Asthma and Chronic Obstructive Pulmonary Disease (COPD) are diseases associated with the airflow in the lungs (WHO, 2013). Inhalation is the most effective route of administration for treating asthma and COPD (Labiris and Dolovich, 2003). Several combination therapies are available on the market in the form of a physical mixture of dry powder inhaler (DPI) for the treatment of asthma and COPD, for example a combination of a LABA:LAMA (indacaterol:glycopyrronium; umeclidinium/vilanterol) and ICS:LABA (Budesonide/formoterol, fluticasone furoate/vilanterol ) formulated as DPIs. Formulation properties are determined by physicochemical properties of the carrier: particle size, shape, density, surface area, roughness, morphology and associated forces of drug-to-drug cohesion and drug-to-carrier adhesion. The higher the surface energy of the carrier, the higher the drug-to-carrier adhesion interaction. Therefore, the reduction in adhesion forces between drug particles and lactose carrier particles appeared to result in drug particles sticking to each other (via cohesive forces) (Zhou and Morton, 2012, Dickhoff et al., 2003). As a result, they display poor flowability and aerosolisation performance and have the tendency to remain within the inhaler. Hence, it is necessary to maintain the balance between cohesive and adhesive forces that gives sufficient adhesion between the carrier and the drug to get a stable formulation. Moreover, this balance facilitates the separation of (drug-carrier) during inhalation process (Hamishehkar et al., 2012, Zhang et al., 2012). The delivery of uniformed dose is essential to ensure the control of the disease which is a major challenge for DPI formulation. This challenge will be much more complicated with dual combination inhalers such as Ultibro Breezhaler®, Seretide and many more. This is due to the fact that the individual drugs have different physiochemical properties and therefore their adhesive/cohesive forces are different. Hence it is highly unlikely that the delivered dose and fine particle dose would still maintain the same ratio of both drugs during inhalation and deposition in the lung considering the fact that most asthma and COPD patients inhale at different flow rate (Abadelah et al., 2017).
Liposomes are vesicles comprising a phospholipid bilayer surrounding an inner aqueous core. Due to their biphasic characteristic and diverse design, composition and construction, liposomes offer dynamic and adaptable technology for modern drug delivery (Hefesha et al., 2011). Furthermore, in contrast to other carrier systems, liposome formulations have ‘generally regarded as safe (GRAS)’ status. They can load hydrophilic, amphiphilic and liphophilic drugs and have been successfully used in many therapeutic applications (mostly by injections) such as anticancer therapy with much improved pharmacokinetic and pharmacodynamic profiles (Anders CK. Et al., 2013).
For the last three decades, liposome delivery systems have been investigated for the treatment of Pulmonary diseases by inhalation in order to enhance the efficacy and reduce the systemic adverse effect, and some products by using nanoliposomes as carriers are being assessed in clinical trials.
Despite these promising results, a systematic study of the effects of physicochemical properties of the liposomes (including phospholipid composition, bilayer membrane fluidity, surface charge, transition temperature and liposome size) on the efficacy of the pulmonary delivery has not yet been investigated. In this study, by choosing the phospholipids with different physicochemical properties (in terms of lipid composition, transition temperature, charge and size), we will examine the effect of liposomal properties on the aerosolization performance of the drugs combination with the aim to enhance content uniformity and the release profile of the drugs, and prolong its residence time in the lung and thus achieve a longer duration of effect. We will use formoterol / budesonide as the dual model drugs to be loaded in liposomes for this study.
- To prepare liposomal formulations using different types of liposomes for some of dual-combination inhalers that are available as physical mixture such as formoterol / budesonide and then to assess the effect of the physicochemical properties of the selected liposomes on the drugs aerosolisation performance at different inspiratory flow rates.
- By choosing the optimal liposomal formulations, we aim to modify the release profile of the drugs in the selected dual combination inhalers (formoterol / budesonide) and prolong their residence time in the lung and thus achieve a longer duration of effect.