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

Improving Transdermal Fentanyl Prescribing Practices Using Electronic Medical Record

Background: Transdermal (TD) fentanyl has a unique place in pain management that is not universally understood, thereby raising concerns for patient safety. This project aimed to improve TD fentanyl prescribing practices through an ordering algorithm in the electronic medical record (EMR). Measures: The main outcome measure was the percentage of erroneous TD fentanyl orders after EMR order implementation. Intervention: After a retrospective chart review to assess TD fentanyl orders, a root cause analysis led to the development and introduction of an enhanced ordering algorithm in EMR in January 2023, accompanied by pharmacy education. Outcomes: After the intervention, a review of TD fentanyl orders over five months showed a reduction in inappropriate ordering from 42.5% to 15.2%. Conclusions: Standardized EMR order sets, combined with provider education, hold promise for enhancing the quality and safety of chronic pain management with TD fentanyl.

Abuse potential of fentanyl and fentanyl analogues

Introduction

In this perspective review, we evaluated the clinical management of fatal fentanyl overdose in several routes of administration, concentrating on both legally prescribed and illegally produced formulations.

Methods

A literature search was conducted on Web of Science, PubMed, and Google Scholar databases, using the following keywords: fentanyl, illicit fentanyl, deaths, misuse, abuse, and naloxone. We included only articles whose abstracts were available in English. All articles were screened using their abstracts to determine their relevance to the current review.

Results

The gold standard for treating both acute and chronic pain is fentanyl, but abuse of the drug has exploded globally since the late 2000s. Fentanyl abuse has been shown to frequently result in serious harm and even death.

Conclusion

By educating patients and physicians, making rescue kits easily accessible, developing vaccines to prevent opioid addiction, and perhaps even creating new tamper-resistant fentanyl formulations, it may be possible to prevent fentanyl misuse, therapeutic errors, and the repercussions that follow.

Naloxone-AuNPs@ZIF-8-Based Impedimetric Sensor Platform for Ultrasensitive Detection of Fentanyl and Fabrication of Fen-Track Prototype for Real-Field Analysis

Opioids are considered to be a global threat, and we are facing the worst opioid crisis of the decade. Synthetic opioids like fentanyl are highly potent and deadly toward human body, and hence its detection is an inevitable requirement globally. Naloxone is known for its antagonist property toward fentanyl, and we performed computational simulations to find their interactions and use this principle to build the first of a kind impedimetric sensor device, transduced by 3D-ZIF-8 with in situ encapsulated naloxone-gold nanoparticles. The probe is synthesized using a unique encapsulation strategy, thoroughly characterized by various physicochemical and microscopic tools. The sensor is highly selective toward fentanyl and can detect fentanyl up to 100 ppm in a synthetic sample. A prototype device is also built based on the synthetic calibration and applied to the spiked urine sample, and the performance is evaluated using statistical and machine learning tools.

High and Hyper: Fentanyl Induces Psychomotor Side-Effects in Healthy Pigs

Analgesic effects of fentanyl have been investigated using behavior. The behavioral effects of fentanyl and possible serotonergic influence are largely unknown. We therefore investigated behavioral effects of fentanyl, with or without the serotonin antagonist ketanserin, in pigs. Fourteen mixed-breed pigs, weighing 17-25 kg were included in a randomised blinded prospective, balanced three-group study. Ten pigs received first 5 and then 10 µg/kg of fentanyl intravenously. Ketanserin at 1 mg/kg or saline was given intravenously as a third injection. Four control pigs received three injections of saline. Behavior was video-recorded. The distance moved was automatically measured by commercially available software, and behaviors manually scored in retrospect. Fentanyl inhibited resting and playing, and induced different repetitive behaviors. The mean (SD) distance moved in the control group and fentanyl group was 21.3 (13.0) and 57.8 (20.8) metres respectively (p < 0.05 for pairwise comparison). A stiff gait pattern was seen after fentanyl injection for median (range) 4.2 (2.8-5.1) minutes per 10 min, which was reduced to 0 (0-4) s after ketanserin administration. Conclusion: fentanyl-induced motor and behavioral effects, and serotonergic transmission may be involved in some of them. The psychomotor side effects of fentanyl could potentially interfere with post-operative pain evaluation in pigs.

An individualized digital twin of a patient for transdermal fentanyl therapy for chronic pain management

Fentanyl transdermal therapy is a suitable treatment for moderate-to-severe cancer-related pain. The inter-individual variability of the patients leads to different therapy responses. This study aims to determine the effect of physiological features on the achieved pain relief. Therefore, a set of virtual patients was developed by using Markov chain Monte Carlo (MCMC) based on actual patient data. The members of this virtual population differ by age, weight, gender, and height. Tailored digital twins were developed using these correlated, individualized parameters to propose a personalized therapy for each patient. It was shown that patients of different ages, weights, and gender have significantly different fentanyl blood uptake, plasma fentanyl concentration, pain relief, and ventilation rate. In the digital twins, we included the virtual patients' response to the treatment, namely, pain relief. Therefore, the digital twin was able to adjust the therapy in silico to have more efficient pain relief. By implementing digital-twin-assisted therapy, the average pain intensity decreased by 16% compared to conventional therapy. The median time without pain increased by 23 h over 72 h. Therefore, the digital twin can be successfully used in individual control of transdermal therapy to reach higher pain relief and maintain steady pain relief. (Created with BioRender.com).

Electrospun Nanofibers for Wound Management

Electrospun nanofibers show great potential in biomedical applications. This mini review article traces the recent advances in electrospun nanofibers for wound management via various approaches. Initially, we provide a short note on the four phases of wound healing, including hemostasis, inflammation, proliferation, and remodeling. Then, we state how the nanofiber dressings can stop bleeding and reduce the pain. Following that, we discuss the delivery of therapeutics and cells using different types of nanofibers for enhancing cell migration, angiogenesis, and re-epithelialization, resulting in the promotion of wound healing. Finally, we present the conclusions and future perspectives regarding the use of electrospun nanofibers for wound management.

