Management of breakthrough pain in patients with cancer

Prevalence and characteristics of breakthrough cancer pain in an outpatient clinic in a Catalan teaching hospital: incorporation of the Edmonton Classification System for Cancer pain into the diagnostic algorithm

BACKGROUND

Breakthrough cancer pain (BTcP) is defined according to its principal characteristics: high intensity, short time interval between onset and peak intensity, short duration, potential recurrence over 24 h and non-responsiveness to standard analgesic regimes. The Edmonton Classification System for Cancer Pain (ECS-CP) is a classification tool that evaluates different dimensions of pain. The aim of this study was to measure prevalence and the main characteristics of BTcP in a sample of advanced cancer patients and to explore the complexity observed when ECS-CP is incorporated into BTcP diagnostics algorithm.

METHODS

Descriptive prevalence study (Retrospective chart review). Davies' algorithm was used to identify BTcP and ECS-CP was used to recognize appropriate dimensions of pain. The study was conducted in a sample of advanced cancer patients attending hospital outpatient clinic in Lleida, Spain. 277 patients were included from 01/01/2014 to 31/12/2015. No direct contact was made with participants. The following information was extracted from the palliative care outpatient clinic database: age, gender, civil status, cognitive impairment status, functional performance status and variables related to tumour. Only BTcP cases were included.

RESULTS

Prevalence of BTcP was 39.34% (63.9% men). Mean of age was 68.2 years. Main diagnosis was lung cancer (n = 154; 31.6%). Metastases were diagnosed in 83% of the sample. 138 patients (49.8%) were diagnosed with 1 type of BTcP and 139 (50.2%) were diagnosed with more than one type of BTcP. In total, 488 different types of BTcP were recorded (mean 1.75 ± 0, 9), 244 of these types (50%) presented a component of neuropathic pain. Addictive behaviour, measured through CAGE test, was present in 29.2% (N = 81) of the patients and psychological distress was present in 40.8% (n = 113).

CONCLUSIONS

Prevalence of BTcP (39.34%) is similar to the one reflected in the existing literature. Study results indicate that the routine use of ECS-CP in a clinical setting allows us to detect more than one type of BTcP as well as additional complexity associated with pain (neuropathic, addictive behavior and psychological distress).

Characteristics of breakthrough cancer pain and its influence on quality of life in an international cohort of patients with cancer

OBJECTIVES

Breakthrough cancer pain (BTP) represents a treatment challenge. Objectives were to examine the prevalence and characteristics of BTP in an international sample of patients with cancer, and to investigate the relationship between BTP and quality of life (QoL).

METHODS

This was an observational cross-sectional multicentre study. Participating patients completed self-report questionnaires on a touch-screen laptop computer, including the Brief Pain Inventory, Alberta Breakthrough Pain Assessment Tool (ABPAT) and European Organisation for Research and Treatment of Cancer 30-item Core Quality of Life Questionnaire (EORTC QLQ-C30). The study was performed in 17 centres in 8 countries and involved 4 languages (Norwegian, Italian, German and English).

RESULTS

Records from a convenience sample of 978 patients with advanced cancer were analysed; mean age was 62.2 years, 48.3% were women and 84.4% had metastatic disease. A total of 296 patients (30%) had no pain, defined as worst pain in the past 24 hours <1 on a 0-10 scale. Of the 682 patients with a pain score ≥1, 393 (58%) reported no BTP on the screening item, while 289 (30%) confirmed flare ups of BTP. Patients with BTP reported significantly higher pain intensity scores (<0.001) than patients without BTP; 57.1% of patients rated BTP at its worst as being severe: ≥7 on a 0-10 scale. Time from onset to peak intensity was <10 min for 42.9%, and average time to pain relief was 27.1 min. BTP was commonly triggered by medication wearing off (28%). Patients with BTP had significantly worse mean outcomes on 10 of 15 functional and symptom scales of the EORTC QLQ-C30 (<0.001). Severe pain intensity in the last week was a powerful predictor of BTP (OR 4.1) and poor QoL (OR 1.9).

CONCLUSIONS

BTP is highly prevalent with prolonged episodes despite analgaesics, and has a pervasive impact on QoL. Patients reporting high pain intensity should be carefully evaluated for BTP and efficacy of analgaesic treatment, to provide optimal pain management and improve QoL.

TRIAL REGISTRATION NUMBER

NCT00972634; Results.

