This invention relates to spacer devices for metered dose inhalers for administering medications.
Metered dose inhalers (MDI) are used for administering medications, such as bronchodilator drugs and corticosteroids, to the lungs.
The canister 92 holds a reservoir 97 of medication and is pressurized with a propellant. A metering valve 93 is located at the bottom of the canister 92 and the medication flows out through a stem 91. The user loads the canister 92 into the boot portion 94 of the actuator 99 such that the stem 91 fits into the spray nozzle 95. When the user presses down on the canister 92, the valve stem 91 presses into the spray nozzle 95, causing it to discharge a preset amount of medication as an aerosolized spray 98 out of the mouthpiece 96 for delivery into the user's lung. When used properly, the user inhales the aerosolized medication 98 through the mouth and into the bronchial passageways of the lungs.
However, MDIs are not very efficient at drug delivery; they deliver only about 10% of the dose to the lungs, with the rest being deposited elsewhere, such as the oropharynx. This is because pressurized MDIs generate an aerosol spray with a velocity that is faster than the patient can inhale. This puts a lot of demand on the users' performance to synchronize their inhalation with the spray actuation in order to release the aerosol spray at the beginning of inhalation. This problem is particularly acute in children and the elderly. With the lack of proper synchronization, instead of being inhaled into the lung, much of the sprayed medication may be deposited onto the back of the mouth or pharynx. In addition to loss of therapeutic effectiveness, this can cause cough, voice hoarseness, fungal infections, and absorption of the medication into the bloodstream.
Because of these difficulties, many patients are advised to use a spacer that is fitted to the mouthpiece of the MDI to overcome some of the problems of poor coordination and oropharyngeal deposition. Spacers work by lengthening the distance between the actuator mouthpiece and the user's mouth, thus giving the user more time to synchronize inhalation and reducing the impaction onto the oropharynx. Also, evaporation of spray solvent would decrease the size of particles, facilitating more deposition in the lungs and better penetration to peripheral airways.
The one-way valve 58 allows the user to inhale the medication through the spacer 54. In case the user exhales, the one-way valve 58 would act to divert the exhaled breath outward rather than entering the chamber 56. Some spacers are also equipped with a whistle as a flow rate indicator, i.e. making a whistling sound if the user is inhaling too quickly.
Yet, there are still problems with existing spacers. There is a tradeoff between size and effectiveness. Spacers can have a compact design, but those are too short and small to be effective. More complex spacer designs, such as the valved holding chambers (VHC), have a wider and longer barrel to improve drug delivery effectiveness, but the problem is that they are too bulky, making them inconvenient to carry around. This is a very serious problem for patients who must carry around their MDIs at all times for acute asthma attacks. Because they are so bulky, MDI users often leave their spacers at home instead of carrying it with them. Thus, there is a need for a spacer device that is compact, sanitary, and easy-to-carry, yet large enough for effective drug delivery.
The present invention provides a compact spacer device for a metered dose inhaler. In one aspect, the present invention is a spacer device for a metered dose inhaler (MDI). The spacer device has a proximal end and a distal end. The proximal/distal designation is made with proximal being towards the user and distal being away from the user. The spacer device may be made as a single unitary structure, or its various segments may be separate parts that are joined together.
Aerosol Chamber: The spacer device comprises an aerosol chamber for holding the aerosolized medication sprayed from the MDI. The aerosol chamber comprises a fixed barrel and a sliding barrel. The fixed barrel is located distal to the sliding barrel. The fixed barrel comprises a double-wall, i.e. two tubular shells that are separated by a narrow gap, i.e. alleyway. The fixed barrel comprises an outer shell and an inner shell which are in coaxial alignment. The outer shell and the inner shell may together form a unitary structure, or they may be separate pieces that are joined together to work cooperatively in the manner described herein.
The sliding barrel is coupled to the fixed barrel by a telescoping arrangement within the alleyway between the outer shell and inner shell of the fixed barrel. Thus, the aerosol chamber is designed such that the sliding barrel can telescope in and out of the fixed barrel. When fully retracted, the sliding barrel is contained inside the alleyway between the outer shell and inner shell. This puts the aerosol chamber (and spacer device) in compact configuration.
