A systematic review of transdermal fentanyl and
buprenorphine for moderate to severe cancer pain21
includes the results of one meta-analysis of four RCTs that
compared oral morphine with fentanyl or buprenorphine49
and one RCT with three parallel arms that compared oral
morphine with fentanyl and methadone.50 No signifi cant
diff erences in effi cacy emerged between either transdermal
preparation and other opioids, but a diff erence in favour
of transdermal preparations was seen for constipation,
and patients’ preference,49 which suggests that in some
cases transdermal opioids are appropriate and eff ective in
patients who have not previously received step III
opioids.5