(DOC)
• 100mg OD single dose,
repeated after 2 wks
Thread
worm(Enterobiasis)
Clinical Uses

23. Other Uses
Trichinosis(200 mg BD for 4 day)
Intestinal capiliariasis(200mg BD for 21 days)
Hydatid disease(200mg BD for 4 wks)
Visceral larva migrans( 100mg TDS for 5days)
Taenia saginata( 200mg BD for 4 days)

24. Adverse effects
Short term(1-3 days)
No significant adverse effects
GI upset
Long term use (3 months)
Fever ,fatigue, alopecia ,Rash, Urticaria
Increased liver enzymes ,Pancytopenia
Not use
In pregnancy
Hypersensitive peoples
Children under 2 years

25. Q. Albendazole is the drug of choice for following EXCEPT.
A. Ascaris lumbricoides
B. Necator americanus
C. Visceral larva migrans
D. Strongyloides

26. First benzimidazole to be used
Mechanism of action– Similar to other benzimidazole
Inhibits tubulin polymerization

27. Pharmacokinetics
Rapidly absorbed
Chelate with iron but not with calcium
 Half- life of 1-2 hrs
Completely metabolized in liver
 90% is excreted in urine( Glucuronide conjugate)
Can also absorbed through skin

28. Therapeutic Uses
 Strongyloides infections
 Cutaneous larva migrans ( topical)
 Trichinosis
 Dose 25mg/kg BD for 2 days

29.  More toxic than other benzimidazoles
 GI disturbances
 Pruritus ,Headache, Drowsiness
 Psychoneurotic symptoms
 Irreversible liver failure
 Stevens –Johnson syndrome
 Not used In young children , pregnancy
Hepatic and renal diseases
Adverse effects

30. Narrow spectrum benzimidazole
DOC for fascioliasis( 10mg /kg single dose)
Paragonimus skrjasbini(10mg/kg orally daily for 3 days)
No significant side effects

31. Piperazine
Alternative drug for ascariasis
Cure rate 90% for 2 days treatment
Readily absorbed orally
Excreted mostly unchanged in urine

32. Hyperpolarization by GABA agonist action
Cause paralysis of worms
Expulsion
Mechanism of action

33. Therapeutic Uses
 Ascariasis
4gm OD for 2 days
 Enterobiasis
2gm OD for 7days

34. Adverse Effects
GI disturbance
CNS effect- Vertigo, Ataxia
Safe in pregnancy

35. Pyrantel Pamoate
Pharmacokinetics
Poorly absorbed from gut
Half of the drug is excreted unchanged in the feces

36. Depolarizing Neuromuscular blocker
Release of Ach and inhibition of cholinesterase
Cause paralysis of worms
Mechanism of action

37. Therapeutic Uses
Ascariasis and Enterobiasis
Dose -11mg/kg single dose
Ankylostomiasis
Dose 11mg/kg /day for 3 days
Not effective against Trichuriasis and Strongyloidiasis

38. GI disturbances
Drowsiness , Headache ,Insomnia, Rash ,Fever
↑ aminotransferase level
Contraindications
Pregnancy
Children under 2 years of age
Adverse Effects

39. Bithionol
M.O.A
Uncouple oxidative phosphorylation
Alternative to triclabendazole for
Fascioliasis
Paragonimiasis
Dose 30mg/kg in two divided doses on alternate day ( 10 doses)
A/E
Nausea, Vomiting ,diarrhea, Abdominal pain,Skin rash

40. Q. Why thiabendazole is not preferred at present for the treatment of
ascariasis?

41. Filariasis is a disease group affecting humans and animals
Filarial worms are nematodes which dwells in subcutaneous
tissue and lymphatics
Eight filarial species infect humans
Affects approximately 170 million persons world wide
W.bancrofti, B.malayi,O.volovolus,L loa
Filariasis

42. Lymphatic filariais
Elephantiasis
Painful and profoundly disfiguring disease
Caused by – W. bancrofti, B. malayi and B. timori
110 million people are affected
Annual loss of 1 billion dollar

44. Dieth)lcarbamazine(DEC)

45. Anthelminthic action
Kills MFs form of W.bancrofti,B.malayi,L.loa
Kills adult form of W.bancrofti,B.malayi,L.loa
MF form of W.bancrofti are not killed in hydrocele fluid
Kill the MF form of O.volvulus
Doesn’t kill the adult form of O.volvulus
MF forms of O. volovulus are not killed in nodules

46.  Rapid oral absorption
 Peak plasma conc. in 2 hrs
 Half- life is 2-10 hours
 Rapid metabolism
 It is excreted in urine as unchanged or metabolite
 Dosage is reduced in renal impairment
Pharmacokinetics

47. Immobilizes microfilaria
Alters their surface structure
Displace them from tissues
Make them susceptible to host defense
mechanism
Mechanism of action

48. • 6-12mg/kg single dose
• Every 6-12 months
Mass prophylaxixs
(W.bancrofti,B.malayi,B.timori)
• 6mg/kg in 3 divided
doses for 2-3 weeksTreatment
(W.bancrofti,B.malayi,B.timori)
• 8-10mg/kg/day in 3 divided
doses for 3 weeksL.loa
• 6-10mg/kg/day in 3 divided
doses for2weeks
Tropical pulmonary
eosinophilia
Clinical Uses

49. Other infections
Toxocariasis
Dipetalonema streptocerca

50. Adverse Effects
Due to drugs
Anorexia,Nausea,Malaise,Vomiting
Due to killing of parasites
Fever,RashLeucocytosis,Eosinophilia,Proteinuria
Retinal hemorrhage,Encephalopathy
lymphangitis and lymphadenopathy,Wheal
Mazzotti reaction