In preparation for use, the sliding barrel is pulled out of the fixed barrel. The sliding barrel slides out from the alleyway between the double-walls of the fixed barrel. When the sliding barrel is fully telescoped out, this puts the aerosol chamber (and spacer device) in extended configuration.
The fixed barrel or sliding barrel could be made of a hard plastic material. The fixed barrel or sliding barrel could have any suitable transverse cross-sectional shape, such as circular, oblong, oval, rounded square, etc. (which may be symmetrical or asymmetrical). Both the fixed barrel and sliding barrel may have matching shapes to allow for telescoping alignment.
MDI Adapter: In use, the MDI is attached to the distal end of the spacer device. The spacer device comprises an MDI adapter to mate the MDI to the aerosol chamber (and spacer device). The MDI adapter could have any suitable design to serve that function. The MDI adapter may be made of any suitable material that is softer and more flexible than the fixed barrel or sliding barrel. For example, it could be made of a soft elastomeric plastic material such as silicone or polyurethane.
The MDI adapter has a fastening means for securing the MDI to the spacer device. For example, the fastening means could be a strap that wraps around the MDI and attaches back onto the MDI adapter. This fastening means helps the user in handling the spacer device and MDI as a single unitary assembly. Also, having the MDI coupled to the spacer device with the fastening means gives the user a perception that this combined assembly is intended to work as a single unit (instead of using the MDI separately). That is, it helps educate and remind the user that (in general) the MDI should always be used with a spacer to improve overall medication efficacy. These factors help improve user compliance in properly using the MDI with the spacer device.
In some embodiments, the fastening means comprises a strap mount and an MDI strap extending from the strap mount. In use, the strap is wrapped around the MDI and could be secured by any suitable means. For example, the strap could have holes that hook onto a strap hook on the strap mount. Other examples of fastening means could use components such as anchoring knobs, through-holes for mating, elastic bands, plastic ties, harnesses, latches, hooks, snaps, Velcro (hook-and-loop fastening), etc.
The MDI adapter may have an adaptor ring for attaching to the distal end of the fixed barrel. The MDI adapter has a rear opening for receiving the spray outlet of the MDI. In some embodiments, the MDI adapter comprises a rigid subframe that is more rigid than the main body of the MDI adapter.
Zero Draft Construction: The construction of the fixed barrel or sliding barrel may have some special characteristics. One or more parts of the fixed barrel may be constructed by zero draft molding. To specifically define the structural result of this type of construction, define a point A and point B on the inner shell or the outer shell of the fixed barrel. The distance between the selected points A and B is 3.0 cm. The thickness of the shell (inner or outer) is substantially or essentially the same at both points. That is, the thickness at point B differs from the thickness at point A by an amount that is less than 8% of the thickness at point A.
In some embodiments, the inner shell has zero draft construction whereas the outer shell does not have zero draft construction. That is, the thickness of the outer shell at point A and point B are different (not essentially the same). In some embodiments, both the inner shell and the outer shell have zero draft construction on their inside surfaces, but have draft angles on their outside surfaces. That is, the thickness of both the inner shell and outer shell at point A and point B are different. However, because of the zero draft construction on their inside surfaces, the alleyway therebetween has constant width.
Likewise, the sliding barrel could be constructed by zero draft molding. To specifically define the structural result of this type of construction, define a point A and point B on the sliding barrel. In this case, the thickness of the sliding barrel is substantially or essentially the same at both points. That is, the thickness at point B differs from the thickness at point A by an amount that is less than 8% of the thickness at point A.
The spatial relationship between the fixed barrel and the sliding barrel may have one or more special features. These spatial relationships could be defined by measurement on a longitudinal cross-section side view of the fixed barrel and the sliding barrel, which delineates the walls thereof. In some embodiments, when the sliding barrel is completely retracted into the fixed barrel, the wall of the sliding barrel has an incline angle relative to the inner shell, the outer shell, or both. This incline angle is very small, such as in the range of 0.3 to 3°. Another way of specifying the incline is to measure the difference in the outer gap, which is the width of the gap between the inner surface of the outer shell and the outer surface of the sliding barrel, when the sliding barrel is fully retracted inside the fixed barrel. Referring to the selected points A and B above, where point A is located distal to point B, the outer gap at point A is wider than the outer gap at point B. In some cases, the outer gap at point A is at least 25% wider than the outer gap at point B.
