An in vitro study to assess facial and ocular deposition from Respimat Soft Mist inhaler

Respimat Soft Mist() inhaler (SMI) is a novel multidose propellant-free inhaler device for delivery of inhaled drugs to patients with asthma and chronic obstructive pulmonary disease. In vitro studies have been undertaken to assess facial and ocular deposition from Respimat SMI in several potential misuse situations. A placebo aqueous drug formulation in Respimat SMI was radiolabeled by addition of (99m)Tc. Deposition was quantified by gamma camera on a removable facemask that was fitted over the head of a resuscitation mannequin. The eyes were simulated by adhesive plaster patches. When Respimat SMI was fired in three preselected positions away from the head, total face deposition (% ex-valve dose) averaged 7.3%, 7.8%, and 9.1%, and eye deposition averaged 0.6%, 0.1%, and 0.3%. When the inhaler was fired into a simulated exhalation, upper face deposition (mean 3.8%) and eye deposition (mean 0.1%) were also small. It is concluded that low deposition on the face, and especially in the eyes, is to be expected when Respimat SMI is fired accidentally outside the body, or is fired at the same time as the patient exhales. When Respimat SMI is misused in the ways described in this study, there is likely to be little potential for unwanted side effects resulting from ocular deposition.