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

Formulations of fentanyl for the management of pain

Fentanyl is an opioid initially developed for parenteral administration. While oral administration is not an option due to a high first-pass metabolism, its high potency and lipophilicity have made a number of new routes of administration feasible. The transdermal therapeutic system offers an excellent option for long-term treatment of cancer and chronic pain, achieving stable plasma concentrations over the treatment period. The recent change from reservoir to matrix systems has made these systems more convenient to wear and safer to use, while being bioequivalent. In contrast, the patient-controlled iontophoretic transdermal system has been developed to enable on-demand delivery of transdermal bolus doses of fentanyl to treat postoperative pain. It offers a needle-free system to provide patient-controlled analgesia otherwise offered by intravenous pumps. However, due to technical difficulties the system is currently not clinically available. Oral transmucosal fentanyl utilizes the rapid uptake through the buccal mucosa to achieve high plasma concentrations rapidly and is indicated to treat breakthrough pain in patients who are not opioid-naive. The recently introduced fentanyl buccal tablets offer slightly better pharmacokinetics for the same indication. The intranasal route is another option to achieve rapid uptake of fentanyl, and is currently being investigated to provide acute and breakthrough pain relief. Transpulmonary administration of fentanyl remains experimental and this route of administration is not yet in clinical use. Overall, the specific pharmacological and physicochemical properties of fentanyl have made this compound highly suitable for novel routes of administration in a range of clinical indications.

Bioequivalence criteria for transdermal fentanyl generics: do these need a relook?

With the increasing appearance of transdermal fentanyl generics since 2004 when patent protection of the reference Duragesic expired, opportunities to switch between different generics have arisen. Transdermal fentanyl is subject to bioequivalence regulation because only approximately 92% of the dose is absorbed as a result of the need to maintain a diffusion gradient from plaster to skin. Considering the high potency of fentanyl and the potential dangerous adverse effects of full mu opioid receptor agonists, we assessed evidence suggesting a revision of the confidence limits of bioequivalence of 80-125%. A few cases have been reported where a prescribed ascension in transdermal fentanyl dosing triggered respiratory depression. Values of concentration that produce a 50% effective response for decreasing the ventilatory volume lie within the plasma concentration range of 1.4-2.5 ng/mL during transdermal fentanyl analgesia. However, an exchange of the reference with a generic with higher bioavailability would trigger respiratory depression only in extreme situations and is clinically supported by only a single case report. Experimental or clinical evidence is required to provide the necessary database for final judgement of bioequivalent limits of fentanyl generics. At present, the evidence is not sufficient to advise other bioequivalence criteria than those previously applied to transdermal fentanyl.

Report of a patient chewing fentanyl patches who was titrated onto methadone

This case report discusses the clinical presentation and management of a patient presenting to substance misuse services reporting chewing fentanyl patches in addition to wearing them transdermally. The patient was successfully titrated onto methadone 30 mg. Only one previously reported case of an individual chewing fentanyl patches was found in the literature; no case reports were found where treatment involved titrating the patient onto methadone. The pharmacology and illicit use of fentanyl are also considered.

A One Year Health Economic Model Comparing Transdermal Fentanyl with Sustained-Release Morphine in the Treatment of Chronic Noncancer Pain

A Markov model was constructed to simulate the resource use and health outcomes of one year of treatment comparing the fentanyl transdermal therapeutic system (fentanyl-TTS) with oral sustained-release (SR) morphine in outpatients with noncancer pain in Denmark. Effectiveness was assessed in terms of days of good pain control and days on initial treatment. Costs included those of baseline pain management, including breakthrough pain; co-medication costs; and control of adverse events. Fentanyl-TTS was more effective than SR-morphine in achieving good pain control (99 vs. 64 days, respectively) and the incremental cost-effectiveness of fentanyl-TTS was US dollars 10.26 per extra day of good pain control. Patients treated with fentanyl-TTS remained considerably longer on initial treatment compared with those treated with SR-morphine (166 days vs. 117 days, respectively). The results of this study suggest that fentanyl-TTS is a competitive therapeutic and economic choice for the treatment of chronic noncancer pain.

[Management of transdermal therapeutics in perioperative care]

OBJECTIVE

To provide guidance on perioperative management of most frequently encountered transdermal therapeutics in anaesthesiology: nicotine, fentanyl, nitroglycerin, scopolamine and estradiol.

DATA SOURCES

A review of the last decade literature was carried out on the Pubmed database using the following keywords (transcutaneous or percutaneous or transdermal or transdermic or skin or dermal) and (drug delivery systems or therapeutic systems or drug administration) grouped under the Mesh terms cutaneous administration, perioperative care, surgery, pharmacokinetics, nicotine, fentanyl, nitroglycerin, scopolamine, estradiol.

STUDY SELECTION

Original articles, general articles reviews, guidelines, letters to the editor and case reports have been selected.

DATA EXTRACTION

Articles were analyzed for each transdermal treatment in terms of pharmacokinetics as well as anaesthetics and surgical interactions.

DATA SYNTHESIS

Transdermal nicotine must be removed before anaesthesia of patients with coronary disease or with high risk of inhalation and in case of reconstructive surgery. Transdermal fentanyl must be maintained during the perioperative period and associated with preventive treatments of hyperalgesia. Transdermal administration of fentanyl by iontophoresis is a promising system for postoperative analgesia. Transdermal nitroglycerin must be maintained before scheduled surgery of a coronary patient. Transdermal scopolamine must be removed the day before surgery because of its side effects. It could have an interest in the prevention of postoperative nausea and vomiting, but its therapeutic method remain to be defined. Transdermal estradiol can be maintained during the perioperative period.