Alleyway: The fixed barrel could be designed such that the width of the alleyway between the outer shell and inner shell has substantially or essentially constant width. For the purpose of defining this constant-width feature of the alleyway, specify a point A and point B on the fixed barrel. The distance between the selected points A and B is 3.0 cm. In some embodiments, the width of the alleyway between the outer shell and inner shell of the fixed barrel is substantially or essentially the same at both points. That is, the width of the alleyway at point B differs from the width at point A by an amount that is less than 8% of the width at point A.
Cushion Bumper: The cushion bumper on the MDI adapter could be specially designed to work with an MDI having an angled shape. For this, the cushion bumper could have an inclined angle so that it can conform to the shape of the MDI. This inclined angle may vary to accommodate the different angles of the various types of MDIs that are available. The elevation of the cushion bumper relative to the strap mount decreases along the direction towards the central longitudinal axis of the spacer device. For the purpose of defining this inclined angle feature of the bumper, specify a point J and point K on the bumper such that point K is located closer to the central longitudinal axis of the spacer device than point J. The distance between the selected points J and K is 0.75 cm. Because of the inclined angle, the elevation of the cushion bumper at point J is higher than the elevation at point K.
Dimensions: There are a range of dimensions suitable for design of the spacer device and its various components. As an example, the full length of the aerosol chamber may be in the range of 3-15 cm in compact configuration and 6-20 cm in extended configuration. As an example, the inner diameter of the fixed barrel or sliding barrel may be in the range of 2-7 cm wide.
Method of Use: In another aspect, the present invention is a method of using an MDI with a spacer device of this invention. The method comprises having an MDI and a spacer device of this invention. The MDI is attached to the spacer device by inserting the spray outlet of the MDI into the rear opening of the MDI adapter. The fastening means of the MDI adapter is used to secure the MDI to the spacer device. In relevant embodiments, the MDI adapter comprises a strap that is wrapped around the MDI to secure the MDI to the spacer device. In relevant embodiments, the strap is hooked onto a strap hook on the MDI adapter.
The sliding barrel is pulled out of the fixed barrel to put the spacer device in extended configuration. In relevant embodiments, the user removes the mouthpiece cap to expose the spacer device mouthpiece. This also frees the sliding barrel from the tether restraint. The user inserts the mouthpiece of the spacer device into their mouth and actuates the MDI. After use, the sliding barrel is pushed back into the fixed barrel to put the spacer device in compact configuration. If relevant, the mouthpiece cap is put back onto the spacer device mouthpiece to cover it and keep the spacer device in compact configuration.
To assist in understanding the invention, reference is made to the accompanying drawings to show by way of illustration specific embodiments in which the invention may be practiced. The drawings herein are not necessarily made to scale or actual proportions. For example, lengths and widths of the components may be adjusted to accommodate the page size.
At its distal end, the spacer device further comprises an MDI adapter 20 designed to hold the MDI (not shown here) to the aerosol chamber of the spacer device. The MDI adapter 20 is a single piece that has several parts, including an adapter ring 22, a strap mount 24, a strap hook 26, an MDI strap 28, strap holes 27, and cushion bumpers 29. The adapter ring 22 is fitted onto the distal end of the fixed barrel 10. This fastens the MDI adapter 20 to the aerosol chamber. Strap mount 24 protrudes upward from the adapter ring 22. MDI strap 28 extends laterally from strap mount 24. In use, the MDI (not shown) is secured to the MDI adapter 20 by MDI strap 28. The MDI (not shown) is inserted into a rear opening of the MDI adapter 20 that is designed to receive and fit snugly around the mouthpiece of the MDI. The MDI adapter 20 is made of soft plastic (e.g. silicone) to promote a snug fit around the mouthpiece of the MDI. To secure the MDI to the MDI adapter 20, the MDI strap 28 is wrapped around the MDI and hooked onto strap hook 26 at one of the several strap holes 27. By this fastening mechanism, the MDI is pressed against the cushion bumpers 29, which may be useful to dampen loose rattling of the MDI.
