Pulmonary administration of aerosolised fentanyl: pharmacokinetic analysis of systemic delivery

Comparative Analysis of Nebulized Versus Intravenous Fentanyl for Pain Control After Tonsillectomy: A Double-Blind, Randomized, Controlled Trial

OBJECTIVES

Effective posttonsillectomy analgesia is crucial for patient comfort and recovery. Fentanyl, notable for its potency, rapid action, and lipophilicity, has been successfully used in various procedures through multiple administration routes. However, the use of its nebulized form for posttonsillectomy pain has not been extensively explored. This study sought to compare the analgesic efficacy, onset time, and complications between nebulized and intravenous fentanyl in posttonsillectomy patients.

METHODS AND METHODS

In this randomized controlled trial, adult patients who underwent tonsillectomy were assigned to either an intravenous fentanyl group (1 mcg/kg) or a nebulized fentanyl group (4 mcg/kg). In both groups, fentanyl was administered when pain scores exceeded three. Pain levels were monitored every 5 minutes until they fell below four. The study also recorded the duration until the next analgesia request and noted complications (such as respiratory depression, bradycardia, chest tightness, drowsiness, nausea, pruritus, sweating, and flushing) within 24 hours. Patient exclusions were based on predetermined criteria.

RESULTS

From an initial cohort of 59 patients, 22 in the intravenous group and 27 in the nebulizer group were eligible for analysis after applying the exclusion criteria. The nebulizer group exhibited a significantly prolonged period before the next analgesia request, with a median of 683.5 minutes (interquartile range 260-1440), in contrast to the 326.7 minutes (145.0-504.7) observed in the intravenous group (P = .009). The time to achieve a pain score less than 4 and the incidence of side effects did not differ significantly between the groups.

CONCLUSION

Nebulized fentanyl provided a longer duration of analgesia than intravenous fentanyl in posttonsillectomy pain management, with similar onset times and side effect profiles. These findings underscore the potential of nebulized fentanyl as an effective alternative for pain control in posttonsillectomy patients.

The Pharmacokinetics of Inhaled Drugs

The pharmacokinetic (PK) profile of a drug after inhalation may differ quite markedly from that seen after dosing by other routes of administration. Drugs may be administered to the lung to elicit a local action or as a portal for systemic delivery of the drug to its site of action elsewhere in the body. Some knowledge of PK is important for both locally- and systemically-acting drugs. For a systemically-acting drug, the plasma concentration-time profile shares some similarities with drug given by the oral or intravenous routes, since the plasma concentrations (after the distribution phase) will be in equilibrium with concentrations at the site of action. For a locally-acting drug, however, the plasma concentrations reflect its fate after it has been absorbed and removed from the airways, and not what is available to its site of action in the lung. Consequently, those typical PK parameters which are determined from plasma concentration measurements, e.g., area under the curve (AUC), Cmax, tmax and post-peak t1/2 may provide information on the deposition and absorption of drugs from the lung; however, the information from these parameters becomes more complicated to decipher for those drugs which are locally-acting in the lung. Additionally, the plasma concentration profile for both locally- and systemically-acting drugs will not only reflect drug absorbed from the lung but also that absorbed from the gastrointestinal (GI) tract from the portion of the dose which is swallowed. This absorption from the GI tract adds a further complication to the interpretation of plasma concentrations, particularly for locally-acting drugs. The influence of physiological and pathological factors needs to be considered in the absorption of some inhaled drugs. The absorption of some hydrophilic drugs is influenced by the inspiratory maneuver used during initial inhalation of the drug, and at later times after deposition. Similarly, the effects of smoking have been shown to increase lung permeability and increase the absorption of certain hydrophilic drugs. The effects of different disease states of the lung have less defined influences on absorption into the systemic circulation.

Does occupational exposure to fentanyl cause illness? A systematic review

INTRODUCTION

The opioid epidemic in the United States continues to result in an increasing number of deaths and is increasingly dominated by fentanyl and fentanyl analogs. As a result, first responders are likely to come into contact with fentanyl-containing substances daily. Concerns persist regarding occupational exposure resulting in intoxication. We performed a systematic review to describe occupational illnesses from fentanyl and its analogs.

