^^^ First off, methadone has no ceiling effect whatsoever; patients can take hundreds of Meg's per day in some cases. Now for maintenance, I agree, that's bs, but some pain patients with chronic malignant pain, who get to a pony of taking a gram of morphine per day actually need very high doses of methadone.
And dosing methadone 4 times per day is silly; the only time they do that I during induction of pain management, and there is a reason; methadone is MUCH MORE effective, once it ga reaches steady state;prior to this, unless you take a single large dose, methadone is widely distributed across the body, reducing it's effect, and then redistributed a few hours later(from the brain to other tissues) which limits it's duration of action.
However, with chronic dosing, tissues become saturated. Once this happens, a subsequent dose is literally twice as potent, and lasts much longer.
That's why one dose(or sometimes 2) is effective in MMT;
To overcome this, it is sometimes initially given 3-4 times per day to patients, and then eventually reduced to two or 3 doses per day.
It is true that pain patients usually take two or three smaller doses per day; this is partially to avoid side effects, an keep a more consistent plasma level. But there is a very big difference between taking methadone for pain, and using it as Maintenence for opioid addiction; the needs of the patient are different, the doses generally lower, and the patients often times not used to high doses of opioids.
With that said, I don't really agree with doctors splitting an MD dose into 3 equal parts(ie: 20mg TID) as it would be more effective to give two larger doses, with sufficient breakthrough medication, but, ITP...