Anthelmintic drugs are used to treat helminth infections. The main classes include benzimidazoles like albendazole and mebendazole, which inhibit microtubule synthesis in worms. Piperazine is only recommended for ascariasis by blocking acetylcholine. Pyrantel pamoate is broad spectrum but not effective against whipworms. Thiabendazole is more toxic than other benzimidazoles and can cause liver failure. Drugs are selected based on the infecting organism and administered orally in single or multiple doses.

1. ANTIHELMINTIC
DRUGS
Indupalli Avinash &
Paruchuri Aswini chand
1

2. INTRODUCTION
 Humans are the primary hosts for the most of helminthic
infections.
 Most worms produce in human sexually by producing
eggs and larvae
 These pass out of body and infect the secondary host
 Imature forms invade humans via skin or GIT and mature
to adult worms with characteristic tissue distribution.
2

3. Types (clinical)
1. Worms live in hosts alimentary canal.
2. Worms or larvae live in other tissues of host
body like muscles , viscera , meninges ,
lungs, subcutaneous tissues.
3

4. INTESTINAL WORMS CON’D
A) INTESTINAL ROUND WORMS
(NEMATODES)
 Ascaris lmubricods (common round worm)
 Enterobius vermicularis (pin worm)
 Trichuris trichuria ( whip worm)
 Strongyloids stercoralis ( thread worm)
 Ankylostoma dudenale (hook worm)
4

5. Ascaris lumbricoids ( common round worm)
5

6. Hookworm
6

7. Pinworm male ,female
7

8. whipworm
8

9. Tricuris tricura(whip worm)
9

10. 1. Alimentary canal(intestinal tape worms)
B)TAPE WORMS (CESTODES)
 Taenia saginata(Beaf) ,
 Taenia solium(Pork),Hymenolepis nana(Dwarf)
,diphylobothrium latum(Fish)
 Humans become infected by eating raw or under
cooked meat containing larvae of infected cattle or pig
which has encysted in the animal muscle tissue.
10

11. Cestodes con’d
 In some conditions this larvae may develop in
humans resulting cysticercosis (i.e. larvae gets
encysted in the muscle and viscera or more
seriously in the brain or eye.)
 In case of H.nana both adult worm and larvae can
be present in the same host.
 In case of D.latum infections occurs by eating raw
11
or undercooked fish

12. Tapeworm
12

13. cysticercosis
13

14. 2. TISSUE WORMS
A.TREMATODES(Schisotomes)OR
FLUKES(leaf like)
 Schistosoma haematobium
 Schistosoma Japonicum
 Schistosoma mansoni
(These cause SCHISTASOMIASIS) also called
(BILHARZIA) means disease of blood vessels.
Adult worms of both sex live and mate in veins or venules
of the gut wall or the bladder, eggs pass into the bladder
or gut and produce inflammation of these organs ,
resulting in haematuria or loss of blood in feces.
14

15. Tremtodes (flukes) con’d
 Eggs hatch in water and develop in to miracidia(1st stage of
larva of trematode and further develop in the body of snail),
which enter to 2ndry host a particular species of snail ,where it
develops to free swimming cercarae (final free-swimming stage
of a trematode),These infect humans by penetrating to skin
15

16.  Paragonimus westermani (lung fluke)
disease is caused by eating raw crab or fish , larvae
move from intestine to blood and settle in lungs
 Clonorchis sinensis(liver fluke)
disease is caused by eating raw fish and worm
settle in the biliary tract
16

17. Tissue worms cont’d
 B. TISSUE ROUND WORMS
Trichnella spiralis.
Dracunulus medinensis (guinea worm)larva migrate
from intestine to tissue of leg or foot and protrude out by
making ulcer
17

18. FILARIAE includes
 Wuchereria bancrofti
 Loa loa
 Onchocerera volvulus
 Brugia malayi
18

19. Trichinela spiralis
19

20. filariasis
20

21. Wuchereria or Brugia obstructs lymphatic vessels producing
elephantiasis
elephantiasis
21

22. Filariae: Wucheria bancrofti ,loa loa , onchocera
volvulus and Brugia malayi
 Adult filariae live in the lymphatics,and cause
lymphadenitis and swelling of limb. connective
tissue or mesentery of host and produce live
embryos or microfilariae, which goes to blood
stream.
 They are ingested by mosquitoes or similar insects,
they develop to larvae in 2ndry host and pass to
mouth parts of insect and
22
re-injected to humans

23. C. Hydatid tape worm
 Echinococcus species .
 These are cestodes ,primary in canines (dogs) and
sheep as intermediate host.
 humans can act intermediate host in which larvae
develop to hydatid cyst with in tissue.
23

