Have an EKG first, to rule out any heart rhythm problems (prolongation of QT).

All FDA approved forms of Methadone adhere to content. There has been
an internet backlash against Methadose by Mallincrodt but much of that hoopla was misinterpreted data on % of bioavailbility stats, and not actual content.

Some tablets are harder than others and dissolve slightly more slowly, and this
gives a perceived different effect to the patient.

Many people prefer Roxane brand, for this reason.

Also, people vary in their metabolism of methadone...some slow some fast.
So going slowly with small doses in the beginning gives you information as to
how the drug works for you. There are drug interactions with methadone...especially SSRI drugs. See the lists in the chronic pain useful websites that I posted here. Combining methadone with other drugs can be
dangerous. It can also be dangerous if you become depleted in potassium and magnesium for whatever reason (diarrhea, flu, diuretics, or poor diet).