CONCLUSION

The management of transdermal therapeutics in peri operative care can be adapted for each treatment and for each patient by knowing pharmacokinetics as well as anaesthetics and surgical interactions. In emergency situations, the actions to be taken do not generally differ, but one must be aware that the effects of trandermal treatments do not disappear immediately when removed, due to their pharmacokinetics properties.

Reservoir based fentanyl transdermal drug delivery systems: effect of patch age on drug release and skin permeation

PURPOSE

To understand and evaluate the stability and skin permeation profiles of fentanyl reservoir systems as a function of patch age.

METHODS

Drug release and skin permeation studies were performed using a modified USP apparatus 5 with a novel sample preparation technique.

RESULTS

The amount of fentanyl present in the EVA/adhesive layer (EAL) increased from about 17% of label claim (LC) at 5 months to 25% LC at 22 months. The increase in the drug concentration was mainly observed in the peripheral EAL. Simultaneously, the alcohol content of the patch decreased as a function of patch age. A significant effect of patch age on the drug content in the EAL and the drug release from the system was observed; however, skin permeation studies did not indicate an increase in drug delivery rate.

CONCLUSIONS

Novel sample preparation technique with USP Apparatus 5 allowed determination of in vitro skin permeation rates for fentanyl transdermal patches with different designs. Permeation rates with cadaver skin as substrate were found not to change with patch age despite changing drug concentration in the EAL.

Pain therapy

Cancer-related pain is a major issue of healthcare systems worldwide. The reported incidence, considering all stages of the disease, is 51%, which can increase to 74% in the advanced and terminal stages. For advanced cancer, pain is moderate to severe in about 40-50% and very severe or excruciating in 25-30% of cases. Pain is both a sensation and an emotional experience. Pain is always subjective; and may be affected by emotional, social and spiritual components thus it has been defined as "total pain". From a pathophysiological point of view, pain can be classified as nociceptive (somatic and visceral), neuropathic (central, peripheral, sympathetic) idiopathic or psychogenic. A proper pain assessment is fundamental for an effective and individualised treatment. In 1986 the World Health Organisation (WHO) published analgesic guidelines for the treatment of cancer pain based on a three-step ladder and practical recommendations. These guidelines serve as an algorithm for a sequential pharmacological approach to treatment according to the intensity of pain as reported by the patient. The WHO analgesic ladder remains the clinical model for pain therapy. Its clinical application should be employed only after a complete and comprehensive assessment and evaluation based on the needs of each patient. When applying the WHO guidelines, up to 90% of patients can find relief regardless of the settings of care, social and/or cultural environment. This is the standard treatment on a type C basis. Only when such an approach is ineffective are interventions such as spinal administration of opioid analgesics or neuroinvasive procedures recommended.

Fentanyl transdermal matrix patch (Durotep MT patch; Durogesic DTrans; Durogesic SMAT): in adults with cancer-related pain

The fentanyl transdermal matrix patch is approved in Japan for the management of moderate to severe cancer-related pain in adults. Bioequivalence, in terms of exposure and the maximum and minimum serum concentrations, has been established between the fentanyl transdermal matrix patch 16.8 mg (100microg/h) and the fentanyl transdermal reservoir patch 10 mg (100microg/h) after single and multiple applications. The fentanyl transdermal matrix patch 2.1-8.4 mg (12.5-50microg/h) effectively managed chronic cancer-related pain in adults in a noncomparative, multicentre, phase II study; 89.4% of recipients rated their global assessment of pain as 'very satisfied', 'satisfied' or 'neither satisfied nor dissatisfied'. Adults with cancer- or non-cancer-related chronic pain were switched from fentanyl transdermal reservoir patch to fentanyl transdermal matrix patch therapy without compromising efficacy; no differences in pain intensity or sleep interference scores were seen between the two formulations in an nonblind, multicentre, switching pilot study. Given the nature of the therapy, the tolerability profile of the fentanyl transdermal matrix patch was generally acceptable. Topical adverse events included erythema, application-site irritation and pruritus. In general, patients and physicians preferred the fentanyl transdermal matrix patch over the fentanyl transdermal reservoir patch in the pilot study.

Transdermal matrix fentanyl membrane patch (matrifen): in severe cancer-related chronic pain

The matrix fentanyl membrane patch is a new transdermal patch designed with a reduced drug load compared with established reservoir and matrix fentanyl patches. The drug is contained within a silicone matrix with a rate-controlling membrane designed to maintain constant serum fentanyl concentrations over the 72-hour application period. The matrix fentanyl membrane patch was equivalent to the reservoir fentanyl patch in terms of transdermal delivery of fentanyl, as demonstrated after both single (100 microg/h) and multiple (50 microg/h) applications by the peak serum fentanyl concentration and the area under the serum concentration-time curve over 72 hours. In a randomized, nonblind, multicentre trial, the transdermal matrix fentanyl membrane patch was noninferior to standard opioid therapy (transdermal reservoir or matrix fentanyl patch or an oral opioid) in terms of analgesic efficacy over 30 days in patients with cancer-related chronic pain requiring long-term opioid use. The transdermal matrix fentanyl membrane patch was as well tolerated as standard opioid therapy; patient-rated tolerability scores for constipation, nausea, daytime drowsiness and sleep disturbance were similar between treatments.

