Drugs used in treatment of Pancreatic infestation

Question 1

what are the 3 major targets of parasitic infections?

Answer 1

1. Unique essential molecule found only in the parasite
2. similar molecules found in both host and parasite but indespensible only for parasite
3. common biochemical functions found in both parasite and host but with different pharmacological properties

Question 2

how can parasites be categorized?

Answer 2

macroscopic: Taenia species (tapeworms), Enterobius (pinworms) and Pediculus (head louse)

Microscopic: Entamoeba (amebiasis), Giardia (beaver fever), Trichomonas and Plasmodium (malaria).

Question 3

What is the Taenia species?

Answer 3

Taenia saginata (beef tapeworm) and Taenia solium (pork tapeworm)

two examples of Taenia species that can infect humans.

Question 4

life cycle of Taenia species

Answer 4

• eggs or gravis proglottids are released into environment
• cattle (T. saginata) or pigs (T. solium) become infected when they ingest vegetation that is contaminated
• oncospheres hatch and penetrate the intestinal wall of the cattle or pigs and eventually circulate to the musculature
• humans become infected via ingestion of raw or undercooked meat
• scolex, or worm’s head, attaches to the intestine and can mature and produce more eggs.

Question 5

what are cestocial drugs

Answer 5

target and treat a category of parasitic worms

ex: Praziquantel and niclosamide

Question 6

what is praziquantel? how does it work

Answer 6

• Synthetic isoquinlone derivative w/ oral bioavail of 80%
• Exact mech not known but binds to integument of parasite and produces focal vacuolisation
• Increases permeability of Ca2+ ions which result in muscle contraction within seconds
• Impairs hooks and suckers at anterior end of worm which can cause paralysis making it drug of choice

Question 7

pharmacokinetics of praziquantel and adverse efefcts

Answer 7

• 80% oral bioavail
• safe and effective as single oral dose
• advised to swallow w/o chewing bc bitter and can cuse retching and vomiting
• bioavailability diminished if taken w/ corticosteroids
• adv effects: mild and transient adverse rxns: nausea, headaches and abdonimal discomfort

Question 8

what is Niclosamide

Answer 8

Salicylanilide derivate that is minimally abs in GI tract

MOA = rapdily killing the scolex and produces segnments of adult tapeworms and inhibition of mitochondrial anaerobic phosphorylation of ADP results in decrease in ATP production

Second line choice of treatment of tapeowrk infections of Taenia aginata and taenia solium

*must avoid alc following dosage!

Question 9

pharmacodynamics and adverse efefcts of niclosamide

Answer 9

• admin as single oral dose, must be chewed
• minimally abs in GI tract
• advantage bc cost effective and available in many parts of world
• adverse effects: minor GI complains: nausea, vomiting and diarrhea
• *MUST avoid alcohol for 24 hours following dosage

Question 10

what is enterbius vermicularis? what are symptoms of infection

Answer 10

• most common nematode infection in temperate countires
• contaminates nightclothes and bedding
• symptoms of infection = itching irritability, incontinence and weight loss

*minimize risk of infection via personal hygene and clean rooms

Question 11

life cycle of enterbius vermicularis

Answer 11

• eggs on perinanal folds which contain larvae that can mature within 4-6 hours, eggs are ingested by humans are larvae hatch in small intestine and adults form in the lumen of the cecum
• Eggs are sticky and can survive long periods of time in the env

Question 12

what drugs are used to treat enterbius vermicularis?

Answer 12

Mebendazole and pyrantel

Question 13

what is mebendazole? how does it work

Answer 13

• treatment of pinworm
• benzimidazole class: borad spec against endoparasites to treat pinworm like round, whip and hook worms

*if treating pinworm treat twice over two week interval

0 binds to B-tubulin and inhibits polymerization to microtubules to inhibit parasite motility, glucose uptake and cell division

• drug slowly kills parasite and will be expelled via feces

Question 14

pharmacokinetics of mebendazole and adverse effects

Answer 14

• if treating pinworm administer twice over two week period
• poor oral bioavailabilty of 10%, but can be improved by ingeting with a fatty meal
• efficacy depends on GI transit time
• if administer over short term wont really get adv effects but may experience: abdominal pain, nausea, and diarrhea

*containdicted during preg bc teratogenic and embryotoxic

Question 15

what is Pyrantel? how does it work

Answer 15

class of tetrahydropyrimidines

• treats round and hook worms but more narrow spec then mebendazole
• acts at neuromusuclar junctions of paraites on nicotinic acetylcholine receptors - causes release of acetylcholine and inhibition of acetylcholinesterase
• worms are paralyzed and will be expelled in feces

Question 16

pharmacokinetics and adv effects of pyrantel

Answer 16

• poorly abs from GI tract to it has activity iwthin the gut
• adv effects = milkd and transient nausea, vomitting and diarrhea

Question 17

what is pediculus capitis

Answer 17

• head louse
• clinical presentation = itchy head and adult live and eggs in hair
• transmission occurs by direct head to head contct, less common by sharing hair burshes

Question 18

life cycle of pediculus capitis

Answer 18

Nymphs and adult lice feed on human blood to grow and mature

Takes 8-9 days for egg to mature to first nymph and then 18-21 days to beocme an adult

Parasites rely on host for surival and can only survive less than two days away from scale at room temp

Question 19

what drugs treat pediculus capitis?

Answer 19

Permethrin and Malathion

Question 20

what is Permethrin?

Answer 20

class = phyrethroids

• synthetic derivative of insecticide pyrethin, from chrysanthemum plants
• acts by cuasing voltage gated Na channels to remain open causing memrbane depolarization and rapid paralysis in parasite
• minimally abs through skin and rapidly degredated by liver into inactive metabolites

*adv effects = mild burning of scalp, also not ovicidal

Question 21

what is Malathion?

Answer 21

Class = organophosphate

• use if permethrin fails
• MOA = irreversible inhibition of acetylcholinesterase cauing acucmulation of acetylcholine and rapid paralysis
• drug is hydorlyzed and inactivated by palsma carboxyesterases much faster in humans than in insects

*adv effects = mild burning of scalp, also not ovicidal