Re: Time to switch meds. Want to go in informed.
Conversion is something for your doctor to do. Often they start low (such as 50% of the expected dose), just to be safe. So, its possible you will have extra pain or even withdrawal in that process. Is your doctor opposed to increasing the dose? Its expected to have tolerance, but it depends on the doctor as whether they want to increase the dose or try to switch to take advantage of the potential lower cross tolerance.
I have been switched straight over from methadone to morphine. They had be wait some time between starting the new med, and started me at such a low dose I was in withdrawal. Often they have you come in every 1-2 weeks during that sort of time, and may give you some extra breakthrough meds. Some doctors prefer to decrease the old med while increasing the new one though.
I'd just go into your next appointment and discuss your decreasing pain relief, and ask what can be done. They will either say they don't want to do anything, try to add in another med or treatment, increase the dose, or switch you. Your best way to be informed is to know what has and has not worked for you in the past, and maybe to double check that your doctor doesn't start you at too high of a dose (unusual).
With trial and error, oddly enough, I've found that methadone is the only realistic long acting med for me. Every other one doesn't give me nearly as much bang for the buck, so I'd require a much higher equivalent dose. Everyone is different though. Surprised you only take the methadone twice a day...I require four times a day, and would do even better with five. Meds burn through my system very fast. Best wishes.
constant headache since 2006