Ectoparasiticide

Variants

Permethrin

Broad-spectrum and potent pyrethroid insecticide and is most convenient for both scabies and lice. First choice drug. Permethrin exerts its therapeutic effect by disrupting sodium transport across neuronal membranes in arthropods, inducing depolarization. This mechanism ultimately leads to respiratory paralysis in the affected arthropod, establishing permethrin as a potent agent in managing scabies and pediculosis.

Additional information about treatment failure rates amongst medications used to treat ectoparasites:

https://www.dermatologyadvisor.com/news/scabies-treatment-failure-rates-increasing-among-children-and-adults/

The above research article, noted from current studies, shows that Permethrin is only 89.2% effective. There is noted resistance that has been increasing each year, as noted in the article.

Crotamiton

Second choice drug. Effective scabicide, pediculicide and antipruritic. Cure rate 60-88%.

Benzyl benzoate

2nd line drug for scabies and is seldom used for pediculosis. Cure rate 76-100%

Lindane

Effective in treating head lice (67-92%cure) and scabies (84-92% cure) with a single treatment. Penetrates through chitinous covers and affecting the nervous system.

Sulfur

Oldest scabicide and weak pediculicide, antiseptic, fungicide and keratolytic. Applied to skin, it is slowly reduced to H2S and oxidized to SO2 and pentathionic acid, which dissolve the cuticle of itch mites and kill it.

Ivermectin

Antihelminthic drug found highly effective in scabies and pediculosis. Acts through a glutamate-gated Cl− ion channel found only in invertebrates.

Dicophan

Insecticide for mosquito, flies and other pests. Penetrates through the exoskeleton and acts as a neurotoxin.

Other Applications

Possible Poaching Deterrent

Ectoparasiticides have seen use as chemical agents in South Africa with the aim of devaluing rhinoceros horns and combating illegal poaching. Lorinda Hern, founder of the Rhino Rescue Project, devised a plan to infuse rhino horns with ectoparasiticides and mark the outer surface with a bright pink dye. This innovative approach seeks to deter poachers by creating health concerns amongst potential buyer communities. The procedure involves drilling into the rhinoceros horn, injecting it with an ectoparasiticide compound, and tagging it with a distinctive pink dye. The drill and inject procedure is considered harmless to the rhinoceros species due to the horn being isolated from both the nervous system and the bloodstream.

References

References

1. Taylor MA. (May 2001). "Recent developments in ectoparasiticides". Vet. J..
2. Tripathi, J.D. (2010). "Textbook of Pharmacology". Jeypee Publications.
3. Henriques, Martha. (2016-01-13). "Ectoparasiticides".
4. Nanda, Japbani. (2024). "Permethrin". StatPearls Publishing.
5. "Poisoning rhino horns doesn't hurt the rhinos, but it may keep poachers away".