Pharmacokinetics and tolerability of different doses of fentanyl following sublingual administration of a rapidly dissolving tablet to cancer patients: a new approach to treatment of incident pain

Continuous Ambulatory Delivery Device Use for Patients Managed by an Inpatient Palliative Care Team

BACKGROUND

The use of Patient Controlled Analgesia (PCA) via a Continuous Ambulatory Delivery Device (CADD) is a common and effective means of pain and symptom management for hospitalized patients with a malignancy. Studies exploring the indications for starting such a device for hospitalized inpatients referred to inpatient palliative care teams are limited.

AIM

This retrospective chart review aims to explore indications, timing of initiation, and barriers to the use of a CADD.

METHODS

Over a six month period, during daily inpatient palliative care consult team rounds, patients who required a CADD were enrolled in this study. Sixty-one adult patients were identified who required a pump for symptom control. The team's database sheets were used to capture patient demographics.

RESULTS

The main reasons for initiating a Continuous Ambulatory Delivery Device in the above setting included: lack of efficacy of oral opioids and to increase patient autonomy of their pain management. Approximately 20% of patients required transfer to another unit that could accommodate the CADD. The median length of stay for these patients was 13 days, with a median length of half a day for a pump to be started.

CONCLUSIONS

This initial study provides the Palliative Care Consult Team with information on the indications for the use of a CADD. The lack of universal access to a CADD in various areas of our hospital due to differences in departmental protocols may compromise good symptom management and patient safety. These results strengthen the argument that the existing hospital policy requires revamping to improve CADD access. A CADD has been shown to provide hospitalized patients, with a malignancy, with timely access to effective symptom management, and in turn, reducing their length of stay in hospital. These findings will help inform this organization's CADD policy and support the need to broaden access to this device.

Improving the Emergency Department Management of Sickle Cell Vaso-Occlusive Pain Crisis: The Role and Options of Sublingual and Intranasally Administered Analgesia

Vaso-occlusive crisis (VOC), characterized by periods of excruciating pain is the most common clinical manifestation of sickle cell disease (SCD), often resulting in emergency room presentation. These patients often experience long wait times in the emergency department before receiving their first dose of analgesia. This delay results from the complexities of the emergency care system. Using the intranasal or sublingual approach to administering analgesia to SCD patients with VOC offers a fast, safe, noninvasive, atraumatic, and easily accessible route of administration which could reduce the time to first dose of analgesia. With the evolving advances in the development and delivery of analgesic medications, providers should be conversant with the nuances of intranasal and sublingual analgesia in the management of acute vaso-occlusive pain crisis. This review explores the pharmacokinetic profiles, dosages, and administration of intranasal and sublingual analgesics with relevance to the SCD population.

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.

A non-injected opioid analgesia protocol for acute pain crisis in adolescents and adults with sickle cell disease

Initial management of the acute pain crisis (APC) of sickle cell disease (SCD) is often unsatisfactory, and might be improved by developing a standardised analgesia protocol. Here, we report the first stages in developing a standard oral protocol for adolescents and adults. Initially, we performed a dose finding study to determine the maximal tolerated dose of sublingual fentanyl (MTD SLF) given on arrival in the acute care facility, when combined with repeated doses of oral oxycodone. We used a dose escalation algorithm with two dosing ranges based on patient’s weight (<50 kg or >50 kg). We also made a preliminary evaluation of the safety and efficacy of the protocol. The study took place in a large tertiary centre in London, UK. Ninety patients in the age range 14–60 years were pre-consented and 31 treatment episodes were evaluated. The first 21 episodes constituted the dose escalation study, establishing the MTD SLF at 600 mcg (>50 kg) or 400 mcg (<50 kg). Further evaluation of the protocol indicated no evidence of severe opioid toxicity, nor increased incidence of acute chest syndrome (ACS). Between 0 and 6 hours, the overall gradient of reduction of visual analogue pain score (visual analogue scale (VAS)) was 0.32 centimetres (cm) per hour (95% confidence interval (CI) = 0.20 to 0.44, p < 0.001). For episodes on MTD SLF, there was median (interquartile range (IQR)) reduction in VAS score of 2.8 cm (0–4.2) and 59% had at least a 2.6-cm reduction. These results are supportive of further evaluation of this protocol for acute analgesia of APC in a hospital setting and potentially for supervised home management.

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.

Feasibility of a transmucosal sublingual fentanyl tablet as a procedural pain treatment in colonoscopy patients: a prospective placebo-controlled randomized study

Since patients often experience pain and unpleasantness during a colonoscopy, the present study aimed to evaluate the efficacy and safety of sublingually administered fentanyl tablets for pain treatment. Furthermore, since the use of intravenous drugs significantly increases colonoscopy costs, sublingual tablets could be a cost-effective alternative to intravenous sedation. We conducted a prospective placebo-controlled randomized study of 158 patients to evaluate the analgesic effect of a 100 µg dose of sublingual fentanyl administered before a colonoscopy. Pain, sedation, nausea, and satisfaction were assessed during the colonoscopy by the patients as well as the endoscopists and nurses. Respiratory rate and peripheral arteriolar oxygen saturation were monitored throughout the procedure. There were no differences between the fentanyl and placebo groups in any of the measured variables. The median pain intensity values, as measured using a numerical rating scale, were 4.5 in the fentanyl group and 5 in the placebo group. The sedation and oxygen saturation levels and the respiratory rate did not differ between the groups. The majority of the colonoscopies were completed.Our results indicate that a 100 µg dose of sublingual fentanyl is not beneficial compared to the placebo in the treatment of procedural pain during a colonoscopy.

