September 24, 2018
I’m a drug that was developed for animals, but I now have a human use as well.
What molecule am I?
Image of Moxidectin 3D Image of Moxidectin

The macrocyclic lactone moxidectin is an anthelmintic drug, which means that it is used to control or prevent parasitic worms (helminths). Its principal use is veterinary, in animals ranging from dogs and cats to cattle and horses. Parasites susceptible to moxidectin include Strongylus vulgaris (“blood worm”) in horses and Ostertagia ostertagi (“brown stomach worm”) in cattle.

Moxidectin, obtained from Streptomyces bacteria, was developed in the 1980s by the now-defunct American Cyanamid Co. Today, it is marketed worldwide under several trade names by major pharma companies such as Bayer Animal Health, Pfizer Animal Health, and Zoetis.

This year, on the basis of only two double-blind studies, the US Food and Drug Administration approved the use of moxidectin on humans. The target disease is river blindness (onchocerciasis), which occurs mainly in sub-Saharan Africa. The disease is caused by the parasitic worm Onchocerca volvulus, which is disseminated by Simulium species of black flies.

Moxidectin was registered by the nonprofit Medicines Development for Global Health (MDGH) with guidance from a World Health Organization initiative. MDGH is the first nonprofit to register a tropical medicine drug through FDA’s priority review voucher program.

Moxidectin hazard information

GHS classification**: acute toxicity, oral, category 3
H301—Toxic if swallowed Chemical Safety Warning
GHS classification: hazardous to the aquatic environment, acute hazard, category 1
H400—Very toxic to aquatic lifeChemical Safety Warning

**Globally Harmonized System of Classification and Labeling of Chemicals. Explanation of pictograms.

Moxidectin fast facts

CAS Reg. No.113507-06-5
Molar mass639.82 g/mol
Empirical formulaC37H53NO8
AppearanceWhite to pale yellow crystals or power
Melting point131–154 ºC*
Water solubility4.3 mg/L

*Scant data in literature

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