Cancer pain and analgesia

Pain ranges in prevalence from 14-100% among cancer patients and occurs in 50-70% of those in active treatment. Cancer pain may result from direct invasion of tumor into nerves, bones, soft tissue, ligaments, and fascia, and may induce visceral pain through distension and obstruction. Cancer pain is multifaceted. Clinicians may describe cancer pain as acute, chronic, nociceptive (somatic), visceral, or neuropathic. Despite implementation of the WHO guidelines, reports of undertreatment of cancer pain persist in various clinical settings and in spite of decades of work to reduce unnecessary discomfort. Substantial obstacles to adequate pain relief with opioids include specific concerns of patients themselves, their family members, physicians, nurses, and the healthcare system. The WHO analgesic ladder serves as the mainstay of treatment for the relief of cancer pain in concert with tumoricidal, surgical, interventional, radiotherapeutic, psychological, and rehabilitative modalities. This multidimensional approach offers the greatest potential for maximizing analgesia and minimizing adverse effects. Primary therapies are directed at the source of the cancer pain and may enhance a patient's function, longevity, and comfort. Adjuvant therapies include nonopioids that confer analgesic effects in certain medical conditions but primarily treat conditions that do not involve pain. Nonopioid medications (over-the-counter agents) are useful in the management of mild to moderate pain, and their continuation through step 3 of the WHO ladder is an option after weighing a drug's risks and benefits in individual patients. Symptomatic treatment of severe cancer pain should begin with an opioid, regardless of the mechanism of the pain. They are very effective analgesics, titrate easily, and offer a favorable risk/benefit ratio. Cancer pain remains inadequately controlled despite the diagnostic and therapeutic means of ensuring that patients feel comfortable during their illness. Therefore, all practitioners need to make control of cancer pain a professional duty, even if they can only use the most basic and least expensive analgesic medications, such as morphine, codeine, and acetaminophen, to reduce human suffering.

Topical fentanyl in a randomized, double-blind study in patients with corneal damage

OBJECTIVES

Corneal damage causes severe pain. This study investigated whether peripheral opioid receptors are present in the human cornea and assessed the efficacy of topical fentanyl in patients with corneal erosion.

METHODS

Immunohistochemical staining experiments were performed to examine the presence of both mu and delta-receptors on peripheral nerve fibers within human corneal tissue. In a randomized, double-blind clinical trial dexpanthenol (n=20) or dexpanthenol plus 10 microg fentanyl (n=20) were topically applied every 4 hours to the eye of patients with a surgical intervention of corneal damage and subjective pain intensity was determined by a numerical rating scale.

RESULTS

Immunohistochemical staining identified peripheral nerve fibers in human cornea expressing both mu and delta-opioid receptors. In patients with corneal damage the ophthalmic intervention in local anesthesia decreased the subjective pain intensity significantly. At 4-hour intervals after the ophthalmic intervention, moderate pain intensity levels were not altered by the application of dexpanthenol with or without fentanyl. At 24 hours pain intensity dropped significantly, most likely owing to a natural decrease in pain, because the erosion was almost healed.

DISCUSSION

Both mu and delta-receptors are localized on nerve fibers within the cornea, which are accessible for topical opioid treatment. However, our formulation and dose of topical fentanyl in combination with dexpanthenol did not show any benefit in relieving pain from corneal erosion. Future studies are planned to determine the optimal protocol and dose of topical opioid treatment.

Effects of fentanyl dose and exposure duration on the affective and somatic signs of fentanyl withdrawal in rats

Fentanyl is a potent mu-opioid receptor agonist that is widely used for the treatment of chronic pain. The aim of the present study was to investigate the effect of the dose of fentanyl and the exposure duration on the affective and somatic signs of fentanyl withdrawal in rats. Fentanyl and saline were chronically administered via osmotic minipumps. A discrete-trial intracranial self-stimulation procedure was used to provide a measure of brain reward function and somatic signs were recorded from a checklist of opioid abstinence signs. The opioid receptor antagonist naloxone elevated the brain reward thresholds of the rats chronically treated with high doses of fentanyl (0.3 and 0.6mg/kg/day), but not those of rats treated with low doses of fentanyl (0.006 and 0.06mg/kg/day). Fentanyl had a dose-dependent effect on the naloxone-induced elevations in brain reward thresholds. On a similar note, the discontinuation of the administration of high doses of fentanyl was associated with elevations in brain reward thresholds and the discontinuation of the administration of low doses of fentanyl did not lead to an elevation in brain reward thresholds. The results also demonstrated that the duration of fentanyl administration does not affect naloxone-induced elevation in brain reward thresholds. In contrast, the somatic withdrawal syndrome gradually developed over time; maximum somatic signs were observed 120h after pump implantation. These studies suggest that the magnitude and duration of the negative affective signs of fentanyl withdrawal depend on the dose of fentanyl administered and not on the duration of fentanyl administration.

Management of malignant bowel obstruction

Malignant bowel obstruction (MBO) is a common and distressing outcome particularly in patients with bowel or gynaecological cancer. Radiological imaging, particularly with CT, is critical in determining the cause of obstruction and possible therapeutic interventions. Although surgery should be the primary treatment for selected patients with MBO, it should not be undertaken routinely in patients known to have poor prognostic criteria for surgical intervention such as intra-abdominal carcinomatosis, poor performance status and massive ascites. A number of treatment options are now available for patients unfit for surgery. Nasogastric drainage should generally only be a temporary measure. Self-expanding metallic stents are an option in malignant obstruction of the gastric outlet, proximal small bowel and colon. Medical measures such as analgesics according to the W.H.O. guidelines provide adequate pain relief. Vomiting may be controlled using anti-secretory drugs or/and anti-emetics. Somatostatin analogues (e.g. octreotide) reduce gastrointestinal secretions very rapidly and have a particularly important role in patients with high obstruction if hyoscine butylbromide fails. A collaborative approach by surgeons and the oncologist and/or palliative care physician as well as an honest discourse between physicians and patients can offer an individualised and appropriate symptom management plan.