Pharmacokinetics of Sublingually Delivered Fentanyl in Head and Neck Cancer Patients Treated with Curatively Aimed Chemo or Bioradiotherapy

Over 90% of patients treated for head and neck cancer with curatively aimed chemo or bioradiotherapy will develop painful mucositis and xerostomia. Sublingually delivered fentanyl (SDL) is a rapid acting opioid to treat breakthrough pain. It is unclear how SDL is absorbed by the mucosa of these patients. Therefore, the aim of this study was to investigate the effects of mucositis and xerostomia on the absorption of SDL. Thirteen patients who received chemo or bioradiotherapy (RT), were given a single dose of fentanyl: Before start of RT, 3 and 6 weeks after start of RT, and 6 weeks after finishing RT. Pharmacokinetic samples were taken. The primary endpoint was the relative difference (RD) between systemic exposure to fentanyl (area under the curve; AUC) at baseline (AUC_baseline) and fentanyl AUC in the presence of mucositis grade ≥2. The secondary endpoint was the RD between AUC_baseline and fentanyl AUC in the presence of xerostomia, which were analyzed by means of a paired t-test on log-transformed data. Mucositis resulted in a 12.7% higher AUC (n = 13; 95% CI: −10.7% to +42.2%, p = 0.29) compared to baseline levels and xerostomia resulted in a 22.4% lower AUC (n = 8; 95% CI: −51.9% to +25.3%, p = 0.25) compared to baseline levels. Mucositis grade ≥2 or xerostomia caused by chemo or bioradiotherapy does not significantly alter the systemic exposure to SDL. Patients with pain during and after chemo or bioradiotherapy may be safely treated with SDL.

Fentanyl Sublingual Tablets Versus Subcutaneous Morphine for the Management of Severe Cancer Pain Episodes in Patients Receiving Opioid Treatment: A Double-Blind, Randomized, Noninferiority Trial

Purpose

Fentanyl sublingual tablets (FST) are a potentially useful alternative to parenteral opioids such as subcutaneous morphine (SCM) to treat severe cancer pain episodes. No direct comparison between FST and SCM is available. The aim of this study was to test noninferiority of FST versus SCM during the first 30 min postadministration.

Methods

Patients receiving stable opioid therapy and experiencing a severe pain episode were randomly assigned to either 100 µg FST or 5 mg SCM in a double-blind, double-dummy trial. Average pain intensity (PI) assessed on a 0 to 10 numerical rating scale at 10, 20, and 30 min postadministration was the main end point. Analysis of covariance, adjusted by baseline PI, was the main analysis. The noninferiority margin (NIm) for the between-group difference was set at −0.6, that is, equal to one third of the minimum clinically important PI difference of two points.

Results

A total of 114 patients were randomly assigned to either FST (n = 58) or SCM (n = 56). One patient (in the FST group) withdrew consent before drug administration and was excluded from analysis. Baseline mean PIs were 7.5 in both groups; mean average PIs assessed at 10, 20, and 30 min postadministration were 5.0 and 4.5 for FST and SCM, respectively, with the 95% CI of the between-group difference including the NIm (−0.49; 95% CI, −1.10 to 0.09). Patients taking FST received a second drug dose after 30 min more frequently than did patients taking SCM (51% v 37%, respectively; risk difference, −13%; 95% CI, −30% to 3%). Both treatments were well tolerated, with average follow-up adverse event scores below the response of “A Little.” Ninety-three percent of patients preferred the sublingual administration.

Conclusion

This trial did not show noninferiority of FST versus SCM within the chosen NIm. Both treatments were safe, and patients preferred the sublingual route of administration. FST provides analgesia with modest to moderate increased risk of lower efficacy compared with SCM.

Rapid acting fentanyl formulations in breakthrough pain in cancer. Drug selection by means of the System of Objectified Judgement Analysis

Drug selection of rapid acting fentanyl formulations in the treatment of breakthrough pain in patients with cancer is performed by the System of Objectified Judgement Analysis method. All seven available formulations were included in the analysis. The following selection criteria were used: number of available strengths, variability in the rate of absorption, interactions, clinical efficacy, side effects, ease of administration and documentation. No direct double-blind comparative studies between two or more formulations were identified and the clinical documentation of all formulations is limited. The most distinguishing criterion was ease of use. This led to slightly higher scores for Abstral, Instanyl and PecFent than for the other formulations. The pros and cons of each formulation should be discussed with the patient, and the most suitable formulation selected for each individual patient.

Sublingual Fentanyl Tablets for Relief of Breakthrough Pain in Cancer Patients and Association with Quality-of-Life Outcomes

BACKGROUND AND OBJECTIVE

Breakthrough pain (BTP) is highly prevalent in patients with cancer and is strongly associated with adverse outcomes related to health status, mood, anxiety and depression. However, studies on the effect of BTP medication on quality of life (QOL) are lacking. The purpose of this study was to provide a qualitative evaluation of the effect of sublingual fentanyl tablets (SFT), a therapy specifically developed for BTP, on the QOL of cancer pain patients.

METHODS

We conducted a multicentre, prospective observation post-authorisation, open-label study between March and December 2013. The study consisted of a screening visit and four assessment points at 3, 7, 15 and 30 days. Pain intensity (PI), frequency of BTP, onset of pain relief and adverse events (AEs) were assessed at each visit. Anxiety and depression were evaluated using the validated Hospital Anxiety and Depression Scale (HADS) and health status using the Short Form 12, version 2 (SF-12v2) Health Survey.

RESULTS

Of the 102 patients considered eligible, 81 (79.4 %) were enrolled; of these, 69 (85.1 %) completed the study. Significant pain reduction was achieved for average PI (p < 0.001) compared with baseline. At the end of the observational period, HADS scores showed significant improvement in the depression subscale (p = 0.005) and the anxiety subscale (p < 0.001). Similarly, SF-12 scores showed significant improvement, both in the mental component score (p < 0.001) and the physical component score (p = 0.002). SFT was well-tolerated and only one patient withdrew from the study due to drug-related AEs.

CONCLUSION

SFT represents an effective, well-tolerated treatment for cancer BTP. Results provide consistent evidence for the positive impact of SFT on health-related QOL and physical functioning as well as other co-morbidities of cancer BTP such as anxiety and depression.

