Anthelminthic Drugs Flashcards
Basic Concepts: Helminths and Anthelminthic Drugs
Round worms or flat worms
Group of biologically diverse creatures
Anthelminthic drugs act via ‘lumically’ or systemically
Roundworms: Subtypes
Geohelminths
Filiarial nematodes
Geohelminths
Parasites
Ascaris Lumbricoides (round worm) Hookworm Whipworm Enterobius vermicularis (pinworm) Trichinella Spiralis
Geohelminths
Ascaris Lumbricoides
Infection via injected food or soil with embryonated eggs
Larvae–> via duodenal wall–> bloodstream–>liver–> heart–>lung: grows. Cough–> GIT–> male and females meet–> eggs
Eggs passed on via feces
Symptoms
coughing pneumonia dyspnea haemoptysis
fever
splenomegaly obstruction appendicitis
Treatment Albendazole Mebendazole Pyrantel pamote (CI: obstruction!) Levamisole
Geohelminths
Hookworm
Larvae live in soil, warm and humid places; infect via skin penetration
Eggs are passed on via feces (dogs, rabbits); humans are dead ends
Itchy rash at site of entry
coughing, fever, anemia
Treatment
Albendazole
Mebendazole
Geohelminths
Whipworm
Diag via microscope
Ingestion of embyronated eggs–> larvae hatch in intestine–> penetrate mucosa. Adults + in large intestine
Passed on via feces
Treatment
Albendazole
Mebendazole
Geohelminths
Pinworm: Enterobius vermicilaris
Most common in temperate climate
Ingestion of embryonated eggs–> hatch in small intestine–> migrate to perianal region–< lay eggs
Heavy itching in perianal region esp at night
Can–>peritonitis if worms go exploring
Albendazole
Mebendazole
Pyrantel pamote
Geohelminths
Trichinella Spiralis
Prevention: thoroughly cook food
Ingestion of undercooked meat–>mature parasites get to stomach–>lay eggs–> tissue invasion from stomach–> move into skeletal muscles and heart
Marked muscle pain and weakness
cardiac problems
increased CK
Albendazole
Mebendazole
Analgesics
Filarial Nematodes
Parasites
Wuchereria Bancofti
Loa Loa
Dracunculus medinensis
Filarial Nematodes
Wuchereria Bancofti
AKA elephantiasis
Bites of infected mosquitos–> adults enter lymphatics-> produced sheathed filariae–> damage lymphatics
Usually asymptomatic
Lymphatic inflammation
Fever
Ivermectin; can be in combo with Albendazole
Diethylcarbamazine
Filarial Nematodes
Loa Loa
Tissue migrating filarial parasite
Bite of infected horse fly–> adults get into SC tissue–> sclera
Adults produce microfilaria–> lymphatics, blood, sputum
Symp:
Eye worm
SC swelling
Ivermectin
Diethylcarbamazine
Filarial Nematodes
Dracunculus medinensis
Drinking of unfiltered water containing larvae
Worms can migrate into skin
–> extraction by slowly pulling it out
No pharmacological therapy (required)
Flat Worms: Subtypes
Tapeworm –> able to fertilise themselves
Flukes
Tapeworm
Taenia Solium
Ingestion of undercooked infected pork
–>maturation in intestines–>adult worms produce proglottis–>release of eggs
Eggs develop into oncospheres–>penetrate muscle and brain.
Symptoms
Usually asymptomatic
anaemia, malnutrition, cysticerci
muscle pain
Albendazole
Parziquantel
Tapeworm
Echinococcus
Types: cystic and alveolar
Ingestion of eggs from dog feces
–> development of cysts in body
Symp depends on localisation of cyst liver--> jaundice, abdominal pain lungs--> SOB, coughing, chest pain brain--> neurological sympt anaphylactoid reaction
Albendazole (slow th to decrease substance release)
Mebendazole
Surgical removal of cyst
Flukes
Fasciola Hepatica
Live in human liver, mainly bile duct and gall bladder
Infection via undercooked water plant food
Passed on via feces
Praziquantel
Ivermectin
Anthelminthics: Drug List
Benzimidazoles: Albendazole, Mebendazole... Diethylcarbamazine Ivermectin Praziquantel Niclosamide Pyrantel Pamoate Levamisole
Benzimidazoles
Albendazole
Mebendazole
Thiabendazole
Wide Spectrum
MoA: selective toxicity via high affinity to b tubulin
binds b tubulin–> inhibits microtubule polymerisation->
immobilisation -> impaired glucose and nutrient uptake
Pharmacokinetics
Erratic GIT absorption, better with fat rich diet
larger intraluminal than systemic effect due to
extensive pre systemic elimination
SE (mild except for thiabendazole)
nausea
anorexia
Uses Ascaris Lumbricoides Hook worm Whip worm Pin worm Trichinella spiralis Wuchereria brancofti Taenia solium Echinococcus
Diethylcarbamazine
MoA
causes organelle damage–> apoptosis
SE : due to destruction of parasites
Lymphangitis
Lymphoid abscess
Uses
Wuchereria brancofti
Loa Loa
Ivermectin
MoA: selectivity due to glutamate gated Cl channels (not present in humans)
–> hyperpolarisation–> flaccid paralysis
Low GIT absorption
Extensive PPB
Extensive biotransformation by CYP system
SE: due to toxic substances released from dying parasite
Itching
Edema
Headache
Uses
Wuchereria brancofti
Fasciola hepatica
Praziquantel
Wide spectrum
MoA
–> Ca release from IC stores–> paralytic muscle contrac.
Rapid GIT absorption, extensive hepatic biotransformation
Also useful in extraluminal parasites
SE: due to destruction of helminth
Abdominal pain
Nausea
Headache
Uses
Taenia solium
Fasciola Hepatica
Niclosamide
MoA
uncouples oxidative phosphorylation
inhibits qlycosylation
Minimal GIT absorption–> remains intraluminal
also means that SE are minimal
Uses
Tapeworm
(((CI in taenia solium as results in release of eggs)))
Pyrantel Pamoate
Wide spectrum
MoA
depolarising NM block–> paralysis (flaccid then spastic)
Intraluminal action
Single dose sufficient in some cases
Uses
Ascaris Lumbricoides (not in obstruction)
Enterobius vermicularis
Levamisole
MoA
Nicotinic R agonist–> spastic paralysis in parasites