Diagnosis and management of breakthrough cancer pain: Have all the questions been resolved? A Delphi-based consensus assessment (DOIRON)

OBJECTIVE

To ascertain the level of agreement and achieve a consensus among cancer pain specialists in Spain with regard to the optimal definition, diagnosis, and management of breakthrough cancer pain (BTcP).

DESIGN

Two-round Delphi methodology survey (February-May 2013) using seven-point Likert scales (ranging from 1 "strongly disagree" to 7 "strongly agree") was carried out. Mean scores >5 or <3 indicated, respectively, agreement or disagreement. Scores from 3 to 5 indicated no consensus.

RESULTS

A total of 126 experienced specialists were surveyed. Response rates were 68 % in round 1 and 90 % in round 2. Agreement (mean Likert score) was strongest for the proposed BTcP definition (6.6), the use of oral (6.1), and intranasal (6.0) transmucosal fentanyl, the need for early assessment after BTcP treatment initiation, and the need to improve staff knowledge of BTcP. Broad agreement was also reached regarding the need to systematically screen all cancer patients for BTcP (5.9). Most respondents (82 %) considered strong opioids to be appropriate treatment. In contrast, no consensus was reached regarding strong opioid treatment for baseline pain as a prerequisite for BTcP diagnosis.

CONCLUSIONS

Consensus was strong for most treatment, and diagnostic aspects were evaluated in the study. However, several important issues remain unresolved, particularly whether the diagnostic criteria must include strong opioids for background pain. Nurses' awareness and understanding of BTcP was considered insufficient, and more training is needed in this area. Overall, agreement among specialists was good, but more work is needed to better define the optimal diagnostic features and treatments for this condition.

Pharmacokinetics and dose proportionality of fentanyl sublingual spray: a single-dose 5-way crossover study

BACKGROUND

Fentanyl sublingual spray is a novel formulation of fentanyl for sublingual delivery that was designed to enhance the rate and extent of absorption of fentanyl for management of breakthrough cancer pain (BTCP).

OBJECTIVES

The primary objective of this study was to determine the pharmacokinetics and dose proportionality of 5 different doses (100, 200, 400, 600, and 800 μg) of fentanyl sublingual spray in healthy subjects under fasted conditions (part A); the secondary objective was to assess the effects of temperature and pH in the oral cavity on relative bioavailability of fentanyl (part B).

METHODS

Analyses were performed on venous blood samples drawn 5 min to 36 h after administration of fentanyl sublingual spray (Subsys(®), Insys Therapeutics, Inc., Chandler, AZ, USA). Part A of this phase I study was a 5-treatment, 5-sequence, 5-period crossover study in which subjects received a single treatment of each of the 5 fentanyl sublingual spray doses. Dose proportionality was assessed using analysis of variance and linear regression techniques. Part B was a 5-treatment, 2-sequence, 5-period crossover study in which subjects received a single assigned dose of fentanyl sublingual spray 200 μg under the following 5 conditions: no pretreatment, pretreatment with cold or hot beverage, and pretreatment with low- or high-pH beverage. Naltrexone was administered to block potential opioid effects associated with fentanyl. Adverse events (AEs) were monitored and recorded throughout the study.

RESULTS

Fifty-three subjects (15 men, 38 women; mean age, 31 years) were enrolled in part A. Fourteen subjects (11 men, 3 women; mean age, 32 years) were enrolled in part B. The first quantifiable mean plasma concentrations of fentanyl were observed at the first sample time (5 min) for all doses. Mean maximum plasma concentration (C(max)) increased with increases in dose, whereas median time to reach C max (t max) tended to decrease with increases in dose. The dose-normalized C(max), area under the plasma concentration-time curve from time zero to infinity (AUC∞), and AUC from time zero to time of last measurable concentration (AUClast) values were linear and consistent with dose proportionality across the 100-800 μg dose range. Pretreatment of the oral cavity with a cold or hot beverage, or low- or high-pH beverage, did not appreciably alter fentanyl absorption (C(max) and AUC∞ values). The most commonly reported AEs were nausea and vomiting.

CONCLUSIONS

In healthy subjects, administration of fentanyl sublingual spray produced a rapid rise in fentanyl plasma concentrations. Dose-dependent parameters (C max and AUC) showed dose proportionality across the range of 100-800 μg. Altering the local environment of the oral cavity (temperature and pH) showed no effects on the bioavailability of fentanyl. The rapid and predictable rise in plasma fentanyl concentrations following administration of fentanyl sublingual spray corresponds with the rapid onset and duration of many BTCP episodes.