The Influence of Low Salivary Flow Rates on the Absorption of a Sublingual Fentanyl Citrate Formulation for Breakthrough Cancer Pain

CONTEXT

Salivary gland hypofunction may affect the absorption of drugs through the oral mucosa, which in turn may affect their clinical efficacy (e.g., onset of action).

OBJECTIVES

The aim of this study was to assess the pharmacokinetics of a sublingual fentanyl orally disintegrating tablet (Abstral, Prostrakan Inc.) in a group of cancer patients with salivary gland hypofunction.

METHODS

Nine cancer patients with salivary gland hypofunction underwent a series of three pharmacokinetic studies with the sublingual fentanyl orally disintegrating tablet. In the first phase, the patients received no pretreatment; in the second phase, the patients were allowed to moisten the oral cavity before dosing; in the third phase, the patients were given pilocarpine hydrochloride (saliva stimulant) before dosing. Fentanyl concentrations were measured using a method of high-performance liquid chromatography with validated tandem mass spectrometric detection.

RESULTS

The Tmax was longer, the Cmax was lower, the AUC0-30 lower, and the AUClast lower in the phase involving no pretreatment; the Tmax/Cmax/AUC0-30/AUClast were similar in the phase involving moistening of the oral cavity and the phase involving giving pilocarpine hydrochloride.

CONCLUSION

The pharmacokinetics of the sublingual fentanyl orally disintegrating tablet appear to be negatively affected by the presence of salivary gland hypofunction, although the moistening of the oral cavity before dosing results in a pharmacokinetic profile similar to that seen with the giving of pilocarpine hydrochloride.

Transmucosal Immediate-Release Fentanyl for Breakthrough Cancer Pain: Opportunities and Challenges for Use in Palliative Care

Opioids are used to treat breakthrough cancer pain (BTCP) and can be classified by relative duration and onset of action. Regulatory approvals of numerous transmucosal immediate-release fentanyl (TIRF) formulations provide alternative options to palliative care-trained providers in the management of BTCP. TIRFs have been formulated as a sublingual tablet, sublingual spray, intranasal spray, pectin-based nasal spray, buccal tablet, and buccal soluble film. Differences exist between TIRFs regarding formulation design and dosing to treat BTCP. Opportunities for use include palliation of BTCP in head and neck cancer and/or radiation-induced mucositis. The purpose of this review is to discuss TIRF formulation and dosing, pharmacokinetics, clinical efficacy, patient acceptability, and safety/tolerability. In addition, barriers to TIRF utilization will be discussed.

Breakthrough pain in elderly patients with cancer: treatment options

The prevalence of pain is high in the elderly and increases with the occurrence of cancer. Pain treatment is challenging because of age-related factors such as co-morbidities, and over half of the patients with cancer pain experience transient exacerbation of pain that is known as breakthrough pain (BTP). As with background pain, BTP should be properly assessed before being treated. The first step to be taken is optimizing around-the-clock analgesia with expert titration of the painkiller. Rescue medication should then be provided as per the requested need, while at the same time preventing identified potential precipitating factors. In the elderly, starting treatment with a lower dose of analgesics may be justified because of age-related physiological changes such as decreased hepatic and renal function. Whenever possible, oral medication should be provided prior to a painful maneuver. In the case of unpredictable BTP, immediate rescue medication is mandatory and the subcutaneous route is preferred unless patient-controlled analgesia via continuous drug infusion is available. Recently, transmucosal preparations have appeared in the medical armamentarium but it is not yet known whether they represent a truly efficient alternative, although their rapid onset of activity is already well recognized. Adjuvant analgesics, topical analgesics, anesthetic techniques and interventional techniques are all valid methods to help in the difficult management of pain and BTP in elderly patients with cancer. However, none has reached a satisfying scientific level of evidence as to nowadays make the development of undisputed best practice guidelines possible. Further research is therefore on the agenda.

Alternative routes to oral opioid administration in palliative care: a review and clinical summary

OBJECTIVE

A major goal of palliative care is to provide comfort, and pain is one of the most common causes of treatable suffering in patients with advanced disease. Opioids are indispensable for pain management in palliative care and can usually be provided by the oral route, which is safe, effective, and of lowest cost in most cases. As patients near the end of life, however, the need for alternate routes of medication increases with up to 70% of patients requiring a nonoral route for opioid administration. In order to optimize patient care, it is imperative that clinicians understand existing available options of opioid administration and their respective advantages and disadvantages.

METHODS

We performed a literature review to describe the most commonly used and available routes that can substitute for oral opioid therapy and to provide a summary of factors affecting choice of opioid for use in palliative care in terms of benefits, indications, cautions, and general considerations.

RESULTS

Clinical circumstances will largely dictate appropriateness of the route selected. When the oral route is unavailable, subcutaneous, intravenous, and enteral routes are preferred in the palliative care population. The evidence supporting sublingual, buccal, rectal, and transdermal gel routes is mixed.

CONCLUSIONS

This review is not designed to be a critical appraisal of the quality of current evidence; rather, it is a summation of that evidence and of current clinical practices regarding alternate routes of opioid administration. In doing so, the overarching goal of this review is to support more informed clinical decision making.

Management of the acute painful crisis in sickle cell disease- a re-evaluation of the use of opioids in adult patients

Management of the acute painful crisis (APC) of sickle cell disease (SCD) remains unsatisfactory despite advances in the understanding and management of acute pain in other clinical settings. One reason for this is an unsophisticated approach to the use of opioid analgesics for pain management. This applies to haematologists who are responsible for developing acute sickle pain management protocols for their patients, and to health care staff in the acute care setting. The objective of this article is to evaluate the evidence for use of opioids in APC management. We have highlighted the possibilities for improving management by using alternatives to morphine, and intranasal (IN) or transmucosal routes of administration for rapid onset of analgesia in the emergency department (ED). We suggest how experience gained in managing acute sickle pain in children could be extrapolated to adolescents and young adults. We have also questioned whether patients given strong opioids in the acute setting are being safely monitored and what resources are required to ensure efficacy, safety and patient satisfaction. We also identify aspects of care where there are significant differences of opinion, which require further study by randomized controlled trial.

