I take the occasional zofran or promethazine. My doc wanted me to take erythromycin or get a Botox injection, but my insurance said no way to both of them. I mostly just don't eat much, and drink nutritional drinks instead of solids.
I love that your insurance company gets to decide what's medically necessary. Seriously, I hope those HMO motherfuckers are the first ones up against the wall when the revolution comes.
Jeez, that's just awful that it's so bad you're not even tolerating solids. I'm so sorry.
So. I don't see any significant downside to taking the Domperidone for > 48 hrs; the exception is that it can also affect cardiac contractility, so that is a small possibility.
I can't recall the rules for the stat dose when it follows a 24 or 48 hr regimen. I'd either research it or split the difference and take 20 mg.
I don't see why the effectiveness would diminish over time, especially such a relatively short period. As
@Stan noted, it may even help give you some relief from your gastroparesis.