Transdermal fentanyl. A review of its pharmacological properties and therapeutic efficacy in pain control

Comparative bioequivalence study between a novel matrix transdermal delivery system of fentanyl and a commercially available reservoir formulation

AIM

To determine the pharmacokinetics, safety and performance of a novel matrix formulation of fentanyl.

METHODS

Transdermal fentanyl was administered as the novel matrix and the Durogesic reservoir formulations (24 subjects, 100 microg h(-1)) in a randomized, fully replicate, four-way crossover study. Serum concentrations of fentanyl were assayed by LC/MS/MS. Pharmacokinetic parameters of fentanyl and performance (adherence and skin irritability) were evaluated.

RESULTS

Test/reference ratio (90% confidence intervals) for AUC(0-t), AUC(inf) and C(max) were 105.5% (99.4, 112.0), 105.3% (99.3, 111.6) and 111.4% (100.4, 123.6), respectively. Adherence and skin irritability results of the two formulations were similar.

CONCLUSION

The two formulations are expected to result in similar efficacy for the management of severe pain.

Inter- and intraindividual variabilities in pharmacokinetics of fentanyl after repeated 72-hour transdermal applications in cancer pain patients

Perception of pain by the patient is frequently one of the early signs preceding a diagnosis of cancer and, later, a sinister sign of disease progression. Among opioid drugs, transdermal fentanyl has been evaluated in the treatment of moderate to severe cancer pain. The objective of this study was to investigate the intra- and interindividual variabilities in pharmacokinetics after fentanyl drug delivery by the transdermal fentanyl patch delivery system in patients with cancer pain. As a first step, a liquid chromatography-mass spectrometry method was developed for the determination of the analgesic fentanyl in human plasma. This method was validated over the concentration range 0.15-100 ng/mL. The study group consisted of 29 inpatients (18 men and 11 women; age range 29-80 years). The initial transdermal fentanyl delivery rate was chosen depending on the patient's analgesic requirements. For 20 patients, the initial TTS fentanyl delivery rate was 25 or 50 microg/h. For 6 patients, the initial delivery rate was 75-150 microg/h. Two patients received up to 300 microg/h fentanyl delivery rate, and 3 patients received up to 350 microg/h fentanyl delivery rate. Fifteen of the 29 patients received rescue doses of subcutaneous or oral morphine, and 26 patients received paracetamol with codeine (30 mg per os). Blood samples were collected at the following intervals: 2-5, 22-26, or 45-47 hours following fentanyl patch application. The severity of pain experienced by the patient was assessed thrice daily using a visual analogue scale. The study period was 46 days. Large patient-to-patient variations in pharmacokinetic parameters occurred, although intraindividual variability was limited. A mean bioavailability of 78% was estimated; the total clearance averaged 41 L/h. From 25 to 100 mug/h fentanyl delivery rate, the pharmacokinetics was linear. At the 2 highest doses, an increase of total clearance was observed (>60 L/h). For the whole group, transdermal fentanyl treatment provided good to excellent pain relief in the majority of patients.

Opioids in pain management of blood-related malignancies

Opioids are basic analgesics used in the treatment of moderate to severe pain in patients affected by blood-related malignancies. They should be sequentially administered according to the World Health Organisation scale for cancer pain. Initial treatment and titration with opioids should be based on immediate-release preparations, to be administered at appropriate intervals in order to relieve pain and to satisfy the individual opioid requirement. Once a relatively good pain control has been achieved, a slow release formulation at equivalent doses can be given. Most patients can be adequately managed using oral formulation opioids. However, a small group, such as those presenting severe mucositis or requiring a rapid pain relief, should be managed by intravenous continuous infusion and/or by a patient-controlled analgesia system; while for patients in the community, there are distinct advantages to using the subcutaneous route. Other available routes of administration for opioids, can be used in selected circumstances, including rectal, transdermal, epidural, intrathecal and intramuscular. The invasive neuraxial route has a very limited role in patients with haematological malignancies, given the high risk of infection and bleeding. Through a close observation and a careful management, opioid-related side effects can be effectively prevented and treated. This article reviews the principles of opioid therapy and how opioids can be adapted for patients with pain due to haematological malignancies.

Transdermal fentanyl in the management of children with chronic severe pain: results from an international study

BACKGROUND

The current study was conducted to assess the safety and tolerability of a transdermal fentanyl delivery system for the relief of chronic pain in a pediatric population, and also to validate titration recommendations and conversion to transdermal fentanyl from oral opioid therapy.

METHODS

This 15-day (with 3-month extension), single-arm, open-label trial was conducted at 66 sites in 10 countries. A total of 199 pediatric patients (ages 2-16 years) with both malignant and nonmalignant conditions who were receiving oral or parenteral opioids for moderate to severe chronic pain were enrolled. Transdermal fentanyl doses were titrated upward according to the rescue medication consumed during the previous application period. Degree of pain was assessed by patients and parents/guardians using visual and numeric scales. Level of play and quality of life were assessed using the Play Performance Scale (PPS) and the Child Health Questionnaire (CHQ). Adverse events were monitored on Days 1-15. Hypoventilation and sedation were monitored every 4 hours during the first 72 hours of the study.

RESULTS

A total of 173 patients completed the primary treatment period and 130 entered the extension phase. The average daily pain intensity scores were reported to have decreased by Day 16 and improvements in the mean PPS scores were observed to the end of the extension period. The CHQ scores demonstrated improvements in 11 of 12 domains after Month 1 of the extension period.

CONCLUSIONS

Transdermal fentanyl was found to be a safe and well tolerated alternative to oral opioid treatment for children ages 2-16 years who were previously exposed to opioid therapy.

Opioid-induced gastrointestinal dysfunction

Use of opioid analgesics is associated with a number of side effects, especially opioid-induced gastrointestinal dysfunction. The extensive use of these compounds and the significant negative impact of the resulting gastrointestinal dysfunction on patients' quality of life make it an important clinical issue. In recent years our understanding of the mechanisms of opioid-induced gastrointestinal dysfunction has advanced greatly. This article reviews the underlying pathophysiological mechanisms of specific gastrointestinal adverse effects of opioids. The role of endogenous opioid peptides in certain gastrointestinal diseases is also discussed. A better understanding of the pathophysiological mechanisms of opioid-induced bowel dysfunction should lead to the development of newer opioid analgesics and improved regimens resulting in reduced gastrointestinal adverse effects.

Transdermal fentanyl for the treatment of pain caused by osteoarthritis of the knee or hip: an open, multicentre study

BACKGROUND

This study was designed to evaluate the utility of transdermal fentanyl (TDF, Durogesic) for the treatment of pain due to osteoarthritis (OA) of the knee or hip, which was not adequately controlled by non-opioid analgesics or weak opioids. The second part of the trial, investigating TDF in patients with rheumatoid arthritis (RA) is reported separately.

METHODS

Current analgesia was optimised during a 1-week run-in. Patients then received 28 days treatment with TDF starting at 25 microg/hr, with the option to increase the dose until adequate pain control was achieved. Metoclopramide was taken during the first week and then as needed.