Single-dose pharmacokinetics of fentanyl sublingual spray and oral transmucosal fentanyl citrate in healthy volunteers: a randomized crossover study

BACKGROUND

Fentanyl sublingual spray (FSS) is a novel fentanyl formulation recently developed for the treatment of breakthrough cancer pain, which is characterized by a fast onset and a relatively short duration.

OBJECTIVE

To compare rate of absorption and systemic bioavailability between FSS and oral transmucosal fentanyl citrate (OTFC) in healthy volunteers.

METHODS

This randomized 3-way crossover study involved 29 healthy volunteers (25 men and 4 women; mean age, 35 years) who received single doses of FSS (400 μg), OTFC (400 μg), and intravenous fentanyl citrate (100 μg) separated by washout periods of ≥7 days. Oral naltrexone was given to minimize potential adverse effects of fentanyl. Plasma fentanyl concentrations were measured for 36 hours after each dose for the calculation of pharmacokinetic parameters.

RESULTS

Mean Cmax values of fentanyl were higher with FSS versus OTFC (0.81 ng/mL vs 0.61 ng/mL) and were attained more quickly; the median Tmax was 1.5 hours with FSS and 2.0 hours with OTFC (P < 0.05). Furthermore, potentially effective fentanyl concentrations were achieved more quickly with FSS than with OTFC. Five and 10 minutes after administration, mean plasma concentrations were 19.0% and 53.7% of Cmax with FSS, respectively, compared with levels below the lower limit of assay quantification and 6.1%, respectively, with OTFC. Plasma concentrations of fentanyl at 10 minutes with FSS were equivalent to those with OTFC at 60 minutes. The Cmax and AUCs were approximately 33% to 36% greater with FSS than with OTFC, and the 90% CIs of the geometric mean ratios for each parameter fell outside the bioequivalence range of 80% to 125%. Systemic bioavailability was also greater with FSS than with OTFC (approximately 76% vs 51%). All 3 fentanyl treatments were well tolerated. All reported adverse events were mild and consistent with those previously reported in healthy volunteers receiving transmucosal fentanyl with naltrexone, and none occurred in >2 participants during any treatment period.

CONCLUSIONS

Absorption of fentanyl in this study was faster and bioavailability was greater with FSS than with OTFC. The pharmacokinetic profile of the sublingual spray closely matches the duration of onset to pain intensity in a breakthrough cancer pain episode. These findings suggest that FSS is appropriate for the treatment of breakthrough cancer pain. ClinicalTrials.gov identifier: NCT01780233.

Pharmacokinetics of non-intravenous formulations of fentanyl

Fentanyl was structurally designed by Paul Janssen in the early 1960s as a potent opioid analgesic (100-fold more potent than morphine). It is a full agonist at μ-opioid receptors and possesses physicochemical properties, in particular a high lipophilicity (octanol:water partition coefficient >700), which allow it to cross quickly between plasma and central nervous target sites (transfer half-life of 4.7-6.6 min). It undergoes first-pass metabolism via cytochrome P450 3A (bioavailability ~30 % after rapid swallowing), which can be circumvented by non-intravenous formulations (bioavailability 50-90 % for oral transmucosal or intranasal formulations). Non-intravenous preparations deliver fentanyl orally-transmucosally, intranasally or transdermally. Passive transdermal patches release fentanyl at a constant zero-order rate for 2-3 days, making them suitable for chronic pain management, as are iontophoretic transdermal systems. Oral transmucosal and intranasal routes provide fast delivery (time to reach maximum fentanyl plasma concentrations 20 min [range 20-180 min] and 12 min [range 12-21 min], respectively) suitable for rapid onset of analgesia in acute pain conditions with time to onset of analgesia of 5 or 2 min, respectively. Intranasal formulations partly bypass the blood-brain barrier and deliver a fraction of the dose directly to relevant brain target sites, providing ultra-fast analgesia for breakthrough pain. Thanks to the development of non-intravenous pharmaceutical formulations, fentanyl has become one of the most successful opioid analgesics, and can be regarded as an example of a successful reformulation strategy of an existing drug based on pharmacokinetic research and pharmaceutical technology. This development broadened the indications for fentanyl beyond the initial restriction to intra- or perioperative clinical uses. The clinical utility of fentanyl could be expanded further by more comprehensive mathematical characterizations of its parametric pharmacokinetic input functions as a basis for the rational selection of fentanyl formulations for individualized pain therapy.

In vitro and in vivo evaluation of a sublingual fentanyl wafer formulation

Background

The objective of this study was to prepare a novel fentanyl wafer formulation by a freeze-drying method, and to evaluate its in vitro and in vivo release characteristics, including its bioavailability via the sublingual route.

Methods

The wafer formulation was prepared by freeze-drying an aqueous dispersion of fentanyl containing sodium carboxymethylcellulose and amylogum as matrix formers. Uniformity of weight, friability, and dissolution testing of the fentanyl wafer was achieved using standard methods, and the residual moisture content was measured. The fentanyl wafer was also examined using scanning electron microscopy and x-ray diffraction. The absolute bioavailability of the fentanyl wafer was evaluated in 11 opioid-naïve adult female patients using a randomized crossover design.

Results

In vitro release showed that almost 90% of the fentanyl dissolved in one minute. In vivo, the first detectable plasma fentanyl concentration was observed after 3.5 minutes and the peak plasma concentration between 61.5 and 67 minutes. The median absolute bioavailability was 53.0%.

Conclusion

These results indicate that this wafer has potential as an alternative sublingual fentanyl formulation.

Fentanyl for the treatment of tumor-related breakthrough pain

BACKGROUND

Breakthrough cancer pain (BTCP) is common among cancer patients and markedly lowers their quality of life. The treatment for BTCP episodes that is recommended in current guidelines involves extended-release formulations in combination with rapid-onset and short-acting opioids. In the past few years, several new preparations of fentanyl, an opioid with a very rapid onset, have been approved for this indication. Treating physicians need to be aware of the clinical differences between the newer fentanyl preparations and immediate-release opioids.

