Surgery – Liquid medicament atomizer or sprayer – Spray impinged against baffle in or adjacent flow conduit
Reexamination Certificate
1999-05-20
2001-05-01
Weiss, John G. (Department: 3761)
Surgery
Liquid medicament atomizer or sprayer
Spray impinged against baffle in or adjacent flow conduit
C128S200140, C128S200210
Reexamination Certificate
active
06223745
ABSTRACT:
The present invention relates to a method for producing a finely atomized aerosol, using a stream of gas which sucks liquid with it from the mouth of a channel, which communicates with a supply of liquid in a container, so as to form an aerosol, after which liquid particles in the resulting aerosol are broken up into smaller particles in a subsequent stage. The invention also relates to an arrangement used for implementing the method.
Arrangements for producing aerosols in accordance with the above are generally referred to as nebulizers and are available in various designs; see, for example, EP-0,191,018, WO95/20411 and WO95/25556.
Nebulizers of this type can be used especially for producing aerosols for medical treatment, i.e. aerosols containing drugs. Such treatment is of great importance for treating asthma and chronic bronchitis, for example, since drugs in aerosol form which are inhaled directly deposit in the airways.
Nebulizers previously available on the market have generally been designed to be used with drugs which have a wide therapeutic dose range, i.e. it has been possible to allow the dosage to be varied within wide limits without serious consequences, e.g. traditional asthma medications. Thus, the demand for exact and reproducible dosage has not been so stringent, and previous nebulizer designs have shown great individual variations, even between apparently identical examples of the same product. Nor has any great importance been attached to the quantity of aerosol produced in relation to the tidal volume, or to the patient's physiological requirements to assimilate the dose of medication. Nor has loss of medication to the environment been regarded as any particular problem.
This situation has changed now that a number of very powerful and usually also very expensive drugs for aerosol therapy have been made available by the drugs companies. Some of these drugs are in powder form. For these types of drugs, completely different and stringent demands have been imposed on the dosing equipment. In addition, the authorities place demands on function and reliability. Attention has also been paid to loss of medicine to the environment.
BRIEF SUMMARY OF THE INVENTION
The main object of the present invention is to solve the abovementioned problems and to make available a method and an arrangement permitting reproducible and documentable production of a medical aerosol which is suitably formulated for the individual patient group and is in a correctly adjusted quantity. In addition, loss of drug to the environment is to be eliminated or minimized.
The equipment must also be easy for the patient to handle, since it is a precondition for good treatment results that the equipment be very easy to handle, even for a very sick patient. The equipment must also be able to be used for administering both medicine in liquid form and also in powder form after mixing with a liquid.
The abovementioned objects are achieved by means of a method of the type indicated in the first paragraph, which method is characterized, according to the present invention, in that the stream of gas is directed essentially at right angles to the axial extent of the liquid channel and so that at least some of this stream of gas passes across the mouth of the liquid channel and thereafter strikes a stop surface situated at a distance from the mouth, whereupon liquid particles in the resulting aerosol are broken up, with a more finely atomized, second aerosol being formed.
The combination of a gas jet passing across the mouth of the liquid channel and a stop plate downstream of the gas jet has been found to give a very finely atomized aerosol, in which, according to a preferred embodiment of the invention, the size distribution of the liquid particles can be adapted to requirements by using one or more slit-shaped passages whose sizes are determined on the basis of the desired size distribution of the liquid particles. The slit-shaped passages are in this case formed expediently between a deflector plate and a surrounding housing, with the deflector plate being arranged in such a way that it catches liquid particles in the second aerosol and returns these to the liquid in the container.
When producing an aerosol for inhalation, this aerosol is expediently produced continuously in a quantity which corresponds to, or is less than, the inspiratory volume of the patient who is to inhale the aerosol, with the aerosol formed between breaths being collected in a dosing bag which empties during the succeeding breath.
Other features of the method according to the invention and of an arrangement for use in implementing the method will become clear from the attached patent claims.
The invention will be described in greater detail below with reference to the attached drawings, which show some embodiments of the invention which have been chosen as examples.
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patent: 4674491 (1987-06-01), Brugger et al.
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Australian Patent Abstract, (11) AU-A1-63 005/80.
Hammarlund Nils
Nilsson Leif
AGA Aktiebolag
Pearne & Gordon LLP
Srivastava V.
Weiss John G.
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