I'm not a vet or a biochemist -- but near as I can tell by googling it, trimethylacetate is just the carrier that dexamethasone is mixed with. Same concept as sodium phosphate being mixed with dex in what you usually use. I'd think you could use the new stuff the same way you've used your other dex in the past. Several sources mentioned dex trimethylacetate being used to induce parturition, so it evidently has the same action. Was there no label attached to the bottle? As I said, I'm not a vet (yet) but I do think it should be okay to use in the same way you've used dex in the past. I'd use it. Do check to make sure the amount of dex in the bottle (in grams) is the same as the dex NaP you usually use so you don't overdose or underdose.