METHODS

We searched the PubMed and Embase databases for randomized controlled trials (RCTs) of fentanyl for buccal, sublingual or intranasal administration in comparison with other opioids or a different fentanyl preparation for the treatment of BTCP.

RESULTS

In 6 trials of buccal, sublingual or intranasal fentanyl versus oral immediate-release opioids for the treatment of BTCP episodes, the use of fentanyl was associated with significantly less intense pain. In particular, fentanyl more often lowered the intensity of pain by at least 33% (range between studies: 13% to 57%) or by at least 50% (range between studies: 9% to 38%) within 15 minutes. Please change to "versus" if you agree.] Dose titration should begin at the lowest dose. When one fentanyl preparation is exchanged for another, the effective dose will probably differ.

CONCLUSION

The newer fentanyl preparations extend the treatment options for BTCP. They relieve pain within a short time better than conventional, immediate-release oral opioids do and may therefore be very helpful for patients with suddenly arising, intense, and short-lasting BTCP episodes. Further comparative trials are urgently needed.

Considerations in selecting rapid-onset opioids for the management of breakthrough pain

Breakthrough pain (BTP) is a transitory pain that occurs despite the use of long-term, around-the-clock analgesia. It is highly prevalent in certain populations and places a significant burden on patients, their families, caregivers, and health-care systems. Despite its prevalence and impact, BTP is sometimes unrecognized and often undertreated. Various formulations of fentanyl – a rapid-onset opioid with short duration of action – are available for the management of BTP. The efficacy of formulations using transmucosal, transbuccal, sublingual, and intranasal administration routes has been demonstrated for BTP treatment in clinical trials. However, a lack of head-to-head trials evaluating their relative efficacy makes it challenging for physicians to reach informed decisions on the most efficacious intervention for individual patients. In the absence of clear data on the relative efficacy of fentanyl formulations, prescribing decisions need to be based on physician understanding and experience and product cost and availability, taking into account the individual patient’s needs, the ability of the patient or caregivers to administer medication, and the patient’s wishes. This review evaluates current pharmacologic methods of alleviating BTP and discusses factors that should be considered when selecting the most appropriate formulation for individual patients. With the range of fentanyl formulations available, it is now possible to successfully address BTP in the majority of patients.

A review of the pharmacokinetic profile of transmucosal fentanyl formulations

BACKGROUND AND OBJECTIVES

Breakthrough pain (BTP) is a transitory flare of moderate-to-severe pain that occurs in patients with stable, controlled persistent pain. Management of BTP episodes is difficult because frequency, time-to-peak intensity, and duration of episodes vary both within and between individuals. Formulations of fentanyl that use a buccal, sublingual, or nasal transmucosal route of administration have been developed for the treatment of BTP in opioid-tolerant patients with cancer. These formulations allow rapid passage into the bloodstream and avoid first-pass metabolism and, therefore, are more likely to match the time-course of BTP episodes than are oral formulations. The purposes of this analysis were to identify and review published data describing the pharmacokinetic properties of rapid-onset fentanyl formulations and to evaluate these properties in view of the temporal dynamic characteristics of BTP in order to help guide medical practice.

METHODS

Relevant publications were searched in the PubMed database from 1998. The plasma drug concentration-time profile of each formulation obtained from the identified studies was adjusted to a consistent scale for comparison.

RESULTS

The data revealed that the various transmucosal formulations resulted in three typical plasma fentanyl concentration profiles: (1) type 1: a very rapid rise and short duration; (2) type 2: a rapid increase and sustained intensity; and (3) type 3: a slower onset and longer duration.

CONCLUSIONS

Given the substantial variability of BTP episodes experienced by patients, these pharmacokinetic differences may provide useful information for a physician who is selecting a rapid-onset opioid medication for a patient.

A comprehensive review of rapid-onset opioids for breakthrough pain

Breakthrough pain (BTP) is a transitory pain (reaching maximum severity in ~15 minutes and lasting ~60 minutes in patients with cancer) that occurs despite the management of chronic pain with long-term around-the-clock analgesia. BTP occurs in 33-65% of patients with chronic cancer pain and in ~70% of patients with chronic noncancer pain. BTP has historically been managed with short-acting opioids; however, these medications have a pharmacokinetic profile that does not correlate with the sudden onset and short time to maximum severity of BTP. Interest in rapid-onset opioids to relieve BTP has therefore been growing. This comprehensive review aims to summarize the currently available clinical data for the approved rapid-onset opioids, which comprise different formulations of fentanyl, a μ-opioid receptor agonist with anaesthetic and analgesic properties. Administration routes for fentanyl in the management of BTP currently include the transmucosal and intranasal routes; an intrapulmonary formulation is also in development. The findings of this review suggest that the efficacy and safety of the approved rapid-onset opioids are comparable.

A phase I pharmacokinetic and bioavailability study of a sublingual fentanyl wafer in healthy volunteers

BACKGROUND

The sublingual administration of opioids is a simple and noninvasive method that provides rapid analgesia. In this phase I study we investigated the pharmacokinetics and bioavailability of a fentanyl wafer in healthy volunteers. The principal study objective was to investigate the pharmacokinetic profile of a new sublingual fentanyl wafer and to establish its absolute bioavailability.

METHODS

Twenty-four healthy volunteers, mean age 23 years, were randomly assigned to receive the equivalent of fentanyl 100 μg by both the sublingual and IV routes. Blood samples were collected in sterile polypropylene tubes for 24 hours after each fentanyl administration. The pharmacokinetic parameters were determined by model-independent pharmacokinetic analyses of the plasma fentanyl concentration-time profiles.

RESULTS

The mean absolute bioavailability of the sublingual fentanyl wafer was 78.9% (90% confidence interval [CI] 51.1% to 121.7%). The first detectable plasma fentanyl concentration time ranged from 2 to 10 minutes in all volunteers, and the mean (±SD) time to peak plasma concentration at 0.91 (±0.73) hours after administration.

