Hi, I'm going to link to two of my older posts about methadone, in case you didn't see them:

http://neurotalk.psychcentral.com/post15298-4.html

http://neurotalk.psychcentral.com/post148705-8.html

There are two major things you should understand about this drug:
1) it can affect the heart....as I explain in the first link. Some doctors today, still don't know this. Methadone is the only one of the opiate family that can cause long QT problems.

2) Methadone is long acting. And the time it sits on the pain receptors is shorter than the half life. So pain relief is gone before the drug is safely cleared from the body. That means that taking doses too close together, may build up and 1) interact with other drugs you may be taking, or 2) put you into a toxic level. Taking 30 milligrams all of a sudden, may not be a good idea, if you have not been screened with a Cardiac EKG and are taking drugs that may add to the QT problem and be additive with methadone.

However, many pain patients do well with methadone as long as the safety precautions are observed. Some of our PN patients here use it, and typically low doses suffice for the most part.

Methadone is inexpensive compared to other opiates, and is also preferrable for that reason. Low blood levels of magnesium and potassium can throw a person into a long QT event, even if they test normal on an EKG. A bout of stomach flu with vomiting and diarrhea may make the methodone more dangerous, in other words.

So please do read my other links. I've been posting about this for years, for the safety of patients, whose doctors are not currently informed about long QT potential and this drug.