RESULTS

Of the 159 patients recruited, 75 with OA knee and 44 with OA hip completed the treatment phase, 30 knee and 18 hip patients entered the one-week taper-off phase. The most frequently used maximum dose of TDF was 25 microg/hr. The number of patients with adequate pain control increased during the run-in period from 4% to 27%, and further increased during TDF treatment to 88% on day 28. From baseline to endpoint, there were significant reductions in pain (p < 0.001) and improvements in functioning (p < 0.001) and physical (p < 0.001) and mental (p < 0.05) health. Scores for 'pain right now' decreased significantly within 24 hours of starting TDF treatment. TDF was assessed favourably and 84% of patients would recommend it for OA-related pain. Nausea and vomiting were the most common adverse events (reported by 32% and 26% of patients respectively), despite prophylaxis with metoclopramide, which showed limited efficacy in this setting.

CONCLUSION

TDF significantly increased pain control, and improved functioning and quality of life. Metoclopramide appeared to be of limited value in preventing nausea and vomiting; more effective anti-emetic treatment may enable more people to benefit from strong opioids such as TDF. This study suggests that four weeks is a reasonable period to test the benefit of adding TDF to improve pain control in OA patients and that discontinuing therapy in cases of limited benefit creates no major obstacles.

An observational study of health-related quality of life and pain outcomes in chronic low back pain patients treated with fentanyl transdermal system

BACKGROUND

The analgesic effect of long-acting opioids, such as transdermal fentanyl, has been demonstrated in patients with cancer, neuropathic pain and chronic low back pain (CLBP). However, the broader effect of long-acting opioids on the patient's health-related quality of life (HRQoL) is less well known.

OBJECTIVE

To evaluate HRQoL outcomes in CLBP patients treated with transdermal fentanyl.

RESEARCH DESIGN AND METHODS

An observational study was conducted at 17 clinical centers in the US. Eligible patients had CLBP diagnosis for at least 3 months and were taking short-acting opioids chronically, and then initiated transdermal fentanyl treatment. Patients completed the Treatment Outcomes in Pain Survey (TOPS), which includes the SF-36 Health Survey, at baseline and > or = 9 weeks of treatment. The HRQoL burden of CLBP was determined by comparing CLBP patients' SF-36 scores to the general US population and low back pain patient norms. HRQoL outcomes were determined by comparing baseline and follow-up TOPS and SF-36 scores. Additionally, HRQoL outcomes were evaluated across patient groups stratified by changes in pain intensity ratings as measured by an 11-point numerical rating scale.

RESULTS

At baseline CLBP patients (N = 131) scored one-to-two standard deviations (SD) below age and gender adjusted SF-36 general population norms (MANOVA F = 127.1, p < 0.0001) and significantly lower than low back pain norms (MANOVA F = 125.3, p < 0.0001). At follow-up, significant improvement (p < 0.05) was observed on six of the SF-36 scales and both SF-36 summary measures and five of the six TOPS pain-related scales. The magnitude of change in scores in effect size units among these scales ranged from 0.17 to 0.80, which are considered small to large effect size changes. HRQoL score improvement was greatest among patients experiencing the greatest pain relief.

CONCLUSION

CLBP patients who chronically used short-acting opioids showed tremendous HRQoL burden. Favorable HRQoL outcomes were observed among patients who reported pain relief.

Transdermal fentanyl: little absorption in two patients with systemic sclerosis?

Two patients suffering from systemic sclerosis (SSc) were treated with the 25 micro/hr transdermal fentanyl patch for pain from either deltoid muscle tendinitis of the left arm or from ischemia of the left-hand thumb. When the medication was changed to either oral morphine or oral methadone, the effects did not correspond to the drug conversion table. These findings suggest that patients with SSc and other systemic skin diseases may be at risk for limited absorption of transdermal fentanyl. In contrast, no restriction of the absorption of transdermal testosterone was observed.

Identification of fentanyl, alfentanil, sufentanil, remifentanil and their major metabolites in human urine by liquid chromatography/tandem mass spectrometry for doping control purposes

Since January 2005, the list of prohibited substances established by the World Anti-Doping Agency prohibits the opioid agent fentanyl as well as its related drugs in professional and amateur sports. Fast, reliable and robust analytical assays are required that allow the sensitive determination of these compounds or respective metabolites in human urine, and liquid chromatography interfaced to mass spectrometry has proven to be a suitable and powerful tool for drug testing for several years. A screening and confirmation method was developed that enables the identification of fentanyl, alfentanil, remifentanil and sufentanil as well as their N-dealkylated or de-esterified metabolites utilizing solid-phase extraction of a 2 mL urine aliquot followed by LC-electrospray-MS/MS analysis. The procedure was validated in terms of recovery (95.8-104.9%), lower limit of detection (0.5 ng mL-1), specificity and interday precision (3.9-19.8%) for the four opioid drugs and the metabolic product norfentanyl. In addition, the mass spectrometric behavior of fentanyl after electrospray ionization and collision-induced dissociation was studied by synthesis and analysis of structurally related compounds, and dissociation pathways were proposed allowing the characterization of target analytes and corresponding metabolites.

Benefits of transdermal fentanyl in patients with rheumatoid arthritis or with osteoarthritis of the knee or hip: an open-label study to assess pain control

OBJECTIVES

To evaluate the effectiveness and safety of transdermal fentanyl (TDF) for the treatment of pain associated with rheumatoid arthritis (RA) or osteoarthritis of the knee or hip (OA), which was not adequately controlled by non-opioid analgesics and/or weak opioids.

METHODS

The study design incorporated a 1-week run-in period when current analgesic medications were optimised, a 28-day treatment period and a 1-week taper-off period. Patients with RA (n = 104) and OA (n = 159) started treatment with TDF 25 microg/h. Patches were replaced every 72 h, with the option to up-titrate until adequate pain control was achieved. Metoclopramide was taken during the first treatment week and as needed thereafter.

RESULTS

203 patients completed the treatment phase, 90 entered the taper-off phase. 25 microg/h was the most frequently used maximum dose (51%). Pain control was increased from 4% to 29% of patients during run-in. The number of patients reaching adequate pain control in the first treatment week was increased to 75%, and increased further to 88% on day 28 and to 80% at endpoint. From baseline (screening) to endpoint, there were significant reductions in pain (p < 0.001) on the Wisconsin Brief Pain Inventory, and significant improvements in quality of life (Short-Form-36: physical p < 0.001; mental health p < 0.05). Eighty per cent of the patients (n = 134) assessed the treatment favourably; nausea and vomiting were the most common adverse events, mainly occurring at treatment initiation. Efficacy of metoclopramide appeared limited. TDF could be initiated in patients pre-treated with non-opioid analgesics or weak opioids and tapered off without major complications.

CONCLUSIONS

TDF significantly improved pain control and quality of life, and was well tolerated in patients with RA or knee/hip OA who continued to experience pain on their current analgesic treatment. Treatment could be discontinued without issues. Nausea and vomiting was usually mild during treatment initiation. Patients' well being could be further accommodated by optimising prophylactic treatment.

