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Treatment of intestinal helminthic infections (Nematodes (Pyrantel…
Treatment of intestinal helminthic infections
Approach differs depending on the pathogenesis
Inflammation
Anti-inflammatory
E.g. steroids
Competition for nutrients
Reduce worm burden and support nutrition
Space occupying lesions
Surgery, decompression
Stimulation of fibrosis
Helminth eradication and treatment of secondary effects
Cestodes
Praziquantel
Action not fully known
Probably increases calcium permeability of membranes depolarising them
May interfere with purine synthesis
Indications
Hydatid disease
Cysticercosis
Schistosomiasis
Clonorchis, fascioliasis and paragnomiasis infection
Significant first pass effect
Well absorbed orally
Short half life
Excreted in the kidneys
Side effects
Dizziness, headache, drowsiness and somnolescence, sometimes seizures
Abdominal cramps, diarrhoea and nausea
Transient asymptomatic rise in transaminases
Urticaria, rash and pruritis
Interacts with rifampicin, carbamazine and phenytoin
Niclosamide
Inhibits glucose uptake, oxidative phosphorylation and anaerobic metabolism
Treatment of tape worm
Causes dizziness, skin rashes, drowsiness and perianal itching
Nematodes
Albendazole is the most effective
Indications
Treatment of nematode infections
Filariasis
Enterobius infection
Ascariasis
Hookworm
Toxocariasis
Strongyloidiasis
Trichiuriasis
Treatment of some protozoa (giardia)
Treatment of some cestode infections
Neurocysticercosis and hydatid disease
Mode of action
Binds to colchicine sensitive receptor or tubulin
This prevents polymerisation into microtubules
Impaired glucose uptake and depleted glycogen stores
Degenerative changes appear in the worm
Side effects
Concentrated in semen and may be teratogenic
Persistent sore throat
Headaches and dizziness and seizures
Acute liver failure
Aplastic anaemia and marrow supression
Levamisole
Nicotinic acetylcholine receptor antagonist
Ascariasis and mixed ascaris hookworm infection
Rapidly absorbed
Side effects
Caution in pregnancy
Abdominal pain, nausea and vomiting
Piperazine
Agonist activity against the gamma butyric acid receptor paralysing muscular activity
Orally active
Metabolism in the liver
Variable half life
Used to treat ascariasis and enterobius infection
Side effects
GI tract upset
Sometimes hypersensitivity and dizziness
Pyrantel
Treatment of hookworms and roundworms
Causes depolarising neuromuscular blockade
Poorly absorbed providing selective toxicity
Excreted unchanged in faeces
Antagonistic with piperazine
Avoid in pregnancy
Can cause intestinal obstruction if there is a heavy worm load
Diethylcarbamazine
Piperazine derviative
Inhibits arachidonic acid making parasites more susceptible to immune attack
Treatment for filaria infection
Side effects
Associated with increase in inflammation (caution of Mazzotti reaction, loss of site in onchocerciasis)
Ivermectin
Binds glutamate-gated chloride increasing the permeability of the membrane to chloride ions
Active against filarial worms, lice, scabies and bed bugs
Currently used for the eradication of lymphatic filariasis and onchocerciasis
Contraindicated in children <5 or breast feeding mothers
Complicated by CNS depression
Increased risk of absorption past the BBB of HIV protease inhibitors, calcium channel blockers and glucocorticoids