Head Lice Flashcards Preview

Rheum/Musculoskeletal/Derm Week 3 > Head Lice > Flashcards

Flashcards in Head Lice Deck (13):

Rundown on lice

Wngless 6-legged blood-sucking insects that live on the human scalp and feed on blood every 3-6 hrs and lay 5-6 eggs/day for 30 days in a 'nit' (shell) glued to the base of hair

The 'infection' may be asymptomatic or itchines may arise from antigenic components in saliva injected into the scalp during feeding 


Treatment of lice

Successful eradication of lice requires killing both the adult and egg stages. For this reason, treatment involves repeated topical application at intervals to kill the recently emerged lice 

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How does Malathion (Ovide) work?

This is a topically given organophosphate insecticide that functions as an acetylcholinesterase inhibitor, leading to excessive cholinergic stimulation and consequent paralysis of lice. When applied topically, as recommended, this product is safe, but you can see typical signs of cholinergic toxicity (chest tightening, wheezing, bradycardia, diarrhea) if ingested 


Apply to wet hair, air dry, and allow to remain on scalp for 8-12 hrs then shampoo thoroughly


How is Malathion typically given?

Would also involve supportive measures as well as the use of the muscarinic antagonist ATROPINE and perhpas the cholinesterase regeneratory PRALIDOXIME


How does Permethrin (Nix) work?

Lethal to lice by blocking LOUSE voltage-gated sodium channels, thus slowing and stopping nervous system activity (paralysis). Permethrin is minimally absorbed (any absorbed is rapidly inactivated by ester hydrolysis, keep away from ears) so it is not toxic to humans (but very toxic to aquatic life and cats- not dogs).


Apply to damp hair, leave for 10 min, and then rinse 


How does Ivermectin (Sklice) work?

Broad-spectrum antiparasitic agent that is lethal via glutamate receptor binding, which causes an increase in the permeability of the cell membrane to chloride ions and hyperpolarizes the cell, leading to paralysis and death of the parasite. May also agonize GAGA, thereby disrupting GABA-mediated CNS transmission. 

Topical administration has minimal AEs




What can PO Ivermectin be used to treat?

Onchocerca volvulus, non-adult stage 


Pesticide-based treatments are linked to lower IQ, diminished attention span, childhood cancers, and other issues. Additionally, insecticide resistance in head lice growing, particularly to permethrin and malathion. 


What are some reisstance mechanisms used by head lice against insecticides?

-mutations in drug targets, increased rates of removal, etc.


What is Dimethicone?

A silicone based polymer that works mechanically to lubricate hair to aid the removla of nits and lice, while physically occluding the respiratory system of the louse. Dimethicone coating inhibits water excretion, which causes prolonged immobilization or, in some cases, internal organ failure. 


What is Air Alle?

A hair dryer where the application of heat dehydrates and consequently kills both adult and egg infestation. 


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What are the effects of AchE inhibitors?


Diarrhea, urination, Miosis/muscle weakness, Bronchorrhea, Bradycardia, Emesis, Lacrimation, Lethargy, Salivation/Sweating