The effect of transdermal fentanyl treatment on serum cortisol concentrations in patients with non-cancer pain

We treated 50 patients with chronic nonmalignant pain using transdermal fentanyl (TDF) 25 microg/hr and concurrently measured pain using a visual analog scale (VAS) and serum cortisol concentration. We determined these outcomes at baseline and on days 30, 60, and 90 of the therapy. The patients also were asked to document any adverse effects. We found that mean cortisol concentrations on days 30, 60, and 90 of therapy were significantly (P < 0.0001) lower than the basal mean cortisol level, and mean VAS scores at days 30, 60, and 90 of therapy were also significantly better than the initial mean value (P < 0.0001). Fourteen patients experienced severe adverse events. These observations suggest that serum cortisol concentrations may be elevated in chronic non-cancer pain states and that TDF therapy can reduce cortisol levels in parallel with reduction in pain.

Chronic fentanyl or buprenorphine infusion in the mouse: similar analgesic profile but different effects on immune responses

It is known that morphine has a negative impact on the immune responses. The potent opioids fentanyl and buprenorphine have recently become available as transdermal preparation for the treatment of chronic pain. We analyze the effect of fentanyl and buprenorphine on splenic cellular immune responses in the mouse. The parameters evaluated were lymphoproliferation, natural killer cell activity and interleukin-2 and interferon-gamma production. Drugs were administered acutely at the equianalgesic doses of 0.25 mg/kg for fentanyl and 5 mg/kg for buprenorphine, or delivered continuously with osmotic pumps for 24 h, 3 and 7 days at the rate of 7.5 microg/h per mouse (fentanyl) and 12.5 microg/h per mouse (buprenorphine). After acute administration, a significant decrease of lymphoproliferation is observed in fentanyl-treated animals only. After 24 h of fentanyl administration all the parameters were significantly reduced. After 3 days of fentanyl infusion NK activity had returned to normal values, while all the other parameters were still significantly reduced. In 7 day fentanyl-treated animals immunological tolerance had developed, since no differences with controls were present. In contrast no immune alterations were ever present in buprenorphine-treated animals. No tolerance to the antinociceptive effect of drugs had yet developed. After 1 week of infusion with fentanyl and buprenorphine, new pumps were implanted releasing double amounts of drugs. Neither fentanyl nor buprenorphine-treated animals showed altered immune responses at any time considered. These results indicate that fentanyl and buprenorphine exert different immune effects. Opioid-induced immunosuppression is less relevant in chronic administration than in acute or short-time administration.

Oral transmucosal abuse of transdermal fentanyl

Transdermal fentanyl is an opioid analgesic that is effective on chronic pain, and which appears to be advantageous due to several factors such as ease of administration, the relatively stable serum concentration and long dose intervals. Nevertheless, the danger of abuse and dependence exists among patients who are prescribed fentanyl patches. We present a case of transdermal fentanyl abuse, where the administration route of the drug was changed. Our patient, who had no history of substance abuse and who suffered from chronic nonmalignant pain, used the fentanyl transdermal patches as oral transmucosal medication, raising the dose by ten-fold. This abuse of the drug was only for analgesic purposes without seeking anxiolysis and/or euphoria. After treatment and progressive reduction of fentanyl, the patient remains in good condition, and is currently taking the initial dose of the drug transdermally, without having experienced any withdrawal symptoms.

Highly sensitive gas chromatographic—mass spectrometric screening method for the determination of picogram levels of fentanyl, sufentanil and alfentanil and their major metabolites in urine of opioid exposed workers

Highly sensitive and specific analytical GC-MS procedures were developed and comprehensively validated for the determination of the opioid narcotics fentanyl, sufentanil and alfentanil and their major nor-metabolites in urine of potentially exposed opioid production workers. A simple, one step extraction protocol was developed using commercially available solid phase extraction (SPE) columns to recover all analytes from urine. The secondary amine functionalities of the nor-metabolites were derivatized to form stable, pentafluorobenzamide (PFBA)-derivatives with good chromatographic properties. Using the penta-deuterated analogues as internal standards, a limit-of-detection (LOD) of 2.5 pg fentanyl/ml, 2.5 pg sufentanil/ml and 7.5 pg alfentanil/ml urine was achieved. For the opioid metabolites the LODs were found to be <50 pg/ml urine. The developed analytical procedures show excellent intra-assay accuracy, particularly considering the ultra low levels of the analytes, with relative errors generally below 10%. Overall, an excellent reproducibility was observed with coefficients of variation below 10% at all spike levels for all opioid parent compounds and their metabolites, except for low norfentanyl concentrations. Upon storage at -30 degrees C urine samples were found to be stable for at least 2 months as no significant losses of either compound were observed. The developed analytical procedures have been successfully applied in a biological monitoring survey of fentanyl exposed production workers.

Transdermal fentanyl in HSCT patients: an open trial using transdermal fentanyl for the treatment of oral mucositis pain

Fentanyl is a synthetic opioid that can be delivered through a transdermal therapeutic system (TTS). The aim of this study was to assess the efficacy of fentanyl TTS in treating oral mucositis pain in 75 adult hematopoietic stem cell transplant (HSCT) patients. The analysis was based on 62 patients who developed mucositis. Pain control was assessed by the patients using a visual analogue scale (VAS) from day 0 to day +33 after HSCT. Fentanyl TTS was administered at the patient's request. In all, 20 patients did not require fentanyl (group A). The first 22 patients asking for the patch received fentanyl 25 microg/h (group B) and the subsequent 20 patients received 50 microg/h (group C). There were no significant differences in pain relief between groups B and C. The expected effect of a decrease in mean pain score (mean of the VAS scores of all of the patients in the same group each day) following the application of fentanyl TTS was not noted. We can conclude that fentanyl TTS at the doses used in this study may not adequately relieve oral mucositis pain.

Pain management of cancer patients with transdermal fentanyl: a study of 1828 step I, II, & III transfers

The aim of this observational study was to examine pain management outcomes and quality of life (QoL) measures in cancer patients with intolerable or chronic severe pain transferring from World Health Organization's step I, II, and III analgesics to the transdermal therapeutic fentanyl system (TTS-F). This study examines the safety and efficacy of TTS-F in long-term pain management, addressing the role of TTS-F in cancer pain. Pain measures were assessed in 1828 patients (step I [naïve], 268; step II [codeine], 1239; and step III [morphine], 321) on the basis of selected questions from the Greek-Brief Pain Inventory. Overall treatment satisfaction (scale, 1 to 4), QoL, and European Collaborative Oncology Group (ECOG) status were also recorded. These were assessed in relation to TTS-F dose, stratified by transfer step, primary cancer, metastases, type of pain, and concomitant use of anti-inflammatory drugs. Of 1828 patients, 100 (5.5%) withdrew, and an addition 14 (0.8%) discontinued because of side effects. A total of 1714 continued on study; 744 patients died, and 970 departed during the study period. In total, 93.8% were satisfied with their pain relief, and complete patient satisfaction was obtained within 2 months. Pain, QoL, and treatment satisfaction measures demonstrated statistically significant improvements over time, independent of the step transfer. Although doses of TTS-F were higher for step III > II > I and for metastatic than nonmetastatic, the median dose for all groups remained 50 microg/h throughout the study period. Pain and QoL improvements were independent of patient characteristic(s). Direct transfer to TTS-F for patients with intolerable or chronic moderate to severe cancer pain offers an efficient and safe long-term analgesic option for palliative care patients. Careful selection and follow-up by experienced palliative care specialists are mandatory. TTS-F as a first-line analgesic approach for severe cancer pain should be considered a viable option because of its durable efficacy and low incidences of side effects.