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.

Inhaled fentanyl aerosol in healthy volunteers: pharmacokinetics and pharmacodynamics

BACKGROUND

Rapid delivery of potent opioid to the systemic circulation is an important feature for the effective treatment of acute and acute-on-chronic breakthrough pain. The delivery of different opioids by the pulmonary route has been inconsistent, usually resulting in low bioavailability of the drug. Staccato® Fentanyl for Inhalation is a handheld inhaler producing a single metered dose of aerosolized fentanyl during a single inspiration. The aerosol is of high purity (≥98%) at a particle size (1 to 3.5 microns) shown to be best for pulmonary absorption.

METHODS

We conducted the study in healthy volunteers in 2 stages. In the crossover stage, 10 subjects received IV fentanyl 25 µg and inhaled fentanyl 25 µg on separate occasions. The dose escalation stage was a multidose, randomized, double-blind, placebo-controlled, single-period dose escalation study of inhaled fentanyl (50 to 300 µg). Serial blood sampling was performed over an 8-hour period after drug administration to determine the pharmacokinetic profile, and serial pupillometry was performed as a measure of pharmacodynamic effect.

RESULTS

In the crossover stage the pharmacokinetic profiles of the inhaled and IV fentanyl showed similar peak arterial concentrations and areas under the curve. The time to maximum concentration was slightly shorter for the inhaled than IV fentanyl, 20.5 and 31.5 seconds, respectively. In the dose escalation stage the administration of repeated doses resulted in predictable, dose-dependent serum concentrations.

CONCLUSIONS

This study has demonstrated that the pharmacokinetic profile of single doses of inhaled fentanyl is comparable to IV administration.

A European survey of oncology nurse breakthrough cancer pain practices

PURPOSE OF THE RESEARCH

Breakthrough cancer pain (BTCP) is a prevalent type of pain in which the nurse can play an important role in improving patients' pain symptoms and overall well-being. Nurses' experience with BTCP (number of patients, and estimates of severity and frequency), the treatment of BTCP (pharmacological and nonpharmacological treatments normally used), ratings of the importance of treatment factors, and reasons given for not advising patients to take strong painkillers are presented in the present paper.

METHODS AND SAMPLE

Nurses from 12 European countries, who cared for patients with cancer, took part in a survey. In total 1618 nurses were recruited and 1241 completed the survey questionnaire.

KEY RESULTS

Almost 90% of the nurses were female, and 50.4% had >9 years of experience in oncology nursing. The majority of the nurses (47%) said that a patient typically suffered from BTCP 2-3 times a day, and the severity of the pain for the patients was described as severe by 75.5%. In all, 38.4% of the nurses were unaware that medications specifically intended for treatment of BTCP exist, and 57% reported that oral opioids were normally prescribed for BTCP at their workplace. While 38% said they did not use nonpharmacological treatments for BTCP, the most common treatment approach was positional change (used by 76.6%). The treatment varied between the European countries.

CONCLUSION

Patients do not receive the appropriate medical treatment for their BTCP. Nurses need better training about BTCP in general, and BTCP assessment and management specifically.

Efficacy and safety of fentanyl sublingual spray for the treatment of breakthrough cancer pain: a randomized, double-blind, placebo-controlled study

BACKGROUND AND OBJECTIVES

A number of transmucosal fentanyl formulations have been developed for the management of breakthrough cancer pain (BTCP). Sublingual delivery of fentanyl, formulated as fentanyl sublingual spray, offers the potential for more rapid and greater absorption of fentanyl and associated onset of analgesic effect compared with other formulations. The objective of this study was to assess the efficacy and safety of fentanyl sublingual spray for the treatment of BTCP.

RESEARCH DESIGN AND METHODS

This was a randomized, double-blind, placebo-controlled phase III trial conducted in opioid-tolerant patients with BTCP. An open-label titration period was followed by a double-blind treatment period during which patients received fentanyl sublingual spray (100-1600 mcg) or placebo.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT00538850.

MAIN OUTCOME MEASURES

The primary efficacy measure was summed pain intensity difference at 30 minutes (SPID(30)). Secondary efficacy measures included total pain relief at 30 minutes (TOTPAR(30)) and patient global evaluation of study medication at 30 minutes. Efficacy measures were also assessed at various time points from 5-60 minutes postdose. Adverse events were monitored throughout the study.

