Characterisation of small changes in the physical properties of powders of significance for dry powder inhaler formulations

Buckton, G. (1997) Characterisation of small changes in the physical properties of powders of significance for dry powder inhaler formulations. Advanced Drug Delivery Reviews, 26 (1). pp. 17-27. 10.1016/S0169-409X(97)00507-3.

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DOI: 10.1016/S0169-409X(97)00507-3


In this paper we address the following issue: Why is surface characterisation important? All pharmaceutical processes (with the exception of mixing two gasses) involve interfacial contact, and, consequently, it is not surprising that surface energetics play an important role in determining the outcome of all events. For a dry powder inhaler system interfacial considerations may relate to drug–drug interactions (cohesion), drug–carrier or drug–device interactions (adhesion) and deaggregation phenomena during use. As all adhesive and cohesive interactions are interfacial phenomena it is reasonable to accept that the basis of interactions within dry powder inhalers is through interfacial forces, which can be divided into apolar (Lifshitz–van der Waals) and polar (electron donor–electron acceptor) components. Further to this it can be accepted that changes in the nature of any surface within the product (the drug, the carrier or the container) can be expected to result in changes in the surface interactions involving that phase. Thus, in essence, the success or failure of a formulated inhalation device is dependent upon the nature of the surface of the materials used, and, as such, measurement of these surfaces becomes of paramount importance. In this review comparatively little effort will be taken to prove the dominant role of surface energetics in inhalation products; this is primarily because much of the proof which exists is held as confidential by manufacturers. Consequently, this review will concentrate on surface characterisation of powders with respect to determination of surface energies and changes in solid-state properties.

Item Type:Article
Uncontrolled Keywords:Isothermal microcalorimetry; Surface energy; Gravimetric sorption; Inverse phase gas chromatography; Lactodes; Amorphous material
Departments, units and centres:Department of Pharmaceutics > Department of Pharmaceutics
ID Code:3252
Journal or Publication Title:Advanced Drug Delivery Reviews
Deposited By:Library Staff
Deposited On:18 May 2012 10:26
Last Modified:18 May 2012 10:26

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