PERSPECTIVE

At a fairly constant dose of 50 microg/h, the transdermal therapeutic fentanyl system offers a safe, well-tolerated pain relief treatment for carefully monitored patients with cancer pain. The authors stress that this includes patients who experience difficulties in their pain management while progressing through the WHO's ladder for pain management.

Investigating the Effects of TTS-Fentanyl for Cancer Pain on the Psychological Status of Patients Naïve to Strong Opioids

Few studies have investigated the effect of fentanyl delivered via the transdermal route with regard to the patient's psychological status. Patients who were naive to strong opioids and were attending a palliative care unit for pain relief from advanced cancer participated in this study to determine the effect of transdermal therapeutic system fentanyl (TTS-F) on their psychological condition. Spielberger State-Trait Anxiety Inventory (STAI), Zung Self-Rating Depression Scale (SDS), the Karnofsky Performance Scale (100-0, optimum-death), and a Visual Analogue Scale (VAS) (0: no pain; 10: worst pain) were used to measure the level of pain. Data were collected at baseline (T0), on the 7th day (T1), and on the 14th day (T2) of TTS-F application in order to determine changes in correlation to TTS-F dose. Patients' status improved according to the Zung SDS questionnaire (P < .0005) and with each of its subscales (P < .05). A similar improvement was observed according to the Spielberger STAI questionnaire (P = .002). Moreover, VAS measures demonstrated that patients achieved significant pain relief (P < .0005), while patients' performance status did not alter significantly over the study period. Furthermore, the Zung SDS showed a statistically significant correlation when compared with the Spielberger STAI (P < .01). These data provide some evidence that the psychological status, as measured with respect to depression and anxiety in patients with advanced cancer, is improved in patients receiving TTS-fentanyl. Future research should use a broad range of psychological measurements in order to assist the development of practices, which are aimed at the improvement of quality of life in these patients.

The Safety and Efficacy of a Fentanyl Patient-Controlled Transdermal System for Acute Postoperative Analgesia: A Multicenter, Placebo-Controlled Trial

A noninvasive method of delivery of parenteral opioids for management of acute pain may offer logistic advantages for patients and nursing staff. A patient-controlled transdermal system (PCTS) under development consists of a preprogrammed, self-contained drug-delivery system that uses electrotransport technology (E-TRANS, ALZA Corp, Mountain View, CA) to deliver 40 micro g of fentanyl HCl over 10 min per on-demand dose for patient-controlled analgesia (PCA). In this randomized, double-blinded, placebo-controlled trial we compared the efficacy and safety of on-demand fentanyl HCl PCTS 40 microg against placebo for postoperative pain up to 24 h after major abdominal, orthopedic, or thoracic surgery in 205 patients. The primary efficacy measurement was the percentage of patients withdrawn from the study because of inadequate analgesia after completing at least 3 h of treatment. Secondary efficacy measures included mean pain intensity (using visual analog scales), patient global assessments, and investigator global assessments. Of 189 patients considered evaluable for efficacy, 25% of patients in the fentanyl HCl PCTS 40 microg group withdrew because of inadequate analgesia, compared with 40.4% of the placebo group (P < 0.05). Use of fentanyl HCl PCTS 40 micro g was associated with lower VAS scores and higher mean patient and investigator global assessment scores compared with placebo. No patient experienced clinically relevant respiratory depression. This study showed that a fentanyl HCl PCTS 40 microg for PCA was superior to placebo and well tolerated for the control of moderate to severe postoperative pain for up to 24 h after major surgery.

IMPLICATIONS

This multicenter, randomized, double-blinded, placebo-controlled trial showed that an on-demand fentanyl HCl patient-controlled transdermal system (PCTS) was superior to placebo and well tolerated for the control of moderate to severe postoperative pain for up to 24 h after major surgery. This fentanyl HCl PCTS is a preprogrammed, needle free, self-contained drug-delivery system that uses electrotransport technology (iontophoresis) to deliver 40 microg of fentanyl per on-demand dose.

Evaluation of long-term efficacy and safety of transdermal fentanyl in the treatment of chronic noncancer pain

The objective of this international, multicenter, open-label trial was to assess the efficacy and safety of up to 12 months of therapy with transdermal therapeutic system (TTS) fentanyl in patients (n = 532) with chronic noncancer pain. The trial was completed by 301 (57%) of the patients. The main outcome measures were pain control assessment, global treatment satisfaction, patient preference for TTS fentanyl, and quality of life. The mean dose of transdermal fentanyl (TDF) increased from 48 to 90 microg/h during a period of 12 months. During treatment, on average 67% of patients within the efficacy analysis group (n = 524) reported very good, good, or moderate pain control. Global satisfaction (very good or good) was also stable at 42%. The majority (86%) of patients reported a preference for TDF over their previous treatment (P < .001, binomial test). Short Form 36 quality-of-life scores improved from baseline for bodily pain. The most frequent treatment-related adverse events were nausea (31%), constipation (19%), and somnolence (18%). With regard to opioid-specific adverse events (respiratory depression [< 1%], adrenal insufficiency [< 1%], drug abuse/dependence [1%], and opioid withdrawal syndrome [3%]), these were extremely rare and, with the exception of opioid withdrawal syndrome, none was considered definitively related to the treatment. Long-term treatment with TDF provided a stable degree of pain control in the majority of patients with moderate to severe chronic noncancer pain. It was preferred by the majority of patients compared with their previous opioid medication. Overall, long-term treatment with TDF was generally well tolerated, particularly in view of the low incidence of potentially serious side effects such as drug abuse/dependence and respiratory depression. However, at present, it is important that patients receiving TDF should still be subject to careful assessment and monitoring.

Plasma fentanyl concentrations in awake cats and cats undergoing anesthesia and ovariohysterectomy using transdermal administration

OBJECTIVE

To measure the plasma fentanyl concentrations achieved over time with transdermal fentanyl patches in awake cats and cats undergoing anesthesia and ovariohysterectomy.

STUDY DESIGN

Randomized prospective experimental study.

ANIMALS

Twenty-four purpose-bred cats.

METHODS

Cats were randomly assigned to three groups for Part I of a larger concurrent study. Group P received only a 25 micro g hour-1 transdermal fentanyl patch. Group P/A received the patch and anesthesia. Group A received only anesthesia. After a minimum 1-week washout period, the cats were randomly reassigned to two groups for Part II of the larger study. Group P/A/O received the patch, anesthesia and ovariohysterectomy. Group A/O received anesthesia and ovariohysterectomy. Patches were left in place for 72 hours and plasma samples were obtained for fentanyl analysis while the patches were in place, and for 8 hours after patch removal for cats in Group P, P/A, and P/A/O.