Effect of voriconazole and fluconazole on the pharmacokinetics of intravenous fentanyl

OBJECTIVE

Fentanyl is a widely used opioid analgesic, which is extensively metabolized by hepatic cytochrome P450 (CYP) 3A. Recent reports suggest that concomitant administration of CYP3A inhibitors with fentanyl may lead to dangerous drug interactions.

METHODS

The potential interactions of fentanyl with triazole antifungal agents voriconazole and fluconazole were studied in a randomized crossover study in three phases. Twelve healthy volunteers were given 5 microg/kg of intravenous fentanyl without pretreatment (control), after oral voriconazole (400 mg twice on the first day and 200 mg twice on the second day), or after oral fluconazole (400 mg once on the first day and 200 mg once on the second day). Plasma concentrations of fentanyl, norfentanyl, voriconazole, and fluconazole were determined up to 24 h. Pharmacokinetic parameters were calculated using compartmental methods.

RESULTS

The mean plasma clearance of intravenous fentanyl was decreased by 23% (range -22 to 48%; p < 0.05) and 16% (-34 to 53%; p < 0.05) after voriconazole and fluconazole administration, respectively. Voriconazole increased the area under the fentanyl plasma concentration-time curve by 1.4-fold (p < 0.05). The initial plasma concentrations and volume of distribution of fentanyl did not differ significantly between phases.

CONCLUSION

Both voriconazole and fluconazole delay the elimination of fentanyl significantly. Caution should be exercised, especially in patients who are given voriconazole or fluconazole during long-lasting fentanyl treatment, because insidiously elevated fentanyl concentration may lead to respiratory depression.

Impact of transdermal fentanyl on quality of life in rheumatoid arthritis

OBJECTIVES

The purpose of the study was to investigate the effectiveness and tolerability of transdermal fentanyl in a treatment regimen in patients with rheumatoid arthritis (RA).

METHODS

Two hundred twenty-six patients (mean age 66 y) with severe pain caused by RA who had not previously been treated with transdermal fentanyl were included in this prospective, open-label study. Pain intensity, functional impairment, and well-being were documented prospectively for 30 days after treatment with transdermal fentanyl had been initiated. Patients evaluated pain on an 11-point numerical rating scale. Quality of sleep, daily and social functioning, and treatment satisfaction were rated using 5-point categorical rating scales. General well-being was assessed by the Marburg questionnaire.

RESULTS

Adding transdermal fentanyl to the ongoing RA therapy reduced pain intensity significantly from 8.0 (7.82 to 8.18) to 4.0 (3.75 to 4.25). Mean functional impairment due to pain also decreased significantly from "severe" at the beginning to "mild to moderate." Treatment with transdermal fentanyl also led to a significant improvement by approximately 1.5 units for all items in the Marburg questionnaire on general well-being. At the end of the study, nearly all patients were satisfied with the pain treatment. Transdermal fentanyl was generally well tolerated. The most frequent side effects were nausea (9.7%) and vomiting (7.1%).

DISCUSSION

Patients with pain caused by RA improved in terms of pain intensity, sleep, function, and general well-being when transdermal fentanyl was added to the treatment regimen. Treatment satisfaction was high. Transdermal fentanyl also demonstrated good tolerability over a period of 30 days.

Clinical experience with transdermal and orally administered opioids in palliative care patients--a retrospective study

BACKGROUND

Transdermal fentanyl is a widely used opioid for the treatment of cancer pain. Simplicity of use and high patient compliance are the main advantages of this opioid. However, based on our clinical experience, transdermal fentanyl is often not efficacious in terminally ill palliative care patients. We thus retrospectively examined the pain management and need for opioid switching in cancer patients admitted to our palliative care unit.

METHODS

Of 354 patients admitted to our palliative care unit from 2004 through 2005, 81 patients were pre-treated with transdermal fentanyl. Demographic and cancer-related data (diagnosis, symptoms, pain score on a numeric rating scale (NRS)), analgesic dose at admission and discharge were compared.

STATISTICS

mean +/- SD, ANOVA, Wilcoxon's test was used for inter-group comparisons, significance P < 0.05, adjusted for multiple testing. Pain scores are given in median (range).

RESULTS

Mean transdermal fentanyl dose at admission was 81.0 +/- 55.8 microg/h. In 79 patients transdermal fentanyl treatment was discontinued. In two patients, analgesic treatment according to WHO I provided sufficient pain relief. The other 77 patients were switched to other opioids: 33 patients to oral morphine and 44 to oral hydromorphone. In patients switched to morphine the dose at discharge (104.7 +/- 89.0 mg) was lower than at admission (165.5 mg morphine equivalence). In patients switched to hydromorphone the dose of 277.8 +/- 255.0 mg morphine equivalent was higher at discharge than at admission (218.2 +/- 131.4 mg morphine equivalence--considering an equianalgesic conversion ratio morphine: hydromorphone = 7.5: 1). Pain scores decreased significantly after opioid rotation (NRS at rest/on exertion: 4 (0-10)/7 (2-10) versus 1 (0-3)/2 (0-5); P < 0.001).

