Influence of body fat in cancer patients on residual content of used fentanyl matrix patches

Abstract

Body fat and estimated fentanyl absorption 207 fentanyl content of used reservoir patches 8, 9) , suggesting that these factors may affect the transdermal absorption of fentanyl in reservoir patches. In a clinical study of patients experiencing cancer-related pain with or without cachexia using the reservoir patch, transdermal fentanyl absorption was impaired in the cachectic patients (mean BMI, 16 kg/m 2 versus 23 kg/m 2) 10). As BMI is a measure of obesity, the body fat level in cancer patients may affect the skin permeability of fentanyl. No previous studies have focused on the correlation between body fat level and transdermal fentanyl absorption. To evaluate the degree of body fat in cancer patients, we measured body fat rate (BFR) and triceps skinfold thickness (TSF). The aim of this study was to determine whether these parameters are associated with estimated transdermal absorption of fentanyl in the matrix patch, in patients treated for moderate to severe cancer pain, by measuring the residual content of fentanyl in the used matrix patches. Materials and methods 1 Patients Adult Japanese inpatients experiencing chronic cancer-related pain and undergoing treatment for the first time with a transdermal fentanyl matrix patch (Durotep®MT patch, Janssen-Pharma, Japan) were included in the present study. The patients were provided with verbal and written information about the study, and then gave their written informed consent. The dose of the patch selected for each patient was based on clinical considerations. Exclusion criteria included the following: impaired cognitive function; fever (≧38 ℃); pregnancy; lactation; clinically significant renal, hepatic, or cardiac insufficiency; skin disease precluding the use of a fentanyl patch; and previous use of either the matrix or the reservoir patch. At the time of patch application and removal, the absent of abnormal findings (e.g. skin separation) was visually confirmed for each patient. Before applying the patch, patients were visually checked to ensure that the application site of the patch had no contamination. The patients were interviewed about the presence or absence of sweating during the study period. This study protocol was reviewed and approved by the Iwate Medical University Ethics Committee. 2 Method of application and removal of the patch Application and removal of the patch were performed by nurses. The application site was the chest or upper arm. One used patch was collected from each patient. After removal from each patient, the patches were wrapped in Saran Wrap®(Asahi Kasei, Japan) and then stored at 4 ℃ until analysis. 3 Measurement of parameters During the initial application period, body weight (BW), body height (BH), BFR, and TSF were measured. To preclude any error in measurement, TSF was measured by an experienced nurse using an adipometer (Abbott Japan Co. Ltd., Japan). BFR was measured using a body fat scale (TBF-533; TANITA Corporation, Japan) and a bioelectrical impedance technique. In addition, BMI (kg/m 2) was also calculated as BW/BH 2 .