[Validity of recommended minimum dose of prior morphine to initiate transdermal fentanyl patch in prescribing information - multicenter survey of on prescriptions by palliative care specialists in Japan].

For initiating the minimum-size (0.25 microg/hour) transdermal fentanyl patch (TDF), 45 mg a day of oral morphine is the recommended minimum dose (RMD) in Japan according to the prescribing information. However, little is known about the validity of the RMD, and we can presume there are many cases where clinicians are inclined to initiate the minimum-size TDF at the early stage contrary to the RMD due to the high morbidity rate of digestive system cancer in Japan. In order to verify the validity of the RMD, we collected 71 retrospective cases where the minimum-size TDF was initiated against the restriction of RMD. The prior morphine (or equivalent doses of other opioids) was prescribed by palliative care specialists at 5 facilities which belong to Symptom Control Research Group (SCORE-G). Then, the side effects and pain control from the 1st to the 4th day were analyzed. The mean age of subjects was 68, and the main reason for initiating TDF therapy was gastrointestinal symptoms (63.4%). The frequency of side effects such as somnolence, nausea, vomiting and constipation did not show a significant correlation with the prior opioid dose.However,severe dyspnea and respiration depression were documented in two patients, and the above rate was three times higher than the nationwide result of the same side effects (0.9 8%). According to the Numeric Rating Scale (from 0: no pain to 10: the worst pain), the pain intensity decreased from 6.6 on the 1st day to 2.8 on the 2nd day, 3.3 on the 3rd day, and 2.9 (p < 0.001) on the 4th day. We conclude that, although introducing the minimum-size TDF against the RMD served to decrease the pain intensity,it raised the side effects on the respiratory system even when prescribed by palliative care specialists. Therefore,the RMD regulation is valid for general practitioners from a medical safety standpoint.