If you are on methadone maintenance, especially at such a large dose the first step would be to swap 1 dose every 24 hours to half the dose every 12 hours - that will already increase analgesia (the T1/2 of methadone is 8.5 hours and although normethadone prevents withdrawal, it isn't an analgesic).
Mixing opioids is absolutely contraindicated and given that methadone is also an NMDA antagonist, it's actually a very GOOD opioid for treating cancer pain.
IF the doctor insists on swapping you to another drug then Levo-Dromoran (Levorphanol) is just about the best option. It can be administered BID and not only is it x16 methadone in potency, it's a more potent NMDA antagonist. It's also typically given BID. 8mg/day is the official limit is 8mg/day but frankly, it's going to be the SAFEST and most appropriate option.
You really should go to a pain clinic because they should know just what is best but more importantly, they deal with strong opioids every day and so they are not afraid to advise your doctor who, having been advised, is going to be more comfortable prescribing the large doses that will be required.
Oxycodone is just the drug doctors are familiar with, it isn't appropriate for someone on methadone maintainence. Why on earth they are insisting on reducing the methadone is a mystery to me.
Methadone has been an unique, versatile, cost effective, synthetic opioid utilized in nociceptive as well as neuropathic pain. Pain and palliative care physicians started accepting methadone in treatment of complex pain associated with advanced ...
www.ncbi.nlm.nih.gov
Send him the above link. As long as you have had an EEG then their shouldn't be an issue. If not when you are on 210mg/day suggests a level of ignorance I find astounding. Notice how methadone's analgesic activity increases in a non-linear fashion to the extent that a small increase and BID dosing would provide the analgesia of simply HUGE doses of morphine.
As it is, 200mg of methadone is a LOT but it's T1/2 means it has to be taken twice a day.
Hope this helps.