Hi, I'm Dr. Jill. I would be happy to assist with your questions.
First, in regard to dosing, follow-up ACTH blood testing can be used to assess the Pergolide dose to see if it's adequate. I also look for clinical improvement as a good indicator of how effective the dose is. That is, if a horse didn't shed their winter coat and does within a few weeks of a dose adjustment, then the dose being used is helping.
Second, in regards XXXXX XXXXX formulations, the only form approved in the US (I'm not sure about the UK) is the tablet form. If you have access to another liquid formulation, the dose will depend on the concentration of the liquid. That is, the mg/ml (or other units of measure). Concentrations can vary so 1ml of one formulation can have a very different amount of drug than 1ml of another. It should be clearly stated on the packaging. If not, don't use it :). You'll have no idea how much you're giving.
I believe the UK has similar compounding options as in the US as well. So, your veterinarian can have a different formulation made at a compounding pharmacy if needed. It is designed to allow specific formulations for individuals who's needs don't fit the approved formulations, and liquid or powder forms are commonly made for pergolide (especially when Prascend wasn't available). That said, compounding pharmacies don't
Adhere to as stringent of regulations as compared to pharmaceutical companies, so drugs sometimes vary in concentration and activity level. (That is, they can degrade and not be present in the labeled concentration anymore.) There have also been several famous incidents recently in the states regarding compounded drug contamination or errors that resulted in human and animal deaths. So, most of the time these alternate formulations are safe, but they do carry higher risks that you should be aware of. I generally prefer the approved formulations (Prascend in this case), but I don’t hesitate to switch, personally, if the approved formulation is really an issue.
Compounded drugs do require a prescription, so this is something you would want to discuss with your regular veterinarian who is prescribing the medication.
I hope this helps address your concerns and shed light on the issue. If there is anything that is still unclear or any way I can further assist, please let me know. I would be happy to continue the conversation. Thanks!