Evaluation of analgesic effect and safety of fentanyl transdermal patch for cancer pain as the first line

Abstract

Initial treatment with morphine followed by fentanyl transdermal patch is the standard in Japan, since even the smallest patch (2.5 mg) could deliver too high an initial dose for Japanese patients. We evaluated the analgesic effect and safety of using the fentanyl transdermal patch as a first-line strong opioid for cancer pain that is resistant to nonsteroidal anti-inflammatory drugs (NSAIDs). For 20 hospitalized patients with cancer pain that could not be controlled by NSAIDs, the fentanyl transdermal patch (1.25 mg; half of a 2.5-mg patch) was administered as a first-line strong opioid. We used rescue medications depending on the degree of pain, and the dose of fentanyl transdermal patch was adjusted every 3 days. To evaluate analgesic efficacy of the patch, the degree of pain was assessed twice a day, in the morning and at night, using a face rating scale. The formulation and dose of morphine used during observation period were recorded. The safety of treatment was evaluated by measuring vital signs once a day, and the severity of side effects were evaluated. Any abnormal findings in blood and urine test were recorded. The median pain score before administration of fentanyl transdermal patch was 3 + or - 0.58 and was decreased to 2 + or - 0.71 on day 9 of administration. The mean dose of fentanyl transdermal patch on day 9 of administration was 2.31 + or - 1.34 mg, and the mean dose of morphine as rescue therapy was 4.62 + or - 7.76 mg. No clinically significant changes in vital signs were observed. No severe adverse events were present when the dose of the fentanyl transdermal patch was 1.25 mg, but two patients experienced dizziness when the dose was increased from 2.5 to 5 mg. No abnormal laboratory data appeared during the administration. The use of 1.25-mg fentanyl transdermal patch (50% of a 2.5-mg patch) seems to be safe and efficient as a first-line strong opioid. The use of 3.75-mg fentanyl transdermal patch may be necessary since adverse events including nausea and sleepiness are likely to occur by increasing from 2.5 to 5 mg.