Ivermectin is considered a semi-synthetic compound, meaning it has both natural and synthetic components to its origin.

Here's why:

* Natural Origin (Avermectins): The initial compounds from which ivermectin is derived are called avermectins. Avermectins are natural products isolated from the fermentation of a soil bacterium called Streptomyces avermitilis. This bacterium was originally discovered in a soil sample collected in Japan.

* Synthetic Modification: Ivermectin itself is a dihydro derivative of avermectin. This means that the naturally produced avermectins undergo a chemical modification (hydrogenation) in a laboratory setting to create ivermectin. This slight chemical alteration enhances its activity and safety as an antiparasitic drug.

So, while the foundational compounds come from a natural source (a bacterium), the final ivermectin molecule is produced through a semi-synthetic process involving chemical modification.