Predicting transdermal fentanyl delivery using physics-based simulations for tailored therapy based on the age

Transdermal fentanyl patches are an effective alternative to the sustained release of oral morphine for chronic pain management. Due to the narrow therapeutic range of fentanyl, the concentration of fentanyl in the blood needs to be carefully monitored. Only then can effective pain relief be achieved while avoiding adverse effects such as respiratory depression. This study developed a physics-based digital twin of a patient by implementing drug uptake, pharmacokinetics, and pharmacodynamics models. The twin was employed to predict the in-silico effect of conventional fentanyl transdermal in a 20–80-year-old virtual patient. The results show that, with increasing age, the maximum transdermal fentanyl flux and maximum concentration of fentanyl in the blood decreased by 11.4% and 7.0%, respectively. However, the results also show that as the patient's age increases, the pain relief increases by 45.2%. Furthermore, the digital twin was used to propose a tailored therapy based on the patient's age. This predesigned therapy customized the duration of applying the commercialized fentanyl patches. According to this therapy, a 20-year-old patient needs to change the patch 2.1 times more frequently than conventional therapy, which leads to 30% more pain relief and 315% more time without pain. In addition, the digital twin was updated by the patient's pain intensity feedback. Such therapy increased the patient's breathing rate while providing effective pain relief, so a safer treatment. We quantified the added value of a patient's physics-based digital twin and sketched the future roadmap for implementing such twin-assisted treatment into the clinics.

Comparison of Pain Scale, Hemodynamics, and Side Effects of Percutaneous and Intravenous Fentanyl in Post Sectio Caesaria Patients at Bunda Hospital

This is novel research about comparison pain scale, hemodynamics, and side effects of percutaneous and intravenous fentanyl in post sectio cesarean patients. Sectio cesarean is a method of delivering a fetus through an incision in the abdominal wall (laparotomy) and the uterus wall. This method induces pain in the incision, so patients feel complicated or afraid to mobilize. Fentanyl is one of the opioid analgesics, which is the main choice in section caesarian surgery because safe for breastfeeding, is more potent than morphine, and acts as balanced anesthesia—comparing the use of percutaneous fentanyl with intravenous fentanyl with pain scale parameters, hemodynamics, and side effects in sectio caesarian patients at Bunda Mother and Child Hospital Jakarta. Before conducting this research, an observational study first makes an ethical approval. Data were taken prospectively and collected simultaneously to compare percutaneous and intravenous fentanyl performed on post sectio cesarean patients with the physical status of the American Society of Anesthesiologists (ASA) I–II at Bunda Mother and Child Hospital Jakarta from September to November 2020. Comparative data observed were pain scale parameters, hemodynamics, and side effects after percutaneous fentanyl therapy or intravenous fentanyl therapy. Data were processed using SPSS 22 version and Microsoft Excell 2016. In conclusion, intravenous fentanyl is more effective in reducing pain scale and has more minor side effects than percutaneous fentanyl. There is no significant difference in hemodynamic parameters (p-value >0.05).

Study on the Mechanism of Fentanyl in Pain Treatment Based on Network Pharmacology

This is a study that is based on network pharmacology, focusing on the pharmacological mechanism of fentanyl in easing pain. Through PPI, GO, and KEGG network pharmacology, the potential pharmacological mechanism of fentanyl was studied. This study compared and analyzed the overlap between the target genes of the active ingredient of fentanyl and the pain treatment target genes. After constructing PPI based on fentanyl, the GO and KEDD pathways were analyzed for enrichment. On the basis of overlapping genes, we constructed the PPI, GO, and KEGG, and analysis showed that the mechanism was likely to be related to some biological process. This study preliminarily identified the important proteins and metabolic pathways related to fentanyl in pain treatment and expected to provide new evidence and research ideas for the use of fentanyl, enhancing effects and alleviating adverse drug reactions.

Pharmacokinetic Characterisation and Comparison of Bioavailability of Intranasal Fentanyl, Transmucosal, and Intravenous Administration through a Three-Way Crossover Study in 24 Healthy Volunteers

Background

For more than 60 years, the synthetic opioid fentanyl has been widely used in anaesthesia and analgesia. While the intravenous formulation is primarily used for general anaesthesia and intensive care settings, the drug's high lipophilic properties also allow various noninvasive routes of administration. Published data suggest that intranasal administration is also attractive for use as intranasal patient-controlled analgesia (PCA). A newly developed intranasal fentanyl formulation containing 47 μg fentanyl, intravenous fentanyl, and oral transmucosal fentanyl citrate were characterised, and bioavailability was compared to assess the suitability of the intranasal formulation for an intranasal PCA product.

Methods

27 healthy volunteers were enrolled in a single-centre, open-label, randomised (order of treatments), single-dose study in a three-period crossover design. The pharmacokinetics of one intranasal puff of fentanyl formulation (47 μg, 140 mL per puff), one short intravenous infusion of 50 μg fentanyl, and one lozenge with an integrated applicator (200 μg fentanyl) were studied, and bioavailability was calculated. Blood samples were collected over 12 hours, and plasma concentrations of fentanyl were determined by HPLC with MS/MS detection.

Results

24 volunteers completed the study. The geometric mean of AUC_0-tlast was the highest with oral transmucosal administration (1106 h ∗ pg/ml, CV% = 32.86), followed by intravenous (672 h ∗ pg/ml, CV% = 32.18) and intranasal administration (515 h ∗ pg/ml, CV% = 30.10). C _max was 886 pg/ml (CV% = 59.38) for intravenous, 338 pg/ml (CV% = 45.61) for intranasal, and 310 pg/ml (CV% = 29.58) for oral transmucosal administration. t _max was shortest for intravenous administration (0.06 h, SD = 0.056), followed by intranasal (0.21 h, SD = 0.078) and oral transmucosal administration (1.20 h, SD = 0.763). Dose-adjusted absolute bioavailability was determined to be 74.70% for the intranasal formulation and 41.25% for the oral transmucosal product. In total, 38 adverse events (AEs) occurred. Fourteen AEs were potentially related to the investigational items. No serious AE occurred.

Conclusion

Pharmacokinetic parameters and bioavailability of the investigated intranasal fentanyl indicated suitability for its intended use as an intranasal PCA option.

Fentanyl use disorder characterized by unprescribed use of transdermal patches: a case report

BACKGROUND

Fentanyl is a synthetic opioid with analgesic potency 75-100 times higher than that of morphine, and its analgesic effect is used for pain treatment, mostly in cancer patients. Using fentanyl patches may reduce misuse potential due to the transdermal route of administration, long-acting action, sustained release delivery property, and maintenance of steady-state serum concentration of the drug. Although there have been reports of transdermal fentanyl patches (TFPs) misuse via transmucosal, trans-nasal, intravenous, and oral routes of administration, fentanyl use disorder via the transdermal route is very rare.

