anti-helminthic drugs Flashcards
what are the anti-helminthic drugs
mebendazole albendazole pyrantel pamoate diethylcarbamizine ivermectin praziquentel
drugs that are used for GI infections are characterized by:
designed to be poorly absorbed by the GI tract to reduce possible systemic toxicity to host
toxicity is usually confined to localized irritation of the GI tract
primary excretion is through the feces
stimulate mass migration of the works in the GI tract causing intestinal or bile duct obstruction that may surgical intervention
a purge may be necessarily adminstered with anti-helminthic in order to flush the work from the GI tract
if they aren’t rapidly flushed, the partially digested female works can invade the intestinal wall and develop larvae (cystercosis)
what are the three categories of parasitic worm infections
tape worms (cestodes)
flukes (trematodes)
nematodes (round worms)
the four cestode organisms are:
taenia solium (pork tape worm) taenia saginata (beef tapeworm) hymenolepis nana (dwarf tapeworm) diphyllobothrium latum (fish tape worm)
beef and pork widespread
fish mostly in europe
dwarfm more prevalent in tropical climates
what drugs are used to treat tapeworm infections
praziquantel
albendazole is drug of choice for cyst larvae of T solium
the three blood flukes (trematodes) are
schistosoma haematobium (africa) schistosoma mansoni (africa, america) schistosoma japonicum (far east)
the liver flukes are -
trematodes
clonorchis sinesis
- encysted larvae from raw fish
inflammation and deformation of bile duct, hepatitis, anemia, edema
the lung flukes are
trematodes
paragonimus westermani
- encysted larvae in crab meat
cough (dry, rusty brown sputum)
pulmonary pain, pleurisy
the drug of choice against schistosomaisis (trematodes)
praziquantel
the nematodes that infest the GI tract are
ascaris lumbricoides trichuris trichiura (whip worm) nector americanus, ancyclostoma duodenal (hook worms) strongyloides stercoralis (threadworm) enterobuius vermicularis (pinworm)
the nematodes that cause systemic infection are
trichinella spiralis
wuchereria bancrofti
onchocerca volvulus
found in warm climates of southern us
lower SES have high incidence due to poor sanitation
ascarius lumbricoides
cause daily blood loss and resulting iron deficiency and anemia
new world - most common in americas, central and southern africa, southern asia, indonesia, australia, pacific islands
old world - dom species in mediterranean region and northern asia
hookworms
necator americanus (new world) ancyclostoma duodenale (old)
found in warm humid climates world wide
infection more common in children and found where infection and ascaris and hook worm can occur
obstruction of appendix may occur in seriously infected patients
whipworm
trichuris trichiura
found in southern parts of US
occasionally found in mines and caves
thread worm
strongyloides stercoralis
most common worm infestation of children in US
no SES or geographical barriers
pinworm or seat worm
enterobius (oxyuris) vermicularis
infects 1-4 percent of US population
due to eating raw or undercooked pork containing encysted larvae
nausea, vomiting, diarrhea, ab pain, headache, muscle pain
tachycardia, vascular thrombosis, mental apaty, delirium, coma
trichinella spiralis
systemic infection to lymphatics, brain, eye
rarely in US, more common in Med region, south pacific, africa
lymphadenitis due to inflam response to the parasite lodged in lymphatic channels and tissue
as worm dies, reaction continues and produces granuloma –> lymph edema, elephantiasis
wuchereria bancrofti
infects eye, skin, lymphatics,
nodular lesions
photophobia, lacrimation, blindness
onchocerca volvulus
drug of choice for t. trichuria (gi nematode)
mebendazole
drug of choice for cysticercosis due to T solium
albendazole
drugs that treat GI nematodes
mebendaozle * choice
albendazole
pyrantel pamoate
drug of choice for e vermicularis (pinworm, GI nematode)
pyrantel pamoate
what drugs treat systemic namtodes
diethylcarbamazine
ivermectin
which drug treats systemic nematodes and also s stercoralis (GI nematode)
ivermectin
mebendazole, albendazole - mechanism
inhibits glucose uptake and uncouples oxphos
causes immobilization, death, and expulsion from the GI tract
mebendazole - use
broad spectrum - GI nematodes
drug of choice for t. trichiura
albendazole - use
absorption is enhanced with fatty food
braod spectrum for Gi nematodes
drug of choice for cysticercosis due to T solium
not effective against larvae in tissues of T spiralis (systemic nem) but is effective against GI phase
pyrantel pamoate - mechanism
depolarizing neuromuscular blocking agent
causes persistant activation of nicotinic acetylcholine receptors
results in worm paralysis and removal by gut peristalsis
pyrantel pamoate - uses
drug of choice for E vermicularis (GI nem)
not as effective for other nematode infections
praziquantel - mechanism
increases parasite permeability to Ca2+
causes severe muscle contractions
directly kills adult schistasomes
dislodges cestodes from their usual sites of attachment in the intestine
praziquantel - uses
broad spectrum - schistomaniasis and cestodes in the GI tract
(effective but not the drug of choice for cyst larvae of T solium)
metabolized by p450
containdicated in patients with ocular cysticercosis due to eye damaging host response
praziquantel - drug interactions
macrolides and HIV proteases increases praziquantel concentration in serum
diethylcarbamazine - mechainsm
sensitizes worms to phagocytosis by macrophages
diethylcarbazine - uses
systemic nematodes (w bancrofti, o volvulus)
diethylcarbazine - toxicity
mazzottis reaction
ivermectin - mechanism
opens chloride channels (glutamate and GABA gated channels) in invertebrates causing paralysis of muscles (mammalian muscles dont have these channels)
ivermectin - use
w bancrofti o volvulus (systemic
s stercoralis (gi nematode)