METHODS

We conducted a systematic review of the literature following the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to assess the danger of occupational exposure to fentanyl. The PubMed, EMBASE, Google Scholar, SCOPUS, CINAHL, and National Institute for Occupational Safety and Health databases were queried to identify occupational fentanyl exposures. Studies included were single case reports, case series, observational studies, controlled studies, and abstracts from scientific presentations. We reviewed articles meeting the eligibility criteria and abstracted outcome data. Outcomes included study design, number of study subjects and study demographics, description of exposure, personal protective equipment used, duration of symptoms, illness developed, medical evaluation performed, treatment provided, hospitalizations, deaths, drug testing performed, and any situation review performed to prevent illness, analytical confirmation of the identity of culprit agent, and concentrations of drug in serum/blood.

RESULTS

Our search yielded 454 citations after deduplication. After abstract and text review, 12 unique reports met the inclusion criteria. All identified studies were observational studies. Ten of the 12 were Health Hazard Evaluation reports from the National Institute for Occupational Safety and Health; two reports describe the same exposure case. There were no reported instances of comprehensive drug testing using liquid chromatography-mass spectrometry or gas chromatography-mass spectrometry in exposed first responders. Among first responders possibly exposed to fentanyl or fentanyl analogs, none were admitted to the hospital, and only three first responders received naloxone. The three officers who received naloxone lacked recommended personal protective equipment and had subjective improvement of symptoms following naloxone. There were no instances of severe respiratory depression requiring assisted ventilation or hospital admission. Among forensic laboratory technicians, only one instance of detectable concentrations of fentanyl in urine was reported, and there were no instances of symptomatic cases.

CONCLUSIONS

Among published reports of 27 first responders with symptoms after possible ambient fentanyl exposure, symptoms, recorded physical findings, and vital signs were inconsistent with acute opioid toxicity. Breaches in the recommended use of personal protective equipment appeared common. Only three persons received naloxone, although none had plausible effects of fentanyl. No suspected exposure to fentanyl led to hospitalization or death. Based on these low-quality data, there were no plausible opioid effects from ambient exposure to suspected fentanyl.

Assessment of Drug-Drug Interaction Risk Between Intravenous Fentanyl and the Glecaprevir/Pibrentasvir Combination Regimen in Hepatitis C Patients Using Physiologically Based Pharmacokinetic Modeling and Simulations

INTRODUCTION

An unsafe injection practice is one of the major contributors to new hepatitis C virus (HCV) infections; thus, people who inject drugs are a key population to prioritize to achieve HCV elimination. The introduction of highly effective and well-tolerated pangenotypic direct-acting antivirals, including glecaprevir/pibrentasvir (GLE/PIB), has revolutionized the HCV treatment landscape. Glecaprevir is a weak cytochrome P450 3A4 (CYP3A4) inhibitor, so there is the potential for drug-drug interactions (DDIs) with some opioids metabolized by CYP3A4, such as fentanyl. This study estimated the impact of GLE/PIB on the pharmacokinetics of intravenous fentanyl by building a physiologically based pharmacokinetic (PBPK) model.

METHODS

A PBPK model was developed for intravenous fentanyl by incorporating published information on fentanyl metabolism, distribution, and elimination in healthy individuals. Three clinical DDI studies were used to verify DDIs within the fentanyl PBPK model. This model was integrated with a previously developed GLE/PIB PBPK model. After model validation, DDI simulations were conducted by coadministering GLE 300 mg + PIB 120 mg with a single dose of intravenous fentanyl (0.5 µg/kg).

RESULTS

The predicted maximum plasma concentration ratio between GLE/PIB + fentanyl and fentanyl alone was 1.00, and the predicted area under the curve ratio was 1.04, suggesting an increase of only 4% in fentanyl exposure.

CONCLUSION

The administration of a therapeutic dose of GLE/PIB has very little effect on the pharmacokinetics of intravenous fentanyl. This negligible increase would not be expected to increase the risk of fentanyl overdose beyond the inherent risks related to the amount and purity of the fentanyl received during recreational use.

Inhaled opioids for cancer pain relief: A narrative review

Despite the many new possibilities, cancer pain treatment is not always effective and often poses a challenge for practitioners. At the end-of-life care, both oral and subcutaneous drug delivery very often are not attainable. The increasing number of patients in terminal stage of chronic diseases forced us to look for the alternative ways of administration of pain treatment. In this context, the potentially rapid onset of action and ease of use make aerosolized drug delivery an attractive option in palliative care settings. The objective of this review was to identify literature on pain relief with inhaled opioids. The evidence suggests that nebulized opioids might be effective in the treatment of pain in various aetiologies; however, randomized controlled studies on nebulization therapy for cancer pain are lacking.

