Targeted Drug Delivery to Upper Airways Using a Pulsed Aerosol Bolus and Inhaled Volume Tracking Method

The pulmonary route presents an attractive delivery pathway for topical treatment of lung diseases. While significant progress has been achieved in understanding the physical underpinnings of aerosol deposition in the lungs, our ability to target or confine the deposition of inhalation aerosols to specific lung regions remains meagre. Here, we present a novel inhalation proof-of-concept in silico for regional targeting in the upper airways, quantitatively supported by computational fluid dynamics (CFD) simulations of inhaled micron-sized particles (i.e. 1-10 μm) using an intubated, anatomically-realistic, multi-generation airway tree model. Our targeting strategy relies on selecting the particle release time, whereby a short-pulsed bolus of aerosols is injected into the airways and the inhaled volume of clean air behind the bolus is tracked to reach a desired inhalation depth (i.e. airway generations). A breath hold maneuver then follows to facilitate deposition, via sedimentation, before exhalation resumes and remaining airborne particles are expelled. Our numerical findings showcase how particles in the range 5-10 μm combined with such inhalation methodology are best suited to deposit in the upper airways, with deposition fractions between 0.68 and unity. In contrast, smaller (< 2 μm) particles are less than optimal due to their slow sedimentation rates. We illustrate further how modulating the volume inhaled behind the pulsed bolus, prior to breath hold, may be leveraged to vary the targeted airway sites. We discuss the feasibility of the proposed inhalation framework and how it may help pave the way for specialized topical lung treatments.

Electrohydrodynamic methods for the development of pulmonary drug delivery systems

Electrospinning and electrospraying are two highly versatile and scalable electrohydrodynamic methods, which have attracted considerable attention during the last years towards the fabrication of polymer-based drug delivery systems. The latter may be obtained in the form of nano- or microfibers (via electrospinning) or as drug-loaded nano- and microparticles (via electrospraying). This review article begins with an introduction on the basic principles and the important influencing parameters governing the electrospinning/electrospraying processes, followed by an overview on their use for the development of nano/microfibers and nano/microparticles destined for use in pharmaceutical applications. Focus is given on research efforts targeting in the formulation of drug delivery systems and devices designed for pulmonary drug delivery applications thus emphasizing on the potential use of electrospinning and electrospraying in the area of inhaled medicines.

Problems of elderly patients on inhalation therapy: Difference in problem recognition between patients and medical professionals

BACKGROUND

There is no systematic analysis to identify problems involved with instruction on inhalation therapy for elderly patients. We conducted a nationwide questionnaire survey for patients and medical professionals.

METHODS

A questionnaire survey was conducted of adult patients on inhaled drugs (ages 18-92 years, 820 individuals) and medical professionals (pharmacists or nurses) who provided instruction on inhalation therapy to these patients in 23 institutions in Japan to investigate the technique and the level of understanding (knowledge) of the inhalation therapy. Changes in the recognition of performance of inhalation technique and inhalation knowledge with increasing age were analyzed.

RESULTS

According to patients' subjective assessment, there was no deterioration in the performance of the inhalation technique or loss of the knowledge with increasing age. On the other hand, medical professionals' objective assessment revealed a significant loss of both inhalation technique and knowledge with increasing age. Not many elderly patients noticed their own problems themselves, revealing a great perception gap between elderly patients and medical professionals. Thus, there was concern that patients would unconsciously practice the inhalation procedure improperly. On the other hand, in comparison with non-elderly patients, elderly patients were less resistant to continuation of therapy, suggesting that they would be more likely to accept instruction on inhalation therapy.

CONCLUSIONS

Elderly patients are apt to assume that they "understand well", therefore, in order to recognize and close the perception gap between elderly patients and medical professionals, it is necessary to provide them with more aggressive (frequent) instructions on inhalation therapy.