Reproducible fentanyl doses delivered intermittently at different time intervals from an electrotransport system

The electrotransport transdermal fentanyl system (ET [fentanyl]), uses a sm all electrical current to enhance delivery of fentanyl to systemic circulat ion. Intermittent doses can be administered by periodic application of the current. The purpose of this study was to compare the effects of the freque ncy of intermittent drug delivery by ET (fentanyl) and compare the drug del ivery to systemic circulation by ET (fentanyl) with intravenous administrat ion. The topical safety was also determined for the ET (fentanyl) system. N ine adult male volunteers completed this three-treatment, randomized, 24-h, crossover study. ET (fentanyl) treatments with 200 mu A direct current app lied for 30 min at frequent (hourly) or infrequent (4-hourly) intervals ove r a 24-h period were compared. Also, the drug delivery to systemic circulat ion from ET (fentanyl) was compared with intravenous fentanyl 75 mu g infus ed over 30 min every 4 h over a 24-hour period. The mean serum fentanyl con centration achieved with the hourly ET (fentanyl) regimen was higher than t hat for the 4-hourly ET (fentanyl) regimen as expected from the higher freq uency of drug doses. The amount of fentanyl delivered estimated per dose fr om the ET (fentanyl) system using the iv fentanyl treatment as the referenc e was similar for the two ET regimens throughout the dosing period. This in dicates consistent drug delivery regardless of the frequency of ET dosing. The majority of subjects reported either no, or barely perceptible, erythem a 24 h after removal of the system.