CASE

In this case report, we present a patient with a history of substance use disorder who developed fentanyl use disorder via transdermal route after using unprescribed TFP in order to quit opium gum. The CARE guidance was followed in the preparation of this case report.

CONCLUSION

The risk of use disorder may be higher, especially in individuals with a history of substance use disorders. This risk should be taken into account when clinicians prescribe this medication.

Expert consensus of the Chinese Association for the Study of Pain on pain treatment with the transdermal patch

Chronic pain lasting more than 3 mo, or even several years can lead to disability. Treating chronic pain safely and effectively is a critical challenge faced by clinicians. Because administration of analgesics through oral, intravenous or intramuscular routes is not satisfactory, research toward percutaneous delivery has gained interest. The transdermal patch is one such percutaneous delivery system that can deliver drugs through the skin and capillaries at a certain rate to achieve a systemic or local therapeutic effect in the affected area. It has many advantages including ease of administration and hepatic first pass metabolism avoidance as well as controlling drug delivery, which reduces the dose frequency and side effects. If not required, then the patch can be removed from the skin immediately. The scopolamine patch was the first transdermal patch to be approved for the treatment of motion sickness by the Food and Drug Administration in 1979. From then on, the transdermal patch has been widely used to treat many diseases. To date, no guidelines or consensus are available on the use of analgesic drugs through transdermal delivery. The pain branch of the Chinese Medical Association, after meeting and discussing with experts and based on clinical evidence, developed a consensus for promoting and regulating standard use of transdermal patches containing analgesic drugs.

An optimized method for sample collection, extraction, and analysis of fentanyl and fentanyl analogs from a non-porous surface

Illicit use of the potent opioid fentanyl and its analogs (fentanyls) are on the rise in the United States. As use increases, drug production tends to also increase, leading to more locations being contaminated with the potentially lethal substance. Because fentanyl-contaminated locations may present a risk to the general public, a method for sampling, identifying, and quantitating these fentanyls from surfaces is in need. This research developed and optimized a surface-wipe collection and extraction method for 17 fentanyls and 10 common fentanyl adulterants from a non-porous surface and quantitated the amount of each compound collected with liquid chromatography tandem mass spectrometry. The final, optimized surface-wipe method resulted in an average collection and extraction efficiency (±SD) of 62.0 (±14.0)%, with a range of 34.1 (±2.6) - 82.5 (±9.6)%. While legislation has yet to be implemented regarding remediation levels for fentanyl-contaminated locations, when such legislation is drafted, this method can be implemented to determine the safety of these locations prior to and after decontamination has occurred.

Efficacy, safety, and tolerability of sublingual fentanyl orally disintegrating tablet in the treatment of breakthrough cancer pain: a randomized, double-blind, placebo-controlled study

BACKGROUND

Breakthrough pain (BTP) is an important challenge in treatment and requires a rapid onset of action for pain control. BTP should be adequately controlled with a stable dose of a short-acting oral opioid. So far, no drug is available for the treatment of BTP in cancer patients in Iran, so we designed the first study in Iran to investigate the effect of sublingual fentanyl in relief of pain episodes in these patients.

OBJECTIVE

The purpose of this study was to evaluate the efficacy and safety of sublingual fentanyl in the treatment of breakthrough pain in cancer patients.

METHOD

This study was a randomized double-blind placebo-controlled clinical trial in cancer patients with breakthrough pain (at least 1-4 episodes of acute pain with moderate to severe pain daily) referred to the pain clinic of Akhtar and Masih Daneshvari hospitals in 2019. The study consisted of two stages: 100 patients were selected by simple, non-random sampling and entered the open-label titration phase. The primary efficacy endpoint was the sum of pain intensity difference over 30 min post-administration. Secondary efficacy endpoints included pain intensity difference (PID) and pain relief (PR) throughout the 60-min post-dose assessment period. In the double-blind study, patients were randomly divided into two groups of placebo (n=50) and intervention (sublingual fentanyl tablet) (n=50). For evaluation of efficacy, 10 episodes were treated in each group and the results were recorded by the patient. (Clinical trial registration: IRCT20131124015515N8).

RESULTS

A total of 100 patients entered the titration phase, primary efficacy of sublingual fentanyl was 3.5±0.6 and secondary efficacy of sublingual fentanyl (60 min, after treatment) was 0.3±0.6 which was statistically significant. In the titration phase, the treatment success rate was 100%. In the double-blind phase of the study, the pain intensity in multiple episodes showed a significant improvement at 15, 30, 45, and 60 min after drug administration (P=0.0001). The intensity of pain in each episode was significantly decreased compared to the next episode (P=0.0001). The mean frequency of pain episodes in the sublingual fentanyl group showed a significant decrease (P=0.0001). The most common adverse drug events in the titration phase were drowsiness (20%), dizziness (7%), and nausea 4%, and in the double-blind phase only drowsiness (12%). (Cancer Research Center, Shahid Beheshti University of Medical Sciences, Survey).

CONCLUSION

Sublingual fentanyl appears to be effective for patients with rapid-onset analgesia, has short-acting duration, is effective medication, safe, and well tolerated. It is a suitable choice in Iranian patients with chronic cancer-related pain controlled suffering from acute pain episodes related to cancer.

Changes in Percutaneous Absorption of Fentanyl Patches in Rats Treated with a Sebum-Like Secretion

The percutaneous absorption of a fentanyl (FEN)-patch is affected by various external factors including the volume of sebum secretion, which causes changes in the skin surface environment. In this study, we prepared a lard-based sebum-like secretion (SLS), and applied it to investigate the effect of different skin surface conditions on the drug penetration of a FEN-patch. In vitro work to test drug release using the Franz diffusion cell indicated that drug release was significantly suppressed by treatment with 5% SLS, which is equivalent to the amount of daily human sebum secretion. Conversely, in ex vivo experiments using rat skin, the amount of FEN that accumulated in the skin tissue of the 5% SLS-treated rats was higher in comparison with the non-SLS treated group. Furthermore, in vivo experiments indicated that the plasma FEN concentration in rats treated with the FEN-patch was significantly increased by treatment with 5% SLS. These results suggest that the sebum affected the release, accumulation, and absorption of FEN from the FEN-patch, and the FEN concentration in the blood was reflected by the balance of the suppression of drug release and the enhancement of drug accumulation in the skin with SLS.

