the valve illustrated in fig1 comprises a valve ferrule ( 2 ) and an associated rim gasket ( 4 ) for engaging an aerosol vial . the rim gasket ( 4 ) may conveniently comprise an ethylene - butylene copolymer e . g . the copolymer commercially available from union carbide under the trade name flexomer gers 1085nt . a metering tank ( 6 ) has walls defining a metering chamber ( 8 ) having an inlet end associated with a tank seal ( 10 ) and an outlet end associated with a diaphragm ( 12 ). an elongate valve stem ( 14 ) having a filling channel ( 16 ), a discharge end ( 18 ) and a discharge orifice ( 20 ) extends through the valve ferrule and metering chamber in sealing engagement with the diaphragm ( 12 ) and tank seal ( 10 ). the tank seal and diaphragm may conveniently comprise a butadiene - acrylonitrile copolymer e . g . type db - 218 commercially available from american gasket & amp ; rubber company . a bottle emptier ( 22 ) surround the metering tank ( 6 ) and valve stem such that a capillary channel ( 24 ) is defined between the metering tank and bottle emptier to allow passage of aerosol formulation from the aerosol vial to the inlet end of the metering chamber . the valve stem ( 14 ) is movable between an extended closed position wherein the filling channel ( 16 ) of the valve stem allows open communication , via the inlet orifice , between the interior and the exterior of the metering chamber , and wherein the outlet end of the metering tank is closed , and a compressed open position wherein the inlet orifice of the metering tank is in sealing engagement with the filling end o the valve stem and the discharge orifice of the valve stem allows open communication between the interior and exterior of the metering chamber . the valve stem ( 14 ) is biased to the extended closed position by spring ( 15 ). fig2 to 4 illustrate a press - and - breathe adaptor for an aerosol vial equipped with dispensing valve suitable for use in the invention . the adaptor comprises a body portion ( 30 ) and a mouthpiece ( 32 ). a plurality of ribs ( 34 ) are positioned within the body portion ( 30 ) in order to locate and support the aerosol vial ( not shown ) in the correct position . the dispensing end of the elongate valve stem of the metered dose dispensing valve is positioned within the nozzle block ( 36 ). the adaptor is made of polypropylene or high density polyethylene . however , to ensure a good seal between the valve stem ( 14 ) and the central aperture ( 38 ), high density polyethylene is preferred . as shown in fig4 the nozzle block ( 36 ) comprises a central aperture ( 38 ) having a flared opening ( 40 ) to accommodate the valve stem . the valve stem is inserted until it abuts the ledge ( 42 ). in use , the patient inserts the mouthpiece into the mouth and depresses the base of the aerosol vial while inhaling . the relative movement between the elongate valve stem and the metering tank causes the discharge orifice to enter the metering tank and the contents thereof are dispensed under pressure through the discharge end of the elongate valve stem to enter chamber ( 44 ) in the nozzle block ( 36 ) and exit through orifice ( 46 ). a plume of droplets of respirable size is directed from the orifice ( 46 ) into the mouthpiece ( 32 ) for inhalation by the patient . it has been found that the dimensions of the orifice ( 46 ) may have a profound effect on the respirable fraction of the formulation dispensed from the mouthpiece of the adaptor . both the jet length “ l ” and diameter “ d ” of the orifice ( 46 ) affect the delivery to the lung of the formulation . this is often assessed by an “ in vitro ” test which uses an andersen cascade impactor , such as described in the u . s . pharmacopoiea . an andersen respirable dose is defined as the weight of drug delivered to plates 3 to 7 and the filter of the impactor from a single actuation of the inhaler . the optimum dimensions are also dependent upon the particular formulation to be dispensed . in general , medication delivery increases with increasing orifice diameter “ d ” and with increasing jet length “ l ”. however , the anderson respirable dose increases with decrease in orifice diameter “ d ”. the selection of particular dimensions of the nozzle orifice enables an andersen respirable dose of greater than 120 micrograms to be achieved for a product delivering 200 micrograms of ciclesonide per actuation ex valve , without significantly detracting from the medication delivery . thus the patient potentially derives the benefit of a higher than usual proportion of dispensed drug reaching the lungs without excessive build - up of drug on the actuator or the product falling short of regulatory stipulations . for formulations containing from 5 to 10 % by weight ethanol , particularly 8 % by weight ethanol it has been found that good respirable doses are achieved with an orifice diameter “ d ” within the range 0 . 20 to 0 . 33 mm , preferably about 0 . 28 mm and a jet length “ l ” in the range 0 . 30 to 0 . 60 mm preferably 0 . 50 mm . in each example , the percentage of ethanol in the ethanol / propellant blend is denoted in brackets . all of the formulations of examples 1 to 15 were clear , colourless solutions in which the ciclesonide was completely solubilized . examples 13 to 15 were the subject of stability trials over several months and proved to be physically and chemically stable . although the invention has been described in terms of preferred formulations and ingredients , it will be understood that these are not intended to be limiting . to the contrary , those skilled in the art will understand that various optional ingredients may be included , such as flavoring agents , preservatives , additional active ingredients , and the like , while still embodying the present invention .
a pharmaceutical aerosol formulation suitable for oral and / or nasal inhalation including an anti - inflammatory steroid of the formula in which : r 1 is 1 - butyl , 2 - butyl , cyclohexyl or phenyl and r 2 is acetyl or isobutanoyl , in particular ciclesonide . the formulations also include hydrofluorocarbon propellants such as hfc 134 a and / or 227 , and cosolvent such as ethanol in an amount sufficient to solubilize the ciclesonide or related steroid . the formulations exhibit very desirable physical and chemical stability , as well as excellent delivery characteristics .