24. Hydateid cyct
24

25. Helminths commonly infecting man
Nematodes( round worm)
Tissue worms wuchereria bancrofti Filariasis
Brugia malayi Filariasis
Loa loa loiasis
Onchocerca River blindness
Dracunculus medinensis Dracunculiaiss
Intestinal human nematodes Enterobius vermicularis Threadworm
Ascaris lumbricoides Roundworm
Trichuris trichiura Whipworm
Nector americanus Hookworm
Ancylostoma duodenale Hookworm
Strongyloides stercoralis Strongyloidosis
Trematodes(flukes)
Blood flukes Schistosoma species Schistosomiasis
Lung flukes Paragonimus speies Paragonimiasis
Intestinal / hepatic flukes Fasciolopsis buski
Fasciola hepatica
Clonorchis sinensis
25

26. Helminths commonly infecting man cont’d
Cestodes(tapeworms)
Intestinal adult worms Taenia saginata Beef tapeworm
Taenia solium Porktaperworm
Diphyllobothrium latum Fishetapeworm
Hymenolepis nana Dwarftapeworm
Larval tissue cysts Taenia solium cysticercosis
Echinococcus granulosus Hydatid disease
Echinococcus multilocularis Hydatid disease
Spirometra mansoni Sparganosis
26

27. Diseases caused by filarial worms
Organism adult worm Microfilariae C.signs
W. bancrofti Lymphatics Blood Fever
lymphangitis
Elephantiasis
B.Malayi lymphatics Blood Fever
lymphangitis
Elephantiasis
Loa loa Subcutaneous Blood Urticaria
Onchocerca Subcutaneous skin,eye subcut nodules
Eye disease
Mansonella perstans Retroperitoneal Blood Allergic eosinophilia
27

28. Dircrocoelium dendriticum
28

29. Fasiola hepatica
29

30. ANTHELMINTIC DRUGS
BENZIMIDAZOLES
1.ALBENDAZOLE:
 It is a broad spectrum
 It is a drug of choice (primary therapeutic
application) for treatment of hydatid disease and
cystecercosis, it is also used for the treatment of
(intestinal nematodes) pinworm, hookworm
30

31. Albendazole con;d
 Mechanism of action:
It inhibits microtubule synthesis in
nematodes(intestinal round worms) that
irreversibly impairs glucose uptake, intestinal
parasites are immobilized and die slowly.
31

32. Pharmacokinetics (Albendazole)
 It is benzimidazole carbamate
 it is adminstered orally , and absorbed erratically
(unpredictable) , absorption can be increased with
fatty meal
 It is metabolized in the liver rapidly to active
metabolite albendazole sulphoxide
32

33. Pharmacokinetics (Albendazole)
 It has a plasma half life of 8-12 hours
 Sulphoxide is mostly protein bound ,
distributes well to tissues and enters bile, csf.
 Metabolites are excreted in urine
33

34. Clinical uses (albendazole)
 used on empty stomach when used against
intraluminal parasites but with fatty meal when
against tissue parasites.
 In hookworm, pin worm infection : children under
2 years 400 mg orally as a single dose repeated
after 2-3 wks for pin worm
2. Hydated diseases:
drug of choice ,400 mg twice with meals for 1
month or longer.
34

35. Albendazole con’d
3. Neurocysticercosis:
It is controversial as it has not proved superior to
corticosteroid alone.
It is used along with cotricosteroid to decrease the
inflammation caused by dying organism and it also
reduces the duration of course i.e. 400 mg twice daily for
21 days
35

36. Albendazole con’d
Adverse effects:
 In short term: use no significant adverse effects.
 In long term use : as used in abdominal distress,
headache ,fever , fatigue, alopecia , increased liver
enzymes , pancytopenia. Blood counts and LFT should be
followed.
 Not given during pregnancy and in hypersensitive
people.
36

37. MEBENDAZOLE(Vermox)
 it is a synthetic benzimidazole
 it has wider spectrum and is more safer than albendazole
Mechanism of action:
It inhibits microtubule synthesis in nematodes that
irreversibly impairs glucose uptake.Intestinal parasites are
immobilized and die slowy.
It kills hook worm, pin worm , ascariasis and trichuris eggs.
37

38. Mebendazole con’t
Pharmacokinetics:
 less than 10% of orally administered drug is absorbed
 Absorption increases with fatty meal.
 Absorbed drug is 90 % protein bound
 It is converted to inactive metabolites rapidly in liver.
 It has half life of 2-6 hours
 It is primarily excreted in urine.
38