Topical agents: a thoughtful choice for multimodal analgesia

For over a thousand years, various substances have been applied to the skin to treat pain. Some of these substances have active ingredients that we still use today. However, some have been discontinued due to their harmful effect, while others have been long forgotten. Recent concerns regarding the cardiovascular and renal risk from nonsteroidal anti-inflammatory drugs, and issues with opioids, have resulted in increasing demand and attention to non-systemic topical alternatives. There is increasing evidence of the efficacy and safety of topical agents in pain control. Topical analgesics are great alternatives for pain management and are an essential part of multimodal analgesia. This review aims to describe essential aspects of topical drugs that physicians should consider in their practice as part of multimodal analgesia. This review describes the mechanism of popular topical analgesics and also introduces the most recently released and experimental topical medications.

Safety, Tolerability, and Dose Proportionality of a Novel Transdermal Fentanyl Matrix Patch and Bioequivalence With a Matrix Fentanyl Patch: Two Phase 1 Single-Center Open-Label, Randomized Crossover Studies in Healthy Japanese Volunteers

Two open‐label, single‐dose, randomized crossover studies were conducted in healthy Japanesemen to (1) assess dose proportionality of 5 doses (1.38, 2.75, 5.5, 8.25, and 11.0 mg) of Lafenta, a novel matrix‐type transdermal fentanyl patch with a rate‐controlling membrane; and (2) compare patch bioequivalence (11.0 mg) with a commercially available reference patch (Durotep MT Patch [16.8 mg]). Pharmacokinetics, adhesion performance, residual fentanyl, and safety parameters were assessed. Increases in mean AUC_0‐t and C_max after application of the test patch were dose proportional. The test patch (11.0 mg) was bioequivalent to the 16.8‐mg reference patch in terms of mean AUC_0‐inf, AUC_0‐t, and C_max. Residual fentanyl levels 72 hours postapplication were lower in the test than in the reference patch. Differences in adhesion performance between the test and the reference patch did not affect delivery efficacy and reliability of the novel matrix patch. Safety findings were in line with previous experiences with fentanyl. Both studies showed low variation in fentanyl exposure and delivery via the test patch. The test patch provided equivalent fentanyl exposure at a lower dose than the reference patch formulation with lower variability and the potential to lower medicinal waste.

Evaluation of Heat Effects on Fentanyl Transdermal Delivery Systems Using In Vitro Permeation and In Vitro Release Methods

Experimental conditions that could impact the evaluation of heat effects on transdermal delivery systems (TDS) using an in vitro permeation test (IVPT) and in vitro release testing (IVRT) were examined. Fentanyl was the model TDS. IVPT was performed using Franz diffusion cell, heating lamp, and human skin with seven heat application regimens. IVRT setup was similar to IVPT, without using skin. Dissolution study was conducted in a modified dissolution chamber. The activation energy of skin permeation for fentanyl was determined using aqueous solution of fentanyl. In IVPT, the increase of temperature from 32 °C to 42 °C resulted in a 2-fold increase in flux for fentanyl TDS, consistent with the activation energy determined. The magnitude of flux increase was affected by the heat exposure onset time and duration: higher flux was observed when heat was applied earlier or following sustained heat application. Heat induced flux increases could not be observed when inadequate sampling time points were used, suggesting the importance of optimizing sampling time points. Drug release from TDS evaluated using IVRT was fast and the skin was the rate-limiting barrier for TDS fentanyl delivery under elevated temperature.

Comparison of Two Commercially Available Fentanyl Screening Immunoassays for Clinical Use

BACKGROUND

Fentanyl is a synthetic opioid associated with illicit drug use and overdose deaths. The SEFRIA Immunalysis (IAL) and ARK fentanyl assays are both FDA-cleared, open channel immunoassays for fentanyl detection in urine. However, limited data are available in the literature comparing these assays. The objective of this study was to perform a direct comparison of these two fentanyl immunoassays.

METHODS

IAL and ARK fentanyl immunoassays were performed on a Roche Cobas e602 automated chemistry analyzer. Repeatability and total imprecision were compared by diluting fentanyl into urine at concentrations above, below, and at the manufacturers' cutoffs of 1.0 ng/mL. Cross-reactivity was assessed for norfentanyl and the fentanyl analogs acetylfentanyl, acrylfentanyl, and furanylfentanyl. Concordance was assessed in 90 patient samples using liquid chromatography-tandem mass spectrometry (LC-MS/MS) as the gold standard.

RESULTS

Repeatability varied from 11.4%-17.8% on the IAL assay and 2.8%-5.5% on the ARK assay. Total imprecision was 18.9%-40.7% on the IAL assay and 2.9%-6.4% on the ARK assay. Both assays cross-reacted with acetylfentanyl (∼100%), acrylfentanyl (∼100%), and furanylfentanyl (∼20%), but only the ARK assay cross-reacted with norfentanyl (∼3%). An admixture of 0.5 ng/mL fentanyl and 6 ng/mL norfentanyl produced a positive result on the ARK assay. Total concordance between IAL and ARK for 90 tested patient samples was 93% (kappa = 0.85). Relative to LC-MS/MS, the IAL assay had a concordance of 90% (kappa = 0.79) and the ARK assay had a concordance of 94% (kappa = 0.88). Including norfentanyl in the LC-MS/MS confirmation increased the concordance of the ARK to 96% (kappa = 0.90).

CONCLUSIONS

The ARK assay recognized the metabolite norfentanyl, demonstrated superior precision, and had better concordance with LC-MS/MS compared to the IAL assay.

A convenient one pot synthesis of fentanyl

Fentanyl, N-(1-phenethyl-4-piperidyl) propionanilide, was prepared by performing three successive one pot reactions at room temparature.

Use of Fentanyl Patch and Intravenous Morphine for Treatment of Leg Bone Fracture: Treatment Profile, and Clinical Effectiveness

BACKGROUND:

Severe pain is one of the major problems in patients with leg bone fracture. Various methods have been proposed to relieve pain. Opioids are one of the most important available medications to control these types of pain. Among the opioids available, fentanyl can be applied for its unique properties as transdermal patches.

AIM:

Therefore, the current study aimed to investigate the effect of intravenous morphine and fentanyl skin patch in patients with a lower leg fracture.

