**3. Aerosolisation of anticancer agents**

#### **3.1 Formulation of anticancer drugs for aerosol delivery**

Particle size is one of the most critical parameters for ensuring efficient drug deposition in the respiratory tract. Several parameters influence drug targeting to the desired lung area: these are the size, shape, density, electrical charge and hygroscopicity of the aerosol particles (Pilcer and Amighi, 2010). It is also essential that the aerosolised drug remains pharmacologically active. Formulations for nebulised drug traditionally include sodium chloride or other salts to adjust the osmolarity, HCl or NaOH to obtain a stabilised neutral pH and a surfactant such as polysorbates to avoid drug aggregates. But other methods have been developed to produce particles with controlled properties; these include jet milling, spray drying and supercritical fluid techniques. Excipients like lipids and polymers are also used to improve pulmonary deposition (Pilcer and Amighi, 2010).

Some drugs are encapsulated into liposome to increase their resident time into the lungs (Cryan, 2005). Liposomal formulations generally provide sustained drug release, prevent local irritation, and improve drug stability. For example, the resident time in the lungs of liposomal cyclosporine A is nearly 17 times longer than that of the standard compound (Arppe et al., 1998). The lipids most commonly used to produce liposome are lecithins (phosphatidylcholines), phosphatidylethanolamines, phosphatidylserines, and phosphatidylinositols. Formulations with microspheres have also been developed. Although, they are mostly used to deliver drugs whose intended actions are systemic, such as vaccines and insulin, more and more formulations of anticancer agents associated with microspheres are being developed. Microspheres are produced using natural or synthetic polymers. The two most commonly used synthetic polymers are polylactic acid (PLA) and polylacticco-glycolic acid (PLGA) (Cryan, 2005). The rate at which a drug is released from microparticles depends on its dissolution and diffusion.

New formulations are today developed for the controlled release of the drug and to enhance anticancer efficacy. Biotinylated-EGF-modified gelatine was tested as a carrier for cisplatin with better anticancer and less toxic effect than free cisplatin after aerosolisation *in vitro* and *in vivo* (Tseng et al., 2009). Encapsulation of anticancer agent in nanoparticles is also evaluated, in particular through airways delivery with some promising results (El-Gendy and Berckland, 2009, Hureaux et al., 2009, Tomoda et al., 2009).

#### **3.2 Pharmacological properties of aerosolised anticancer agents**

Most anticancer drugs resist the physical constraints of aerosolisation, retain their pharmacological properties, and produce particles with aerodynamic properties that are

Great care should be taken when administering anticancer agent *via* the pulmonary route. Anticancer agents are potentially toxic for the lung and may impair the pulmonary function in some patients, but most of them are not very toxic when the inhalation procedure is standardized and the dose well defined. The safety of healthcare workers should be considered. Aerosolised chemotherapy should be delivered in a well-ventilated room with an efficient air filtering system (Gagnadoux et al., 2007). Wittgen et al demonstrated the advantages of combining a mobile HEPA (High Efficiency Particulate Air) filter air cleaning system with a demistifier tent to prevent aerosol propagation during inhalation of nebulised

Particle size is one of the most critical parameters for ensuring efficient drug deposition in the respiratory tract. Several parameters influence drug targeting to the desired lung area: these are the size, shape, density, electrical charge and hygroscopicity of the aerosol particles (Pilcer and Amighi, 2010). It is also essential that the aerosolised drug remains pharmacologically active. Formulations for nebulised drug traditionally include sodium chloride or other salts to adjust the osmolarity, HCl or NaOH to obtain a stabilised neutral pH and a surfactant such as polysorbates to avoid drug aggregates. But other methods have been developed to produce particles with controlled properties; these include jet milling, spray drying and supercritical fluid techniques. Excipients like lipids and polymers are also

Some drugs are encapsulated into liposome to increase their resident time into the lungs (Cryan, 2005). Liposomal formulations generally provide sustained drug release, prevent local irritation, and improve drug stability. For example, the resident time in the lungs of liposomal cyclosporine A is nearly 17 times longer than that of the standard compound (Arppe et al., 1998). The lipids most commonly used to produce liposome are lecithins (phosphatidylcholines), phosphatidylethanolamines, phosphatidylserines, and phosphatidylinositols. Formulations with microspheres have also been developed. Although, they are mostly used to deliver drugs whose intended actions are systemic, such as vaccines and insulin, more and more formulations of anticancer agents associated with microspheres are being developed. Microspheres are produced using natural or synthetic polymers. The two most commonly used synthetic polymers are polylactic acid (PLA) and polylacticco-glycolic acid (PLGA) (Cryan, 2005). The rate at which a drug is released from

New formulations are today developed for the controlled release of the drug and to enhance anticancer efficacy. Biotinylated-EGF-modified gelatine was tested as a carrier for cisplatin with better anticancer and less toxic effect than free cisplatin after aerosolisation *in vitro* and *in vivo* (Tseng et al., 2009). Encapsulation of anticancer agent in nanoparticles is also evaluated, in particular through airways delivery with some promising results (El-Gendy

Most anticancer drugs resist the physical constraints of aerosolisation, retain their pharmacological properties, and produce particles with aerodynamic properties that are

liposomal cisplatin (Wittgen et al., 2006).

**3. Aerosolisation of anticancer agents** 

**3.1 Formulation of anticancer drugs for aerosol delivery** 

used to improve pulmonary deposition (Pilcer and Amighi, 2010).

microparticles depends on its dissolution and diffusion.

and Berckland, 2009, Hureaux et al., 2009, Tomoda et al., 2009).

**3.2 Pharmacological properties of aerosolised anticancer agents** 

compatible with lung deposition. A study by Gagnadoux et al. showed that the cytotoxicity of a nebulised formulation of the nucleoside analog gemcitabine (GCB) was similar to that of the native drug when tested against NCI-H460 and A549 Non-Small Cell Lung Cancer (NSCLC) cells (Gagnadoux et al., 2006). Another study of the cytotoxicity of a nebulised farnesol formulation containing polysorbate 80 (Tween 80) in vitro for NSCLC lines (H460 and A549) showed that the anticancer properties of nebulised farnesol were essentially the same as those of the native drug (Wang et al., 2003). The cytotoxic effects of doxorubicin before and after encapsulation were compared *in vitro* using growth inhibition assays. Azarmi et al. (2006) studied doxorubicin (DOX)-loaded nanoparticles formulated as a dry powder by spray-freezedrying. The cytotoxic effects of free DOX, carrier particles containing blank nanoparticles and DOX-loaded nanoparticles were assessed using H460 and A549 lung cancer cells. The DOXnanoparticles were more cytotoxic for both cell lines a higher than were the blank nanoparticles and the free DOX. The aerosolisation of therapeutic proteins such as anticancer antibodies has also been tested. The results showed that some inhalers are suitable for limiting the formation of aggregates and preserving the pharmacological activity of the antibody *in vitro* (Maillet et al., 2008). Cetuximab, a chimeric IgG1 that targets the epidermal growth factor receptor (EGFR), was tested with three types of nebulisers: jet, mesh and ultrasonic. The immunological and pharmacological properties of nebulised cetuximab were evaluated using A431 cells. Flow cytometric analyses and assays of EGFR-phosphorylation and the inhibitions of A431 cell growth demonstrated that the mesh and jet nebulisers did not destroy the ability of cetuximab to bind to EGFR or its inhibitory activity.
