People need to understand the 1.87%. Just to explain the math you used a little more. The 6.08 gram tube (or 6,080 mg) of the horse medicine contains only 113 mg of ivermectin (1.87% times 6,080 mg).
Consequently, if you need 30 mg of ivermectin you need to take 1,604 mg (30 mg /.0187) of horse paste or 1.6 grams. You can use the computer to convert to ounces.
It seems like there should be more problems with people taking too little of the horse paste, not enough. Of course the establishment is not worried about people not taking enough.
It has a wide safety profile even at higher levels. I was talking to my vet years ago (he was confirming my math to make my own heartworm preventative for my dogs with 1% ivermectin). He said most recipes he sees online are about 10 times too high, but it doesn’t worry him because it is very safe (except for certain breeds, or dogs prone to seizures)
That said, it is processed through the liver - should probably work with a doctor on dosing if you have cirrhosis, etc.