ANTHELMINTIC DRUGS Helminth Infections 1-Tapeworms ( cestodes) Beef tapeworm / fish tapeworm 2- Intestinal round worms ( nematodes) Ascaris, pinworm ,whipworm, strongyloides, ancylostoma ( hookworm ). A skin infection is termed cutaneous larva migrans Visceral larva migrans .

Anthelminthic Drugs *Worms or larvae live in tissues of host May act by causing : 1- paralysis of the worm. 2- damaging the worm leading to partial digestion or rejection by immune mechanisms. 3- interfere with the metabolism of the worm. *Worms or larvae live in tissues of host body like muscles , viscera , menninges , subcutaneous tissues.

Adult filariae live in the lymphatics, 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 re-injected to humans

Ascaris lumbricoids ( common round worm)

filariasis

Hookworm

Pinworm male ,female

Tapeworm

whipworm

Dircrocoelium dendriticum

Fasiola hepatica

Tricuris tricura

Trichinela spiralis

elephantiasis

Hydateid cyct

cysticercosis

ANTHELMINTIC DRUGS ALBENDAZOLE Broad spectrum oral anthelmintic Drug of choice for treatment of hydatid disease and cysticercosis,it is also used for the treatment of ascariasis ,tricurasis and strongyloidiasis, pinworm, hookworm

Mechanism Of Action Inhibits microtubule synthesis by binding to β –tubulin. Inhibits mitochondrial reductase causing reduced glucose transport.. Intestinal parasites are immobilized and die slowly. larvicidal in hydatid ,cysticercosis , ascariasis and hook worm infections. Ovicidal in ascariasis ,hookworm , trichuriasis

Pharmacokinetics Benzimidazole carbamate Administered orally , absorption increased with a fatty meal Metabolized in the liver to the active metabolite albendazole sulfoxide

Pharmacokinetics Plasma half life is 8-12 hours sulfoxide is mostly protein bound distributes well to tissues and enters bile,CSF & hydatid cysts. Metabolites are excreted in urine

Clinical uses Used on empty stomach when used against intraluminal parasites but with a fatty meal when used against tissue parasites. In ascariasis ,trichuriasis ,hookworm, pin worm infections : children over 2 years & adults (single dose 400mg, repeated for 2-3 day in heavy ascaris infection . For 2 wks for pin worm infection 2. Hydatid diseases: drug of choice for medical therapy& adjunctive to surgical removal or aspiration of cysts.

Albendazole (con’) Neurocysticercosis: Used with corticosteroid to decrease the inflammation caused by dying organism and it also reduces the duration of course for 21 days 4. Other infections: Drug of choice in cutaneous and visceral larva migrans , intestinal capillariasis, giardiasis & taeniasis.

Adverse Effects In short term(1-3 days): Mild epigastric pain,diarrhea, nausea, headache & insomnia. In long term use : for hydatid cyst and cysticercosis : abdominal pain, headache ,fever ,fatigue, alopecia , increased liver enzymes , pancytopenia. Blood counts and liver enzymes should be followed. Not given during pregnancy, hypersensitive people to benzimidazole drugs & children under 2 years .

MEBENDAZOLE (Vermox) Synthetic benzimidazole Wide spectrum and low incidence of adverse effects Mechanism of action: Inhibits microtubule synthesis . It kills hookworm, pin worm , ascaris and trichuris eggs.

Pharmacokinetics less than 10% of orally administered drug is absorbed Absorption increases with fatty meal. Absorbed drug is 90 % protein bound Converted to inactive metabolites . Half- life of 2-6 hours Excreted mostly in urine .

Clinical Uses It is taken orally before or after meal , tablets should be chewed before swallowing. Pinworm , trichuriasis, hookworm & ascaris infections. in adults and children over 2 years cure rate is 90-100 % except hookworm it is less.

Adverse Effects & Precautions Short term therapy.Mild GI disturbance. High dose : hypersensitivity reactions, agranulocytosis , alopecia ,elevation of liver enzymes . Used with caution under 2ys of age may cause convulsion. Contraindicated in pregnancy. Enzyme inducers and inhibitors affect plasma level of the drug.