CONCLUSION

Sublingual administration of fentanyl as a wafer product resulted in rapidly detectable plasma fentanyl concentrations. The absolute bioavailability of 78.9% indicated a high systemic availability of fentanyl and suggests that further development of this wafer is justified.

Breakthrough pain in patients referred to pain clinics: the Italian pain network retrospective study

INTRODUCTION

Despite breakthrough pain (BTP) being one of the most severe forms of pain, there are no definitive data on its prevalence.

METHODS

The authors performed a retrospective survey of the prevalence of BTP in consecutive patients in four Italian pain clinics, subsequent to application of an Italian law mandating detailed clinical records on pain characteristics, treatment, and results. Mean pain intensity was assessed with a numerical rating scale from 0 to 10.

RESULTS

The authors analyzed records of 1,401 patients (58% women, 33.1% patients with cancer). Transient episodes of severe pain or BTP were referred by 790 patients (56.4%), including 58.2% of the men (342 of 588) and 55.1% of the women (448 of 813). Among the 464 patients with cancer, 70.3% reported daily exacerbation of pain. The mean BTP intensity was 8.31 ± 1.58 and 31.1% of patients reported experiencing three episodes per day.

CONCLUSION

Despite some limitations of the study, the authors show that transient episodes of severe pain or BTP are significantly present both in cancer and other diseases, and that many patients are not yet receiving appropriate opioid therapy. The authors need validated tools at international level for the diagnosis and treatment of BTP in patients with cancer and for transitory and patients with severe non-cancer pain. A survey at national level is needed to estimate the prevalence of BTP in different settings, to plan specific medical education.

Fentanyl for breakthrough pain: a systematic review

The purpose of this article is to systematically review the use of fentanyl as an analgesic for breakthrough pain. This article found that the oral transmucosal fentanyl (OTFC) had a quicker onset to analgesia than oral immediate-release opioids. Intranasal fentanyl (INFS) had a quicker onset to analgesia than buccal tablets, which in turn had a quicker onset to analgesia than OTFC. Patient acceptance and global rating of efficacy were greater for INFS than for buccal fentanyl. OTFC and INFS have been used effectively to reduce acute pain in children who are opioid-naive. Abuse and addiction to OTFC, fentanyl buccal tablets and INFS was low, owing to patient selection.

Fentanyl transmucosal tablets: current status in the management of cancer-related breakthrough pain

Breakthrough pain is a newly recognized pain category that was first described by Portenoy and Hagen in 1990. The term describes pain that increases in intensity to "break through" chronic pain that is being controlled by a scheduled opioid regimen. The development of fluctuations in pain intensity is challenging due to their unpredictable nature, rapid onset, and need for rapid treatment intervention. Breakthrough pain has been treated by using an extra opioid dose in addition to the scheduled opioid being used for pain. Recommendations for dose and frequency are based on expert opinion only, and have included dosing based on a percentage of the total opioid dose. Other recommendations include increasing the regularly scheduled opioid dose. Clinical trials have now focused on delivery of opioids that have both potency and a rapid onset of action. Lipophilic opioids have received a substantial amount of study due to their quick absorption and rapid onset of analgesia. Lipophilic opioids that have been studied to date include transmucosal fentanyl, sublingual fentanyl, intranasal sufentanil, and oral and sublingual methadone. Initial clinical trials have established the superiority of transmucosal fentanyl as a breakthrough analgesic when compared with immediate-release oral opioid formulations. Problems with bioavailability have led to a search for newer formulations of transmucosal delivery. Newer formulations, such as fentanyl transmucosal tablets, have been developed to ensure superior delivery for the patient suffering from breakthrough pain. The purpose of this paper is to discuss the current status of transmucosal tablet formulations for cancer breakthrough pain.

[Cancer breakthrough pain. Indications for rapidly effective opioids]

The pharmacotherapy of tumor pain has two main aims: to deliver an adequate basic analgesia using long-term retarded opioid medication and an effective treatment of tumor breakthrough pain using rapidly effective non-retarded opioids. Breakthrough pain is characterized by a sudden onset and rapid increase in the pain level and should be treated with correspondingly rapidly effective opioids. The pharmacological characteristics of previously available and routinely prescribed non-retarded opioids do not always correspond in oral galenics to the demands resulting from the definition of tumor breakthrough pain. As alternatives to these substances five different rapidly effective fentanyl preparations are now available for transmucosal administration.

Fentanyl sublingual: in breakthrough pain in opioid-tolerant adults with cancer

Fentanyl is a potent opioid with a short duration of action. Fentanyl sublingual has been formulated as a rapidly disintegrating tablet that is quickly absorbed, producing a fast onset of analgesia. In two randomized, double-blind clinical trials, fentanyl sublingual as single fixed or titrated doses reduced pain intensity during breakthrough pain episodes to a significantly greater extent than placebo in opioid-tolerant cancer patients. In a fixed-dose phase II trial and a titrated-dose phase III trial, fentanyl sublingual (as a single 400 μg dose and as titrated doses) reduced mean pain intensity difference (PID) to a significantly greater extent than placebo over the entire treatment period (up to 60 minutes), reaching statistical significance 15 minutes post-dose. In the titrated-dose study, the mean sum of PID (area under the PID vs time curve) at 30 minutes post-dose was significantly greater with fentanyl sublingual than placebo, with significant improvements in PID seen at 10 minutes maintained at 60 minutes post-dose. In the phase III study, patients receiving fentanyl sublingual were more satisfied with their treatment than patients receiving placebo (measured using the Patient Global Evaluation of Medication score), and almost half of all fentanyl sublingual recipients were satisfied or very satisfied with their treatment. Fentanyl sublingual was generally well tolerated in the two trials and most adverse events were mild to moderate in intensity.