RESULTS

The 25 micro g hour-1 transdermal fentanyl patches were well tolerated by the cats in this study (mean body weight of 3.0 kg) and no overt adverse effects were noted. Mean plasma fentanyl concentrations over time, mean plasma fentanyl concentrations at specific times (8, 25, 49, and 73 hours after patch placement), time to first detectable plasma fentanyl concentration, time to reach maximum plasma fentanyl concentration, maximum plasma fentanyl concentration, mean plasma fentanyl concentration from 8 to 73 hours, elimination half-life, and total area under concentration (AUC) were not statistically different among the groups.

CONCLUSIONS

Halothane anesthesia and anesthesia/ovariohysterectomy did not significantly alter the plasma fentanyl concentrations achieved or pharmacokinetic parameters measured, when compared with awake cats. There was a high degree of individual variability observed both within and between groups of cats in parameters measured.

CLINICAL SIGNIFICANCE

The high degree of variability observed suggests that careful observation of cats with fentanyl patches in place is required to assess efficacy and any potential adverse effects. Anesthesia and anesthesia/ovariohysterectomy do not appear to alter plasma fentanyl concentrations achieved by placement of a 25 micro g hour-1 transdermal fentanyl patch when compared to cats not undergoing these procedures.

The use of long-acting opioids in chronic pain management

The consensus statement from the American Pain Society and American Academy of Pain Medicine states that the undertreatment of pain is unjustified [6]. It has been suggested that opioid therapy can be used effectively to treat noncancer pain in a subset of patients [26], and this is becoming more acceptable [3]. Providing sustained analgesia is an important aspect of therapy, and medications should be administered on an around-the-clock basis, because regular administration of doses maintains a constant level of drug in the body and helps prevent recurrence of pain. Ideal treatment for persistent pain is a long-acting opioid administered around the clock to prevent baseline pain, with the use of short-acting opioids as supplemental agents for breakthrough pain. Controlled-release formulations can lessen the inconvenience associated with around-the-clock administration of short-acting opioids. Sustained analgesia also can be achieved with transdermal fentanyl, which combines a strong opioid with a 72-hour release profile and the benefits of a parenteral route, avoiding first-pass metabolism. Controlled-release formulations of morphine and oxycodone are available in the United States, and hydromorphone preparations are being reviewed for approval. Clinical experience with these formulations and transdermal fentanyl indicates that these agents are equally effective in controlling pain. Studies have demonstrated improved quality of life with the transdermal route and with controlled-release morphine and oxycodone. Because of patch reapplication every 72 hours, the transdermal route also enhances compliance. Use of an opioid without the need for oral or intravenous administration and the opportunity to improve compliance are among the advantages of the transdermal route in clinical practice. The nurse has an important role in the management of patients receiving long-acting opioids for chronic noncancer pain, Facilitation of the conversion from short-acting to long-acting opioids may be the initial step. Individualization of therapy to determine which route and product best suits the patient's needs and lifestyle can be accomplished through a comprehensive nursing assessment. Titration of dose along with institution of a short-acting opioid for break-through pain may require frequent interventions that a nurse familiar with the patient can provide. Prevention and management of opioid-related adverse events are essential for effective opioid therapy. Providing patient and family education regarding administration, monitoring, and management of opioid therapy is an important nursing role. Lastly, documentation of pain level, functional status, and opioid-related adverse events is required for each contact with the patient, to make this information available to all who assist in the management of the patient's pain. Chronic noncancer pain is an experience that affects all aspects of a patient's life. Effective pain management with long-acting opioids may help the patient to focus on the positive aspects of life, decreasing the focus on pain.

Fentanyl and its analogue N-(1-phenylpyrazol-3-yl)-N-[1-(2-phenylethyl)-4-piperidyl]propanamide: 1H- and 13C-NMR spectroscopy, X-ray crystallography, and theoretical calculations

The oxalate salts and free bases of fentanyl and N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide, a new lead compound for long-acting analgesia, have been characterized by (1)H- and (13)C-NMR spectroscopy. The crystal structure of the hydrochloride of N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide monohydrate has been determined. Two centrosymmetrically related cations, joined through C(phenyl)-H em leader pi contacts, encapsulate a large void that contains pairs of anions and bridged water molecules into a zero-dimensional (0D) supramolecular motif. The cations are linked to this framework via N(+)H em leader Cl(-) contacts. GIAO/B3LYP calculations have been carried out to compare the experimental (13)C chemical shifts with the absolute shieldings thus calculated. The protonation of both molecules takes place on the piperidine ring (axial protonation), as has been verified both in the solid state (X-ray) and in solution (NMR).

Treatment of Chronic Pain

Chronic pain is a symptom associated with ongoing physical or mental illness or a combination of both that may not have a clear, identifiable pathophysiology. Assessment of chronic pain varies in the clinical presentation related to age, gender, racial, and cultural differences. Headache, low back pain, musculoskeletal pain, and neuropathic pain are the most common types of chronic pain complaints by patients. Pharmacologic therapy is based on best practice standards, published clinical trials, and guidelines by professional organizations. Current medications reviewed include opioids, anticonvulsants, antidepressants, clonidine, local anesthetics, muscle relaxants, N-methyl-D-aspartate antagonists, and nonsteroidal anti-inflammatory drugs.

Benefit-Risk Assessment of Transdermal Fentanyl for the Treatment of Chronic Pain

Transdermal fentanyl is effective and well tolerated for the treatment of chronic pain caused by malignancy and non-malignant conditions when administered according to the manufacturer's recommendations. Compared with oral opioids, the advantages of transdermal fentanyl include a lower incidence and impact of adverse effects (constipation, nausea and vomiting, and daytime drowsiness), a higher degree of patient satisfaction, improved quality of life, improved convenience and compliance resulting from administration every 72 hours, and decreased use of rescue medication. Transdermal fentanyl is a useful analgesic for cancer patients who are unable to swallow or have gastrointestinal problems. Transdermal fentanyl forms a depot within the upper skin layers before entering the microcirculation. Therapeutic blood levels are attained 12-16 hours after patch application and decrease slowly with a half-life of 16-22 hours following removal. Patients with chronic pain should be titrated to adequate relief with short-acting oral or parenteral opioids prior to the initiation of transdermal fentanyl in order to prevent exacerbations of pain or opioid-related adverse effects. Transdermal fentanyl can then be initiated based on the 24-hour opioid requirement once adequate analgesia has been achieved. The prolonged elimination of transdermal fentanyl can become problematic if patients develop opioid-related adverse effects, especially hypoventilation. Adverse effects do not improve immediately after patch removal and may take many hours to resolve. Patients who experience opioid-related toxicity associated with respiratory depression should be treated immediately with an opioid antagonist such as naloxone and closely monitored for at least 24 hours. Because of the short half-life of naloxone, sequential doses or a continuous infusion of the opioid antagonist may be necessary. Transdermal fentanyl should be administered cautiously to patients with pre-existing conditions such as emphysema that may predispose them to the development of hypoventilation. Transdermal fentanyl is indicated only for patients who require continuous opioid administration for the treatment of chronic pain that cannot be managed with other medications. It is contraindicated in the management of acute and postoperative pain, as pain may decrease more rapidly in these circumstances than fentanyl blood levels can be adjusted, leading to the development of life-threatening hypoventilation. Cognitive and physical impairments such as confusion and abnormal co-ordination can occur with transdermal fentanyl. Therefore, patients should be instructed to refrain from driving or operating machinery immediately following the initiation of transdermal fentanyl, or after any dosage increase. Patients may resume such activities once the absence of these potential adverse effects is documented.

