“Morphine is the best first choice for chronic potent opioid therapy (SOR B). It is reliable and inexpensive, and equivalent doses can be easily calculated if the patient must later be switched to another medication.
Transdermal fentanyl and hydromorphone are reasonable second-line choices; however, they are not recommended as first-line therapy because they are expensive and can produce tolerance relatively quickly (SOR B).
Methadone is another second-line option and tolerance is usually less of a problem. It is inexpensive and long-acting but also has unique pharmacokinetics. It has a very long elimination half-life, and its morphine-equivalent equianalgesic conversion ratio increases as dosages increase. Methadone can prolong the QT interval, especially in patients who are taking other QT-prolonging medications (SOR B).
Buprenorphine is a partial opioid agonist that is usually used for treatment of patients with opioid addictions. Although it can be effective for treatment of pain, it is expensive and requires special prescriber training, so it is currently not recommended as a first-line agent for treatment of chronic pain (SOR C).” From ABFM Intraining question response.
