Surgery – Means for introducing or removing material from body for... – Treating material applied to or removed from external...
Reexamination Certificate
1999-09-13
2004-04-27
Lewis, Kim M. (Department: 3761)
Surgery
Means for introducing or removing material from body for...
Treating material applied to or removed from external...
C604S294000, C604S296000
Reexamination Certificate
active
06726665
ABSTRACT:
This invention relates to ocular treatment devices, and particularly to a device of the kind which is operable to deliver to the eye treatment fluids in the form of a jet and/or small droplets.
Ophthalmic treatment fluids are commonly administered to the eye by means of eye drops or ointments. The use of eye drops has a number of disadvantages, primarily as a consequence of the difficulty with which drops are accepted by the patient. The drops are relatively large, and the instinctive blink that is provoked by the arrival of a drop on the eye severely limits the amount of or proportion of fluid that actually contacts the target area on the eye. Typically less than 10% of a 50 &mgr;l drop can be effective, the remainder being lost by drainage, either externally or through nasolacrimal drainage. Such use of expensive treatment fluids is wasteful, as well as leading to substantial uncertainty regarding the effectiveness of a treatment. Similar comments apply to the use of ointments, although levels of wastage can be reduced by careful delivery. The greater viscosity of ointments reduces their tendency to drain or be washed away.
In our International Patent Application No. PCT/GB95/01482 there are proposed various techniques for delivering treatment fluid to the eye. These employ systems in which treatment fluid is drawn from a reservoir and discharged in a controlled manner to the eye. While these techniques are useful, there are difficulties arising from the repeated use of the multi-dose nozzle. Specifically, it is difficult to maintain the sterility of the treatment fluid in a system in which doses of fluid are successively drawn from a reservoir, and passed through a re-usable nozzle without the use of preservatives. The use of preservatives has caused some concern as discussed on pages 8-11 of “Ophthalmic Drug Delivery Systems” (Drugs in the Pharmaceutical Sciences, Volume 58), published in 1993 by Marcel Dekker.
Reference is also directed to U.S. Pat. No. 3,934,585 which discloses a variety of mechanisms for delivering unit doses of treatment fluid to the human eye. The doses are held in dispensing tubes which are fitted in the mechanisms when treatment is required. The mechanisms are operative to apply compressed air to one end of a tube resulting in the discharge of treatment fluid from the other end.
It is an aim of the present invention to minimise or eliminate the need to use preservatives in ophthalmic treatment fluids without risking contamination. Thus, in a primary aspect, the present invention provides a unit container for a treatment fluid comprising a sealed enclosure of which one wall section thereof is formed with at least one opening, the enclosure being pressuriseable to discharge its contents through said at least one opening, which opening is of sufficient diameter to enable the generation of a jet and/or discrete droplets of treatment fluid discharged therefrom.
The wall section of a container according to the invention formed with the opening or openings is typically a flat section of the enclosure wall, and the enclosure is typically a blister pack, with the wall section at a planar base of the blister. However, we have found that some particular benefits arise from the adoption of a non-planar wall section in which the opening or openings are formed. More particularly, we have found that the adoption of a dome shape in the respective wall section can result in a more reliable performance of the containers in use, and facilitate certain other beneficial developments of the containers. Thus, in preferred embodiments of the invention, a unit container for a treatment fluid comprising an enclosure of which one wall section is dome shaped and formed with at least one opening in the top region of the dome shape, the enclosure being adapted to confine a sealed volume of treatment fluid, and pressurisable to discharge the contents of the sealed volume through said at least one opening. One or more other wall sections may also define a dome shape complementary to that with the opening, which is capable of inversion into the one wall section in the discharge of the container contents.
The enclosure of a unit container of the invention can be pressurised by the application of an external force on the side of the enclosure opposite the wall section formed with the opening or openings. Where the respective wall section is substantially flat, this method of pressurising the enclosure contents can create high stresses in the wall section, and particularly around the opening or openings. In some situations, this can result in the wall section itself tearing around the opening or openings with the consequence that the discharge of the enclosure contents becomes less predictable. By locating the opening or openings at the top of a dome shape, these stresses are reduced.
Either a single opening or an array of openings may be found in the respective wall section of the container. Various arrays are possible, and a particular choice will be influenced by a number of factors. A larger number of openings will dispense treatment fluid over a larger target area. Smaller openings produce narrower jets and/or smaller drops which will be subject to greater deceleration in their passage to the target area. This may allow the use of higher pressures. A single opening can direct a jet or stream of drops accurately to a specific target area, and minimise the time taken to deliver the treatment fluid to beat the blink response. The preferred minimum opening diameter is at least 10 &mgr;m to avoid creating a spray of droplets with insufficient linear momentum to reach their target. The use of a single opening of 100 &mgr;m diameter is particularly preferred. The intention is to create droplets no smaller than say 20 &mgr;m to avoid the creation of an inhalable spray.
Another-benefit arising from the adoption of a dome shaped wall section in which the opening or openings are defined is that discharge of substantially the entire contents of the enclosure is facilitated. If the device used to pressurise the enclosure is a piston or hammer, its operative end can be shaped to complement that of the dome such that in operation the other wall sections of the enclosure, which can similarly be shaped to complement that of the dome, are inverted against the dome shaped wall section thus substantially evacuating the entire enclosure.
The wall section of the enclosure in a container of the invention may be provided with a removable cover overlaying the opening or openings, which cover is only removed just prior to the contents of the enclosure being discharged. In this way, the contents are protected from the environment until required. In an alternative arrangement the or each opening in the wall section of the enclosure is closed by a membrane adapted to rupture upon pressurisation of the enclosure. These means demonstrate how treatment fluids can be kept sterile in containers of the invention. As a consequence, the need for the use of preservatives in the contents is minimised or eliminated.
The use of a dome wall section in preferred containers of the present invention facilitates the creation of a separate sealed volume within the enclosure. In these circumstances, the removable cover overlaying the opening or openings can be dispensed with, or at least the requirements for its sealing qualities can be reduced. According to this aspect of the invention, which can of course also be applied to a container without a dome shaped wall section with the opening or openings, a dividing wall is included within the enclosure, which dividing wall separates the wall section with the opening or openings from a region within the enclosure which defines the sealed volume. The dividing wall is adapted to rupture prior to discharge of the contents from the enclosure. Conveniently, the dividing wall can be adapted to rupture upon pressurisation of the enclosure as part of the step of discharging the contents of the sealed volume through the opening or openings in the wall section. However, the dividing wall m
Embleton Jonathan K.
Houzego Peter J.
Jones Stephen P.
Malcolmson Richard J.
Martini Luigi G.
Lewis Kim M.
McDonnell Boehnen Hulbert & Berhoff
Pharmacia Aktiebolag
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