39. Mebendazole con’t
Clinical uses:
 It is taken orally before or after meal tablets should be chewed
before swallowing.
 Pinworm infection: 100 mg as a single dose, to be repeated after
2-3 weeks.
 in adults and children over 2 years cure rate is 90-100 % except
hook worm but there occurs marked reduction
39

40. Mebendazole con’d
 Intestinal cappilliaris: 400 mg /day in divided
doses for 21 day or more.
 Trichinosis :it has limited efficacy against adult
worm.200-300 mg for 3 days ,then 400-500 mg for
10 days with fatty meal and co-administration with
corticosteroids in sever infection
40

41. Mebendazole con’d
Adverse effects and precautions:
 No adverse effects in short term therapy.Mild GI disturbance.
 With high dose Hypersensitivity reactions,agranulocytosis , alopecia
,elevation of liver enzymes .
 used with caution under 2ys of age may cause convulsion in this
group.
 enzyme inducers and inhibitors affect plasma level of the drug.
 hepatic parenchymal disease 41

42. Thiabendazole
 it is benzimidazole
 it is chelating agent and form stable complexes with metals
including iron, but does not bind with calcium.
 it is rapidly absorbed
 it has half life of 1.2 hrs
 It is completely metabolized in liver and 90% is excreted in urine
 it can also get absorbed through skin
42

43. Thiabendazole con’d:
 mechanism of action: similar to other benzimidazoles.It is ovicidal
for some paracites
 clinical uses:
 should be given after meals .and tablets should be chewed
 for thread worms infections: 25 mg /kg ( not more than 1.5 grams)
twice daily for 2 days ,can be repeated after 2 week. In hyper infection
syndrome drug is continued twice daily for 5-7 days.
43

44. Thiabendazole con’d
 adverse reactions and contraindications:
 It is more toxic than other benzamidazoles
 GI disturbances
 Pruritus ,headache, drowsiness , psychoneurotic symptoms.
 Irreversible liver failure.
 Fatal Steven –Johnson syndrome(inflammation of skin)
 Not used in children below 15 kg weight. pregnancy, hepatic and renal
diseases.
44

45. PYRANTEL PAMOATE
 It is a broad specturm anthelmintic
 but it is not effective against tricuriasis(whip worms), and
trichostrongylus orientalis infections. Oxalate pamoate is effective
 Pharmacokinetics:
 It is poorly absorbed orally ,
 Half of the drug is excreted unchanged in the feces.
 Mechanism of action:
 It is a depolrazing neuromuscular blocking agent that causes
release of acetylcholine and inhibition of cholinestrase leads to
paralizes of worms.
45

46. Pyrantel pamoate con’d
Efficacy and clinical uses:
 it is very effective against luminal organisms.
 It is not effective against migratory stages in the tissues or
against ova
 pin worm: 11 mg /kg as a single dose to be repeated in 2
wks.
 common round worm: single dose to be repeated after
2wks
 hook worm: single dose for light infection but a 3 days
course is necessary for heavy infection.especially N
amerianus. 46

47. Pyrental pamoate con’d
 Adverse Effects .
 Infrequent mild transient GI disturbance
 drowsiness , headache ,insomnia.
 Rash ,fever
Contraindciations
 Should not be used in liver diseases.
 Pregnancy
 and child under 2 years of age
47

48. PIPERAZINE
 Only recommended for the treatment of
ascariasis.
 it is absorbed orally and excreted in urine
 Mechanism of action:
it causes paralysis of ascaris by blocking
acetylcholine at myoneural junction ,expelling the
live worm by normal peristalsis.
Not recommended for other helminth infections
48

49. Piperazine con’d
 pharmacokinetics :
 it is readily absorbed orally and excreted
unchanged in urine.
 75 mg /kg/day for 2 days once daily
 treatment is continued for 3-4 days or
repeated after one week in case of heavy
infections.
49

50. Piperazine con’d
 Adverse effects:
 GI disturbance
 Neurotoxicity ,allergic reactions serum sickness like
syndrome
 Contraindications
 Epilepsy
 Impaired liver or kidney functions
 pregnancy
 Malnutrition
50

51. NICLOSAMIDE
 It is a useful drug for treatment of tape worm
(cestodes)infestation
 Mechanism of action:
 Adult worm is rapidly killed by inhibition of oxidative
phosphorylation or stimulation of ATPase activity.
 Pharmacokinetics:
 It is poorly absorbed from gut
 Neither drug nor its metabolites are found in blood or
urine
51

52. Niclosamide con’d
 Clinical uses:
 Beef tape worm, pork tape worm, fish tape worm.
 2 gram of single dose is given in the morning on
the empty stomach.
 not effective against cysticercosis or hydatic
disease.
 Hymenolepis nana: It is effective against adult
parasite
52

