Electrospray as Means to Produce Monodisperse Drug Particles

Abstract

In the treatment of asthma and other chronic obstructive lung diseases, inhalation therapy is the most frequently applied method to administer drugs. Direct local administration into the lungs leads to an immediate effect, and smaller doses are needed compared with oral administration. However, with the use of conventional inhalation devices, only a fraction of the inhaled drug reaches the lower airways, where it has its therapeutic effect (Biddiscombe et al. 1993). A large part is deposited in the mouth and the throat, after which it is swallowed and subsequently may be absorbed in the gastrointestinal tract. The low efficiency of the inhalation equipment is related to the less optimal size distribution of the particles released, although recently developed inhalers can show improved distributions (Kunkel et al. 2000, Zierenberg 1999). Research has shown that, in adults, monodisperse 2.8 jam bronchodilator particles were optimal in terms of efficacy (Zanen et al. 1995, Zanen et al. 1996). These experiments point to the fact that the range of optimal aerosol particle sizes might be much smaller (2.0–3.5 urn) than the currently assumed 1–5 im. It was also shown that administration of these monodisperse aerosols opened the way to reduce the dose emitted from metered or dry powder inhalers by approximately 80% without losing any clinical effect (Zanen et al. 1998). Large particles are less efficacious; therefore, they may be eradicated from the emitted dose without reducing the therapeutic effect. However, if they enter the body they still have the potential to elicit side effects.