Sustained Delivery by Leucine-modified Chitosan Spray-dried Respirable Powders

Learoyd, T.P., Burrows, J.L., French, E. and Seville, Peter C. ORCID: https://orcid.org/0000-0001-8546-3474 (2009) Sustained Delivery by Leucine-modified Chitosan Spray-dried Respirable Powders. International Journal of Pharmaceutics, 372 (1-2). pp. 97-104. ISSN Print: 0378-5173 Online: 1873-3476

Abstract

The controlled co-delivery of multiple agents to the lung offers potential benefits to patients. This study investigated the preparation and characterisation of highly respirable spray-dried powders displaying the sustained release of two chemically distinct therapeutic agents. Spray-dried powders were produced from 30% (v/v) aqueous ethanol formulations that contained hydrophilic (terbutaline sulphate) and hydrophobic (beclometasone dipropionate) model drugs, chitosan (as a drug release modifier) and leucine (aerosolisation enhancer). The influence of chitosan molecular weight on spray-drying thermal efficiency, aerosol performance and drug release profile was investigated. Resultant powders were physically characterised: with in vitro aerosolisation performance and drug release profile investigated by the Multi-Stage Liquid Impinger and modified USP II dissolution apparatus, respectively. It was found that increased chitosan molecular weight gave increased spray-drying thermal efficiency. The powders generated were of a suitable size for inhalation-with emitted doses over 90% and fine particle fractions up to 72% of the loaded dose. Sustained drug release profiles were observed in dissolution tests for both agents: increased chitosan molecular weight associated with increased duration of drug release. The controlled co-delivery of hydrophilic and hydrophobic entities underlines the capability of spray drying to produce respirable particles with sustained release for delivery to the lung.

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