Recent advances in drug delivery to the central nervous system by inhalation

INTRODUCTION

Drugs need to enter the systemic circulation efficiently before they can cross the blood-brain barrier and reach the central nervous system. Although the respiratory tract is not a common route of administration for delivering drugs to the central nervous system, it has attracted increasing interest in recent years for this purpose.

AREAS COVERED

In this article, we compare pulmonary delivery to three other common routes (parenteral, oral, and intranasal) for delivering drugs to the central nervous system, followed by summarising the devices used to aerosolise neurological drugs. Recent studies delivering drugs for different neurological disorders via inhalation are then discussed to illustrate the strengths of pulmonary delivery.

EXPERT OPINION

Recent studies provide strong evidence and rationale to support inhaling neurological drugs. Since inhalation can achieve improved pharmacokinetics and rapid onset of action for multiple drugs, it is a non-invasive and efficient method to deliver drugs to the central nervous system. Future research should focus on delivering other small and macro-molecules via the lungs for different neurological conditions.

The use of heat to deliver fentanyl via pulmonary drug delivery

The golden standard to treat acute pain is by intravenous drug delivery of opioids such as fentanyl or morphine. Intravenous drug delivery requires the placement of an intravenous (IV) port, which can cause infections, dislodgments, and distress to the patients, and therefore a non-invasive method is desirable. Pulmonary drug delivery is a non-invasive method that has been shown to be a good alternative to intravenous administration. New devices have been investigated for treating acute pain by delivering fentanyl by heat. The pure drug, fentanyl, is applied onto a surface which is then heated up to 350 °C and inhaled, resulting in no formation of degradation products. Furthermore, forced degradation of fentanyl has been studied which showed that longer heating time and higher temperatures will result in the formation of degradation products. The evidence indicates that heat can be used to deliver drugs to the lungs where fast onset reaction can be obtained giving fast and non-invasive pain relief.

Protein and peptide delivery to lungs by using advanced targeted drug delivery

The challenges and difficulties associated with conventional drug delivery systems have led to the emergence of novel, advanced targeted drug delivery systems. Therapeutic drug delivery of proteins and peptides to the lungs is complicated owing to the large size and polar characteristics of the latter. Nevertheless, the pulmonary route has attracted great interest today among formulation scientists, as it has evolved into one of the important targeted drug delivery platforms for the delivery of peptides, and related compounds effectively to the lungs, primarily for the management and treatment of chronic lung diseases. In this review, we have discussed and summarized the current scenario and recent developments in targeted delivery of proteins and peptide-based drugs to the lungs. Moreover, we have also highlighted the advantages of pulmonary drug delivery over conventional drug delivery approaches for peptide-based drugs, in terms of efficacy, retention time and other important pharmacokinetic parameters. The review also highlights the future perspectives and the impact of targeted drug delivery on peptide-based drugs in the coming decade.

Drivers of absolute systemic bioavailability after oral pulmonary inhalation in humans

There are few studies in humans dealing with the relationship between physico-chemical properties of drugs and their systemic bioavailability after administration via oral inhalation route (Fpulm). Getting further insight in the determinants of Fpulm after oral pulmonary inhalation could be of value for drugs considered for a systemic delivery as a result of poor oral bioavailability, as well as for drugs considered for a local delivery to anticipate their undesirable systemic effects. To better delineate the parameters influencing the systemic delivery after oral pulmonary inhalation in humans, we studied the influence of physico-chemical and permeability properties obtained in silico on the rate and extent of Fpulm in a series of 77 compounds with or without marketing approval for pulmonary delivery, and intended either for local or for systemic delivery. Principal component analysis (PCA) showed mainly that Fpulm was positively correlated with Papp and negatively correlated with %TPSA, without a significant influence of solubility and ionization fraction, and no apparent link with lipophilicity and drug size parameters. As a result of the small sample set, the performance of the different models as predictive of Fpulm were quite average with random forest algorithm displaying the best performance. As a whole, the different models captured between 50 and 60% of the variability with a prediction error of less than 20%. Tmax data suggested a significant positive influence of lipophilicity on absorption rate while charge apparently had no influence. A significant linear relationship between Cmax and dose (R² = "0.79) highlighted that Cmax was primarily dependent on dose and absorption rate and could be used to estimate Cmax in humans for new inhaled 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.

