Backgrounds: The development of high dose inhalers is becoming obvious with the emerging use of inhalation route for the delivery of antibiotics and vaccines. The purpose of this study was to evaluate the mechanical dry coating process to develop drug alone formulation of high dose delivery capacity. Methods: Fine inhalable grade lactose was dry coated with 1% magnesium stearate (w/w), and the powder was dispersed from two devices, the Rotahaler® (RH) and Monodose Inhaler® (MI) at three flow rates of 60Lmin-1 with dose loads of 10, 25 and 40mg. The primary particle size distributions, tapped density and work of cohesion were determined by laser diffraction method, tapped density apparatus and inverse gas chromatography, respectively. Results: Fine particle dose (FPD, amount of drug that can reach in lower respiratory tract) displayed a marked increase after mechanofusion. The maximum FPD of 14mg was obtained when 40mg dose was dispersed from Monodose Inhaler at 60L/min. No significant difference was observed between the untreated and mechanofused powder (P>0.05). After mechanofusion, the poured and tapped densities as well as the packing fraction increased while the work of cohesion decreased. Conclusions: Although further studies are required, these preliminary findings indicate that mechanical dry coating with magnesium stearate is promising in developing dry powder inhalers for high dose delivery efficiency.