Inhaled nicotine replacement therapy

Advances in soft mist inhalers

INTRODUCTION

Soft mist inhalers (SMIs) are propellant-free inhalers that utilize mechanical power to deliver single or multiple doses of inhalable drug aerosols in the form of a slow mist to patients. Compared to traditional inhalers, SMIs allow for a longer and slower release of aerosol with a smaller ballistic effect, leading to a limited loss in the oropharyngeal area, whilst requiring little coordination of actuation and inhalation by patients. Currently, the Respimat® is the only commercially available SMI, with several others in different stages of preclinical and clinical development.

AREAS COVERED

The primary purpose of this review is to critically assess recent advances in SMIs for the delivery of inhaled therapeutics.

EXPERT OPINION

Advanced particle formulations, such as nanoparticles which target specific areas of the lung, Biologics, such as vaccines, proteins, and antibodies (which are sensitive to aerosolization), are expected to be generally delivered by SMIs. Furthermore, repurposed drugs are expected to constitute a large share of future formulations to be delivered by SMIs. SMIs can also be employed for the delivery of formulations that target systemic diseases. Finally, digitalizing SMIs would improve patient adherence and provide clinicians with fundamental insights into patients' treatment progress.

E-Liquids from Seven European Countries–Warnings Analysis and Freebase Nicotine Content

Electronic cigarettes are available in a variety of devices with e-liquids also available in many flavors, and nicotine concentrations, albeit less than 20 mg/mL in Europe. Given the dynamics of these products, it is important to evaluate product content, including labeling, nicotine content versus labeled claim, nicotine form, and other aspects that may help policy decisions and align with the Tobacco Product Directive (TPD). Herein, we performed a study on 86 e-liquids from seven European countries (Croatia, Czech Republic, France, Germany, Italy, Poland, and the United Kingdom) with 34 different liquid brands and 57 different flavors. Nicotine content versus labeled claim, labeling, volume, pH, and nicotine form (i.e., freebase nicotine) were evaluated. From all tested products, eight of them from Germany, Poland, and UK (from 3 to 18 mg/mL), met the ±2% criteria. The ±10% criteria was fulfilled by 50 (58.1%) liquids from all countries. Among 71 liquids which contained nicotine, (one e-liquid labeled as 6 mg/mL had no nicotine level quantified), the amount of freebase nicotine differed from 0 to 97.8%, with a mean value 56.5 ± 35.7. None of the tested liquids had nicotine salt listed in the ingredients. Therefore, a low level of freebase nicotine in some liquids was most likely achieved by added flavorings. All tested liquids presented in this study met the basic requirements of the TPD. There were differences in the scope of information about harmfulness, type of warnings on packaging, attaching leaflets, placing graphic symbols, and discrepancies between the declared and quantified nicotine concentrations.

Inhaled Medicines: Past, Present, and Future

The purpose of this review is to summarize essential pharmacological, pharmaceutical, and clinical aspects in the field of orally inhaled therapies that may help scientists seeking to develop new products. After general comments on the rationale for inhaled therapies for respiratory disease, the focus is on products approved approximately over the last half a century. The organization of these sections reflects the key pharmacological categories. Products for asthma and chronic obstructive pulmonary disease include β -2 receptor agonists, muscarinic acetylcholine receptor antagonists, glucocorticosteroids, and cromones as well as their combinations. The antiviral and antibacterial inhaled products to treat respiratory tract infections are then presented. Two "mucoactive" products-dornase α and mannitol, which are both approved for patients with cystic fibrosis-are reviewed. These are followed by sections on inhaled prostacyclins for pulmonary arterial hypertension and the challenging field of aerosol surfactant inhalation delivery, especially for prematurely born infants on ventilation support. The approved products for systemic delivery via the lungs for diseases of the central nervous system and insulin for diabetes are also discussed. New technologies for drug delivery by inhalation are analyzed, with the emphasis on those that would likely yield significant improvements over the technologies in current use or would expand the range of drugs and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of approved orally inhaled drug products for a variety of respiratory diseases and for systemic administration should be helpful in making judicious decisions about the development of new or improved inhaled drugs. These aspects include the choices of the active ingredients, formulations, delivery systems suitable for the target patient populations, and, to some extent, meaningful safety and efficacy endpoints in clinical trials.

