Low-voltage electrohydrodynamic (EHD) spray drying of respirable particles

Revealing facts behind spray dried solid dispersion technology used for solubility enhancement

Poor solubility and bioavailability of an existing or newly synthesized drug always pose challenge in the development of efficient pharmaceutical formulation. Numerous technologies can be used to improve the solubility and among them amorphous solid dispersion based spray drying technology can be successfully useful for development of product from lab scale to commercial scale with a wide range of powder characteristics. Current review deals with the importance of spray drying technology in drug delivery, basically for solubility and bioavailability enhancement. Role of additives, selection of polymer, effect of process and formulation parameters, scale up optimization, and IVIVC have been covered to gain the interest of readers about the technology. Design of experiment (DoE) to optimize the spray drying process has been covered in the review. A lot more research work is required to evaluate spray drying as a technology for screening the right polymer for solid dispersion, especially to overcome the issue related to drug re-crystallization and to achieve a stable product both in vitro and in vivo. Based on the recent FDA recommendation, the need of the hour is also to adopt Quality by Design approach in the manufacturing process to carefully optimize the spray drying technology for its smooth transfer from lab scale to commercial scale.

Pharmaceutical spray freeze drying

Pharmaceutical spray-freeze drying (SFD) includes a heterogeneous set of technologies with primary applications in apparent solubility enhancement, pulmonary drug delivery, intradermal ballistic administration and delivery of vaccines to the nasal mucosa. The methods comprise of three steps: droplet generation, freezing and sublimation drying, which can be matched to the requirements given by the dosage form and route of administration. The objectives, various methods and physicochemical and pharmacological outcomes have been reviewed with a scope including related fields of science and technology.

Optimizing the primary particle size distributions of pressurized metered dose inhalers by using inkjet spray drying for targeting desired regions of the lungs

Conventional suspension pressurized metered dose inhalers (pMDIs) suffer not only from delivering small amounts of a drug to the lungs, but also the inhaled dose scatters all over the lung regions. This results in much less of the desired dose being delivered to regions of the lungs. This study aimed to improve the aerosol performance of suspension pMDIs by producing primary particles with narrow size distributions. Inkjet spray drying was used to produce respirable particles of salbutamol sulfate. The Next Generation Impactor (NGI) was used to determine the aerosol particle size distribution and fine particle fraction (FPF). Furthermore, oropharyngeal models were used with the NGI to compare the aerosol performances of a pMDI with monodisperse primary particles and a conventional pMDI. Monodisperse primary particles in pMDIs showed significantly narrower aerosol particle size distributions than pMDIs containing polydisperse primary particles. Monodisperse pMDIs showed aerosol deposition on a single stage of the NGI as high as 41.75 ± 5.76%, while this was 29.37 ± 6.79% for a polydisperse pMDI. Narrow size distribution was crucial to achieve a high FPF (49.31 ± 8.16%) for primary particles greater than 2 µm. Only small polydisperse primary particles with sizes such as 0.65 ± 0.28 µm achieved a high FPF with (68.94 ± 6.22%) or without (53.95 ± 4.59%) a spacer. Oropharyngeal models also indicated a narrower aerosol particle size distribution for a pMDI containing monodisperse primary particles compared to a conventional pMDI. It is concluded that, pMDIs formulated with monodisperse primary particles show higher FPFs that may target desired regions of the lungs more effectively than polydisperse pMDIs.

Physico-chemical aspects of lactose for inhalation

A dry powder inhaler (DPI) is a dosage form that consists of a powder formulation in a device which is designed to deliver an active ingredient to the respiratory tract. It has been extensively investigated over the past years and several aspects relating to device and particulate delivery mechanisms have been the focal points for debate. DPI formulations may or may not contain carrier particles but whenever a carrier is included in a commercial formulation, it is almost invariably lactose monohydrate. Many physicochemical properties of the lactose carrier particles have been reported to affect the efficiency of a DPI. A number of preparation methods have been developed which have been claimed to produce lactose carriers with characteristics which lead to improved deposition. Alongside these developments, a number of characterization methods have been developed which have been reported to be useful in the measurement of key properties of the particulate ingredients. This review describes the various physicochemical characteristics of lactose, methods of manufacturing lactose particulates and their characterization.

The nano spray dryer B-90

INTRODUCTION

Spray drying is an extremely well-established technology for the production of micro-particulate powders suited for a variety of drug delivery applications. In recent years, the rise in nanomedicine has placed increased pressure on the existing systems to produce nanoparticles in good yield and with a narrow size distribution. However, the separation and collection of nanoparticles with conventional spray dryer set ups is extremely challenging due to their typical low collection efficiency for fine particles < 2 μm. Currently, nanoparticles have to be agglomerated into larger microparticles, via a two-step approach, in order to collect them in a sizeable amount. However, this method has to contend with the issue of adequate redispersibility of the primary particles to reap the full benefits of nanosizing.

AREAS COVERED

An overview on the advances in spray drying technology is provided in this review with particular emphasis on the novel Buchi® Nano Spray Dryer B-90. Readers will appreciate the limitations of conventional spray drying technology, understand the mechanisms of the Buchi® Nano Spray Dryer B-90, and also learn about the strengths and shortcomings of the system.

EXPERT OPINION

The Buchi® Nano Spray Dryer B-90 offers a new, simple and alternative approach for the production of nanoparticles suited for a variety of drug delivery applications.