Opioid switching from morphine to transdermal fentanyl for toxicity reduction in palliative care

The study objective was to determine whether switching patients from morphine to transdermal fentanyl resulted in a reduction of morphine-associated side effects, and an improvement in cognitive function and patients' well being while maintaining adequate pain and symptom control. Nineteen patients aged 42-86 with terminal cancer, maintained on morphine for pain and distressed as a result of morphine toxicity, were given the dose of fentanyl corresponding to their current morphine dose. Pain control was then maintained (mostly fentanyl 50-100 microg/h) over the 14-day study period. Throughout the study, patients' global assessment of well being (primary efficacy variable) was statistically significantly improved. Sleepiness and drowsiness were significantly less of a problem. There was a trend towards improvement in attention span/concentration, and in the power and quality of concentration. Cognitive function tests also revealed a significant improvement in working (short term) and speed of memory although not in secondary (long term) memory. Patients did not experience hallucinations or delusions and there was no change in levels of anxiety or depression (Hospital Anxiety Depression Scale). The incidence of dizziness was significantly reduced, and there was a nonsignificant decrease in number of patients who suffered myoclonus and in the severity of this condition over the 14 days. The investigator's overall impression of treatment with transdermal fentanyl was 'fair', which was not in agreement with the positive impression expressed by patients (score 74, range: 0 worst, 100 best). Further work is required to determine if the improvement in patients' well being and cognitive function is achieved in larger study populations.

Synthesis and opioid activity of new fentanyl analogs

Three new fentanyl analogs (compounds 3-4-5) have been synthesized and evaluated for antinociceptive properties using the writhing test. The analgesic property of the active compound, N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl)] propenamide (compound 4), was tested using the hot plate test in mice. Its opioid agonistic activity was characterized using three isolated tissues: guinea pig ileum, mouse vas deferens, and rabbit vas deferens. Compound 4 was as effective as fentanyl or morphine and it showed less antinociceptive potency than fentanyl but it was more potent than morphine. The duration of the antinociception was similar to that of fentanyl. This compound inhibited the electrically evoked contractions of myenteric plexus-longitudinal muscle strips of guinea pig ileum and of mouse vas deferens but not those of rabbit vas deferens. These effects could be reversed by micro selective antagonists (naloxone and/or CTOP) but not by the delta selective antagonist naltrindole, thus indicating that the compound acted as a micro opioid agonist. Finally, the binding data confirmed that compound 4 had high affinity and selectivity for the micro-receptor.

Costs of opioid therapy for chronic nonmalignant pain in Germany: an economic model comparing transdermal fentanyl (Durogesic) with controlled-release morphine

The fentanyl transdermal therapeutic system (fentanyl-TTS;Durogesic) has a distinct route of administration and safety profile compared with other opioids used in the treatment of moderate to severe pain.These aspects are likely to have an impact on patient acceptance and functioning as well as efficacy. We compared the cost-utility of fentanyl-TTS and controlled-release morphine (cr-morphine) in the treatment of moderate to severe nonmalignant pain in outpatients in Germany. A 1-year, three-phased decisionanalytic model was constructed, incorporating estimates of a variety of aspects of pain control.Use of fentanyl-TTS was predicted to incur higher costs than cr-morphine over 1 year of treatment (DM 6950 vs.DM 6186, respectively) but was associated with a higher number of quality-adjusted life days (234 vs. 216, respectively), thus achieving an incremental cost-utility ratio of DM 15,960 per quality-adjusted life-year gained.The results of the decision-analytic model support the use of fentanyl-TTS as a favorable cost-effective option for the treatment of moderate to severe nonmalignant pain.

Supportive therapy of elderly cancer patients

Elderly cancer patients often require supportive care due to the physiologic decline of organs and apparatus linked with the aging process per se, and for the effects of tumor or of anticancer treatments. Pain and nutritional deficits are some clinical aspects requiring supportive care. Lack of studies on these latter topics does not allow an in depth analysis of the problem. The present review deals with literature concerning pain and nutritional problems in the general cancer population with emphasis on aspects typical for elderly cancer subjects. Physiologic and cancer-related changes in body composition, physical function and cognitive capacity of the elderly are presented and, when appropriate, linked with pathogenetic factors of pain and malnutrition, as well as their treatment. Pain demographic data, pain intensity evaluation and currently available techniques to provide pain relief such as etiologic treatment, analgesic pharmacotherapy and invasive analgesic procedures, are extensively discussed. Causes and assessment of malnutrition as well as available nutritional approaches such as oral, enteral and parenteral nutrition are also debated.

Transdermal fentanyl for the management of acute pancreatitis pain

Although the hazards of using Demerol for pain management is well documented, physicians at a 350-bed tertiary-care center in the upper midwest continued to follow the antiquated practice of ordering intramuscular Demerol and Vistaril to manage pain for patients with acute pancreatitis. Their reasoning was based on early evidence that Demerol, unlike morphine, does not cause biliary-tract spasms resulting in epigastric or right upper quadrant pain. In an effort to change practice patterns, a multidisciplinary team was formed to study the efficacy of using Transdermal Therapeutic System (TTS) fentanyl to manage pain in this patient population. Thirty-two subjects were enrolled in a double-blind, placebo-controlled study to evaluate the efficacy of using TTS fentanyl with intramuscular Demerol for breakthrough pain in comparison to using a placebo system and intramuscular Demerol. There was no statistically significant difference in self-reported pain intensity between the control and experimental groups on the first day of hospitalization. This finding would be expected because serum fentanyl concentrations rise gradually during the first 12 to 14 hours after application of the TTS fentanyl and plateau at 24 hours. There was a statistically significant difference between groups at 36 hours (exact p <.0154) and 45 hours (exact p <.0132) after application of the TTS fentanyl. This is probably because of greater serum fentanyl concentrations observed during the 36- to 48-hour period after application of TTS fentanyl. Although not statistically significant, trends in the data revealed that the experimental group had lower self-reported pain intensity scores than the control group throughout the course of hospitalization. Even though the experimental group had significantly more previous hospitalizations for acute pancreatitis and a higher pain intensity score on admission, this group had a significantly shorter length of stay in the hospital c2 (1, N = 31) = 4.3706 p <.05. There was no statistically significant difference between the two groups for self-reported satisfaction with pain management.

