Hello DLF,
I've been on methadone for about 20 years. For myself, it's inexpensive, and has minimal side effects. I wouldn't change to any other med, and I've tried lots of them.

PRN though, (as needed), is not a great way to go, is my personal opinion.
I think you should try something like, breaking them in half, and try twice, 3, or 4 times/ day. Then, another half for breakthrough pain.
See if that's enough.

The average dose is 60mg/ day, and I've been at anywhere from 15, to 100mg / day.
Now, I do pretty well at 50/60 mg/ day.

It IS the kind of med, that will let you know when you forget to take it!
So, my suggestion is try a low dose, and use it as I said, with the extra for Break through pain.

I hope that might help you.
Feel free to PM me if you like...

Pete
asb

PS, it can be constipating, but, if you're active, and eat well and get enough fluids, it'll be fine. I do take a dose of Miralax everyday.
and all is well...