Anthelmintics Flashcards
What has a prevalence of 1000mil
And A funding of
Ascariasis
Schistosomiasis
What does it do
What is its prevalence and funding
Adults live in mesoteric blood vessels
Eggs go to the bladder and are released into water
Larve barrow into snail, sticking their tail out
Swimmers catch these larve
They barrow through the skin
Prevalence - 200m funding - 3m
Pathophysiology of helminths infection
What are the 3 methods
Presence of adult - blocking gut
Migration of the larvae- causes symptoms of neumonia
Allergic reaction
Tapeworm
What do they do
Intermediate host are cattle/ pigs
Eating uncooked meat
Which have larvae encysted in the animals tissue
Roundworm
What do they do
Uncooked meat
Larvae oenetrates the skin
Causes blood loss in intestinak areas
Causing anemia
Flukes
What does it cause
Schistosomiasis
Flukes
What do they do
Both sex adults live and mate in blood vessels of the bladder or gut wall
Females lay eggs that pass into blad/gut
Produces inflammatory response
Resulting in haematuria, loss of blood in faeces
Eggs hatch in water
Enter 2nd host (specific species of snail)
After a period of development in host free swimming cercariae emerge
Penetratung human skin
River blindness
What does it do
Black flies in fast funning water
Adults live in connective tissue and lymphatics
Produce live microfilaries
Find their way into bloodstream
Ingested by mosquito
In 2ndary host larves pass to mouth of mosquito and is injected into humans
Anthelmithic drugs how do they work
Either by paralysing or damage to worm so immune system works or by altering metabolism
Only effective against 1 type as metabolic requirements of paracites vary for each drug
Must be able to penetrate tough exteriour cuticles and access its alimentary tract
What do helmiths contain
Active drug efflux pumps that reduce the conc. Of the drug in the paracite
Benzimidazoles
What does it inhibit
Inhibits polymerisation of beta-tubulin
Interfering with microtubule dependant function such as glucose uptake
What inhibits polymerisation of beta tubulin
Benzimidazole
Whats benzimidazoles selective toxicity
250 - 400x more effective in helminth then mammals
Whats benzimidazoles dis
Effects take time to develop
Worm may not be expelled for several days
Mebendazole
What is it used for a other facts
Single dose for threadworm, twice daily for hook worm
Only 10% absorbed - fatty meals increase this
Rapidly metabolised
Dis for mebendazole
Gi disturbances
Praziquantel what is it affective against
Schistosomiasis (mature and immature forms)
What is a drug used against schistosomisis
Praziquantel
What does praziquantel do
Drug disrupts ca2+ homeostasis
By binding to consensus PKC- binding site in beta- subunit of schistosome VGCa channel
Induces influx of ions
, a rapid and prolonged contraction of musculature
Disrupts tegment, unmasking novel antigens
Side effects of praziquantel
Safe for pregnant women
Heavy worm load - deaths of worms
Ascariasis
What does it do and
what is its prevalence and funding
1/4 mill eggs produced in human feaces Feaces used as fertiliser Eggs infect crops Prevalence - 1000 mil Funding -
Piperazine
What does it treat
Treats roundworm
What does piperazine do
Reversibly inhibits nmj
Probably my mimicing GABA
At GABA gated chloride channels in nematode muscle
What does piperazine do to the worm
Paralysed worm are expelled alive by normal intestinal peristaltic movement
With a laxative such as senna
Unwanted effects of piperazine
Gi disterbances
Bronchospasm
Should not be given to pregant women
Or those with renal and hepatic failure
Niclosamide what does it treat
And with combo
Tapeworm
With praziquantel
What does niclosamide do
The head if the worm and proximal segment are irreversibly damaged by the drug
Such that worm seporate from the intestinal wall and is expelled
Selective toxicity of niclosamide
Negligable absorbance of drug in gi
What are the unwanted effects of niclosamide
Nausea
Vomiting
Light headedness
Levamisole what is it used against
Roundworm
What is the moa of levamisole
Nicotine like action
Stimulates and subsequently blocks the nmj
Paralyses worm and is expelled in faeces
But ova are not killed
Single does therapy
Crosses bbb
Unwanted effects of levamisole
Mild gi disturbance