CONCLUSIONS

In the patient group switched to morphine, sufficient pain relief was achieved by lower equianalgesic morphine doses, compared with the doses at admission. In the patient group switched to hydromorphone, higher equianalgesic morphine doses were needed at discharge, considering an equianalgesic conversion ratio of morphine: hydromorphone = 7.5: 1. Patients with far advanced cancer often suffer from sweating and cachexia, which may have negative effects on the absorption of transdermal fentanyl. Opioid switching to oral morphine or hydromorphone was well tolerated and proved to be an efficacious option for cancer pain treatment.

The effects of buprenorphine on fentanyl withdrawal in rats

RATIONALE

Fentanyl is a potent mu-opioid receptor agonist that is widely used for the treatment of severe chronic pain. Discontinuation of fentanyl administration has been shown to induce a negative emotional state.

OBJECTIVES

The aim of the present studies was to investigate the effects of the partial mu-opioid receptor agonist buprenorphine on the negative emotional state associated with precipitated and spontaneous fentanyl withdrawal in rats.

MATERIALS AND METHODS

Fentanyl and saline were chronically administered via osmotic minipumps. A discrete-trial intracranial self-stimulation procedure was used to provide a measure of brain reward function. Somatic signs were recorded from a checklist of opioid abstinence signs.

RESULTS

Naloxone induced a deficit in brain reward function in rats chronically treated with fentanyl. Buprenorphine dose-dependently prevented the naloxone-induced deficit in brain reward function. Discontinuation of fentanyl administration was also associated with a deficit in brain reward function. After explantation of the minipumps, the administration of buprenorphine induced a potentiation of brain reward function in the fentanyl-withdrawing rats, but did not affect brain reward function of saline-treated control rats. Buprenorphine prevented the somatic withdrawal signs associated with spontaneous fentanyl withdrawal and attenuated the somatic signs associated with precipitated fentanyl withdrawal.

CONCLUSIONS

Buprenorphine prevents affective and somatic fentanyl withdrawal signs. Moreover, buprenorphine is rewarding in rats previously exposed to fentanyl, but not in opioid-naïve rats. This pattern of results suggests that buprenorphine may be an effective treatment for the anhedonic-state associated with fentanyl withdrawal, but further study of buprenorphine's abuse potential is warranted.

Fentanyl HCl iontophoretic transdermal system (ITS): clinical application of iontophoretic technology in the management of acute postoperative pain

The fentanyl HCl iontophoretic transdermal system (fentanyl ITS) is a novel patient-controlled analgesia (PCA) system that has been approved in the USA and Europe for the management of acute, moderate-to-severe postoperative pain. This system extends the applicability of transdermal drug delivery to acute pain management, allowing patients to self-administer pre-programmed doses of fentanyl non-invasively through the use of iontophoretic technology. Iontophoresis is the process by which an electric current is used to drive ionized drug molecules across the skin and into the systemic circulation. Results of a recent US clinical trial found the fentanyl ITS to provide pain control equivalent to a standard regimen of morphine i.v. PCA, with a similar incidence of opioid-related adverse events. The fentanyl ITS may offer a number of clinical advantages over existing PCA modalities. Its method of drug delivery avoids the risk of complications from needle-related injuries and infection, and its pre-programmed electronics eliminate the potential for manual programming errors and excessive dosing. In addition, the compact size of the system could enable greater patient mobility following surgery. The fentanyl ITS has the potential to become a valuable option in the management of acute postoperative pain.

Validated GC–MS analysis for the determination of residual fentanyl in applied Durogesic® reservoir and Durogesic® D-Trans® matrix transdermal fentanyl patches

The method development and validation characteristics are described of a simple gas chromatographic-mass spectrometric (GC-MS) analytical procedure to determine residual fentanyl in used Durogesic reservoir patches and Durogesic D-Trans matrix technology based systems to estimate the actual rate of transdermal fentanyl delivered in individual patients. The sample preparation protocol constituting a saline based extraction of sets of new patches of each nominal dose available, resulted in fentanyl extraction recoveries to increase steadily as a function of increasing extraction time. For the reservoir type transdermal therapeutic system (TTS), fentanyl extraction efficiencies at equilibrium (16 h) ranged from approximately 60% (100-microg/h TTS) to 95% (25-microg/h TTS), whereas for the matrix type system considerable lower recoveries were demonstrated for the highest nominal dose rates (35%-52%), while reaching 90% for the 25-microg/h system. For the latter type of fentanyl TTS, an optimized methanol based extraction protocol yielded virtually quantitative fentanyl recoveries for each matrix patch nominal dose level at substantially shorter extraction periods (15 min). The GC-MS analytical method using selected ion monitoring (SIM) and deuterated fentanyl as internal standard was shown to be adequately selective with regard to the presence of other compounds in the Durogesic patches. It was further demonstrated that the developed analytical protocols provided highly reproducible and accurate estimates of the initial fentanyl content of each patch type at all available nominal doses, with coefficients of variation and relative errors generally below 10%. These advantageous assay validation characteristics can be further transposed to the application of residual fentanyl level estimates in used patches, provided that with each batch of samples also a set of new TTSs with equal dose is assayed to perfectly mimic extraction phenomena. Finally, the presented GC-MS analytical protocol was successfully applied for the determination of residual fentanyl in a subset of 57 reservoir type patches obtained from four palliative patients.

