Ivermectin

Agent: ivermectin

If you practice in a healthcare institution, you will likely be treated to at least one scabies outbreak over your career, if not one each year. While scabies is most often treated with permethrin cream, patients or their healthcare providers who are unable or unwilling to baste themselves in the cream will receive oral ivermectin. Ivermectin is also given to patients with the highly contagious “Norwegian scabies” (an unwarranted aspersion on Scandinavian hygiene). In addition to scabies, ivermectin is also effective in treating several diseases that may be endemic in tropical settings, such as the causative agents of river blindness, strongyloidiasis, and cutaneous larva migrans, the latter two occurring infrequently in the United States. It can also be used for treatment of Strongyloides hyperinfection syndrome, an increasingly recognized cause of life-threatening illness in immunocompromised patients.

Spectrum

Ectoparasites: Sarcoptes scabei (scabies mite), Pediculus humanus (lice)

Nematodes (roundworms): Onchocerca volvulus  (river blindness),  Strongyloides stercoralis  (strongyloidiasis), Ancylostoma brazilense (cutaneous larva migrans), other nematodes

Adverse Effects

In treatment of scabies, ivermectin is very well tolerated. Severe adverse reactions, including fever, myalgia, and hypotension, have been reported when ivermectin is used for management of nematode infections in endemic settings. These effects are thought to be a result of the host’s immune response to antigens released from killed parasites. These effects are more severe in patients with higher worm burdens, and they generally resolve soon after drug administration.

Important Facts

• Yes, ivermectin is the same drug you use to treat your dog’s heartworms. It’s also at the center of a heartworming story: after ivermectin was shown to be effective as a once-yearly treatment for river blindness, the pharmaceutical company Merck offered to donate, free of charge, as much ivermectin as was needed to treat the disease. It’s estimated that 200 mil-lion free treatments have been provided to date, avoiding more than half a million cases of blindness. Hey, at this point in the book, we figured you could use some good news (and bad puns).  for treatment of head or body louse infestation, and for treatment of Ancyclostoma infections. It is also a drug of choice for infection caused by  Strongyloides or Onchocerca.

Don’t Forget!

For treatment of ectoparasitic (scabies or lice) infestation, ivermectin should be administered as 2 doses, approximately one week apart. Administration of a single dose increases the risk of relapse.

What It’s Good For

Ivermectin is used as an alternative to topical permethrin for scabies infection, to topical therapies

References

Gallagher ,J.C. and MacDougall ,c. (2012). Antibiotics Simplified. Second Edition. Jones & Bartlett Learning, LLC.