METHODS:

We entered 60 patients in this randomised, one-blind randomised clinical trial among patients referring to the emergency department of Vali-e-Asr Hospital in Arak with a fracture of the leg. Demographic and clinical data were recorded for patients. The case group (n = 30) received the fentanyl patch in the same area. Patients in the control group (30) received 0.1mcg/kg of morphine intravenously. In both groups, the severity of pain was measured every 20 minutes within two hours after onset of treatment based on VAS criteria and subsequently recorded in the checklist. Data were analysed by SPSS v.22 software package.

RESULTS:

The results of the present study demonstrated that the mean visual analogue scale (VAS) pain score at minutes 20, 40, 60 and 80 were statistically lower in intervention group when compared with the control group (p = 0.000).

CONCLUSION:

Our results indicated a considerable risk-benefit profile for the treatment of pain in patients suffering from dysphagia, nausea and vomiting, or resistance to other opioids. The use of fentanyl patch is also suitable for patients who are not able to take their medication at their scheduled time.

DARK Classics in Chemical Neuroscience: Fentanyl

Fentanyl rose to prominence as an alternative analgesic to morphine nearly 50 years ago; today, fentanyl has re-emerged as a dangerous recreational substance. The increased potency and analgesic effect of fentanyl are advantageous in the treatment of pain but are also responsible for the rise in unintentional opioid overdose deaths. In response to this crisis, fentanyl, its analogues, and even precursors are under heightened regulatory scrutiny. Despite this controversial history, derivatization of fentanyl has resulted in numerous synthetic analogues that provide valuable insights into opioid receptor binding and signaling events. In this review, the impact of fentanyl on chemical neuroscience is shown through its synthesis and properties, manufacturing, metabolism, pharmacology, approved and off-label indications, adverse effects, and the responsibility it has in the opioid epidemic.

Effects of smoking and body mass index on the exposure of fentanyl in patients with cancer

The transdermal fentanyl patch is widely used to treat cancer-related pain despite its wide inter- and intrapatient variability in pharmacokinetics. The aim of this study was to investigate whether smoking and body size (i.e. body mass index) influence fentanyl exposure in patients with cancer. These are factors that typically change during treatment and disease trajectories. We performed an explorative cohort study in patients with cancer using transdermal fentanyl patches (Durogesic®), by taking a blood sample for pharmacokinetic analysis one day after applying a patch in patients with a stable fentanyl dose. A total of 88 patients were evaluable. Although no statistically significant difference was found, the plasma concentrations of non-smokers was 28% (95% CI [-14%; +89-%]) higher than those of smokers normalizing for a dose of 25μg/min. Patients with a low BMI (< 20 kg/m2) had almost similar (10% (95% CI [-39%; +97%]) higher) plasma concentrations compared to patients with a high BMI (> 25 kg/m2). A wider variation in fentanyl plasma concentrations was found in this study than anticipated. Due to this variation, studies in larger patient cohorts are needed to further investigate the effect of smoking on plasma concentration of fentanyl and thereby clarify the clinical significance of our findings.

Management of chronic neuropathic pain with single and compounded topical analgesics

The goal of our review was to emphasize important aspects that physicians should take into consideration when prescribing topical analgesics as part of chronic neuropathic pain treatment. We discuss the dermatopharmacokinetics and microstructural components of the skin, differences between topical and transdermal drug delivery, and topical medication effects on peripheral neuropathy and central sensitization. Even though the US FDA approved topical analgesics are 8%-capsaicin and 5%-lidocaine patches for treating postherpetic neuralgia, there are many other studies conducted on the efficacy of topical ketamine cream, clonidine gel, topical gabapentin, topical baclofen and topical phenytoin for peripheral neuropathic pain, either alone or in combination with other formulations. Furthermore, we discuss new compounded topical analgesics that are becoming more popular and that are showing promising results in the management of chronic peripheral neuropathies. However, more studies are needed for elucidation of the role of topical analgesics and their effects, especially when combined with other treatments.

Antinociceptive and respiratory effects following application of transdermal fentanyl patches and assessment of brain μ-opioid receptor mRNA expression in ball pythons

OBJECTIVE To quantify plasma fentanyl concentrations (PFCs) and evaluate antinociceptive and respiratory effects following application of transdermal fentanyl patches (TFPs) and assess cerebrospinal μ-opioid receptor mRNA expression in ball pythons (compared with findings in turtles). ANIMALS 44 ball pythons (Python regius) and 10 turtles (Trachemys scripta elegans). PROCEDURES To administer 3 or 12 μg of fentanyl/h, a quarter or whole TFP (TFP-3 and TFP-12, respectively) was used. At intervals after TFP-12 application in snakes, PFCs were measured by reverse-phase high-pressure liquid chromatography. Infrared heat stimuli were applied to the rostroventral surface of snakes to determine thermal withdrawal latencies after treatments with no TFP (control [n = 16]) and TFP-3 (8) or TFP-12 (9). Breathing frequency was measured in unrestrained controls and TFP-12-treated snakes. μ-Opioid receptor mRNA expression in brain and spinal cord tissue samples from snakes and turtles (which are responsive to μ-opioid receptor agonist drugs) were quantified with a reverse transcription PCR assay. RESULTS Mean PFCs were 79, 238, and 111 ng/mL at 6, 24, and 48 hours after TFP-12 application, respectively. At 3 to 48 hours after TFP-3 or TFP-12 application, thermal withdrawal latencies did not differ from pretreatment values or control treatment findings. For TFP-12-treated snakes, mean breathing frequency significantly decreased from the pretreatment value by 23% and 41% at the 24- and 48-hour time points, respectively. Brain and spinal cord tissue μ-opioid receptor mRNA expressions in snakes and turtles did not differ. CONCLUSIONS AND CLINICAL RELEVANCE In ball pythons, TFP-12 application resulted in high PFCs, but there was no change in thermal antinociception, indicating resistance to μ-opioid-dependent antinociception in this species.