Three-cycle fentanyl patch system significantly improves pain control in gynecologic cancer

Pain affects many cancer patients, and in advanced stages of the disease it can significantly affect the quality of their lives. Morphine has long been the 'gold standard' for the treatment of cancer pain. However, its side-effects, particularly sedation and cognitive impairment at high doses, have encouraged the use of 'opioid rotation'. The transdermal fentanyl patch has advantages over oral morphine, with reduced side-effects and increased convenience in practical usage. The side-effects were reduced in patients who changed to the fentanyl patch, but rescue analgesia was often needed because of the decrease of fentanyl release from the patch, especially on the patch replacement day. We have developed a three-cycle fentanyl patch system that provided an appropriate pain control, and this system should be considered for pain relief in cancer patients.

Fatal outcome in a child after ingestion of a transdermal fentanyl patch

The case history and toxicological findings of a fatal fentanyl intoxication due to ingestion of a transdermal patch are presented. A 1-year-old otherwise healthy girl was put to bed and 2 h later she was found dead. The autopsy revealed a 25-microg/h (4.2 mg) transdermal fentanyl patch in the stomach. Toxicological analysis by liquid chromatography-tandem mass spectrometry with positive electrospray ionization yielded fentanyl and norfentanyl concentrations in the peripheral blood of 5.6 and 5.9 ng/ml, heart blood 19.0 and 8.9 ng/ml, and liver 235 and 26 ng/g, respectively. The cause of death was determined to be a fentanyl overdose. The investigation established that the child has unintentionally swallowed the patch, which had been lying on the floor.

Analysis of the Effects of Fentanyl in the Feline Pulmonary Vascular Bed

The objective of this study was to test the hypothesis that fentanyl induces a depressor response in the pulmonary vascular bed of the cat and to identify the receptors involved in the mediation or modulation of these effects. The authors conducted a prospective vehicle-controlled study at a university research laboratory using intact chest preparation in adult mongrel cats. In separate experiments, the effects of diphenhydramine (histamine receptor blocker), glibenclamide (ATP-sensitive K+ channel blocker), L-N5-(1-Iminoethyl) ornithine hydrochloride (L-NIO) (nitric oxide synthase inhibitor), nimesulide (selective cyclooxygenase [COX]-2 inhibitor), and naloxone (opiate receptor antagonist) were investigated on pulmonary arterial responses to fentanyl and other agonists in the pulmonary vascular bed of the cat. The systemic pressure and lobar arterial perfusion pressure were continuously monitored, electronically averaged, and recorded. In the feline pulmonary vascular bed of the isolated left lower lobe, fentanyl induced a dose-dependent vasodepressor response that was not significantly altered after administration of glibenclamide, L-NIO, and nimesulide. However, the responses to fentanyl were significantly attenuated after administration of diphenhydramine and naloxone. The results of the present study suggest that fentanyl has potent vasodepressor activity in the pulmonary vascular bed of the cat and that this response may be mediated or modulated by both histaminergic and opiate receptor sensitive pathways.

Pulmonary delivery of opioids as pain therapeutics

Pulmonary opioid delivery, on the basis of the fact that small molecular entities can be rapidly and completely absorbed from the peripheral lung, poses a unique opportunity for the treatment of severe (breakthrough) pain, which currently is treated with intravenous therapy. Early clinical studies involving inhaled opioids were focused on treatment of dyspnoea and not pain management, but they showed that inhalation of various opioid compounds is safe, even in severely ill patients. The advent of specialized and efficient pulmonary drug delivery systems has facilitated the evaluation of inhaled opioids, such as morphine and fentanyl, for management of severe pain associated with surgery or malignant disease. This review will summarize recent literature on the pharmacokinetics and pharmacodynamics of inhaled opioids and will discuss safety and efficacy in comparison to injection and other opioid dosage forms available for pain therapy. Finally, regulatory considerations will be discussed towards the approval of this new delivery paradigm for opioid drugs.

Toward evidence-based prescribing at end of life: a comparative analysis of sustained-release morphine, oxycodone, and transdermal fentanyl, with pain, constipation, and caregiver interaction outcomes in hospice patients

OBJECTIVE

The primary goal of this investigation was to examine selected outcomes in hospice patients who are prescribed one of three sustained-release opioid preparations. The outcomes examined include: pain score, constipation severity, and ability of the patient to communicate with caregivers.

PATIENTS AND SETTINGS

This study included 12,000 terminally ill patients consecutively admitted to hospices and receiving pharmaceutical care services between the period of July 1 and December 31, 2002.

DESIGN

We retrospectively examined prescribing patterns of sustained-release morphine, oxycodone, and transdermal fentanyl. We compared individual opioids on the aforementioned outcome markers, as well as patient gender, terminal diagnosis, and median length of stay.

RESULTS

Patients prescribed a sustained-release opioid had similar average ratings of pain and constipation severity, regardless of the agent chosen. Patients prescribed transdermal fentanyl were reported to have more difficulty communicating with friends and family when compared with patients prescribed either morphine or oxycodone. On average, patients prescribed transdermal fentanyl had a shorter length of stay on hospice as compared with those receiving morphine or oxycodone.

CONCLUSION

There was no difference in observed pain or constipation severity among patients prescribed sustained-release opioid preparations. Patients receiving fentanyl were likely to have been prescribed the medication due to advanced illness and associated dysphagia. Diminished ability to communicate with caregivers and a shorter hospice course would be consistent with this profile. Further investigation is warranted to examine the correlation between a patient's ability to interact with caregivers and pain control achieved.

Cutaneous Reactions to Transdermal Therapeutic Systems

Transdermal therapeutic systems have been increasingly used in the past two decades. However, cutaneous side effects are fairly common and may result in poor patient compliance. This review article summarizes the spectrum of reactions due to transdermal therapeutic systems and provides a current list of known allergens.