A new role for opioids in the treatment of arthritis

Arthritis, rheumatic diseases, spinal and peripheral joint disorders share in common a legacy of chronic pain. At the turn of the millennium, nonsteroidal anti-inflammatories (NSAIDs) had replaced aspirin as the agents most commonly used to deal with rheumatic symptoms, including pain. Paracetamol (acetaminophen) was the most common alternative analgesic for minor pain. Opioids were most commonly used on an ad-lib basis, usually for 'breakthrough' pain. However, neurobiological research has confirmed the basis for 24-hour around-the-clock complete suppression of chronic nonmalignant pain. This avoids the 'wind up' that leads to intractable pain progression. Proper monitoring, in the absence of the end organ toxicity seen with NSAIDs, allows a change in direction to opioids for arthritis for more severe pain. This requires understanding the responsibilities of maintaining opioids, in properly selected patients, based upon host response and informed consent. Under such circumstances, evidence-based trials support the use of stronger opioids in recalcitrant chronic pain of arthritis. Thus, we endeavour to better fulfill our Oath of Hippocrates: 'to relieve pain and suffering'.

Long-acting fentanyl analogues: synthesis and pharmacology of N-(1-phenylpyrazolyl)-N-(1-phenylalkyl-4-piperidyl)propanamides

The synthesis of new fentanyl analogues in which the benzene ring of the propioanilido group has been replaced by phenylpyrazole is described. Antinociceptive activity was evaluated using the writhing and hot plate tests in mice. Two compounds, and, showed interesting analgesic properties, being more potent than morphine and less than fentanyl but with longer duration of action. These compounds inhibited the electrically evoked muscle contraction of guinea pig ileum and mouse vas deferens but not that of rabbit vas deferens and the effects could be reversed by antagonists (naloxone and/or CTOP), thus indicating that the compounds acted as mu agonists. Finally, the binding data confirmed that the compounds had high affinity and selectivity for the mu receptor.

Transdermal fentanyl: an updated review of its pharmacological properties and therapeutic efficacy in chronic cancer pain control

Fentanyl is a synthetic opioid agonist which interacts primarily with the mu-opioid receptor. The low molecular weight, high potency and lipid solubility of fentanyl make it suitable for delivery by the transdermal therapeutic system. These patches are designed to deliver fentanyl at a constant rate (25, 50, 75 and 100 microg/h), and require replacement every 3 days. Data from randomised, nonblind trials suggest that transdermal fentanyl is as effective as sustained-release oral morphine in the treatment of chronic cancer pain, as reported by patients using visual and numerical analogue scales as well as verbal description scales. No obvious differences in health-related quality of life were found in patients with chronic cancer pain when comparing transdermal fentanyl with sustained-release oral morphine. Nevertheless, significantly more patients expressed a preference for transdermal fentanyl than for sustained-release oral morphine after a randomised, nonblind, crossover trial. Because of the formation of a fentanyl depot in the skin tissue, serum fentanyl concentrations increase gradually following initial application, generally levelling off between 12 and 24 hours. Thereafter, they remain relatively constant, with some fluctuation, for the remainder of the 72-hour application period. Once achieved, steady-state plasma fentanyl concentrations can be maintained for as long as the patches are renewed. The most frequently observed adverse events during transdermal fentanyl administration (as with other opioid agonists) included vomiting, nausea and constipation. Data from a nonblind, randomised trials suggest that constipation occurs less frequently in patients receiving transdermal fentanyl than in those given sustained-release oral morphine. The most serious adverse event reported in US premarketing trials was hypoventilation, which occurred with an incidence of approximately 2%. Adverse reactions related to skin and appendages (i.e. rash and application site reactions - erythema, papules, itching and oedema) were reported in 153 patients with cancer at a frequency between 1 and 3%.

CONCLUSION

Transdermal fentanyl is a useful opioid-agonist for the treatment of moderate to severe chronic cancer pain. The advantages of transdermal fentanyl include ease of administration and the 3-day application interval. These factors coupled with a lower incidence of constipation are likely to contribute to the reported patient preference of transdermal fentanyl over sustained-release oral morphine.

New mu-opioid receptor agonists with phenoxyacetic acid moiety

New muq-opioid receptor (MOR) agonists containing 4-hydroxypiperidine, piperidine and piperazine moieties were synthesized and evaluated to find a peripheral opioid analgesic. Among the synthesized compounds, 12-[1-[3-(N,N-dimethylcarbamoyl)-3,3-diphenylpropyl]-4-hydroxypiperidin-4-yl]phenoxy]acetic acid (8: SS620) having phenoxyacetic acid and 4-hydroxypiperidine moieties showed the highest agonist potency on the MOR in an isolated guinea-pig ileum preparation, and it also had selectivity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells compared with the same types of delta- and kappa-opioid receptors (DOR and KOR). In addition, compound 8 showed a 10 times more potent MOR agonist activity than loperamide. Furthermore, compound 8 showed a peripheral analgesic activity in vivo screening on rat.

Longitudinal follow-up of TTS-fentanyl use in patients with cancer-related pain: results of a compassionate-use study with special focus on elderly patients

GOALS OF THE WORK

This open compassionate-use prospective registration study evaluated the tolerability, ease of use and applied doses of transdermal (TTS) fentanyl in adult patients with cancer-related pain requiring strong opioid analgesia. Elderly patients were particularly focussed on.

PATIENTS AND METHODS

Previous pain medication was converted to an appropriate dose of TTS-fentanyl. Immediate-release morphine rescue medication was allowed as needed for breakthrough pain. Dose adjustments of TTS-fentanyl, rescue morphine requirements, the ease of use and side-effects were assessed monthly, with special emphasis paid to the severity of constipation and the use of laxatives.

MAIN RESULTS

A total of 663 patients with cancer-related pain, including 8% opioid-naive patients, were enrolled; 661 patients used at least 1 patch of TTS-fentanyl. Of these, 455 subjects were assessed at baseline and at 1 post-baseline visit at least. Individual treatment ranged from a few days to 2 1/2 years; TTS-fentanyl doses ranged from 25 to 950 microg/h. The major reason for study termination was non-drug-related death (61%). Approximately 40% of patients reported constipation. The frequency of constipation depended on the rescue morphine dose used, but no dose-relationship was found for TTS-fentanyl. Patient acceptance of the patches was high; around 85% of patients rated convenience as good to excellent The ease of use and tolerability of TTS-fentanyl in the elderly patients were comparable to that in the total population, except for a slight increase of non-serious adverse events.

CONCLUSIONS

TTS-fentanyl can be applied as long-term therapy to patients with cancer-related pain, including the elderly.

Myoclonus secondary to withdrawal from transdermal fentanyl: case report and literature review

Myoclonus is a common and well-described adverse effect of opioids. Most cases reported in the literature have been associated with opioid administration, rather than with opioid withdrawal. We describe a case of myoclonus secondary to withdrawal from transdermal fentanyl. We review the literature regarding myoclonus related to opioid therapy (opioid-induced myoclonus) and withdrawal (opioid withdrawal myoclonus), and discuss possible mechanisms and therapies for these phenomena.