A review of factors explaining variability in fentanyl pharmacokinetics; focus on implications for cancer patients

Fentanyl is a strong opioid that is available for various administration routes, and which is widely used to treat cancer-related pain. Many factors influence the fentanyl pharmacokinetics leading to a wide inter- and intrapatient variability. This systematic review summarizes multiple studied factors that potentially influence fentanyl pharmacokinetics with a focus on implications for cancer patients. The use of CYP3A4 inhibitors and inducers, impaired liver function, and heating of the patch potentially influence fentanyl pharmacokinetics in a clinically relevant way. In elderly patients, current data suggest that we should carefully dose fentanyl due to alterations in absorption and metabolism. The influence of BMI and gender on fentanyl pharmacokinetics is questionable, most probably due to a large heterogeneity in the published studies. Pharmacogenetics, e.g. the CYP3A5*3 gene polymorphism, may influence fentanyl pharmacokinetics as well, although further study is warranted. Several other factors have been studied but did not show significant and clinically relevant effects on fentanyl pharmacokinetics. Unfortunately, most of the published papers that studied factors influencing fentanyl pharmacokinetics describe healthy volunteers instead of cancer patients. Results from the studies in volunteers may not be simply extrapolated to cancer patients because of multiple confounding factors. To handle fentanyl treatment in a population of cancer patients, it is essential that physicians recognize factors that influence fentanyl pharmacokinetics, thereby preventing potential side-effects and increasing its efficacy.

Synthesis and biological evaluation of fentanyl acrylic derivatives

Synthesis and biological evaluation of fentanyl acrylic derivatives.

Opioid Equivalency: A Review

Opioid analgesics are often used for the treatment of both acute and chronic pain. These agents can differ in regard to opioid receptor interactions, pharmacological actions, and side effect profiles. Furthermore, an agent can be differentiated by its relative potency and duration of action. This paper highlights the major differences between the opioid analgesics and presents a comparative table which includes equianalgesic doses for available opioid formulations. Also, guidelines for making rational prescribing decisions are discussed.

Drug use evaluation of transdermal fentanyl in a tertiary hospital

Objectives

The primary objective of the study was to assess the rationale of fentanyl patch initiation and continuation for pain. The secondary objectives were to analyse prescribing pattern between disciplines, monitoring criteria and adverse events profile of fentanyl patch in the inpatient wards for a tertiary hospital.

Methods

A retrospective case series review was undertaken of patients who received transdermal fentanyl for pain from April to June 2013 at the National University Hospital, Singapore. Relevant data were collected from electronic and physical medical records and audit criteria applied for indication, opioid tolerance, dosage regimen, adverse events and monitoring criteria.

Results

40 patients were prescribed fentanyl patches for pain in the study period. 15 patients (62.5%) had one or more problems during initiation of fentanyl patch. Appropriate use during initiation was low with only 9 (38%) patients meeting all the required criteria. Most of the inappropriate use involved a lack of bridging opioids (58%), wrong opioid conversion dose (42%) and use in opioid-naïve patients (42%). In addition, three cases of inappropriate placement were observed. Monitoring for efficacy and adverse effects generally met audit criteria. There was a low incidence of discontinuation (21%) due to its well-tolerated side effect profile.

Conclusions

This study highlighted high incidence of inappropriate initiation of fentanyl patch, and we proposed an in-house guideline to aid physicians in initiating fentanyl patches during admission and to educate nursing staff of the monitoring parameters for efficacy and toxicity.

PHARMACOKINETIC EVALUATION OF A LONG-ACTING FENTANYL SOLUTION AFTER TRANSDERMAL ADMINISTRATION IN HELMETED GUINEAFOWL (NUMIDA MELEAGRIS)

The objective of this study was to investigate the pharmacokinetics of a long-acting fentanyl solution in helmeted guineafowl ( Numida meleagris ) after transdermal administration. Twenty-one guineafowl received a single administration of 5 mg/kg of fentanyl transdermal solution. No adverse effects on behavior were appreciated. Plasma fentanyl concentrations were determined by liquid chromatography-mass spectrometry analysis of protein-precipitated samples. Mean maximum plasma concentration was 228.8 ng/ml at 4 hr. The mean plasma terminal half-life was 33.2 hr. At 168 hr the mean plasma concentration was 1.3 ng/ml. A single topical dose of 5 mg/kg appears to be safe for use in this species and maintained plasma concentrations above those reported to be analgesic in dogs for at least 7 days.

Transdermal Fentanyl for Cancer Pain Management in Opioid-Naive Pediatric Cancer Patients

BACKGROUND

 Transdermal therapeutic system fentanyl with a drug release rate of 12 µg/h should be of special value in pediatric cancer pain control. Such a fentanyl formulation allows for a stepwise dose increase, similar to that reported for sustained-release morphine.

PATIENTS AND METHODS

 Sixty-four male and female pediatric patients with moderate to severe chronic cancer pain, ages ranging 2-14 years, were included. Patients did not receive opioids prior to enrollment. Patients were observed for pain relief using the Visual Analog Scale and the Wong-Baker FACES Pain Rating Scale, play performance score, and for side effects.

RESULTS

 There was significant improvement of visual analog scale and FACES pain scores from the baseline to the second day of application (P < 0.001). By the 15th day, scores reached 1.18 ± 0.393 and 1.13 ± 0.35, respectively (P < 0.001). Play performance scale improved from the third day of application of the patch when compared with the baseline (P < 0.001), reaching 55.02 ± 8.35 (P < 0.001) at the end of the study. The sedation score increased on the second day to 2 in 10 patients and to 3 in 54 patients. By the seventh day, 56 patients had a sedation score of 1. All patients returned to baseline by the 15th day. Itching was reported in 16 cases, and erythema occurred in 10 cases. No significant side effects were reported.

CONCLUSION

 Transdermal fentanyl was found to be an effective, safe, and well-tolerated treatment for pediatric cancer-related pain in opioid-naive patients with chronic moderate to severe pain. In this study population, evaluation of vital signs and physical examination did not suggest any safety concerns while using transdermal fentanyl.

Acute Pain Management

Acute pain management is improving steadily over the past few years, but training and professional education are still lacking in many professions. Untreated or undertreated acute pain could have detrimental effects on the patient in terms of comfort and recovery from trauma or surgery. Acute undertreated pain can decrease a patient's vascular perfusion, increase oxygen demand, suppress the immune system, and possibly risk increased incidence of venous thrombosis. Although acute postoperative pain needs to be managed aggressively, patients are most vulnerable during this period for developing adverse effects, and therefore, patient assessment and careful drug therapy evaluation are necessary processes in therapeutic planning. Acute pain management requires careful and thorough initial assessment and follow-up reassessment in addition to frequent dosage adjustments, and managing analgesic induced side effects. Analgesic selection and dosing must be based on the patient's past and recent analgesic exposure. There is no single acute pain management regimen that is suitable for all patients. Analgesics must be tailored to the individual patient.