An iontophoretic, fentanyl HCl patient-controlled transdermal system for acute postoperative pain management

Patient-controlled modalities using intravenous or epidural routes have dramatically improved postoperative pain management. However, acute post-operative pain continues to be undermanaged. Intravenous patient-controlled analgesia (PCA), the current standard of care for acute postoperative pain management, requires the patient to be attached to a staff-programmed pump apparatus via an intravenous catheter and tubing, rendering it invasive and mobility-limiting. An innovative, needle-free, iontophoretic, fentanyl HCl patient-controlled transdermal system (PCTS) is being developed for acute postoperative pain management. Fentanyl HCl PCTS is a compact, self-contained system that is easily applied to the upper outer arm or chest. It provides pain relief therapeutically equivalent to that of a standard regimen of morphine intravenous PCA, with pharmacokinetics similar to those of intravenous fentanyl infusion. Fentanyl HCl PCTS may be an effective, non-invasive alternative to currently available PCA modalities.

Topical diclofenac patch for postoperative wound pain in laparoscopic gynecologic surgery: A randomized study

STUDY OBJECTIVE

To compare pain management of standard analgesic and standard analgesic plus diclofenac transdermal patch in patients who undergo laparoscopic gynecologic surgery.

DESIGN

Randomized prospective study (Canadian Task Force classification I).

SETTING

University hospital.

PATIENTS

One hundred twenty patients requiring laparoscopic surgery for gynecologic benign diseases.

INTERVENTIONS

Patients were divided into two groups, one medicated with a diclofenac patch (diclofenac group) and the other medicated with standard skin medication (placebo; control group) at all incisional areas at the end of the operation.

MEASUREMENTS AND MAIN RESULTS

The principal measures of outcome were pain intensity at 6, 12, and 24 hours after surgery and consumption of analgesics. The two treatment groups were comparable with respect to demographic and intraoperative characteristics. No significant difference was observed between the two groups in mean pain intensity at 6 hours after surgery. Mean pain intensity at 12 and 24 hours, respectively, after surgery was significantly lower in the diclofenac group (3.7 +/- 1.3 and 2.0 +/- 0.6) than that observed in the control group (5.7 +/- 1.9 and 4.6 +/- 0.5) (p value, respectively, .002 and <.001). Twenty-one patients (35.0%) in the diclofenac group required analgesics in the first 36 hours after the operation versus 43 patients (71.7%) in the control group (p <.001). Hospital discharge was significantly more rapid in the diclofenac group (28 +/- 5 hours vs 39 +/- 3 hours; p = .031).

CONCLUSION

Diclofenac transdermal administration seems a valid help to standard analgesic treatment in postoperative pain control and could also help reduce the period of hospitalization of patients who undergo laparoscopic benign gynecologic surgery.

Development of an enzyme-linked immunosorbent assay for fentanyl and applications of fentanyl antibody-coated nanoparticles for sample preparation

A sensitive enzyme-linked immunosorbent assay (ELISA) was developed for the detection of fentanyl in serum and urine. The ELISA used an indirect competitive method produced by coating the plate with thyroglobulin conjugated with fentanyl hapten. Antibodies against fentanyl-hemocyanin were detected by a goat-anti-rabbit antibody conjugated with alkaline phosphatase. Calibration standard curves ranged from 0.5ng/ml to 50mug/ml (IC(50)=10ng/ml), and the limits of detection were 0.5 and 1.0ng/ml for serum and urine, respectively. The intra- and inter-assay variations were less than 8% and 10%, respectively. The antibody produced against fentanyl completely cross-reacted with p-fluorofentanyl, thienylfentanyl and 3-methylthienylfentanyl, cross-reacted highly with carfentanil (85%), but was considered non-cross-reactive with alpha-methylfentanyl (5%), sufentanil (<1%), alfentanil (<1%) and lofentanil (<1%). Nano-sized iron oxide magnetic particles coated with the developed fentanyl antibody were capable of specific binding and releasing of fentanyl from urine samples. This enabled the drug to be effectively pre-concentrated and decreased the limit of detection by approximately one order of magnitude. The analytical background noise was significantly reduced to enable fentanyl detection at concentrations originally below chromatographic limit of detection. The change of platform for antibody binding with nanoparticles demonstrated a novel use of antibodies for sample preparation and should facilitate drug screening by traditional ELISA.

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.

Transdermal opioids for cancer pain

Patients with moderate to severe malignancy-related pain frequently require the use of opioid pharmacotherapy. Unfortunately, many cancer patients continue to be prescribed subtherapeutic doses of pain medications resulting in undo suffering and diminished quality of life. The choice of analgesic pharmacotherapy should be individualized and based on the intensity and etiology of pain reported by the patient. Health care providers must be able to readily quantify the relative analgesic potency when converting from one opioid to another or from one route of administration to another. Transdermal fentanyl is effective and well tolerated pharmacotherapy for the cancer pain patients. However, clinicians need to be cognizant that the U.S./U.K. manufacturer's recommendations for equilalagesic dosing of transdermal fentanyl may result in initial doses that produce subtherapeutic levels and unrelieved pain in some patients. A more aggressive dosing algorithm for transdermal fentanyl using a 2:1 (mg/day of oral morphine: mcg/hr of transdermal fentanyl) conversion ratio that considers both a review of the literature and clinical experience should help clinicians individualize cancer pain pharmacotherapy. Transdermal buprenorphine is now being prescribed in Europe and Australia for chronic and cancer pain management. Buprenorphine's mixed agonist/antagonist activity, dosage ceiling, and high affinity to the opiate receptor limits its use to those patients who do not already require large daily doses of opioids. Thus, buprenorphine may not be an appropriate medication for some patients with advanced unremitting cancer pain.

