ANTIHELMINTHIC DRUGS
Overview
- helminths are eukaryotic hermaphroditic parasitic worms that replicate sexually, either by heterologous fertilization (“sequential hermaphrodites”) or by autologous fertilization (“synchronous hermaphrodites”)
- they may exist in 3 common forms
FORM DESCRIPTION
EGG - the inactive, fetal form of the helminth
- only occurs in some species of helminths (other species of helminths give birth to live larvae, see below)
LARVA - the immature, non-reproductive form of the helminth
ADULT - the mature, reproductive form of the helminth
DRUGS USED AGAINST NEMATODES
Overview
- “roundworms”
- species include
SPECIES DESCRIPTION ASCARIS LUMBRICOIDES
ANCYCLOSTOMA DUODENALE NECATOR AMERICANUS ENTEROBIUS VERMICULARIS STRONGYLOIDES STERCORALIS TRICHURIS TRICHIURA TRICHINELLA SPIRALIS WUCHERERIA BANCROFTI
BRUGIA MALAYI
Relevant Drugs
- 7 types
DRUG NAME DESCRIPTION PYRANTEL General information
- an irreversible nicotinic receptor agonist
(“depolarizing neuromuscular blocking agent”,)
- irreversibly binds to nicotinic receptors at the neuromuscular junction, thus causing spastic paralysis of the helminths
- administered orally
Medical uses
- first-line treatment of ascaris lubricoides, ancyclostoma duodenale, necator americanus and/or enterobius vermicularis infection
Side effects
- vertigo
- nausea, vomiting and/or diarrhea
LEVAMISOLE General information
- same as pyrantel (see above)
- may cross the blood-brain barrier
Medical uses
- second-line treatment of ascaris lumbricoides, ancyclostoma duodenale, necator americanus and/or strongyloides stercoralis infection
Side effects
- vertigo
- nausea, vomiting and/or diarrhea
- mazzotti reaction (hypersensitivity reaction leading to fever, headache , skin rashes, myalgias and/or arthralgias caused by dying helminths)
MEBENDAZOLE General information
- a microtubule inhibitor
- binds to depolymerized tubulin, thus inhibiting the polymerization of tubulin into microtubules and following inhibition of microtubule-dependent glucose
uptake by the helminths
- administered orally
Medical uses
- first-line treatment of tricuris trichiura and/or trichinella spiralis infection
- second-line treatment of ascaris lubricoides, ancyclostoma duodenale, necator americanus, enterobius vermicularis and/or strongyloides stercoralis infection
- first-line treatment of echinococcus granulosus and/or ecchinococcus multilocularis infection (cestodes, see below)
Side effects
- nausea, vomiting and/or diarrhea
- epigastric pain
THIABENDAZOLE General information
- same as mebendazole
Medical uses
- first-line treatment of strongyloides stercoralis infection
- also used in the treatment of scabies due to sarcoptes scabiei infection
Side effects
- vertigo
- nausea, vomiting and/or diarrhea
- epigastric pain
- mazzotti reaction (see above)
DIETHYLCARBAMAZINE General information
- inhibits the metabolism of arachidonic acid within the helminths, thus rendering the helminths susceptible to the host’s immune defense system
- administered orally
Medical uses
- first-line treatment of wuchereria bancrofti, brugia malayi and/or onchocera volvulus infection
Side effects
- headache
- nausea, vomiting and/or diarrhea
- mazzotti reaction (see above)
IVERMECTIN General information
- a GABA agonist
- binds to presynaptic GABA receptors of the cholinergic neurons responsible for neuromuscular transmission, thus leading to hyperpolarization of the cholinergic neurons and following flaccid paralysis of the helminths
- administered orally
Medical uses
- first-line treatment of onchocera volvulus infection
Side effects
- mazzotti reaction (see above)
PIPERAZINE General information
- same as ivermectin (see above)
Medical uses
- second-line treatment of enterobius vermicularis infection
Side effects
- vertigo
- paresthesia
- motor disturbances
- bronchospasms
- nausea, vomiting and/or diarrhea
DRUGS USED AGAINST TREMATODES
Overview
- “flukes”
- species include
SPECIES DESCRIPTION SCHISTOSOMA HEMATOBIUM
SCHISTOSOMA JAPONICUM
SCHISTOSOMA MANSONI
Relevant Drugs
- 2 types
DRUG NAME DESCRIPTION PRAZIQUANTEL General information
- increases the permeability of the muscle cells to calcium, thus
leading to depolarization of the muscle cells and following spastic paralysis of the helminths
- administered orally
Medical uses
- first-line treatment of schistosoma hematobium, schistosoma japonicum and/or schistosoma mansoni infection
- first-line treatment of hymenolepis nana infection (cestodes, see below)
- second-line treatment of taenia solium, taenia sagginata and/or diphyllobothrium latum infection (cestodes, see below)
Side effects
- vertigo
- nausea, vomiting and/or diarrhea
- mazzotti reaction (see above)
OXAMNIQUINE General information
- interposes between adjacent base pairs in the DNA, thus causing an inability of DNA polymerase to move along the DNA during replication of helminthic cells
- administered orally
Medical uses
- second-line treatment of schistosoma hematobium, schistosoma japonicum and/or schistosoma mansoni infection
Side effects
- headache
- vertigo
- dysphoria
- convulsions
- nausea, vomiting and/or diarrhea
- mazzotti reaction (see above)
DRUGS USED AGAINST CESTODES
Overview
- “tapeworms”
- species include
SPECIES DESCRIPTION ECHINOCOCCUS GRANULOSUS
ECHINOCOCCUS MULTILOCULARIS TAENIA SOLIUM
TAENIA SAGGINATA DIPHYLLOBOTHRIUM LATUM HYMENOLEPIS NANA
Relevant Drugs
- 3 types
DRUG NAME DESCRIPTION MEBENDAZOLE General information
- a drug used against nematodes (see above)
PRAZIQUANTEL General information
- a drug used against trematodes (see above)
NICLOSAMIDE General information
- uncouples oxidative phosphorylation in the helminths
- administered orally
Medical uses
- first-line treatment of taenia solium, taenia sagginata and/or diphyllobothrium latum infection
- second-line treatment of hymenolepis nana infection
Side effects
- nausea and/or vomiting
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