Comparison between Transdermal Buprenorphine and Transdermal Fentanyl for Postoperative Pain Relief after Major Abdominal Surgeries

INTRODUCTION

Opioid is generally regarded as an important part of multimodal, perioperative analgesia, especially for moderate to severe pain. Amongst the various modes of delivery transdermal route has several potential benefits over oral and parentral administration. These include noninvasive dosing, better absorption and lack of first-pass metabolism. A transdermal drug delivery system provides steady and continuous drug delivery resulting in steady plasma concentration. Bolus dosing of systemic analgesic results in supra and sub therapeutic plasma resulting in toxic and sub analgesic plasma drug concentration. It also improves patient compliance.

MATERIALS AND METHODS

Sixty patients undergoing major abdominal surgery under GA were randomly divided in two groups (n=30). Group A received buprenorphine 10 mcg/h TDS and group B received 25 mcg/h fentanyl TDS, 6 hours prior to surgery. Patients were followed for three days for postoperative pain relief and adverse effects.

RESULTS

Baseline and demographic variables are comparable in both groups. The mean level of VAS was significantly lower in group B as compared to group A at Day 1, 2 and 3. The mean level of sedation score was significantly lower in Group B than Group A. Haemodynamic variables in both groups (SBP, DBP and HR), shows comparable values in both groups and no significant difference was observed. Five out of 30 (16.7%) patients in group A required single dose of rescue analgesic while 0 out of 30 patients (0.00%) in group B required rescue analgesic. This difference in rescue analgesic requirement in not quiet statistically significant (p-value 0.0522). Twenty percent patient in fentanyl group and 16.7% patients in buprenorphine group experienced some adverse effects. Nausea and vomiting were main side effects of the drugs. The incidence of nausea and vomiting were 6.7% and 10% in buprenorphine and fentanyl group respectively.

CONCLUSION

Fentanyl and buprenorphine TDS were effective and safe in controlling postoperative pain. Fentanyl is better than buprenorphine in this respect.

Life-threatening opioid toxicity from a fentanyl patch applied to eczematous skin

A 19-year-old man with a history of eczema was admitted to the emergency department following collapsing at home. The paramedics found him unresponsive with poor respiratory effort and a widespread erythematous rash. Anaphylaxis, thought to be secondary to flucloxacillin he had recently been prescribed, was diagnosed. Epinephrine, steroids and antihistamines were administered without clinical improvement. On arrival to hospital, constricted pupils were noted prompting the emergency physicians to consider opiate toxicity. Intravenous naloxone brought about an immediate recovery. His father subsequently disclosed that he had given his son one of his own fentanyl patches to alleviate the distressing symptoms of eczema. Although the patient had removed the patch prior to collapsing, he had suffered life-threatening opioid toxicity likely due to enhanced opiate absorption through eczematous skin. This case highlights the risks associated with fentanyl patches in patients with chronic skin conditions.

Epidural analgesia with amide local anesthetics, bupivacaine, and ropivacaine in combination with fentanyl for labor pain relief: a meta-analysis

Background

The study compares the effectiveness of bupivacaine and fentanyl (BUPI-FEN) and ropivacaine and fentanyl (ROPI-EFN) in epidural analgesia for labor pain through a meta-analysis of relevant randomized clinical trials.

Material/Methods

Multiple electronic databases were searched using appropriate MeSH terms and keywords for original English language research papers published between 1990 and March 2014. Meta-analyses results were based on the mean differences between the groups as well as odds ratios where appropriate. Statistical heterogeneity amongst the included studies was tested by I² index.

Results

Nine studies that met the inclusion criteria were selected for analysis which consisted of 556 parturient patients. The duration of the second stage of labor was significantly shorter in the BUPI-FEN group by a mean of −6.87 (−10.98, −2.77; P<0.002). On the other hand, the ROPI-FEN group had a significantly lower incidence of motor blockade by a mean of 0.31 (0.18, 0.51; P<0.00001). A positive relationship between the amide local anesthetic concentration and the number of women having motor blockade was observed, but a negative relationship between fentanyl concentration and the number of women experiencing a motor block. Moreover, a positive correlation was found between the concentration of ropivacaine and the incidence of instrumental delivery and between the concentration of bupivacaine and the incidence of cesarean delivery.

Conclusions

In combination with fentanyl, bupivacaine and ropivacaine exhibit comparable efficacy and safety. However, BUP-FEN analgesia led to a shortened second-stage labor and ROPI-FEN resulted in a significantly lower incidence of motor block.

Oral transmucosal drug delivery for pediatric use

The formulation of medicines for children remains a challenge. An ideal pediatric formulation must allow accurate dose administration and be in a dosage form that can be handled by the target age group. It is also important to consider the choices and the amount of excipients used in the formulation for this vulnerable age group. Although oral formulations are generally acceptable to most pediatric patients, they are not suitable for drugs with poor oral bioavailability or when a rapid clinical effect is required. In recent years, oral transmucosal delivery has emerged as an attractive route of administration for pediatric patients. With this route of administration, a drug is absorbed through the oral mucosa, therefore bypassing hepatic first pass metabolism and thus avoiding drug degradation or metabolism in the gastrointestinal tract. The high blood flow and relatively high permeability of the oral mucosa allow a quick onset of action to be achieved. It is a simple and non-invasive route of drug administration. However, there are several barriers that need to be overcome in the development of oral transmucosal products. This article aims to provide a comprehensive review of the current development of oral transmucosal delivery specifically for the pediatric population in order to achieve systemic drug delivery. The anatomical and physiological properties of the oral mucosa of infants and young children are carefully examined. The different dosage forms and formulation strategies that are suitable for young patients are discussed.

Fentanyl-related compounds and derivatives: current status and future prospects for pharmaceutical applications

Fentanyl and its analogs have been mainstays for the treatment of severe to moderate pain for many years. In this review, we outline the structural and corresponding synthetic strategies that have been used to understand the structure-biological activity relationship in fentanyl-related compounds and derivatives and their biological activity profiles. We discuss how changes in the scaffold structure can change biological and pharmacological activities. Finally, recent efforts to design and synthesize novel multivalent ligands that act as mu and delta opioid receptors and NK-1 receptors are discussed.