Respiratory Tract: Structure and Attractions for Drug Delivery Using Dry Powder Inhalers

Respiratory tract is one of the oldest routes for drug delivery. It can be used for local and systemic drug deliveries. Inhalation therapy has several advantages over oral. It delivers the drug efficiently to the lung with minimal systemic exposure, thus avoiding systemic side effects common with oral route. In this review, different types of inhaler devices are illustrated like metered dose inhalers (MDIs), dry powder inhalers (DPIs), nebulizers, and the new soft mist inhalers (SMIs). Since dry powder is more stable than when in liquid form, we will discuss in detail DPIs highlighting different techniques utilized in preparation of dry powders with or without carrier to improve flowability and drug delivery to deep lungs. Types of DPIs are briefly discussed with examples from the market. Several mechanisms for particle deposition are mentioned with factors governing the process. Pharmacokinetic profile of the inhaled particles is detailed starting from the dissolution, followed by the rapid absorption and ending with systemic clearance. New technologies like 3D printing in pulmonary field are also highlighted.

Nebulized Fentanyl for Dyspnea: A Retrospective Chart Review

Nebulized fentanyl is well established for analgesia but its use for dyspnea requires further investigation. The aim of our study was to determine the effectiveness of nebulized fentanyl in treating patients with dyspnea and to determine if there were harmful side effects described by patients or their providers. We used a convenience sample of patients from July 1 2014 to July 1 2018 and performed a retrospective chart review. We found that 360 doses of nebulized fentanyl were given to 73 patients during that time period. Of the 73 patients evaluated, 32 patients (43.8%) were female and forty-one were male (56.1%). The median age was 67 and the median length of stay was 9 days. There were no documented findings of bronchospasm, hypotension, or allergic reaction in any of the medical records reviewed. Patients treated with nebulized fentanyl for dyspnea showed a mean decreased respiratory rate of 4.3 breaths/min and a mean increased oxygen saturation of 2.3%. Also, 71% of patients with documented responses experienced an improvement in their dyspnea. Our preliminary data suggest that nebulized fentanyl has limited side effects and may have a role in the treatment of dyspnea. Further research is necessary to determine its efficacy.

Efficacy of nebulized fentanyl and low dose ketamine for pain control of patients with long bone fractures: A randomized, double-blind, clinical trial

INTRODUCTION

Fentanyl is a lipid soluble, highly potent opioid. The lipid solubility of fentanyl makes it an ideal opioid to be administrated by inhalation. The current study compared ketamine infusion and nebulized fentanyl in bone fracture pain relief.

METHODS

In this double-blind, randomized clinical trial, patients aged 18 to 55 years who were admitted to the emergency department (ED) with limb fracture were recruited. A total of 127 patients were included in the study, 51.1% (65) of whom were male and 48.9% (62) of whom were female. The patients were divided equally into two groups: Group I received 100 cm3 IV infusion of normal saline and 4 μg/kg of 50 μg/ml nebulized fentanyl; Group II received 0.4 mg/kg ketamine in 10 min and 5 cm3 nebulized normal saline. Pain was assessed using a visual analog scale just before treatment and 5, 10, 15, 30, and 60 min post-treatment.

RESULTS

Before intervention, the pain scores of both groups showed no significant difference. However, log linear analysis in both groups showed a significantly decrement during the follow up (60 min) (p < 0.0001). Multiple comparison analysis showed that pain scores were significantly higher in the patients of Group I. Moreover, patients in Group I required additional treatment.

CONCLUSION

Ketamine can be used as an alternative non-invasive treatment to successfully relieve pain in patients with limb fractures.

Fentanyls and the safety of first responders: Science and recommendations

Opioids have many beneficial uses in medicine, but, taken inappropriately, they can cause life-threatening health effects. The increasing use of physician-prescribed and illicit opioids, including highly potent fentanyl and its analogs, have contributed to a significant increase in opioid-related drug overdoses in the United States, leading to a public health emergency. There have been a number of reports describing adverse health effects experienced by police officers, fire-fighter emergency medical services providers, and private sector ambulance personnel when responding to drug overdose incidents. Several sets of exposure prevention recommendations for first responders are available from government and the private sector. Understanding the scientific basis for these recommendations, increasing awareness by responders of the potential risks associated with opioid exposure during a response, and educating responders about safe work practices when exposure to opioids is suspected or confirmed are all critical prevention measures that can keep first responders safe.

A retrospective analysis of nebulized versus intravenous fentanyl for renal colic

STUDY OBJECTIVE

To assess the effectiveness of nebulized fentanyl used for analgesia in renal colic.

