Improving the risk-to-benefit ratio of inhaled corticosteroids through delivery and dose: current progress and future directions

INTRODUCTION

Inhaled corticosteroids (ICS) are known to increase the risk of systemic and local adverse effects, especially with high doses and long-term use. Hence, considerable resources are invested to improve pharmacokinetic/pharmacodynamic (PK/PD) properties of ICS, effective delivery systems and novel combination therapies to enhance the risk-to-benefit ratio of ICS.

AREAS COVERED

There is an unmet need for new solutions to achieve optimal clinical outcomes with minimal dose of ICS. This paper gives an overview of novel treatment strategies regarding the safety of ICS therapy on the basis of the three most recent molecules introduced to our everyday clinical practice - ciclesonide, mometasone furoate, and fluticasone furoate. Advances in aerosol devices and new areas of inhalation therapy are also discussed.

EXPERT OPINION

Current progress in improving the risk-to-benefit ratio of ICS through dose and delivery probably established pathways for further developments. This applies both to the improvement of the PK/PD properties of ICS molecules but also includes technical aspects that lead to simplified applicability of the device with simultaneous optimal drug deposition in the lungs. Indubitably, the future of medicine lies not only in the development of new molecules but also in technology and digital revolution.

The evolution of insulin therapy

Evolution in medicine is generally driven by clinical need, hand in hand with opportunities generated by novel chemical and mechanical engineering technologies. Since 1921 that has been a continuing paradigm for insulin therapy, some advances being a continual process, and others arising from external scientific or engineering developments. Purification of insulin preparations was an early issue, resolved in the 1970s, then challenged by the switch to manufacture in microorganisms. The nature of insulin was established serially, in 1928 as a polypeptide, in 1955 by amino acid sequence, and later by 3-dimensional structure (1969), laying foundations for understandings on routes of administration, and later the engineering of novel insulins. Insulin was the first, and remains the predominant, pharmaceutical therapy to benefit from scientific advances underlying the genetic code, and thus recombinant DNA technology. Advances in mechanical and chemical engineering have contributed to important changes in insulin delivery devices. Biological science, including both cellular mechanisms and whole organism physiology, has led to considerable understandings of clinical defects in insulin action, but currently has been disappointing in its applicability to the insulins available for clinical practice, something perhaps now changing. The pathways of these changes are reviewed here.

Design of a self-unfolding delivery concept for oral administration of macromolecules

Delivering macromolecular drugs, e.g. peptides, to the systemic circulation by oral administration is challenging due to their degradation in the gastrointestinal tract and low transmucosal permeation. In this study, the concept of an oral delivery device utilizing an elastomeric material is presented with the potential of increasing the absorption of peptides, e.g. insulin. Absorption enhancement in the intestine is proposed as a result of self-unfolding of a polydimethylsiloxane foil upon release from enteric coated capsules. A pH-sensitive polymer coating prevents capsule disintegration until arrival in the small intestine where complete unfolding of the elastomeric foil ensures close contact with the intestinal mucosa. Foils with close-packed hexagonal compartments for optimal drug loading are produced by casting against a deep-etched silicon master. Complete unfolding of the foil upon capsule disintegration is verified in vitro and the insulin release profile of the final delivery device confirms insulin protection at gastric pH. In vivo performance is evaluated with the outcome of quantifiable plasma insulin concentrations in all rats receiving duodenal administration of the novel delivery device. By taking advantage of elastomeric material properties for drug delivery, this approach might serve as inspiration for further development of commercially viable biocompatible devices for oral delivery of macromolecules.

Delivery devices for exposure of biological cells to nanosecond pulsed electric fields

In this paper, delivery devices for nanosecond pulsed electric field exposure of biological samples in direct contact with electrodes or isolated are presented and characterized. They are based on a modified electroporation cuvette and two transverse electromagnetic cells (TEM cells). The devices were used to apply pulses with high intensity (4.5 kV) and short durations (3 and 13 ns). The delivery devices were electromagnetically characterized in the frequency and time domains. Field intensities of around 5, 0.5, and 12 MV m^-1 were obtained by numerical simulations of the biological sample positioned in the three delivery devices. Two delivery systems had a homogenous electric field spatial distribution, and one was adapted to permit a highly localized exposure in the vicinity of a needle. Experimental biological investigations were carried out at different field intensities for five cancer cell lines. The results using flow cytometry showed that cells kept polarized mitochondrial membrane but lost plasma membrane integrity following a dose-response trend after exposure to different electric field intensities. Certain cell types (U87, MCF7) showed higher sensitivities to nsPEFs than other lines tested.

Vial usage, device dead space, vaccine wastage, and dose accuracy of intradermal delivery devices for inactivated poliovirus vaccine (IPV)

Introduction

Intradermal delivery of a fractional dose of inactivated poliovirus vaccine (IPV) offers potential benefits compared to intramuscular (IM) delivery, including possible cost reductions and easing of IPV supply shortages. Objectives of this study were to assess intradermal delivery devices for dead space, wastage generated by the filling process, dose accuracy, and total number of doses that can be delivered per vial.

Methods

Devices tested included syringes with staked (fixed) needles (autodisable syringes and syringes used with intradermal adapters), a luer-slip needle and syringe, a mini-needle syringe, a hollow microneedle device, and disposable-syringe jet injectors with their associated filling adapters. Each device was used to withdraw 0.1-mL fractional doses from single-dose IM glass vials which were then ejected into a beaker. Both vial and device were weighed before and after filling and again after expulsion of liquid to record change in volume at each stage of the process. Data were used to calculate the number of doses that could potentially be obtained from multidose vials.

Results

Results show wide variability in dead space, dose accuracy, overall wastage, and total number of doses that can be obtained per vial among intradermal delivery devices. Syringes with staked needles had relatively low dead space and low overall wastage, and could achieve a greater number of doses per vial compared to syringes with a detachable luer-slip needle. Of the disposable-syringe jet injectors tested, one was comparable to syringes with staked needles.

Discussion

If intradermal delivery of IPV is introduced, selection of an intradermal delivery device can have a substantial impact on vaccine wasted during administration, and thus on the required quantity of vaccine that needs to be purchased. An ideal intradermal delivery device should be not only safe, reliable, accurate, and acceptable to users and vaccine recipients, but should also have low dead space, high dose accuracy, and low overall wastage to maximize the potential number of doses that can be withdrawn and delivered.

Microneedle patches for vaccination in developing countries

Millions of people die of infectious diseases each year, mostly in developing countries, which could largely be prevented by the use of vaccines. While immunization rates have risen since the introduction of the Expanded Program on Immunization (EPI), there remain major challenges to more effective vaccination in developing countries. As a possible solution, microneedle patches containing an array of micron-sized needles on an adhesive backing have been developed to be used for vaccine delivery to the skin. These microneedle patches can be easily and painlessly applied by pressing against the skin and, in some designs, do not leave behind sharps waste. The patches are single-dose, do not require reconstitution, are easy to administer, have reduced size to simplify storage, transportation and waste disposal, and offer the possibility of improved vaccine immunogenicity, dose sparing and thermostability. This review summarizes vaccination challenges in developing countries and discusses advantages that microneedle patches offer for vaccination to address these challenges. We conclude that microneedle patches offer a powerful new technology that can enable more effective vaccination in developing countries.