Antihelmintic drugsBy

Dr.Mohamed Abd AlMoneim Attia

Antihelmintic drugs

Drugs active against nematodes

Drugs active against trematodes

Drugs active against cestodes

Diethylcarbamazine (systemic)

Albendazole

Mebendazole

Pyrantel pamoate

Ivermectin

Praziquantel

Metrifonate

oxamnquine

Niclosamide

Praziquantel

Albendazole

mebendazole

Drugs active against nematodes

Intestinal nematodes includes:

1-enterobius vermicularis (pinworm)

2-ascaris lumbricoides (roundworm)

3-ancyclostoma & necator species (hookworm)

4-strongyloides stercoralis (threadworm) Tissue nematodes: onchocerca,filariasis

Round wormthreadworm

hookwormpinworm

Albendazole

Mechanism of action:

block glucose uptake by the parasite leading to decrease production of energy and subsequent parasite immobilization

Uses:

1-treatment of roundworm,pinworm,hookworm infection

2-alternative treatment of threadworm,filariasis

3-hydatid disease & cysticercosis

Side effects:

1- short course treatment :has few side effects

2-long course treatments: leucopenia, alopecia & elevation of liver enzymes

Diethylcarbamazine

Mechanism of action:

Immobilizes microfilaria by unknown mechanism increase host susceptibility to attack it.

Uses:

1. Drug of choice in filarial

infection of the eye (loa loa)

1. Alternate drug in elephantiasis.

Side effects:

1-headache,malasie,weakness,nausea

2-reaction to dying filaria includes: fever, rash,ocular damage, joint pain and lymphangitis

Ivermectin

Mechanism of action: facilitates GABA mediated neurotransmission in nematodes causing immobilization of the parasite, facilitating its removal by reticuloendothelial system.

Uses:Drug of choice in treatment of onchocercosis,

and threadworm infection

Side effects:

Mazzotti reactions(due to killing of microfilaria) and includes,fever, joint pain, rash hypotension,tachycardia

Mebendazole

Mechanism of action:

Inhibit glucose uptake and microtubule synthesis in nematodes.

Uses:

Primary drug in roundworm and pinworm infection

Side effects:

GIT upsets, alopecia and agranulocytosis in high dose

Piperazine

Mechanism of action:

Act as GABA receptor agonist causing paralysis of the parasite and expelled live by normal intestinal peristalsis

Uses: alternate drug in treatment of roundworm infection.

Side effects: GIT upsets, teratogenic

Pyrantel pamoate

Mechanism of action:

Stimulate nicotinic receptor present at the NMJ of nematode.contraction of the muscle occurs followed by depolarization induced paralysis.

Uses:

1- drug of choice for hookworm & roundworm infection

2-alternate drug in pinworm infection

Side effects: mild GIT upsets

Thiabendazole

Mechanism of action: like mebendazole Uses: alternate drug in threadworm infection Side effects: unsafe drug

1-GIT irritation,headache,drowsiness

2-leukopenia,haematuria

3-allergic reaction

Drugs active against trematodes

Medically important trematodes are:

1-schistosoma species (blood fluke)

2-clonorchis sinesis (liver flukes in southeast Asia)

3-paragonimus westermani ( lung fluke in Asia,India)

Praziquantel

Mechanism of action:

Increase membrane permeability to calcium causing muscle contraction followed by paralysis leading to vacuolization and death of the parasite.

Uses:

1- drug of choice of all trematodes infection

2-one of 2 drugs of choice in cestodes infection

Side effects:

1-common adverse effects: GIT upset,headach,malaise,skin rash

2-intracranial hypertension and convulsion if used in ttt of neurocysticercosis

Contraindication: ocularcysticercosis

Bithionol

Uses:

Drug of choice in ttt of fascioliasis ( sheep liver fluke)

Side effects:

1-common: N/V,headache,phototoxcity

2-less common: protenuria,leucopenia

Drugs active against cestodes

The 4 important cestodes are:

1-taenia saginata ( beef tapeworm)

2-taenia solium ( pork tapeworm that causes cysticerci in brain and eye)

3-diphyllobothrium latum ( fish tapeworm)

4-echinococcus granulosus (dog tapeworm that cause hydatid cysts in lung,liver,and brain)

beef tapeworm

Hydatid cyst in liver

Niclosamide

Mechanism of action:Act by activating ATPases Uses:1- 1 of 2 drugs of choice ( with praziquantel) in ttt of

fish,pork,and beef tapeworms infection2-not effective in cycticercosis (albendazole or

praziquantel is used)3- not effective in hydatid disease ( albendazole is

used). Side effects:Mild GIT upset, rash headache

Infecting organism Drug of choice Alternative drug

Ascaris(roundworm) Albendazole,mebendazole,pyrantel pamoate

piperazine

Ancylostoma(hookworm) Albendazole,mebendazole, pyrantel pamoate

Strongyloids stercoralis(threadworm

ivermectin Albendazole,mebendazole,

Enterobius vermicularis(pinworm)

Mebendazole,pyrantel pamoate

albendazole

filariasis diethylcarbamazine ivermectin

onchocericasis ivermectin --------

Drug for treatment of nematodes

Infecting organism Drug of choice Alternative drug

s,.haematobium praziquantel metrifonate

s.mansoni praziquantel oxamniquine

s.japonicum praziquantel

Fasciola hepatica bithional

Fasciolopsis buski Praziquantel or niclosamide

Drug for treatment of trematodes

Infecting organism Drug of choice Alternative drug

t.Saginata (beef tapeworm) Praziquantel or niclosamide

mebendazole

t.Solium(pork tapeworm) Praziquantel or niclosamide

Cysticercosis(pork tapeworm larval stage)

albendazole praziquantel

Diphyllobothrium latium(fish tapeworm)

Praziquantel or niclosamide

Hydatid disease albendazole

Drug for treatment of cestodes

Drugs for leishmaniasis

Sodium stibogluconate: for all types of leishmania ( must be given by injection and cardiotoxic)

Alternate drugs:

1-Pentamidine for visceral leishmaniasis

2-Fluconazole or metronidazole for cutaneous lesions

3-Amphotricin B for mucocutaneous lesions

ANTIHELMINTHIC DRUGSTherapeutic Strategies

Inhibit muscle contraction Inhibit energy metabolism Limit distribution of generally toxic drugs

Thank you