Dynamic tensiometry studies on interactions of novel therapeutic inhalable powders with model pulmonary surfactant at the air–water interface

• Impact of novel inhalable powders on model lung surfactant (LS) is investigated.
• Maximum bubble pressure method is applied as a measuring technique.
• All powders affect LS surface activity either positively or negatively.
• Both types of deviation depend partially on powder composition and concentration.
• Results can help design more effective and safe medical products for inhalation.

Assessing the influence of therapeutic formulations on biophysical properties of lung surfactant is an essential step in optimal design of pharmaceutical products intended for inhalation. In the present study, maximum bubble pressure (MBP) tensiometry was employed to evaluate the physicochemical impact of several novel multifunctional composite powders, suitable for drug delivery by inhalation, on the dynamic activity of model pulmonary surfactant at the air–water interface. Bi- and tri-component powders consisted of mannitol or dextran, N-acetylcysteine and disodium cromoglycate were obtained by spray drying technique and subsequently their interaction with modified bovine surfactant extract (Survanta) were analysed. Several dynamic surface tension parameters were investigated as measures of alteration of surface activity in Survanta-powder solutions. All discussed powders demonstrated significant impact on surface activity of Survanta solution, either positive or negative, depending on powders composition and concentration. Although it is problematic to explain all observed effects in the framework of known mechanisms, the present study provides a new insight into the possible changes in the dynamic interfacial behaviour of pulmonary surfactant after therapeutic interventions. Obtained results may be applied during development of more effective and safe medical products suitable for drug delivery by inhalation.

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