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Updated: Jul 20, 2026

Hydrophobic Salt-modified Nafion for Enzyme Immobilization and Stabilization
Published on: July 11, 2012
Stabilisation of deoxyribonuclease in hydrofluoroalkanes using miscible vinyl polymers
Stuart A Jones1, Gary P Martin, Marc B Brown
1Department of Pharmacy, Pharmaceutical Sciences Research Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NN, UK. stuart.jones@kcl.ac.uk <stuart.jones@kcl.ac.uk>
Abstract:
A mix of biocompatible macromolecules (poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP)) has been shown previously to enhance the physical stability of non-aqueous pharmaceutical suspensions. The aim of this work was to assess the feasibility of employing such a combination to facilitate the formulation of deoxyribonuclease I (DNase I) in a metered dose inhaler (MDI) using hydrofluoroalkane (HFA) propellants. DNase I was combined with the selected excipients and formed into an inhalable microparticle by spray-drying. When spray-dried alone DNase I lost almost 40% of its original biological activity, but stabilising DNase I with trehalose and PVA (DTPVA) retained 85% biological activity and trehalose, PVA and PVP (DTPVAPVP) retained 100%. Suspending the DTPVAPVP microparticles within a HFA pMDI for 24 weeks led to no further reduction in the biological activity of DNase I and the formulation delivered almost 60% of the dose expelled to the second stage of a twin-stage impinger. The solubility of PVP in HFA propellants suggests that the enhanced physical stability observed with PVA and PVP may partially be as a result of steric stabilisation. However, the large zeta potential associated with the suspensions suggested that charge stabilisation may also influence the pMDI physical stability.
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