51. Ivermectin
Semi-synthetic macrocyclic lactone
Mixture of avermectin B1a and B1b
Rapidly absorbed on oral administration
High apparent volume of distribution
Excreted in feces

52. Binds to glutamate activated Cl channel in nerve and muscle
Hyperpolarisation by increasing permeability of
Cl channel
Cause paralysis of worms
Mechanism of action

53. Anthelminthic action
In O. volvulus, ivermectin causes a marked decrease in MF
counts in the skin and ocular tissues but has little effect on
adult parasites, even at doses as high as 800 mg/kg
Ivermectin is effective against microfilaria but not against
adult worms of W. bancrofti, B. malayi, L. loa, and M. ozzardi

54. • 200mcg/kg /day for 2
days
Strongyloidiasis
• 150mcg/kg single doseOnchocerciasis
• 400mcg/kg/yr
Lymphatic filariasis
• 8-10mg/kg/day in 3 divided
doses for 3 weeksL.loa
• 6-10mg/kg/day in 3 divided
doses for 3 weeks
Tropical pulmonary
eosinophilia
Clinical Uses

55. Other infections
Cutaneous larva migrans
Scabies
Pediculosis

56. Adverse Effects
Fatigue ,dizziness, GI disturbance
Fever, headache, dizziness, somnolence
Hypotension , tachycardia, peripheral edema
Mazzoti like reaction
Corneal opacities

57. Q. Which of following about DEC is NOT true?
A. It kills microfilaria and adult form of W.bancrofti
B. It is used in Mazzotti test
C. It causes Mazzoti reaction
D. It doesn’t kill the MF of Onchocerca volvulus

58. Praziquantel
 Pyrazino Isoquinoline derivative
 80% bioavailability
 80% protein bound
 Widely distributed
 Bioavailability ↑ with carbohydrate meals, Cimetidine
 ↓with concomitant Phenytoin,
CBZ,Corticosteroids
not against Nematodes

59. Increase permeability of cell membrane to calcium
Paralysis
Dislodgement and death
Mechanism of action

60. 1.Schistosomiasis(Blood flukes)
Dose 20mg/kg per dose—2to 3 dose
2.Neurocysticercosis
50mg/kg/day in 3 divided doses for 15 days
3.Tape worm
T.saginata,T.solium,D.latum(10 -20mg/kg single dose)
H.nana- 25mg/kg single dose ,repeat after 1 wk
Others
Lung flukes(25mg/kg TDS for 2 days)
Intestinal and Liver flukes(25mg/kg TDS)
Therapeutic Uses

61. Adverse Effects
Headache, Dizziness, Drowsiness
Skin rash,Pruritus,Urticaria,Arthralgia,Myalgia
Headache,Meningismus,Seizure,Mental abnormalities
Contraindicated in ocular cysticercosis
Safe in pregnancy

62. Niclosamide
Salicylamide derivative
Second-line drug for treatment of tape worm infections
Poorly absorbed from gut & excreted in urine
Acts by inhibiting oxidative phosphorylation
Kills scoleces but no effect on ova

63. Clinical Uses
T. saginata,T. solium,D.latum
Purgative is necessary to purge all dead segments& prevent
liberation of ova
Dose 2gm
2 tab of 500mg in morning on empty stomach and 2 more after
1 hr
Purgative should be given 2hrs after second and last dose

64. Adverse effects
 No significant side effects
GI disturbance
Not indicated in children under 2 years of age
Safe in pregnancy

65. Metrifonate
Organophosphorous compound
Alternative for S.hematobium
Not effective against S.mansoni,S.japonicum
Dose 7.5-10 mg TDS at intervals of 2 weeks
A/E
Cholinergic side effects
C/I
Pregnancy, Recent insecticides exposure, with Succinyl
choline

66. Oxamniquine
S.Mansoni
Not effective against S.hematobium,S.japonicum
A/E
Drwosiness,Dizziness,Seizures
Pruritus, Urticaria
Dose 15-20mg/kg single dose
C/I
Pregnancy,Epilepsy

67. Niridazole
Alternative for guinea worm
Schistosoma hematobium
Intestinal and extra intestinal amoebiasis
Dose 25mg/kg

68. Q.A patient Ram present with fever, urticaria, swollen and
tender lymph nodes tachycardia, hypotension, arthralgias,
oedema, and abdominal pain within seven days of treatment
of onchocerciasis with DEC.
A. What is this known as ?
B. Why this has happened and how would you manage this
patient.

69. Q. An anti helminthic drug that is effective against blood
fluke,liver fluke,lung fluke and cystecercus is.
A.Albendazole
B.Praziquantal
C.Ivermectin
D.Thiabendazole

70. Infecting organism Drug of choice
Nematodes
Ascaris ( round worm) Albendazole
Ankylostoma (hookworm) Albendazole
T. Trichura (whipworm) Albendazole
Enterobius ( pinworm) Mebendazole
Strongyloides( thread worm) Ivermectin
Trchinella Albendazole Mebendazole
Dracunculus MTZ
Onchocerca Ivermectin
Cutaneous larva migrans Al/Ivermectin
Visceral larva migrans Al

71. Tape worm(cestode)
T.saginata ( beef tape worm) praziqunatel
T.solium ( pork tape worm) praziqunatel
D latum ( Fish tape worm) praziqunatel

72. Trematode (flukes)
S hematobium Praziquantel
C.Sinensis (liver fluke) Praziquantel
P. Westermani (lung fluke) Praziquantel
F.hepatica(Sheep liver fluke) Bithionol
F.Buski ( intestinal fluke Praziqunatel

73. References
Katzung
Good man gilman
Harrison

74. Q.Which of the following drug causes flaccid paralysis?
A.Albendazole
B.Pyrantel pamoate
C.Piperazine
D.Ivermectin.

75. Thank you