There is a one-way check valve 42 that allows the user to inhale the aerosolized medication in the aerosol chamber. But in case the user exhales, the one-way valve 42 diverts the exhaled breath outward rather than entering the aerosol chamber. See also MDI opening 48 that receives the mouthpiece of the MDI. See also a vent hole 44 that allows necessary airflow when the patient inhales the aerosolized medication. The vent hole 44 is covered with a free swinging vent flap to prevent debris intrusion into the aerosol chamber. This vent flap is designed to swing inward into the aerosol chamber, but not outward.
The user then inserts the spacer device mouthpiece 14 into the user's mouth for inhaling the aerosolized medication. After finishing treatment, the user collapses the spacer device by pushing sliding barrel 12 back into fixed barrel 10, and then puts the mouthpiece cap 30 back onto spacer device mouthpiece 14.
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The inner shell 40 of fixed barrel 10 and the sliding barrel 12 are mold-constructed with no draft angle. This makes the manufacturing process more difficult, but results in providing a better sealing engagement. Because sliding tube 12 has uniform thickness, its outer surface is in continuous contact with the outer shell 40 to provide a sealing edge at all telescoping positions. For the purpose of defining this zero draft angle feature in numeric terms, on the inner shell 40 of the fixed barrel 10, there is a point A and point B that are separated by a distance of 3 cm. The thickness of the inner shell 40 at point A and point B are essentially the same. Likewise, on sliding barrel 12, there is a point A and point B that are separated by a distance of 3 cm. The thickness of sliding barrel 12 at point A and point B are essentially the same.
The inner and outer shells do not have to be constructed with zero draft on all sides to achieve a constant-width alleyway between the inner and outer shells.
The width of this alleyway 126 is constant throughout, except for minor accessory features like ridges or bumps. For the purpose of defining this constant-width feature, again consider point A and point B which are separated by a distance of 3.0 cm. The width P of alleyway 126 at point A is substantially the same as width S at point B. Note that complete zero draft construction is not needed to have this constant-width feature. A disadvantage of zero draft molding is that it makes the manufacturing process more difficult. In particular, note that outer shell 122 has a tapered draft angle on the outside (see compared to dashed line), but zero draft angle for the inside surface. Likewise, inner shell 124 has a tapered draft angle on the outside (see compared to dashed line), but zero draft angle for the inside surface.
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Three prototypes of the device were made and benchtop testing performed in comparison against a comparable predicate spacer device. The following aerosol tests were performed by conventional cascade impactor techniques using a solution of albuterol sulfate as the test drug. The following parameters were measured for the amount of drug expelled by the spacer devices: total drug amount expelled, total respirable drug amount expelled, coarse drug particle amount, fine drug particle amount, and ultra-fine drug particle amount. In comparison to the predicate spacer device, the prototype devices expelled (per burst) 11% more total drug dose amount, 4% more total respirable drug dose amount, 32% more coarse particle amount, 10% more fine particle amount, and 61% more ultra-fine particle amount. Thus, by all parameters, the prototype devices outperformed the predicate device.
The descriptions and examples given herein are intended merely to illustrate the invention and are not intended to be limiting. Each of the disclosed aspects and embodiments of the invention may be considered individually or in combination with other aspects, embodiments, and variations of the invention. In addition, unless otherwise specified, the steps of the methods of the invention are not confined to any particular order of performance. Modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, and such modifications are within the scope of the invention.
Any use of the word “or” herein is intended to be inclusive and is equivalent to the expression “and/or,” unless the context clearly dictates otherwise. As such, for example, the expression “A or B” means A, or B, or both A and B. Similarly, for example, the expression “A, B, or C” means A, or B, or C, or any combination thereof.
Number | Date | Country | |
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63378299 | Oct 2022 | US |