Electrospun α-Lactalbumin Nanofibers for Site-Specific and Fast-Onset Delivery of Nicotine in the Oral Cavity: An In Vitro, Ex Vivo, and Tissue Spatial Distribution Study

Nicotine replacement therapy (NRT) formulations for oromucosal administration induce a delayed rise in nicotine blood levels as opposed to the immediate nicotine increase obtained from cigarette smoking, this being a shortcoming of the therapy. Here, we demonstrate that α-lactalbumin/polyethylene oxide (ALA/PEO) electrospun nanofibers constitute an efficient oromucosal delivery system for fast-onset nicotine delivery of high relevance for acute dosing NRT applications. In vitro, nicotine-loaded nanofibers showed fast disintegration in water, with a weight loss up to 40% within minutes, and a faster nicotine release (26.1 ± 4.6% after 1 min of incubation) of the loaded nicotine compared to two relevant marketed NRT formulations with a comparable nicotine dose (i.e., 7.9 ± 5.1 and 2.2 ± 0.3% nicotine was released from a lozenge and a sublingual tablet, respectively). Model-fitting of the release data indicated that the release mechanism of nicotine from the hydrophilic nanofibers was possibly governed by more than one type of release phenomena. Remarkably, ex vivo studies using porcine buccal mucosa demonstrated a more efficient permeation of the nicotine released from the nanofibers [flux of 1.06 ± 0.22 nmol/(cm²·min)] compared to when dosing even a ten-fold concentrated nicotine solution [flux of 0.17 ± 0.14 nmol/(cm²·min)]. Moreover, matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI MS) imaging of ex vivo porcine buccal mucosa exposed to nicotine-loaded nanofibers clearly revealed higher amounts of nicotine throughout the epithelium, as well as in the lamina propria and submucosa of the tissue. Our findings suggest that nicotine-loaded ALA/PEO nanofibers have potential as a mucosal, fast-releasing, and biocompatible delivery system for nicotine, which can overcome the limitations of the currently marketed NRTs.

Bridging inhaled aerosol dosimetry to physiologically based pharmacokinetic modeling for toxicological assessment: nicotine delivery systems and beyond

One of the challenges for toxicological assessment of inhaled aerosols is to accurately predict their deposited and absorbed dose. Transport, evolution, and deposition of liquid aerosols are driven by complex processes dominated by convection-diffusion that depend on various factors related to physics and chemistry. These factors include the physicochemical properties of the pure substance of interest and associated mixtures, the physical and chemical properties of the aerosols generated, the interplay between different factors during transportation and deposition, and the subject-specific inhalation topography. Several inhalation-based physiologically based pharmacokinetic (PBPK) models have been developed, but the applicability of these models for aerosols has yet to be verified. Nicotine is among several substances that are often delivered via the pulmonary route, with varied kinetics depending upon the route of exposure. This was used as an opportunity to review and discuss the current knowledge and state-of-the-art tools combining aerosol dosimetry predictions with PBPK modeling efforts. A validated tool could then be used to perform for toxicological assessment of other inhaled therapeutic substances. The Science Panel from the Alliance of Risk Assessment have convened at the "Beyond Science and Decisions: From Problem Formulation to Dose-Response Assessment" workshop to evaluate modeling approaches and address derivation of exposure-internal dose estimations for inhaled aerosols containing nicotine or other substances. The discussion involved PBPK model evaluation criteria, challenges, and choices that arise in such a model design, development, and application as a computational tool for use in human toxicological assessments.

