Position paper: recommendation on the adoption of breathing patterns for infants and small children in general chapter 2.9.44. Preparations for nebulisation

The treatment of infants and small children with nebuliser-based therapy is commonplace. However, the breathing pattern proposed for general chapter 2.9.44 covering preparations for nebulisation, in development for the European Pharmacopoeia, is that of an adult at rest. This position paper is a concise summary of recommendations for 3 breathing patterns that would be applicable to a neonate, a 12-month-old infant, and a child approximately 4 years old. The information presented herein is intended to inform the development of the proposed general chapter with the intention that information be provided to assist those involved with the evaluation of preparations for paediatric use in the choice of more appropriate breathing patterns for the assessment of active substance delivery rate and total active substance delivered.

Cooling the NGI - an approach to size a nebulised aerosol more accurately

The European Pharmaceutical Aerosol Group (EPAG) has undertaken investigations with the aim of developing robust methods for the droplet size analysis of nebuliser-produced aerosols in support of the proposed European Pharmacopeia general chapter 2.9.44 covering preparations for nebulisation. A multi-centre study was designed to investigate the effects of cooling the Next Generation pharmaceutical Impactor (NGI) before sample collection, as a means of reducing bias and variability caused by heat transfer-related evaporation. Droplets containing salbutamol were sized from 3 different nebulisers chosen to offer fundamentally different modes of aerosol generation: AeroNeb Go, a vibrating mesh nebuliser; PARI LC Plus, a breath-enhanced jet nebuliser; and MistyMax, a constant-output jet nebuliser. Each laboratory undertook determinations at ambient temperature, using an NGI pre-cooled in a refrigerator (5 degrees C for at least 90 min). The corresponding measurements were made using an ambient NGI as a benchmark. Salbutamol solution 5 mg/2 ml (Teva, Runcorn, UK) was used throughout the study. Analysis of individual and pooled results from 5 of the participants showed a similar trend insofar as the cooled NGI yielded a coarser nebulised aerosol than that obtained by the ambient NGI. Mass Median Aerodynamic Diameter (MMAD) was on average reduced by 9.5-21.9 % and the Fine Droplet Fraction < 5 microm (FDF) increased on average by 5.5-17.4 % for all the nebuliser designs when comparing ambient to cooled NGI. Despite the more laborious procedure of cooling the NGI, variability in data was generally similar to that obtained with the ambient NGI. We conclude that it is beneficial to cool the NGI when sizing nebulised aerosol. Furthermore, occasional findings during this study revealed a build-up of solute deposits within the interior of the NGI, and a more rigorous impactor cleaning/drying procedure is therefore recommended.

Assessment of the need to coat particle collection cups of the NGI to mitigate droplet bounce when evaluating nebuliser-produced droplets

The European Pharmaceutical Aerosol Group (EPAG) has been undertaking a series of investigations in support of developing robust methods for the droplet size analysis of nebuliser-produced aerosols for the proposed European Pharmacopoeia general chapter 2.9.44 covering preparations for nebulisation. The present two-centre study, which was designed to confirm whether or not coating the collection cups of the Next Generation pharmaceutical Impactor (NGI, the recommended impactor for the proposed monograph) is required, forms part of these investigations. The study evaluated NGI-measured aerodynamic droplet-size distributions of aerosols of a generic salbutamol solution for nebulisation generated by two different jet nebulisers. The results demonstrated that there was no indication of biased stage deposition when silicone oil was used to coat the impaction surfaces, as compared to uncoated surfaces. The conclusion was that there is no need to coat the NGI cups when nebulised products are investigated.

Laser diffractometry and cascade impaction for nebulizer product characterization

The techniques of laser diffractometry and multi-stage cascade impaction are widely used in the in vitro characterization of liquid droplet aerosols generated from nebulizing systems. This position paper is a concise summary of key aspects relating to both techniques and is intended to inform the development of the proposed general chapter 2.9.44 "Preparations for Nebulization" for the European Pharmacopeia, as well as assist in the development of a proposed International Standard (ISO 27427) for nebulizing systems.

Oxygen monitoring in supercritical carbon dioxide using a fibre optic sensor

Investigations of enzymatic reactions in supercritical CO(2) are often hindered by the high pressure involved in these processes, making reaction monitoring extremely difficult. This paper describes the implementation of a fiber optic based oxygen sensor into a high pressure reactor for supercritical carbon dioxide. The sensor is pressure resistant, working in supercritical carbon dioxide and reusable after depressurisation. The sensor signal is found to be affected by pressure changes, but stable at constant pressure. Oxygen concentration in supercritical CO(2) is monitored using the disproportionation of hydrogen peroxide as a simple oxygen producing reaction.

The formation of plasmid DNA loaded pharmaceutical powders using supercritical fluid technology

The invention of novel drugs based on biological macromolecules requires the development of specialized formulation methods. Supercritical fluid technology offers the possibility to produce dry powder formulations suitable for inhalation or needle-free injection. In this article we describe the first application of a process involving supercritical carbon dioxide for the production of plasmid DNA-loaded particles. The technique of solution enhanced dispersion by supercritical fluids (SEDS) is used to coformulate the 6.9 kb plasmid pSV beta with mannitol as excipient. After initial experiments showed a high degradation of the plasmid during powder formation, a systematic investigation of the process revealed pH effects to be crucial for the recovery of intact DNA. The application of high-buffer concentration led to an increase of the recovered supercoiled proportion from 7% to 80%.