Dosing considerations with transdermal formulations of fentanyl and buprenorphine for the treatment of cancer pain

Opioids continue to be first-line pharmacotherapy for patients suffering from cancer pain. Unfortunately, subtherapeutic dosage prescribing of pain medications remains common, and many cancer patients continue to suffer and experience diminished quality of life. A large variety of therapeutic options are available for cancer pain patients. Analgesic pharmacotherapy is based on the patient's self-report of pain intensity and should be tailored to meet the requirements of each individual. Most, if not all, cancer pain patients will ultimately require modifications in their opioid pharmacotherapy. When changes in a patient's medication regimen are needed, adequate pain control is best maintained through appropriate dosage conversion, scheduling immediate release medication for withdrawal prevention, and providing as needed dosing for breakthrough pain. Transdermal opioids are noninvasive, cause less constipation and sedation when compared to oral opioids, and may improve patient compliance. A relative potency of 100:1 is recommended when converting the patient from oral morphine to transdermal fentanyl. Based on the limited data available, there is significant interpatient variability with transdermal buprenorphine and equipotency recommendations from oral morphine of 75:1-110:1 have been suggested. Cancer patients may require larger transdermal buprenorphine doses to control their pain and may respond better to a more aggressive 75-100:1 potency ratio. This review outlines the prescribing of transdermal fentanyl and transdermal buprenorphine including how to safely and effectively convert to and use them for those with cancer pain.