Effect of dose escalation with single opioid, fentanyl matrix in patients not controlling cancer pain: a multicenter, prospective, observational study in Korea

PURPOSE

End-of-dose failure (EOD) is a clinically common observation and many cancer patients increase the frequency of opioid administration. Fentanyl matrix use is known to be effective in patients with chronic cancer pain. To measure the effectiveness of increase in a single dose of fentanyl matrix in patients whose pain was not controlled sufficiently, we perform this study.

MATERIALS AND METHODS

A multi-center, open-label, prospective, observational study was conducted in 30 hospitals in Korea, between August and December 2008.

RESULTS

A total of 452 patients were enrolled; 404 patients completed the study. The mean pain intensity decreased from 5.27 at the first visit to 3.37 at the end of the trial. There was a significant difference in pain intensity (p < 0.001) between the first and last visits. The percentage of pain intensity difference was 30.1%. The prevalence of EOD at the first visit was 73% from the 452 enrolled patients. After the use of fentanyl patch, EOD decreased from 73% to 56%. Pain intensity of patients experiencing EOD was 5.64 at the baseline compared to 4.27 in patients without EOD. On final visit, pain intensity in patients with and without EOD was 4.02 and 2.54, respectively. The observed adverse events were mainly nausea, asthenia, constipation and diarrhea.

CONCLUSION

This study demonstrated that increasing dose of fentanyl patch decreased pain intensity and decreased the rate of patients experiencing EOD. Thus, fentanyl patch may be an effective modality in cancer patients whose pain was previously not controlled sufficiently; the side effects were as could be expected with an opioid.

Transdermal fentanyl for cancer pain

BACKGROUND

Opioid drugs have been used for many years to relieve pain. Transdermal fentanyl offers one option for delivering and maintaining pain relief in patients with moderate or severe cancer pain.

OBJECTIVES

To determine the analgesic efficacy of transdermal fentanyl for relief of cancer pain, and to assess the adverse events associated with the use of transdermal fentanyl for relief of cancer pain.

SEARCH METHODS

The following databases were searched: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 4 of 12); MEDLINE (1966 to May 2013); EMBASE (1974 to May 2013; CANCERLIT (PubMED) (November 2012); and ClinicalTrials.gov (May 2013).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) using placebo or active comparators reporting on the analgesic effect of transdermal fentanyl in adults and children with cancer pain. Studies with fewer than 10 participants were excluded.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two review authors. We extracted any available data on the number or proportion of patients with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales), together with information about adverse events and withdrawals.

MAIN RESULTS

We identified nine studies meeting the inclusion criteria, including a Turkish study that is awaiting formal translation. There were 1244 participants randomised in classically designed RCTs, of whom 1197 had evaluable data, and 138 patients enrolled in an enriched enrolment, randomised withdrawal (EERW) trial. Overall, 600 participants were treated with transdermal fentanyl patches, 382 with various formulations of morphine, 36 with methadone, and 221 with paracetamol plus codeine. There were major sources of potential bias, including lack of blinding, small size, high levels of attrition, and inconsistent reporting.We could not compare data in a meaningful analysis regarding adverse events such as nausea, abdominal pain, gastrointestinal bleeding, and confusion. These events may have been attributable to the underlying disease process.There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNT) for the analgesic effect. In seven studies with 461 participants reporting pain intensity results after about two weeks, the mean or median pain scores were on the borderline of mild and moderate pain. Most participants would have had no worse than mild pain on treatment. Another reported that 77% of participants using transdermal fentanyl had an undefined successful outcome. Fewer participants experienced constipation with transdermal fentanyl (28%) than with oral morphine (46%), giving a risk ratio of 0.61 (95% CI 0.47 to 0.78); the NNT to prevent constipation was 5.5 (95% CI 3.8 to 10).

AUTHORS' CONCLUSIONS

The randomised trial literature for effectiveness of transdermal fentanyl is limited, but it is an important medicine. Most studies recruited fewer than 100 participants and did not provide data appropriate for meta-analysis. Only a few reported how many patients had good pain relief but, where data were reported, a majority had no worse than mild pain within a reasonably short time period. The evidence pointed to a useful and significant reduction in complaints about constipation for transdermal fentanyl compared with oral morphine.

Pharmacokinetics, Tolerability, and Performance of a Novel Matrix Transdermal Delivery System of Fentanyl Relative to the Commercially Available Reservoir Formulation in Healthy Subjects

A novel transdermal formulation of fentanyl-containing dipropylene glycol droplets dispersed in a silicone matrix with a rate-controlling membrane was developed. Healthy male subjects (n = 24) received repeated 72-hour applications of fentanyl (50 mug/h) as the novel matrix and the conventional reservoir formulations in a randomized, 2-way crossover study. Blood samples were collected, and serum concentrations of fentanyl were assayed using liquid chromatography with mass spectrometry detection. The mean area under the curve (AUCtau) and peak concentrations (C(max)) of the matrix formulation were 84 838 pg.h/mL and 1680 pg/mL, respectively. Ratio and 90% confidence intervals of AUCtau and C(max) between the 2 formulations were within 80% to 125%. Adherence of the matrix formulation was higher than the reservoir formulation (62.5 vs 56.2%, P < .0001), without affecting skin irritation. Vital signs and adverse events of the 2 formulations were similar in nature and frequency. The novel matrix formulation displayed enhanced adherence and resulted in similar pharmacokinetics and tolerability as the reservoir formulation.

Pharmacokinetics and Pharmacodynamics of a Transdermal Contraceptive Patch and an Oral Contraceptive

This open-label, randomized, 2-way crossover study characterized the pharmacokinetics and pharmacodynamics of a transdermal contraceptive patch and a norgestimate-containing oral contraceptive. Healthy women (n = 34) applied a patch once weekly for 3 consecutive weeks during each of 2 cycles and received an oral contraceptive for 21 consecutive days during each of 2 cycles. Plasma concentrations of norelgestromin and ethinyl estradiol peaked and waned after daily oral contraceptive administration, whereas they rose and reached steady-state levels after first patch application. Norelgestromin exposure was similar; ethinyl estradiol exposure was higher for the patch than oral contraceptive. Hepatic estrogenic activity, assessed by hepatic globulin synthesis, was similar for corticosteroid-binding globulin and corticosteroid-binding globulin-binding capacity and higher for sex hormone-binding globulin for the patch versus oral contraceptive. The clinical significance of the differences in pharmacokinetic and pharmacodynamic profiles between the patch and oral contraceptive is not fully known. No serious adverse events or discontinuations due to adverse events were recorded.