MATERIALS/METHODS

This research was planned as a randomized, blinded study in which prospectively collected data were analyzed retrospectively to compare nebulized and intravenous (iv) fentanyl therapies. Patients with renal colic with 'moderate' or worse pain on a four-point verbal pain score (VPS) or with pain of 20mm or above on a 100-mm visual analogue score (VAS) at time of presentation were randomized into iv fentanyl (n=62) or nebulized fentanyl (n=53) study groups. Decreases in VAS and VPS scores at 15 and 30min compared to baseline, rescue analgesia requirements and side-effects between the groups were compared.

RESULTS

Both iv fentanyl and nebulized fentanyl provided effective analgesia in renal colic patients at the end of 30min. However, iv fentanyl provided more rapid and more effective analgesia than nebulized fentanyl. Patients receiving iv fentanyl had lower rescue analgesia requirements than those receiving nebulized fentanyl (37.1% vs 54.7%), although the difference was not statistically significant (p=0.058). In addition, side-effects were more common in the iv fentanyl group compared to the nebulized fentanyl group (22.1% vs 9.4%), although the difference was also not significant (p=0.058).

CONCLUSION

Nebulized fentanyl provides effective analgesia in patients with renal colic. However, iv fentanyl exhibits more rapid and more powerful analgesic effects than nebulized fentanyl. Nonetheless, due to its ease of use and few potential risks and side-effects the nebulized form can be used as an alternative in renal colic.

Effect of Modulated Electrohyperthermia on the Pharmacokinetics of Oral Transmucosal Fentanyl Citrate in Healthy Volunteers

PURPOSE

This study aimed to determine whether changes occur in fentanyl absorption and disposition when administered in conjunction with modulated electrohyperthermia (mEHT) treatment.

METHODS

A randomized, single-dose, crossover, open-label study was used to investigate the effect of mEHT on the pharmacokinetic properties of fentanyl in 12 healthy volunteers. The 12 healthy volunteers were each administered a single dose of oral transmucosal fentanyl citrate (OTFC) or a single dose of OTFC with mEHT. mEHT was performed on the abdomen for 1 hour. Blood samples were collected for 24 hours after dosing. The temperature of the abdominal skin surface was assessed before dosing and at 10, 20, and 60 minutes after dosing.

FINDINGS

Geometric mean ratios (ratio of fentanyl with mEHT to fentanyl alone) for the C_max and AUC_0-last were 1.20 (90% CI, 1.09-1.32) and 1.15 (90% CI, 0.99-1.33), respectively. The mean temperature of the abdominal skin surface increased by approximately 4°C.

IMPLICATIONS

There was an increase in the overall exposure to the drug without implications of any clinical significance. OTFC can be administered without limitations in combination with mEHT, and it is not necessary to modify the dosing regimen. cris.nih.go,kr Identifier: KCT0001286.

Nebulized Fentanyl in Acute Pain: A Systematic Review

OBJECTIVE

To provide a systematic review of the current role of nebulized fentanyl in acute pain and potentially other conditions.

DATA SOURCES

A MEDLINE literature search inclusive of the dates 1946 to May 2016 was performed using the following search terms: fentanyl and administration, inhaled Excerpta Medica was searched from 1980 to May 2016 using the following search terms: exp fentanyl/inhalation drug administration Additionally, Web of Science was searched using the terms fentanyl and pain inclusive of 1945 to May 2016.

STUDY SELECTION AND DATA EXTRACTION

We utilized the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines to select English language, human primary literature, review articles, and supporting data assessing the efficacy of nebulized fentanyl in acute pain.

DATA SYNTHESIS

Seven clinical trials have demonstrated no difference in efficacy between nebulized fentanyl and intravenous (IV) opioids. Few adverse effects were reported; however, the trials were of short duration. Nebulized fentanyl appeared to be a rapid-acting analgesic that does not require IV access.

CONCLUSION

Evidence suggests that nebulized fentanyl is as effective as IV opioids in the treatment of acute pain, with relatively few adverse effects. However, questions remain about the extemporaneous preparation of fentanyl nebulized solution, the variability in nebulization devices, and ensuring consistent drug delivery to distal airways in the clinical setting. The abuse potential of nebulized fentanyl should also be considered.