RESULTS

A total of 130 patients were treated during the titration period, of whom 98 (75.4%) entered the double-blind period. Relative to placebo, fentanyl sublingual spray significantly improved mean SPID scores from 5 minutes (p = 0.0219) through 60 minutes (p < 0.0001), including the primary endpoint at 30 minutes (p < 0.0001). Fentanyl sublingual spray produced significantly greater pain relief (expressed in terms of TOTPAR) from 5 through 60 minutes (p < 0.0001), and significantly greater global evaluation of treatment effectiveness (p < 0.0001), compared with placebo. During double-blind treatment, the most frequently reported adverse events were nausea (7.1%), hyperhidrosis (5.1%), and peripheral edema (5.1%). Serious adverse events occurred in seven patients (5.4%) during titration and six (6.1%) during double-blind treatment; none were considered related to treatment.

CONCLUSIONS

These findings indicate that treatment with fentanyl sublingual spray results in effective relief of BTCP, with a rapid onset of action, and is well tolerated.

[Experiences of cancer patients with breakthrough pain and pharmacological treatments]

BACKGROUND

of cancer patients receiving palliative care, 80% suffer from cancer pain, and again 80% of these patients report breakthrough pain. This study explores the patients' perception of breakthrough pain, their experiences with existing therapeutic regimens and their expectations regarding an ideal breakthrough pain medication.

METHOD

from November 2008 to February 2010 two German palliative care units recruited 80 in- or outpatient cancer patients who completed a standardized questionnaire on breakthrough pain characteristics, analgesic medication, attitudes towards new treatment approaches for breakthrough pain, and experiences with alternative routes of drug administration as part of the "European Survey of Oncology Patients' Experience of Breakthrough Pain".

RESULTS

the study participants suffered from 1-12 episodes of either incident (47.5%) or spontaneous pain (37.5%) per day which were perceived as "severe" in 71% of all cases. These exacerbations highly interfered with the patients' general activity, mood, walking ability, and normal work. Overall, 64% of the patients reported alleviation from pharmacological (26%) and non-pharmacological (73%) interventions. Subcutaneous (40%) and oral (39%) routes were used frequently; intranasal (1.25%) and intrapulmonary (1.25%) routes were used rarely. Only 64% of all participants stated an overall satisfaction with their breakthrough analgesia.

CONCLUSION

the diagnosis and treatment of breakthrough pain seems to be conducted in a suboptimal manner, and standard recommendations on breakthrough pain relief are not implemented consistently. Possible causes of pain should be taken into account as well as multi-professional treatment interventions and alternative routes of administration of fast onset, effective drugs should be considered.

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.

Single-dose pharmacokinetics of fentanyl buccal soluble film

Objective

The objectives of the study were to determine the absolute bioavailability of fentanyl from fentanyl buccal soluble film, estimate the percentage of a fentanyl dose absorbed through the buccal mucosa, and compare the bioavailability of equivalent doses administered either as single or multiple dose units.

Design

Open-label, randomized, four-period, Latin-square crossover pharmacokinetic study.

Setting

Inpatient phase 1 unit.

Patients

Twelve healthy volunteers.

Interventions

Injectable fentanyl citrate (200 µg) administered by intravenous infusion, injectable fentanyl citrate (800 µg/16 mL) administered orally, and fentanyl buccal soluble film (800 µg) administered as a single film and as four separate 200 µg films simultaneously.

Outcome Measures

Plasma concentrations after fentanyl dosing; pharmacokinetic parameters.

Results

The two buccal film treatments were bioequivalent and both had an absolute bioavailability of 71%. The percentage of an administered dose absorbed through the buccal mucosa was calculated to be 51%.

Conclusions

Fentanyl buccal soluble film effectively delivers a high percentage of the administered fentanyl dose and nearly identical plasma profiles are obtained when equivalent doses are delivered by single or multiple dosage units.

Cancer pain: part 2: physical, interventional and complimentary therapies; management in the community; acute, treatment-related and complex cancer pain: a perspective from the British Pain Society endorsed by the UK Association of Palliative Medicine and the Royal College of General Practitioners

OBJECTIVE

This discussion document about the management of cancer pain is written from the pain specialists' perspective in order to provoke thought and interest in a multimodal approach to the management of cancer pain, not just towards the end of life, but pain at diagnosis, as a consequence of cancer therapies, and in cancer survivors. It relates the science of pain to the clinical setting and explains the role of psychological, physical, interventional and complementary therapies in cancer pain.

