Expert: Leo Carr - 7/17/2006

Question
The Ivermectin solution I'm referring to is a cattle injectable. Ivermectin is the same chemical used as a heartworm prevention in a product called Heartgard. Many kennel owners take the cattle ivermectin and dilute it down to the right dosage for a dog as a cost effective heartworm prevention without a perscription. I did some research online and found info that says mixing with water is not adviced. Below is something I found about mixing water with ivermectin:

"We see many people diluting Ivermectin sheep, cattle, and horse products with water and this is not recommended by the developer of Ivermectin, Merial. The following note is self explanatory.

IVOMEC sheep liquid is formulated as an emulsion with the Ivermectin dissolved in a solvent and this solution then held emulsified in water by a delicate balancing act with various additives including surfactants. Once you add more water to the mix you then change the balance and at some stage the emulsion will collapse and the Ivermectin will crash out. How much dilution causes this... don't know but it will happen. We have a concentrate product called Jetamec which is formulated to take more significant dilution but it is registered only as a jetting fluid for sheep.

As far as pour ons and injections are concerned - they are all solvent with no water - any dilution with water is ill-advised."

David R Homer BVSc (hons 1) PG Dip. (Macq)
Technical Services Manager, Merial (Aust) Pty Ltd.
Date: 7-11-2003



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Followup To

Question -
Hi Leo,

Would propylene glycol be a good solution to mix with an Ivermectin solution. I'm wanting to reduce a 1% solution down to a .05% solution and was wondering if you could tell me if propylene glycol is a good mix. I'v read in several places that propylene glycol is good, but I wanted to see what your thoughts are on it. Thank you.

Cheryl

Answer -
I am not sure what ivermectin solution is, but after a quick search I see it is an anti-parasite drug.  Propylene glycol has several OH groups which make is very polar.  It looks like the ivermectin is very polar as well with multiple -OH groups.  Is there any reason not to use water?

I don't see why you cannot use propylene glycol.  

Answer
It makes perfect sense not to dilute it in water if it carries with it surfactants, buffers, and stabilizers.  I have had a problem with a cholesterol standard I bought with the same sort of added things.  So, I had to make my own in my own solvent in order to set up a linear curve.

I did not know what type of solvent the drug is dissoved in. Now the question why propylene glycol?  Wouldn't this also dilute out the drug with the additives?

I would recommend that if other indviduals you know (and trust) are doing this cost-effective method without any ill-results to the cows then it would probably be OK.

As a chemist and small farmer (goats, chickens) I know sometimes you just have to do things on your own. Good luck.