http://www.petapothecary.com/
This pet pharmacy is right near my house and was suggested by our IMS. They sell both compounded and name brand. I use the name brand Vetoryl from them as their compounded Trilostane is not much cheaper. I think you can do much better then the prices your vet is charging, they seem high. I cant find my last bill but we don't pay that. Alot of our members purchase from Diamondback Drugs in AZ when the use compounded. Not all compounding pharmacies are created equal so you need to purchase from a reputable pharmacy.
I do know that we all have read that it is easier to control blood sugars when the cortsiol is more evenly controlled throughout the day, which means twice day dosing.
I am not sure why your vet thinks a post of 6ug/dl is low unless it has something to do with controlling Scoop's diabetes. It is not low.
Yes, a dog's cortisol can continue to drop on the same dose but it also can go higher. Keep in mind hormones fluctuate so that is why we have a range of numbers to begin with. My Zoe was appx 6.2 in September, 10.2 post in October and dropped to 7.1 in January all on the same dose. ( I may be off a bit on those numbers, but you understand my point) She has bounced around when she first started on the same dose going lower, then gowing higher.
There can be a difference in Trilostane and Vetoryl as far as how much of the acting ingredient is in a capsule. With the name brand, it does not vary, so we know for sure that 10mg is exactly 10mgs. There was a study done where I think it was 5 different compounding pharmacies Trilostane capsules were tested. Not all of the pharmacies passed the test and the amount of Trilostane in a 10mg capsule varied. This is why we say only use a reputable compounding pharmacy.
Hope this helps a little. Oh- I see Marianne and I were typing at the same time.