Long-term effectiveness and tolerability of sublingual fentanyl orally disintegrating tablet for the treatment of breakthrough cancer pain

BACKGROUND AND OBJECTIVES

Breakthrough cancer pain (BTcP) is a transient exacerbation of cancer pain in patients with otherwise stable, persistent background pain. This study evaluated the long-term effectiveness and tolerability of sublingual fentanyl orally disintegrating tablet (sublingual fentanyl ODT), for the treatment of BTcP in opioid-tolerant patients with cancer.

RESEARCH DESIGN AND METHODS

This was a non-randomized, open-label, multi-center, Phase III study conducted in opioid-tolerant patients (aged ≥17 years) with BTcP. The study comprised a 2-week titration phase, followed by a maintenance phase of up to 12 months. Patients self-administered sublingual fentanyl ODT for episodes of BTcP. Effectiveness was assessed using patients' global evaluation of medication (PGEM), the brief pain inventory (BPI) and the depression, anxiety and positive outlook scale (DAPOS). Adverse events were recorded throughout.

CLINICAL TRIAL REGISTRATION

NCT00263575 (http://www.clinicaltrials.gov/).

RESULTS

Of 139 recruited patients, 69% identified an effective dose of sublingual fentanyl ODT (a dosage that successfully treated all episodes of BTcP over two consecutive days) and entered the maintenance phase, during which they were treated for a median of 149.0 days (mean dose 507.5 µg). The study recorded a significant increase in reported satisfaction with pain medication at the 6-month and end-of-study visits, compared to screening (p ≤ 0.01). Evaluation of quality of life using BPI and DAPOS identified no deterioration in scores and significant improvements in certain parameters (p < 0.05). Sublingual fentanyl ODT was well tolerated, with no study drug-related deaths, and 49 patients (35.3%) experiencing ≥1 study drug-related adverse event. The most common of these included nausea (8.6%), constipation (5.8%) and somnolence (5.8%). There was no evidence of sublingual mucosal irritation due to the study medication. The pattern of adverse events was similar to that previously observed with transmucosal fentanyl.

CONCLUSIONS

Sublingual fentanyl ODT was effective and well tolerated for the long-term treatment of BTcP in opioid-tolerant cancer patients. There was an increase in satisfaction with pain medication during the study, and sublingual fentanyl ODT showed an acceptable safety profile over 12 months of treatment.

Breakthrough pain in cancer patients

Breakthrough pain is a transient exacerbation of pain that occurs either spontaneously or in relation to a specific predictable or unpredictable trigger, despite relatively stable and adequately controlled background pain. A typical episode of breakthrough pain has a fast onset and short duration, yet despite the self-limiting nature of each breakthrough pain, the repeated episodes can have a significant effect on patients' quality of life. Normal-release oral opioids have been the mainstay pharmacological approach for patients who are receiving an around the clock opioid regimen, but the onset and duration of action of oral opioids such as morphine may not be suitable for treating many breakthrough pains. Efforts to provide non-parenteral opioid formulations that could provide more rapid, and more effective, relief of breakthrough pain have led to the development of transmucosal opioid formulations.

Pharmacokinetics, safety, and tolerability of ascending doses of sublingual fentanyl, with and without naltrexone, in Japanese subjects

This open-label, nonrandomized study assessed single and repeat ascending doses of a new sublingual fentanyl (SLF) formulation in 48 healthy Japanese opiate-naïve subjects (47 completed). Subjects received single-dose SLF 100, 200, 400, or 800 µg followed by 13 doses 6 hourly, at their dose level. Subjects taking repeat-dose 400 and 800 µg were pretreated with naltrexone in order to block opiate-receptor-mediated effects on respiration, monitored by pulse oximetry and transcutaneous pco(2). Sublingual fentanyl was rapidly and consistently absorbed. After single doses, median t(first) was 0.08 to 0.25 hours and t(max) 0.50 to 1.00 hours. After repeat dosing, median t(max) (t(max,ss)) was 0.50 to 2.00 hours. Plasma concentrations were dose proportional both after single and repeat dosing, and naltrexone appeared to have no effect on SLF pharmacokinetics. Plasma fentanyl reached steady state within the 72-hour dosing period and accumulation was approximately 2-fold. After single doses, effects on respiratory variables were evident after the 400-µg and 800-µg doses. Transcutaneous pco(2) was not helpful in detecting respiratory depression. Thus, SLF yielded rapid absorption of fentanyl and dose-proportional plasma concentrations that, for 400 µg and 800 µg, were within the typical analgesic range. Respiratory depression in these opioid-naïve volunteers was manageable with simple clinical measures.

Efficacy of intranasal fentanyl spray versus other opioids for breakthrough pain in cancer

OBJECTIVE

To compare the efficacy of intranasal fentanyl spray (INFS), oral transmucosal fentanyl citrate (OTFC), fentanyl buccal tablet (FBT) and oral morphine (OM) for the treatment of breakthrough cancer pain (BTCP).

METHODS

A systematic literature review (Medline, EMBASE, BIOSIS; 1996-2007) identified six randomised controlled trials (RCTs) investigating the effects of INFS, OTFC, FBT and OM for the treatment of BTCP. The endpoint of interest was pain intensity difference (PID, reported on a 0-10 numeric rating scale [NRS]) up to 60 minutes after intake. Results of all trials were analysed simultaneously with a mixed treatment comparison (extended meta-analysis). MTC can be considered a valid method when included studies are comparable regarding effect modifying baseline patient and study characteristics.

RESULTS

INFS provided the greatest reduction in pain relative to placebo: PID 1.7 points (95% CrI: 1.4; 1.9) at 15 minutes, 2.0 (1.6; 2.3) at 30 minutes, 2.0 (1.5; 2.4) at 45 minutes and 1.9 (1.5; 2.4) at 60 minutes. PID for OTFC and FBT relative to placebo were 0.4 (0.0; 0.8) and 0.5 (0.3; 0.7) at 15 minutes. Both treatments provided a reduction in pain superior to placebo at other time points. INFS displayed a more than 99% probability of providing the greatest pain reduction out of all interventions compared at 15 minutes after intake. This was maintained for any measured time point before 45 minutes when compared to FBT and for any measured time point before 60 minutes when compared to OTFC. Only from 45 minutes onwards did OM show a greater pain reduction than placebo.