The Digital Asthma Patient: The History and Future of Inhaler Based Health Monitoring Devices

The wave of digital health is continuously growing and promises to transform healthcare and optimize the patients' experience. Asthma is in the center of these digital developments, as it is a chronic disease that requires the continuous attention of both health care professionals and patients themselves. The accurate and timely assessment of the state of asthma is the fundamental basis of digital health approaches and is also the most significant factor toward the preventive and efficient management of the disease. Furthermore, the necessity of inhaled medication offers a basic platform upon which modern technologies can be integrated, namely the inhaler device itself. Inhaler-based monitoring devices were introduced in the beginning of the 1980s and have been evolving but mainly for the assessment of medication adherence. As technology progresses and novel sensing components are becoming available, the enhancement of inhalers with a wider range of monitoring capabilities holds the promise to further support and optimize asthma self-management. The current article aims to take a step for the mapping of this territory and start the discussion among healthcare professionals and engineers for the identification and the development of technologies that can offer personalized asthma self-management with clinical significance. In this direction, a technical review of inhaler based monitoring devices is presented, together with an overview of their use in clinical research. The aggregated results are then summarized and discussed for the identification of key drivers that can lead the future of inhalers.

Nebulized fentanyl vs intravenous morphine for ED patients with acute limb pain: a randomized clinical trial

OBJECTIVE

Intravenous morphine has been used as a common method of pain control in emergency care. Nebulized fentanyl is also an effective temporary substitute. This study was designed to compare the effectiveness of nebulized fentanyl with intravenous (IV) morphine on management of acute limb pain.

METHODS

This was a placebo-controlled, double-blind randomized clinical trial. Ninety emergency department patients with moderate to severe pain aged 15 to 50 years were blocked randomized and enrolled in this study. Forty-seven patients in the experimental group received nebulized fentanyl (4 μg/kg) and IV normal saline as placebo, and the remaining 43 patients in the control group received IV morphine (0.1 mg/kg) and nebulized normal saline as placebo. All participants' pain scores were assessed by Numerical Rating Scale before and after intervention at 5-, 10-, 15-, 30-, 45-, and 60-minute intervals. Patients' vital sign and possible adverse effects were recorded respectively. Finally, all participants were assessed for their satisfaction.

RESULTS

The mean initial pain score in the experimental group was 8.7 and 8.4 in the control group (P = .1). Pain relief in both groups after 5 and 10 minutes were similar (P = .72). Although the pain relief was significantly greater with fentanyl at 15 minutes, this difference is not clinically significant. Pain management in both groups was successful and was more than 3 scores reduction in Numerical Rating Scale. Patient satisfaction in both groups was similar. No adverse effects were reported in the experimental group.

CONCLUSION

This study suggests that nebulized fentanyl is a rapid, safe, and effective method for temporary control of acute limb pain in emergency department patients.

Nebulised fentanyl for post-operative pain relief, a prospective double-blind controlled randomised clinical trial

Background and Aim:

Intravenous (IV) route for fentanyl administration is the gold standard for post-operative pain relief, but complications such as respiratory depression, bradycardia and hypotension have limited this route. The aim of this randomised controlled trial was to compare the efficacy of nebulised fentanyl with IV fentanyl for post-operative pain relief after lower abdominal surgery.

Methods:

In the post-operative care unit, at the time of first onset of pain (visual analogue scale- VAS score > 4) patients were randomised into three groups and fentanyl was administered either IV 2 μg/kg or by nebulisation of solution containing 3 or 4 μg/kg fentanyl over 8 min in 90 patients divided into three groups of 30 each. Observation were made for pain relief by visual analogue scale score 0-10. Adverse effects such as respiratory depression, bradycardia and hypotension were also recoded. Statistical analysis was performed using Medcalc software version 12, 2012. (MedCalc Software, Ostend, Belgium).

Results:

In the nebulisation group, it was observed that the analgesic efficacy of fentanyl was dose dependent with a delayed onset of analgesia (10 min vs. 5 min). Nebulisation with 4 μg/kg fentanyl produced analgesia at par to 2 μg/kg IV fentanyl with prolonged duration (90 min vs. 30 min) and with significantly less adverse effects.

Conclusions:

This study shows that nebulisation with 4 μg/kg fentanyl may be used as an alternative to IV 2 μg/kg fentanyl for adequate post-operative pain relief.