Thiabendazole Benzimidazole Chelating agent and form stable complexes with metals including iron, but does not bind with calcium. Rapidly absorbed Half- life of 1-2 hrs Completely metabolized in liver and 90% is excreted in urine Can also absorbed through skin

Mechanism Of Action Similar to other benzimidazoles. It is ovicidal for some parasites Clinical uses: Should be given after meals .and tablets should be chewed Strongyloidal infections & cutaneous larva migrans .Thiabendazole cream is applied topically or drug can be given orally for 2 days.

Adverse Effects & Contraindications More toxic than other benzamidazoles GI disturbances Pruritus ,headache, drowsiness , psychoneurotic symptoms. Irreversible liver failure. Fatal Stevens –Johnson syndrome Not used in young children , pregnancy, hepatic and renal diseases.

PYRANTEL PAMOATE Mechanism of action: Broad spectrum Pharmacokinetics: Poorly absorbed from GIT Half of the drug is excreted unchanged in the feces. Mechanism of action: result in paralysis of worms. It is a neuromuscular blocking agent Efficacy Very effective against luminal organisms( mature or immature forms). Not effective against migratory stages in the tissues or against ova

Clinical uses Pin worm given orally with or without food. Ascariasis Hookworm

Adverse Effects Infrequent mild transient GI disturbance drowsiness , headache ,insomnia. Rash ,fever Contraindications & Cautions Should be used with caution in liver dysfunction. Pregnancy Children under 2 years of age

PIPERAZINE Mechanism of action: Only recommended for the treatment of ascariasis cure rate 90% for 2 days treatment. Readily absorbed orally and excreted mostly unchanged in urine Mechanism of action: Causes paralysis of ascaris by blocking acetylcholine at myoneural junction , the live worms expelled by normal peristalsis.

Treatment is continued for 3-4 days or repeated after one week in case of heavy infections.

Adverse Effects GI disturbance Neurotoxicity ,allergic reactions . Contraindications Epilepsy or a history of epilepsy Impaired liver or kidney functions pregnancy Chronic neurologic disease

NICLOSAMIDE Second-line drug for treatment of most tapeworm infections. Mechanism of action: Adult worm( not ova) is rapidly killed by inhibition of oxidative phosphorylation . Pharmacokinetics: Poorly absorbed from gut & excreted in urine.

Clinical Uses Treatment of most forms of tapeworms. Not effective against cysticercosis or hydatic disease. Given in the morning on empty stomach. Purgative is necessary to purge all dead segments& prevent liberation of ova.

Adverse effects & Contraindications Mild ,infrequent and transitory GI disturbance Alcohol consumption should be avoided Not indicated in children under 2 years of age or in pregnancy.

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.

Mechanism Of Action Immobilizes microfilariae and alters their surface structure ,displacing them from tissues & making them susceptible to destruction by host defense mechanism It has immunosuppressive effects

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

Contraindications & Cautions * Hypertension * Renal disease *patient with lymphangitis

IVERMECTIN Drug of choice for treatment of strongyloidiasis Macrocyclic lactone ring Given only orally Rapidly absorbed Does not cross BBB. Half- life is 16 hrs Excretion is mainly in feces.

Mechanism Of Action Acts on the parasitte,s glutamate-gated Cl- channel receptors . Chloride influx increased , hyperpolarization occurs , resulting in paralysis of the worm. Or Paralyze nematodes by intensifying GABA- mediated transmission of signals in peripheral nerves.

Clinical uses Drug of choice for cutaneous larva migrans & strongyloidiasis. Onchocerciasis It is also used for scabies , lice . Filariasis.

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.

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

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

Adverse Effects GI disturbance ( N., V., D., A.) Dizziness, headache Skin rashes , urticaria, Leucopenia Contraindications and precautions: Hepatitis , leucopenia Used with caution in children under 8 years of age.