METHODS

This document has been produced by a consensus group of relevant healthcare professionals in the United Kingdom and patients' representatives making reference to the current body of evidence relating to cancer pain. In the second of two parts, physical, invasive and complementary cancer pain therapies; treatment in the community; acute, treatment-related and complex cancer pain are considered.

CONCLUSIONS

It is recognized that the World Health Organization (WHO) analgesic ladder, whilst providing relief of cancer pain towards the end of life for many sufferers world-wide, may have limitations in the context of longer survival and increasing disease complexity. To complement this, it is suggested that a more comprehensive model of managing cancer pain is needed that is mechanism-based and multimodal, using combination therapies including interventions where appropriate, tailored to the needs of an individual, with the aim to optimize pain relief with minimization of adverse effects.

Palliative care for the cancer patient

Palliation of symptoms to optimize QOL is the foundation of cancer care regardless of stage of disease or level of anticancer treatment. Patients commonly experience pain, constipation, nausea, vomiting, dyspnea, fatigue, and delirium. Many valid clinical tools are available to the primary care clinician to screen for symptoms, assess severity, measure treatment response, and elicit the patient's subjective symptom experience. Although there is limited evidence regarding the relative efficacy of symptom interventions from randomized controlled trials, clinical practice guidelines are available.

Fentanyl buccal soluble film (FBSF) for breakthrough pain in patients with cancer: a randomized, double-blind, placebo-controlled study

BACKGROUND

Fentanyl buccal soluble film (FBSF) has been developed as a treatment of breakthrough pain in opioid-tolerant patients with cancer. The objective of this study was to evaluate the efficacy of FBSF at doses of 200-1200 microg in the management of breakthrough pain in patients with cancer receiving ongoing opioid therapy.

PATIENTS AND METHODS

This was a multicenter, randomized, double-blind, placebo-controlled, multiple-crossover study that included opioid-tolerant adult patients with chronic cancer pain who experienced one to four daily episodes of breakthrough pain. The primary efficacy assessment was the sum of pain intensity differences at 30 min (SPID30) postdose.

RESULTS

The intent-to-treat population consisted of 80 patients with > or =1 post-baseline efficacy assessment. The least-squares mean (LSM +/- SEM) of the SPID30 was significantly greater for FBSF-treated episodes of breakthrough pain than for placebo-treated episodes (47.9 +/- 3.9 versus 38.1 +/- 4.3; P = 0.004). There was statistical separation from placebo starting at 15 min up through 60 min (last time point assessed). There were no unexpected adverse events (AEs) or clinically significant safety findings.

CONCLUSIONS

FBSF is an effective option for control of breakthrough pain in patients receiving ongoing opioid therapy. In this study, FBSF was well tolerated in the oral cavity, with no reports of treatment-related oral AEs.

A new transmucosal drug delivery system for patients with breakthrough cancer pain: the fentanyl effervescent buccal tablet

Breakthrough pain, a transitory severe pain with the background of otherwise controlled persistent pain has a prevalence between 52% and 67% in outpatients with cancer. Medications for such sudden-onset pain require non-invasive delivery of a potent and short-acting opioid for rapid pain relief. Although oral transmucosal delivery of fentanyl citrate (OTFC) has been shown to provide better pain relief than a typical oral opioid administration such as morphine sulfate immediate release (MSIR) in the management of breakthrough pain in patients with cancer-related pain, newer delivery systems offer a potential for further enhancement of pain relief. The fentanyl effervescent buccal tablet (FBT) formulation employs a novel drug delivery system that relies on an effervescence reaction to improve buccal fentanyl absorption. Using the effervescence reaction results in the production and dissipation of carbon dioxide with a dynamic shift in pH as the tablet dissolves. The induced low pH favors dissolution of fentanyl citrate in saliva (higher water solubility). The subsequent increase in pH thereafter favors the buccal absorption of non-ionized fentanyl across the buccal mucosa. Such a pH “pumping” mechanism increases the permeation of fentanyl into and through the buccal to the vascular system from where the agent is transported to the specific opioid receptor sites in the CNS. Compared with OTFC, data in healthy volunteers show that the effervescence reaction employed in FBT increases the total amount and the speed of absorption of fentanyl being absorbed. Compared with OTFC there is an increase in peak fentanyl blood concentrations, and an enhancement of the amount of buccal delivery of fentanyl. Such favorable data are underlined by the results of clinical studies where the FBT technology was studied in patients with breakthrough pain in chronic malignant pathologies.