Pharmacokinetics and Acute Safety of Inhaled Testosterone in Postmenopausal Women

This was a preliminary feasibility study to assess the pharmacokinetics and acute safety of a single dose of orally inhaled testosterone via the AERx system, a novel handheld aerosol delivery system in postmenopausal women. Twelve postmenopausal women stabilized on oral estrogen therapy were treated with a single dose of testosterone (0.1, 0.2, or 0.3 mg) by inhalation. Plasma concentrations of sex steroids were measured between 1 and 360 minutes. Pulmonary and cardiovascular adverse events were monitored. Inhaled testosterone produced a dose-dependent increase in plasma total and free testosterone. At the highest dose (0.3 mg), total and free testosterone increased from baseline (mean +/- SD, 0.6 +/- 0.3 nmol/L, 2.5 +/- 1.0 pmol/L) to maximum levels of 62.6 +/- 20.4 nmol/L (total) and 168.2 +/- 50.2 pmol/L(free), occurring 1 to 2 minutes after dosing. A 2-compartment model best described the free and total testosterone pharmacokinetic profile. Dihydrotestosterone levels were higher than baseline at 60 minutes (P < .0002). Estradiol did not vary, but sex hormone binding globulin and albumin fell. There were no adverse events related to the treatment. Administration of inhaled testosterone is safe and achieves a supraphysiologic "pulse" kinetic profile of total and free testosterone with a rapid return to pretreatment levels.

Back to the future: inhaled drug products

Inhaled therapeutic aerosols continue to be an important treatment for asthma and pulmonary diseases. A variety of dosage forms are employed for different indications and demographics including pressurized or propellant-driven metered dose inhalers, dry powder inhalers, and nebulizers/nebules. Research and development in this field has shown remarkable innovation in the past decade. Important new drug products for the treatment of asthma, chronic obstructive pulmonary disease, cystic fibrosis, diabetes, and a range of neurological disorders have been developed. New devices in each of the dosage form categories also have been developed, and new formulation technologies have been adopted. Unlike many other dosage forms, as new inhaled products appeared few of the existing products were converted to generic form. This may be explained by the formulation and device complexity, the implications for degree of difficulty in obtaining regulatory approval, and the prevalence of intellectual property in the field. After the setback of the initial approval and subsequent withdrawal of the Exubera®-inhaled insulin, there appeared to be reluctance to consider the pulmonary route of administration for systemically acting agents, particularly peptides and proteins. However, recent product development activities and approvals suggest that attitudes may be changing in favor of systemic delivery following inhaled aerosol administration. The new inhaled drug technologies seem to be driving reconsideration of therapeutic categories for indications that were of interest at the inception of modern inhaled drug therapy in the past century. We should embrace the opportunity to use new drugs and technologies to go back to the future!

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 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.

Pulmonary delivery of therapeutic compounds for treating CNS disorders

Delivering therapeutic compounds via the lungs presents potential advantages relative to other routes of administration. Depending on the compound and the disease state, these advantages may include: non-invasive medication delivery, ease of administration, higher bioavailability leading to dose sparing and lower systemic toxicity, potentially greater blood–brain barrier penetration and rapid pharmacodynamic effect. The practice of inhaling drugs has been around for centuries, including both medical and recreational usage. It is only more recently that formal clinical development programs have been undertaken specifically to use medication delivery via the lung to achieve systemic blood levels for the treatment of CNS disorders. At present, there are several CNS therapies being developed for pulmonary administration, with some of those programs at or near the marketing authorization stage. While there are still regulatory hurdles before these therapies can be put into practice, the success of these programs thus far demonstrates the scientific viability of inhalation therapies for treating CNS disorders.

Convective flow dominates aerosol delivery to the lung segments

Most previous computational studies on aerosol transport in models of the central airways of the human lung have focused on deposition, rather than transport of particles through these airways to the subtended lung regions. Using a model of the bronchial tree extending from the trachea to the segmental bronchi (J Appl Physiol 98: 970-980, 2005), we predicted aerosol delivery to the lung segments. Transport of 0.5- to 10-μm-diameter particles was computed at various gravity levels (0-1.6 G) during steady inspiration (100-500 ml/s). For each condition, the normalized aerosol distribution among the lung segments was compared with the normalized flow distribution by calculating the ratio (R(i)) of the number of particles exiting each segmental bronchus i to the flow. When R(i) = 1, particle transport was directly proportional to segmental flow. Flow and particle characteristics were represented by the Stokes number (Stk) in the trachea. For Stk < 0.01, R(i) values were close to 1 and were unaffected by gravity. For Stk > 0.01, R(i) varied greatly among the different outlets (R(i) = 0.30-1.93 in normal gravity for 10-μm particles at 500 ml/s) and was affected by gravity and inertia. These data suggest that, for Stk < 0.01, ventilation defines the delivery of aerosol to lung segments and that the use of aerosol tracers is a valid technique to visualize ventilation in different parts of the lung. At higher Stokes numbers, inertia, but not gravitational sedimentation, is the second major factor affecting the transport of large particles in the lung.

