Cachectic patients should not receive a higher initial dose unless they have been receiving the equivalent of 135 mg of oral morphine. Most patients are maintained with patch applications at 72 hour intervals. Adequacy of analgesia should be evaluated at 72 hours. The dose should be increased to maintain the 72-hour interval if possible, but application every 48 hours is another option. Supplemental opiates may be required with initial use to control pain and to determine optimal fentanyl dose.
Tolerance occurs with extended courses, but there is considerable individual variation.
Local effects include erythema, papules, pruritis, and edema at the site of application. Drug interactions include increased fentanyl levels with PIs given concurrently. Application is to a dry, nonirritated, flat surface of the upper torso by firm pressing for 30 seconds. Avoid external heat to the site since absorption is temperature-dependent. Use different sites with sequential use.