CONCLUSION

Based on currently available evidence, INFS is expected to provide the greatest improvement in the treatment of BTCP. Due to its slow onset to effect OM cannot be considered an efficacious treatment for BTCP.

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.

Sublingual administration of fentanyl to cancer patients is an effective treatment for breakthrough pain: results from a randomized phase II study

In this study we evaluated the efficacy and tolerability of sublingual fentanyl (SLF) for breakthrough pain (BTP) in adult opioid-tolerant cancer patients. Patients received one dose of placebo, SLF 100, 200 and 400 microg in random order at four pain episodes. The primary efficacy endpoint was pain intensity difference (PID) from baseline. Twenty-seven patients received study medication. Overall PID increased significantly with SLF 400 microg versus placebo (8.57 mm, p <0.0001). Improvements were statistically different from placebo at 15 min (p = 0.005). SLF 100 and 200 microg showed a numerical trend towards improved pain relief. A dose that gave a clinically important reduction in pain (PID > 20 mm) was identified by 95% of patients. Reduced use of rescue medication (p < 0.001, SLF 400 microg) and improved global assessment of treatment (p = 0.0146, SLF 400 microg) confirmed these differences as clinically important. Nausea and dizziness were the most common treatment-related adverse effects. SLF appears to be a fast, effective and well-tolerated treatment for BTP.

Efficacy and long-term tolerability of sublingual fentanyl orally disintegrating tablet in the treatment of breakthrough cancer pain

BACKGROUND AND OBJECTIVES

Breakthrough cancer pain (BTcP) represents an important clinical challenge in the care of patients with cancer. This trial evaluated the efficacy and long-term tolerability of a sublingual formulation of the fast-acting opioid fentanyl, for the treatment of BTcP in opioid-tolerant patients with cancer.

RESEARCH DESIGN AND METHODS

This was a randomized, placebo-controlled, multi-center, phase III trial, conducted in opioid-tolerant male and female patients (aged > or =17 years) with BTcP. The study was conducted at 36 centers across the USA. The study comprised a 2-week open-label titration phase, followed by a double-blind efficacy phase, during which patients received sublingual fentanyl citrate orally disintegrating tablet (sublingual fentanyl ODT) or placebo, in a random order. The primary efficacy endpoint was the sum of pain intensity difference (SPID) 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. Following efficacy evaluation, patients entered a long-term safety phase of up to 12 months. Adverse events were recorded throughout the study. [

CLINICAL TRIAL REGISTRATION

NCT00262678]

RESULTS

A total of 131 patients entered the titration phase, of whom 61 were included in the primary efficacy analysis. Sublingual fentanyl ODT provided significant improvements in SPID relative to placebo at 30 min (49.5 vs. 36.6, p = 0.0004) and 60 min post-administration (143.0 vs. 104.5, p = 0.0002). Furthermore, sublingual fentanyl ODT provided significant improvements in PID and PR compared to placebo, from 10 min post-dose (p = 0.0055 and p = 0.049 for PID and PR, respectively). Patient recruitment was stopped early, due to positive interim analysis results (significant at prespecified level, p < or = 0.0414). Overall, sublingual fentanyl ODT was well-tolerated both systemically and sublingually, with 41 patients experiencing > or =1 study drug-related adverse event (AE). The most common AEs included nausea (12.2%), vomiting (5.3%) and somnolence (4.6%). One serious AE (mild affect lability) was considered possibly related to study medication. The observed pattern of AEs was consistent with that previously observed with fentanyl.

CONCLUSIONS

Sublingual fentanyl ODT was efficacious and well-tolerated for the treatment of BTcP in opioid-tolerant patients with cancer. Sublingual fentanyl ODT provided significant improvements in pain intensity compared to placebo, from 10 min post-administration and throughout the 60-min post-dose assessment period. Sublingual fentanyl ODT was well tolerated over 12 months of treatment.

Recent advances in the use of opioids for cancer pain

Opioids are the mainstay of treatment for moderate to severe cancer pain. In recent years there have been many advances in the use of opioids for cancer pain. Availability and consumption of opioids have increased and opioids other than morphine (including methadone, fentanyl, oxycodone) have become more widely used. Inter-individual variation in response to opioids has been identified as a significant challenge in the management of cancer pain. Many studies have been published demonstrating the benefits of opioid switching as a clinical maneuver to improve tolerability. Constipation has been recognized as a significant burden in cancer patients on opioids. Peripherally restricted opioid antagonists have been developed for the prevention and management of opioid induced constipation. The phenomenon of breakthrough pain has been characterized and novel modes of opioid administration (transmucosal, intranasal, sublingual) have been explored to facilitate improved management of breakthrough cancer pain. Advances have also been made in the realm of molecular biology. Pharmacogenetic studies have explored associations between clinical response to opioids and genetic variation at a DNA level. To date these studies have been small but future research may facilitate prospective prediction of response to individual drugs.

Exploratory assessment of dose proportionality: review of current approaches and proposal for a practical criterion

This article reviews currently used approaches for establishing dose proportionality in Phase I dose escalation studies. A review of relevant literature between 2002 and 2006 found that the power model was the preferred choice for assessing dose proportionality in about one-third of the articles. This article promotes the use of the power model and a conceptually appealing extension, i.e. a criterion based on comparing the 90% confidence interval for the ratio of predicted mean values from the extremes of the dose range (R(dnm)) to pre-defined equivalence criterion (theta(L),theta(U)). The choice of bioequivalence default values of theta(L)=0.8 and theta(U)=1.25 seems reasonable for dose levels only a doubling apart but are impractically strict when applied over the complete dose range. Power calculations are used to show that this prescribed criterion lacks power to conclude dose proportionality in typical Phase I dose-escalation studies. A more lenient criterion with values theta(L)=0.5 and theta(U)=2 is proposed for exploratory dose proportionality assessments across the complete dose range.