The use of transdermal fentanyl in pediatric oncology palliative care

Transdermal fentanyl offers a noninvasive approach to the management of patients with opioid dependent and stable, chronic cancer pain. The transdermal delivery system offers distinct advantages where oral administration of opioids is difficult as a consequence of progressive disease and in patients whose compliance with oral medications is poor. Thirteen patients ranging in age from three years and nine months to 18 years and seven months were treated with transdermal fentanyl for between six hours and 112 days. All had previously been receiving oral morphine prior to the commencement of fentanyl and were transferred to fentanyl because of oral opioid side effects and poor oral compliance. Fentanyl was well tolerated and provided effective pain relief for 11 of 13 patients. Overall, patients and parents experienced satisfaction with fentanyl, both in terms of pain relief and improvement in quality of life.

New mu-opioid receptor agonists with piperazine moiety

New mu-opioid receptor (MOR) agonists containing piperazine and homopiperazine moieties in the structures were synthesized and their affinities to and agonist potencies on MOR were evaluated. Among the synthesized compounds, 4-[4-(2-methoxyphenyl)piperazin-1-yl]-N,N-dimethyl-2,2-diphenylbutanamide (20 Aa) showed the highest affinity to the human MOR expressed in Chinese hamster ovary (CHO)-K1 cells, and the highest agonist potency on the MOR in isolated guinea-pig ileum preparation.

Randomised crossover trial of transdermal fentanyl and sustained release oral morphine for treating chronic non-cancer pain

OBJECTIVES

To compare patients' preference for transdermal fentanyl or sustained release oral morphine, their level of pain control, and their quality of life after treatment.

DESIGN

Randomised, multicentre, international, open label, crossover trial.

SETTING

35 centres in Belgium, Canada, Denmark, Finland, the United Kingdom, the Netherlands, and South Africa.

PARTICIPANTS

256 patients (aged 26-82 years) with chronic non-cancer pain who had been treated with opioids.

MAIN OUTCOME MEASURES

Patients' preference for transdermal fentanyl or sustained release oral morphine, pain control, quality of life, and safety assessments.

RESULTS

Of 212 patients, 138 (65%) preferred transdermal fentanyl, whereas 59 (28%) preferred sustained release oral morphine and 15 (7%) expressed no preference. Better pain relief was the main reason for preference for fentanyl given by 35% of patients. More patients considered pain control as being "good" or "very good" with fentanyl than with morphine (35% v 23%, P=0.002). These results were reflected in both patients' and investigators' opinions on the global efficacy of transdermal fentanyl. Patients receiving fentanyl had on average higher quality of life scores than those receiving morphine. The incidence of adverse events was similar in both treatment groups; however, more patients experienced constipation with morphine than with fentanyl (48% v 29%, P<0.001). Overall, 41% of patients experienced mild or moderate cutaneous problems associated with wearing the transdermal fentanyl patch, and more patients withdrew because of adverse events during treatment with fentanyl than with morphine (10% v 5%). However, within the subgroup of patients naive to both fentanyl and morphine, similar numbers of patients withdrew owing to adverse effects (11% v 10%, respectively).

CONCLUSION

Transdermal fentanyl was preferred to sustained release oral morphine by patients with chronic non-cancer pain previously treated with opioids. The main reason for preference was better pain relief, achieved with less constipation and an enhanced quality of life.

Long-term observations of patients receiving transdermal fentanyl after a randomized trial

We observed 73 cancer patients receiving transdermal fentanyl for 1-29 (mean 5.5) months immediately after participation in a randomized clinical trial. Of these, 32 received fentanyl until death, 18 were lost to follow-up, 11 required alternative analgesia, and 12 withdrew for other reasons. The median first recorded dose (not necessarily the patient's first fentanyl dose) was 75 microg/h. The median final dose was 100 microg/h. All but 3 patients required <300 microg fentanyl/h. In the 16 who received fentanyl for > or =3 months until death, the median dose was unchanged (100 microg/h) 3 months before death and at death; 8/16 required no dosage change. The incidence of constipation, skin reactions, nausea, and vomiting was low. No significant respiratory depression was associated with fentanyl. Most patients (85%) and investigators (86%) rated the treatment as good or excellent. We conclude that long-term treatment with transdermal fentanyl is safe and acceptable to many cancer patients.

Treatment options to manage pain at the end of life

Experts believe that the time preceding death can be comfortable if people die without pain, with dignity, and in their own way. Given current analgesic options, psychological and spiritual interventions, and an effective health care delivery system, all these goals are achievable. Pain management is one of the most important aspects of end-of-life care. Effective analgesics should be chosen carefully, in keeping with the patient's overall condition, level and stability of pain, and specific patient/family wishes. Ideally, analgesics should be initiated as soon as appropriate. The variety of routes of delivery, ranging from oral to transdermal or epidural to intrathecal, allows a selection that will achieve comfort and yet be least troublesome for the caregiver and patient. As the palliative care specialty continues to grow in the United States, it is imperative that health care professionals in the field develop basic to advanced primers to assist in equipping colleagues in all specialties with an understanding of effective opioid use, as well as the multidimensional aspects of helping patients achieve comfort at the end of life.

Treatment of cancer pain with transdermal fentanyl

Pain is a feature of many cancers, particularly in the advanced stages at which the palliative care approach to symptom control achieves the best outcomes. The holistic approach generally dictates that any treatment of the cancer per se has symptom control as the primary objective at this advanced stage. Pain, which invariably increases with disease progression, is treated with opioids and adjuvant analgesic drugs together with physical therapies. Orally administered opioid drugs are used preferentially because of cost and convenience, but other routes of administration (subcutaneous, rectal, spinal) are also possible. More recently, transdermal fentanyl has been evaluated in the treatment of moderate to severe cancer pain. The rate of fentanyl absorption is constant (after a lag period), and the dose is altered by increasing or decreasing the area of skin covered by the patch (size and/or number of patches). The dosing interval for these systems is generally 3 days. The extent of pain relief provided by transdermal fentanyl and sustained release morphine formulations is similar, with quality-of-life instruments showing no consistent preference for either formulation. Open studies have suggested a lower risk of constipation. Transdermal fentanyl is effective in the treatment of severe cancer pain, particularly when the oral route is unavailable.

Economic evaluation of the fentanyl transdermal system for the treatment of chronic moderate to severe pain

The fentanyl transdermal system (Duragesic) is an opioid analgesic indicated for the management of chronic moderate to severe pain. The purpose of this analysis is to estimate its economic value compared to two long-acting oral opioids. A cost-utility analysis was performed using a three-phased decision analytic model. The transdermal system had the highest expected cost during the first year of therapy ($2,491), moderately higher than the cost of a year of therapy with controlled-release morphine ($2,037) or controlled-release oxycodone ($2,307). The system also had the highest expected number of quality-adjusted life-days (QALDs) (244 compared to 236 for morphine and 231 for oxycodone), despite conservative assumptions. The fentanyl transdermal system achieved incremental cost-utility ratios of $20,709 (vs. morphine) and $5,273 (vs. oxycodone) per quality-adjusted life year (QALY) gained. In a conservative modeled analysis, the fentanyl transdermal system led to increased QALDs at a nominal increased cost. In the absence of head-to-head clinical trials, models help clarify cost and outcome trade-offs and provide a consistent theoretical framework for use by individual decisionmakers.