Identification at autopsy of pulverized pills in lungs of a first-time methadone user

We recently encountered a 25-year-old white man who died of substance abuse including methadone. The route of administration of the drug(s) appears to have been insufflation. He was found dead at home. There were bottles of prescribed medications and an empty bottle of non-prescribed methadone. There was a grinding device nearby. At autopsy, no needle tracts were identified. Microscopically, the bronchi had desquamated ciliated respiratory epithelium admixed with red-brown pigment, which was found under plane-polarized light to be comprised of birefringent finely-granular material consistent with pulverized pills. Blood toxicology was positive for tetrahydrocannabinol, sertraline, nicotine, and methadone. The cause of death was ruled drug interactions with cerebral and pulmonary edema, the manner of death accidental. The decedent fit a profile of a victim of prescription drug abuse, for whom the mode of administration of drugs may be altered from intended use in as many as 80% of cases.

Current therapies and technological advances in aqueous aerosol drug delivery

Recent advances in aerosolization technology have led to renewed interest in pulmonary delivery of a variety of drugs. Pressurized metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) have experienced success in recent years; however, many limitations are presented by formulation difficulties, inefficient delivery, and complex device designs. Simplification of the formulation process as well as adaptability of new devices has led many in the pharmaceutical industry to reconsider aerosolization in an aqueous carrier. In the acute care setting, breath-enhanced air-jet nebulizers are controlling and minimizing the amount of wasted medication, while producing a high percentage of respirable droplets. Vibrating mesh nebulizers offer advantages in higher respirable fractions (RFs) and slower velocity aerosols when compared with air-jet nebulizers. Vibrating mesh nebulizers incorporating formulation and patient adaptive components provide improvements to continuous nebulization technology by generating aerosol only when it is most likely to reach the deep lung. Novel innovations in generation of liquid aerosols are now being adapted for propellant-free pulmonary drug delivery to achieve unprecedented control over dose delivered and are leading the way for the adaptation of systemic drugs for delivery via the pulmonary route. Devices designed for the metered dose delivery of insulin, morphine, sildenafil, triptans, and various peptides are all currently under investigation for pulmonary delivery to treat nonrespiratory diseases. Although these devices are currently still in clinical testing (with the exception of the Respimat), metered dose liquid inhalers (MDLIs) have already shown superior outcomes to current pulmonary and systemic delivery methods.

The pharmacokinetics and bioavailability of prochlorperazine delivered as a thermally generated aerosol in a single breath to volunteers

A thermally generated aerosol (TGA) system can effect reliable delivery of excipient-free drug to alveoli, resulting in rapid systemic drug absorption. We developed a pharmacokinetic model of prochlorperazine, administered by inhalation and as a rapid intravenous infusion, and we determined absolute TGA bioavailability in eight healthy volunteers in this institutional review board-approved, two-period crossover study. After the drug was administered as either a 5-s intravenous infusion or a TGA single-breath inhalation, blood was collected at various times for up to 24 h. Plasma prochlorperazine concentrations were measured using liquid chromatography-tandem mass spectrometry. Inhalation and rapid intravenous administration produced similar plasma prochlorperazine concentration profiles. Intravenous and inhalation pharmacokinetics were well characterized by a simultaneous two-compartment model with multiple absorption delays. Prochlorperazine pharmacokinetic parameters were similar to those reported for single intravenous doses. The geometric mean bioavailability after TGA delivery was 1.10. The administration of prochlorperazine by inhalation resulted in pharmacokinetics similar to that seen after intravenous administration, in terms of speed, extent, and consistency of absorption.

Advanced formulation design: improving drug therapies for the management of severe and chronic pain

Chronic pain is a condition affecting a vast patient population and resulting in billions of dollars in associated health care costs annually. Sufferers from severe chronic pain often require [correction of requite] twenty-four hour drug treatment through intrusive means and/or repeated oral dosing. Although the oral route of administration is most preferred, conventional immediate release oral dosage forms lead to inconvenient and suboptimal drug therapies for the treatment of chronic pain. Effective drug therapies for the management of chronic pain therefore require advanced formulation design to optimize the delivery of potent analgesic agents. Ideally, these advanced delivery systems provide efficacious pain therapy with minimal side effects via a simple and convenient dosing regime. In this article, currently commercialized and developing drug products for pain management are reviewed with respect to dosage form design as well as clinical efficacy. The drug delivery systems reviewed herein represent advanced formulation designs that are substantially improving analgesic drug therapies.