norfentanyl and Pain

A study of the urinary concentration of fentanyl (F) and its major metabolite norfentanyl (NF) in chronic pain patients treated with the Duragesic continuous release transdermal patches is presented. These patches are available in 10, 20, 30, and 40 cm(2) sizes releasing 25, 50, 75, and 100 microg/h F, respectively. F is rapidly and extensively metabolized, with NF as the major metabolite. Five hundred-forty six random urine specimens were collected from chronic pain patients wearing 25, 50, 75, or 100 ug F transdermal patches. Urine specimens were collected from hours after application to several days later after continuous F release. Each specimen was analyzed for F, NF, creatinine, and pH. Additionally, each was screened by enzyme immunoassay for the following: amphetamines, barbiturates, benzodiazepines, cocaine metabolite, methadone, phencyclidine, d-propoxyphene, opiates, and marijuana metabolites. All positive screening results were confirmed by gas chromatography-mass spectrometry (GC-MS). F and NF were isolated from urine by solid-phase extraction then identified and quantified by GC-MS in SIM mode. The LODs and LOQs for F and NF were 3 ng/mL, respectively. The results of F and NF analysis of urine form those wearing 25-microg patches (N = 142) was mean F, 47 ng/mL with a range of 0 to 983 ng/mL, and 97% of the specimens contained < 200 ng/mL and mean NF, 175 ng/mL with a range of 0-980 ng/mL, while 95% of the specimens contained < 400 ng/mL. The results of F and NF analysis of urine form those wearing 50 microg patches (N = 184) was: mean F, 74 ng/mL with a range of 0 to 589 ng/mL, and 92% of the specimens contained < 200 ng/mL and mean NF, 257 ng/mL with a range of 0-2200 ng/mL, and 98% of the specimens contained < 1000 ng/mL. The results of F and NF analysis of urine form those wearing 75 microg patches (N = 85) was mean F, 107 ng/mL with a range of 0 to 1280 ng/mL, and 98% of the specimens contained < 400 ng/mL and mean NF, 328 ng/mL with a range of 0-5630 ng/mL, and 99% of the specimens contained < 1000 ng/mL. The results of F and NF analysis of urine form those wearing 100 ug patches (N = 135) was mean F, 100 ng/mL with a range of 0 to 1080 ng/mL, while 96% of the specimens contained < 400 ng/mL and mean NF, 373 ng/mL with a range of 0-5730 ng/mL, and 95% of the specimens contained < 1000 ng/mL. The incidence of other drugs detected as a percentage the specimens was opiates, 48%, benzodiazepines, 43%; barbiturates, 3%; methadone, 4%; mariju

Topics: Administration, Cutaneous; Analgesics, Opioid; Chronic Disease; Delayed-Action Preparations; Fentanyl; Gas Chromatography-Mass Spectrometry; Half-Life; Humans; Immunoenzyme Techniques; Pain

Fentanyl is widely used to relieve cancer pain. However there is great interpatient variation in the dose required to relieve pain and little knowledge about the pharmacokinetic and pharmacodynamic (PK/PD) relationship of fentanyl and pain control. Patients with cancer are fragile and there is reluctance on the part of health professionals to take multiple plasma samples for PK/PD studies. The relationship between plasma and saliva fentanyl concentrations was investigated to determine whether saliva could be a valid substitute for plasma in PK/PD studies.. One hundred sixty-three paired plasma and saliva samples were collected from 56 patients prescribed transdermal fentanyl (Durogesic, Janssen-Cilag Pty Limited, NSW, Australia) at varying doses (12-200 µg/h). Pain scores were recorded at the time of sampling. Fentanyl and norfentanyl concentrations in plasma and saliva were quantified using HPLC-MS/MS.. Saliva concentrations of fentanyl (mean = 4.84 μg/L) were much higher than paired plasma concentrations of fentanyl (mean = 0.877 μg/L). Both plasma and saliva mean concentrations of fentanyl were well correlated with dose with considerable interpatient variation at each dose. The relationship between fentanyl and norfentanyl concentrations was poor in both plasma and saliva. No correlation was observed between fentanyl concentration in plasma and saliva (r(2) = 0.3743) or free fentanyl in plasma and total saliva concentrations (r(2) = 0.1374). Pain scores and fentanyl concentration in either of the matrices were also not correlated.. No predictive correlation was observed between plasma and saliva fentanyl concentration. However the detection of higher fentanyl concentrations in saliva than plasma, with a good correlation to dose, may allow saliva to be used as an alternative to plasma in PK/PD studies of fentanyl in patients with cancer.

Topics: Administration, Cutaneous; Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Chromatography, High Pressure Liquid; Female; Fentanyl; Humans; Male; Middle Aged; Neoplasms; Pain; Pain Measurement; Saliva; Tandem Mass Spectrometry