A randomised, open-label, cross-over clinical study to evaluate the pharmacokinetic profiles of cigarettes and e-cigarettes with nicotine salt formulations in US adult smokers

E-cigarettes containing 'nicotine salts' aim to increase smoker's satisfaction by improving blood nicotine delivery and other sensory properties. Here, we evaluated the pharmacokinetic profiles and subjective effects of nicotine from two e-cigarette device platforms with varying concentrations of nicotine lactate (nicotine salt) e-liquid relative to conventional cigarettes. A randomised, open-label, cross-over clinical study was conducted in 15 healthy US adult smokers. Five different e-cigarette products were evaluated consecutively on different days after use of own brand conventional cigarette. Plasma nicotine pharmacokinetics, subjective effects, and tolerability were assessed following controlled use of the products. The rate of nicotine absorption into the bloodstream was comparable from all e-cigarettes tested and was as rapid as that for conventional cigarette. However, in all cases, nicotine delivery did not exceed that of the conventional cigarette. The pharmacokinetic profiles of nicotine salt emissions were also dependent upon the properties of the e-cigarette device. Subjective scores were numerically highest after smoking a conventional cigarette followed by the myblu 40-mg nicotine salt formulation. The rise in nicotine blood levels following use of all the tested e-cigarettes was quantified as 'a little' to 'modestly' satisfying at relieving the desire to smoke. All products were well tolerated with no notable adverse events reported. These results demonstrate that, while delivering less nicotine than a conventional cigarette, the use of nicotine salts in e-cigarettes enables cigarette-like pulmonary delivery of nicotine that reduces desire to smoke.

Evaluation of Nicotine Pharmacokinetics and Subjective Effects following Use of a Novel Nicotine Delivery System

Introduction

Novel nicotine delivery systems represent an evolving part of the tobacco harm reduction strategy. The pharmacokinetic (PK) profile of nicotine delivered by P3L, a pulmonary nicotine delivery system, and its effects on smoking urges and craving relief in relation to Nicorette inhalator were evaluated.

Methods

This open-label, ascending nicotine levels study was conducted in 16 healthy smokers. Three different nicotine delivery levels, 50, 80, and 150 µg/puff, delivered by the P3L system were evaluated consecutively on different days after the use of the Nicorette inhalator. Venous nicotine PK, subjective effects, and tolerability were assessed.

Results

Geometric least-squares means for maximum plasma nicotine concentration (C_max), generated by the mixed-effect model for exposure comparison, were 9.7, 11.2, and 9.8 ng/mL for the 50, 80, and 150 µg/puff P3L variants, respectively, compared to 6.1 ng/mL after Nicorette inhalator use. Median time from product use start to C_max was 7.0 minutes for all P3L, compared to 30.0 minutes for the Nicorette inhalator. Craving reduction was slightly faster than with the Nicorette inhalator as assessed with the visual analog scale craving score. The mean Questionnaire of Smoking Urges -brief total scores did not differ for both products. P3L was well tolerated.

Conclusions

At all three nicotine levels tested, the inhalation of the nicotine lactate aerosol delivered with the P3L provided plasma nicotine concentrations higher and faster compared to the Nicorette inhalator. The plasma nicotine concentration–time profile supports a pulmonary route of absorption for P3L compared to the oromucosal absorption of the Nicorette inhalator.

Implications

The combination of nicotine and lactic acid with the P3L device shows potential over existing nicotine delivery systems by delivering nicotine with kinetics close to published data on conventional cigarettes and without exogenous carrier substances as used in current electronic nicotine delivery systems. Altogether, the PK profile, subjective effects, and safety profile obtained in this study suggest P3L is an innovative nicotine delivery product that will be acceptable to adult smokers as an alternative to cigarettes.