A comparison of the skin irritation potential of transdermal fentanyl versus transdermal buprenorphine in middle-aged to elderly healthy volunteers

OBJECTIVE

Establishing local tolerability of transdermal opioid systems is important as more systems become available for use in a range of indications. We compared the skin irritation potential of a single application of transdermal fentanyl (Durogesic D-trans; DDTDF) and transdermal buprenorphine (Transtec; TDB) patches in healthy volunteers.

METHODS

46 healthy males and females (mean age [range]: 59.6 [50-69] years) with healthy skin received a single dose of both the DDTDF 25 mug/h patch and the TDB 35 mug/h patch in a randomised order under naltrexone cover. The incidence and severity of erythema was assessed at various timepoints after patch removal.

RESULTS

There was a non-significant trend towards a higher incidence of erythema 60 min after patch removal with TDB compared with DDTDF. The severity of erythema at 60 min and the incidence of erythema at 72 h after patch removal were significantly higher with TDB than with DDTDF (p = 0.01 and 22% versus 4.9%, p = 0.04, respectively). In general, the results from the chromametric assessment of treated skin were in agreement. The incidence of topical adverse events (AEs) was lower with DDTDF than with TDB (one versus six events) and subjects preferred the DDTDF patch and felt it was less noticeable on the skin. The DDTDF patch was considered less painful to remove, and, consistent with that, the TDB patch was judged to have better adhesion. Twenty-one subjects reported systemic AEs with DDTDF plus naltrexone and 22 with TDB plus naltrexone, most of which were considered treatment-related, 34 and 60 AEs, respectively.

CONCLUSIONS

Local tolerability of transdermal opioid systems should be considered when making a therapeutic choice. Even after a single application in healthy volunteers, differences in local tolerability, assessed both clinically and by chromametry, and patch comfort were shown between DDTDF and TDB, in favour of DDTDF.

Severe deficit in brain reward function associated with fentanyl withdrawal in rats

BACKGROUND

During the last decade, there has been a strong increase in the use of the mu-opioid receptor agonist fentanyl. The aim of these studies was to investigate the effects of fentanyl withdrawal on brain reward function and somatic withdrawal signs.

METHODS

Fentanyl and saline were chronically administered via minipumps. An intracranial self-stimulation procedure was used to provide a measure of brain reward function. Somatic signs were recorded from a checklist of opioid abstinence signs.

RESULTS

The opioid receptor antagonist naloxone induced a dose-dependent elevation in brain reward thresholds and somatic withdrawal signs in fentanyl-treated rats. Discontinuation of fentanyl administration resulted in a time-dependent elevation of brain reward thresholds and somatic withdrawal signs.

CONCLUSIONS

These findings indicate that fentanyl withdrawal is associated with affective and somatic withdrawal signs. The severity of the deficit in brain reward function in this animal model suggests that affective fentanyl withdrawal symptoms may be a strong deterrent to abstinence.

The role of opioids in cancer pain

Columba Quigley, as a specialist in palliative medicine, works in a hospital based support team. She also works with a community based palliative care team and in a hospice, where patients are admitted for terminal care, respite, and control of symptoms. Pain occurs often in patients with cancer, particularly those with advanced disease. In addition, pain is one of the most feared symptoms in people with a diagnosis of cancer. Using analgesics (particularly opioids) appropriately effectively controls cancer pain in most patients

The fentanyl HCl patient-controlled transdermal system (PCTS): an alternative to intravenous patient-controlled analgesia in the postoperative setting

Inadequate pain control in the postoperative period not only contributes to patient discomfort, but also causes physiological changes that may result in increased risk of myocardial ischaemia, deep vein thrombosis and pulmonary embolism. These events complicate postoperative recovery and may lead to longer hospital stays as well as increased healthcare costs. Patient-controlled analgesia (PCA) has emerged as an effective way for patients to manage their pain, allowing self-administration of small doses of analgesics to maintain a certain level of pain control. PCA is most commonly delivered via an intravenous (IV) or epidural route, and while patient satisfaction is higher with PCA than with conventional methods of analgesic administration, the invasiveness, costs and risk of errors associated with currently available modalities may limit their utility. These systems also require significant healthcare resources, as nurses must manually program the pumps to deliver the correct amount of medication. Several new PCA modalities are being developed to address these limitations. These systems deliver drug through a variety of routes, including nasal transmucosal and transdermal. Most notably, a self-contained, credit card-sized, transdermal PCA system is currently in the final stages of development. The fentanyl HCl patient-controlled transdermal system (PCTS; IONSYS, Ortho-McNeil Pharmaceutical, Inc., Raritan, NJ) uses an imperceptible, low-intensity direct current to transfer fentanyl on demand across the skin into the systemic circulation. This compact system is patient-activated, can be applied to the patient's upper arm or chest, and is designed to manage moderate-to-severe pain requiring opioid analgesia. The system delivers a preprogrammed amount of fentanyl HCI over 10 minutes, for a total of 80 doses, or for 24 hours, whichever occurs first. The on-demand dosing and pharmacokinetics of this system differentiate it from the passive transdermal formulation of fentanyl designed for the management of chronic pain. Clinical studies have shown that the fentanyl HCl PCTS is effective in the management of acute postoperative pain. These studies have also demonstrated that the system is safe and well tolerated by patients.