53. Niclosamide con’d
 Adverse effects:
 Mild ,infrequent and transitory GI
disturbance
 Alcohol consumption should be
avoided
 not indicated in children under 2
years of age.
53

54. DIETHYLCARBAMAZINE
 Is a drug of choice for the treatment of filariasis and
tropical eosinophillia.
 Pharmacokinetics:
 It is synthetic peprazine derivative
 Rapidly absorbed from gut
 It has a half life of 2-3 hours which increases in
alkaline urine to 10 hours.
 It is excreted in urine unchanged.
 dosage is reduced in urinary alkalosis and renal
impairment.
54

55. DIETHYLCARBAMAZINE con’d
 Mechanism of action:
 It immobilizes microfilariae and alters its surface
structure ,making them susceptible to destruction by
host defense mechanis
 It is not teratogenic
55

56. DIETHYLCARBAMAZINE con’d
 It is a drug of choice for the treatment of W.bancrofti,
B.malayi,B.timori, loa loa
 Microfiliariae are rapidly killed .adult worms are killed
slowly requiring several course of treatment
 It is highly effective against L.loa. for these infections the
dose is 2mg/kg three times a day for 2-3 weeks.
 for W.bancrofti infections to reduce the incidence of
allergic reactions to dying microfilariae a single dose is
administered on the first day , two doses on the second day
and three doses on the 3rd day. 56

57. DIETHYLCARBAMAZINE con’d
 For loa ( with risk of encephalopathy) or B.malayi infections
,individual
doses should start at 1 mg /kg once on the first day and gradually
increased over 5-6 days
 Anti histamines and corticosteroids are given in allergic
manifestations.
 Complete Cure may be require several courses of treatment over 1-2
years.
 The drug may be used in prohylaxis
300 mg weekly or 300 mg on 3 successive day each month for
57
loiasis.

58. DIETHYLCARBAMAZINE con’d
 Reactions induced by Dying parasites:
 Fever , mailase, papular rash, headache, GI
disturbance,cough, chest,muscle,joint pain
 Leucocytosis
 Retinal haemorrhage
 Encephalopathy
 lymphangitis and lymphadenopathy.
58

59. DIETHYLCARBAMAZINE con’d
 contraindications and precautions
Hypertension
Renal disease
Patient suspected of malaria
patient with lymphangitis
59

60. IVERMECTIN
 It is drug of choice for treatment of filaria and
onchoceriais,elephantiasis
 it is a macrocyclic lactone
 It is used orally and is rapidly absorbed, posses
wide volume of distribution.
 It has a half life of 16 hrs
 It is exclusively excreted in urine
60

61. IVERMECTIN con’d
 Mechanism of action:61
it intensifies GABA –mediated transmission of
singals in peripheral neverse
 In onchoceriasis it is microfilaricidal
 It does not kill adult worm
61

62. IVERMECTIN con’d
 Clinical uses:
 Onchoceriasis: a single dose of 150 mg/kg with
water on empty stomach,repeated after every 3
months for one year,after this it is repeated
yearly untill adult worm dies which may take a
year or more
62

63. IVERMECTIN con’d
 Strongyloidiasis: 200mg for 2 days in
immunosuppresed patient ,repeated treatment is
often needed.
 Bancrofti filaricidal: as it is mirofilaricidal
 It is also used for scabies and cutaneous larva
migrains.
63

64. IVERMECTIN con’d
 Adverse effects:
 Fatigue ,dizziness, GI disturbance
 In onchoceriasis:
 Mazotti reaction i.e. fever, headache, dizziness,
somonlence, weekness, rash ,diarrhea, arthralagia,
hypotension, lymphadenitis, peripheral edema due to
killing of microfiliariae, for this steroids may be
necessary for several days
 Swelling and abscess at site of adult worm
 Punctuate corneal opacities.
64

65. IVERMECTIN con’d
 Contraindication: other drugs that enhance
GABA
e.g Barbiturates, bnezodiazepines, valproaic acid.
 pregnancy
 Imparied blood brain barrier
 Children under 5 years of age.
65

66. BITHIONOL
 it is drug of choice for the treatment of
fasioliasis ( sheep liver fluke)
 It is also alternative drug for pulmonary
paragonimiasis
 Pharmacokinetics:
 It is orally administered and excreted in urine.
66

67. BITHIONOL
 Clinical uses:
 30-50 mg /kg in 2-3 divided doses administered orally
after meals on alternate day for 10 – 15 days.
 Adverse effects:
GI disturbance
Dizziness,headache
Pruriuts ,urticaria,Leucopenia
 Contraindications and precautions:
hepatitis ,leucopenia
Used with caution under 8 years of age.
67

68. 68