Devices for Improved Delivery of Nebulized Pharmaceutical Aerosols to the Lungs

Nebulizers have a number of advantages for the delivery of inhaled pharmaceutical aerosols, including the use of aqueous formulations and the ability to deliver process-sensitive proteins, peptides, and biological medications. A frequent disadvantage of nebulized aerosols is poor lung delivery efficiency, which wastes valuable medications, increases delivery times, and may increase side effects of the medication. A focus of previous development efforts and previous nebulizer reviews, has been an improvement of the underlying nebulization technology controlling the breakup of a liquid into droplets. However, for a given nebulization technology, a wide range of secondary devices and strategies can be implemented to significantly improve lung delivery efficiency of the aerosol. This review focuses on secondary devices and technologies that can be implemented to improve the lung delivery efficiency of nebulized aerosols and potentially target the region of drug delivery within the lungs. These secondary devices may (1) modify the aerosol size distribution, (2) synchronize aerosol delivery with inhalation, (3) reduce system depositional losses at connection points, (4) improve the patient interface, or (5) guide patient inhalation. The development of these devices and technologies is also discussed, which often includes the use of computational fluid dynamic simulations, three-dimensional printing and rapid prototype device and airway model construction, realistic in vitro experiments, and in vivo analysis. Of the devices reviewed, the implementation of streamlined components may be the most direct and lowest cost approach to enhance aerosol delivery efficiency within nonambulatory nebulizer systems. For applications involving high-dose medications or precise dose administration, the inclusion of active devices to control aerosol size, guide inhalation, and synchronize delivery with inhalation hold considerable promise.

Endotracheal Aerosolization Device for Laboratory Investigation of Pulmonary Delivery of Nanoparticle Suspensions: In Vitro and in Vivo Validation

The objective of this study was to perform the in vitro and in vivo validation of an endotracheal aerosolization (ETA) device (HRH MAG-4, HM). Solid lipid nanoparticle suspension (SLNS) formulations with particle sizes of approximately 120, 240, 360, and 480 nm were selected as model nanoparticle suspensions for the validation. The emission rate (ER) of the in vitro aerosolization and the influence of aerosolization on the physicochemical properties were investigated. A high ER of up to 90% was obtained, and no significant alterations in physicochemical properties were observed after the aerosolization. The pulmonary deposition of model drug budesonide in Sprague-Dawley rats was determined to be approximately 80%, which was satisfactory for pulmonary delivery. Additionally, a fluorescent probe with aggregation-caused quenching property was encapsulated in SLNS formulations for in vivo bioimaging, after excluding the effect of aerosolization on its fluorescence spectrum. It was verified that SLNS formulations were deposited in the lung region. The results demonstrated the feasibility and reliability of the HM device for ETA in laboratory investigation.

Models of deposition, pharmacokinetics, and intersubject variability in respiratory drug delivery

INTRODUCTION

Aerosol drug delivery to the lungs via inhalation is widely used in the treatment of respiratory diseases. The deposition pattern of inhaled particles within the airways of the respiratory tract is key in determining the initial delivered dose. Thereafter, dose-dependent processes including drug release or dissolution, clearance, and absorption influence local and systemic exposure to inhaled drugs over time.

AREAS COVERED

Empirical correlations, numerical simulation, and in vitro airway geometries that permit improved prediction of extrathoracic and lung deposition fractions in a variety of age groups and breathing conditions are described. Efforts to link deposition models with pharmacokinetic models predicting lung and systemic exposure to inhaled drugs over time are then reviewed. Finally, new methods to predict intersubject variability in extrathoracic deposition, capturing variability in both size and shape of the upper airways, are highlighted.

EXPERT OPINION

Recent work has been done to expand in vitro deposition experiments to a wide range of age groups and breathing conditions, to link regional lung deposition models with pharmacokinetic models, and to improve prediction of intersubject variability. These efforts are improving predictive understanding of respiratory drug delivery, and will aid the development of new inhaled drugs and delivery devices.

Pulmonary drug delivery system: newer patents

Inhalational route for drug delivery and desired effects has been known since centuries. This lung-targeted therapy has benefited asthmatics and those with chronic respiratory problems. The technique has evolved greatly from crude pots and pipes to modern sophisticated drug-dispensing devices. This mode is effective, rapid and safe. Its outcome, however, is majorly determined by drug formulation, device structure and patient's coordinating skill. In spite of great advances in this field, more efforts are required to meet the unmet needs. This noninvasive mode is being increasingly studied for transfer of drugs for systemic action with promising results. The present article is an attempt to capture the recent development and progress in this field and review relevant newer patents.