Monitoring fentanyl concentration in saliva and plasma may be useful in pharmacokinetic/pharmacodynamic studies. Salivettes(®) have been used widely for collecting saliva samples. However due to its lipophilicity, fentanyl adsorbs to the cotton dental bud (CDB) used in this device. Furthermore, due to dry mouth being a common adverse effect seen in patients treated with opioids, obtaining enough saliva for analysis is often a challenge. Hence, a simple simultaneous method to quantify fentanyl and its metabolite in both human plasma and saliva was developed and validated. A novel extraction method was also developed and validated to recover fentanyl in saliva directly from the CDB. This extraction method utilises acetonitrile to recover the fentanyl directly from the CDB rather than recovery by centrifugation, which is not always possible. Reverse phase chromatographic separation was performed on a Shimadzu LC 20A HPLC system using gradient elution. The electrospray ion source (ESI) was operated in positive ion mode using an Applied Biosystems API 3200 LC/MS/MS as detector. Deuterated fentanyl (D5) and nor-fentanyl (D5) were used as internal standards (IS). The retention times for fentanyl and nor-fentanyl were 3.70 min and 3.20 min respectively. The lower limit of quantitation (LLOQ) was determined to be 0.030 μg/L in plasma and 0.045 in saliva for fentanyl and nor-fentanyl. Acceptable linearity for fentanyl and nor-fentanyl in both plasma and saliva was demonstrated from 0.02 to 10 μg/L (R(2) 0.9988-0.9994). Accuracy for fentanyl and nor-fentanyl in both plasma and saliva samples was between 96% and 108%. Total imprecision expressed as the co-efficient of variation was between 1.0 and 15.5% for both analytes in both matrices. The validated method was applied successfully in 11 paired plasma and saliva samples obtained from patients with cancer pain receiving transdermal fentanyl (Duragesic(®)) at doses from 25 μg to 100 μg.

Topics: Chromatography, High Pressure Liquid; Drug Monitoring; Drug Stability; Fentanyl; Humans; Linear Models; Pain; Reproducibility of Results; Saliva; Sensitivity and Specificity; Tandem Mass Spectrometry

Delivery rates and plasma concentrations vary among patients treated with fentanyl patches. Absorption and urinary excretion characteristics of fentanyl were studied in patients undergoing palliative care. Almost 500 patches were analyzed for residual fentanyl content. Fentanyl and norfentanyl levels were determined in the urine of 50 patients. General and mixed effects linear regression models were established for the relationship between fentanyl dose rate and urinary excretion and to incorporate influencing factors. For different patch nominal dose strengths, wide but comparable variability in estimated dose rate and delivery efficiency was observed (coefficients of variation of 15% to 17%). Fentanyl delivery efficiency was 8.5% higher for patches of 25 microg/h as compared to 75 microg/h and, accordingly, 7.5% for patch application on the arm as compared to the leg. Urinary fentanyl and norfentanyl concentrations varied considerably. The general linear model revealed a positive effect of the calculated transdermal dose rate on urinary fentanyl levels, explaining 34% of the variability (P < .0001). In addition, gender (P = .04) and type of cancer pathology (P = .03) exerted significant effects on the linear model, explaining 40% and 64% of the variability, respectively. Delivery efficiency of fentanyl patches can vary substantially, possibly leading to either underdosing or overdosing.

Topics: Administration, Cutaneous; Adult; Aged; Aged, 80 and over; Analgesics, Opioid; Chronic Disease; Dose-Response Relationship, Drug; Drug Carriers; Female; Fentanyl; Humans; Male; Middle Aged; Neoplasms; Pain; Palliative Care; Skin Absorption

Fentanyl is a potent synthetic narcotic analgesic administered in the form of a transdermal patch for the management of chronic pain. A 78-year-old woman with a history of cancer was found dead in bed. She was lying on her back. The external examination revealed 10 Durogesic transdermal therapeutic systems (100 microg/h fentanyl) on the body. Liquid-liquid extraction and liquid chromatography tandem mass spectrometry with electrospray source in positive ionization mode was applied for the quantitation of fentanyl and its major metabolite norfentanyl in the post-mortem samples. Fentanyl-d5 and norfentanyl-d5 were used as internal standards. Multiple reaction monitoring was used for specific detection. Calibration was performed by addition of standard solutions to drug-free matrix (blood, urine and liver) prior to extraction. The method showed good linearity for fentanyl and norfentanyl over a concentration range of 5-150 microg/L in reconstituted extracts with coefficients of determination equal or greater than 0.998. Percent mean within-day precision and accuracy of 0.9-1.0% and 99.4-101.1% for fentanyl and 2.0-4.5% and 93.1-101.0% for norfentanyl were obtained. Mean extraction recoveries varied between 95.5% and 100.3% for fentanyl and 39.2-57.4% for norfentanyl. The following fentanyl (norfentanyl) concentration in the post-mortem samples were measured; 28.6 microg/L (3.0 microg/L) in right and 28.2 microg/L (3.5 microg/L) in left subclavian blood, 21.3 microg/L (<2 microg/L) in right and 20.9 microg/L (<2 microg/L) in left femoral blood, 37.6 microg/L (4.2 microg/L) in right and 33.9 microg/L (4.4 microg/L) in left ventricular blood, 282.9 microg/L (121.2 microg/L) in urine, 688.2 microg/L in stomach contents, 122.5 microg/L (25.4 microg/L) in bile, 19.5 microg/L (< 2 microg/L) in vitreous humour, 203.0 microg/kg (26.6 microg/kg) in liver and 78.6 microg/kg (46.3 microg/kg) in kidney. We concluded that the woman's death was caused by acute intoxication with fentanyl. The manner of death was presumed to be suicide due to excessive administered Durogesic transdermal therapeutic systems.

Topics: Administration, Cutaneous; Aged; Analgesics, Opioid; Bile; Chromatography, Liquid; Female; Fentanyl; Forensic Toxicology; Gastrointestinal Contents; Humans; Kidney; Liver; Neoplasms; Pain; Spectrometry, Mass, Electrospray Ionization; Suicide; Vitreous Body