Abstract:
A method and apparatus for making a patch comprising a foam supplier for supplying a foam backing having a predetermined porosity, a dispensing device for applying an ointment to the foam backing in a predetermined pattern, and a cooling device for cooling the foam backing prior to application of the ointment, wherein the ointment thickens and cures upon contact with the cooled foam backing.

Description:
In accordance with 35 U.S.C. § 119(e), the benefit of provisional application Ser. No. 60/051,057, filed Jun. 27, 1997, is hereby claimed. The entire contents of this provisional application are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an improved method of making a patch to be applied to the skin. This invention further relates to an apparatus for making a patch. 
     BACKGROUND OF THE INVENTION 
     Many variations of patches have been used for applying medication topically, either for local or systematic effect. For example, U.S. Pat. No. 5,536,263 describes a non-occlusive medication patch to be applied to the skin including a porous self-supporting backing layer and a flexible hydrophilic pressure-sensitive adhesive reservoir comprising a hydrocolloid for sustained release of medication to be absorbed topically through the skin. U.S. Pat. No. 5,536,263 teaches that the porosity of the backing layer is important because it provides openings for receiving the medication-containing hydrocolloid reservoir and helps to assure that the patch is non-occlusive. Further, the infusion of the hydrocolloid medication-containing reservoir into the backing sheet is accomplished by controlling manufacturing parameters to keep the hydrocolloid sufficiently fluid to penetrate the backing sheet despite its tendency to thicken rapidly when applied. In order to prevent the hydrocolloid from becoming too viscous to penetrate the backing sheet, the device which applies the hydrocolloid is chilled to remove heat and to keep the hydrocolloid cool. Therefore, U.S. Pat. No. 5,536,263 teaches cooling an application device to lower viscosity of a medication-containing hydrocolloid within the device. 
     U.S. Pat. No. 5,635,201 discloses a method and apparatus for manufacturing a wound dressing. The method includes coating an upper surface of a perforated carrier material with a curable silicone mixture, blowing cold air onto the underside of the carrier material, and applying heat to the silicone mixture until it is cured to a silicone gel. The cold air is applied by an air blowing unit to remove an applied silicone mixture from perforations in the carrier material, thereby maintaining the porosity of the wound dressing. The cold air further prevents the silicone mixture from curing before it has time to spread over the carrier material. Thus , U.S. Pat. No. 5,635,201 teaches cooling a silicone mixture applied to a carrier strip to prevent curing of the silicone mixture. 
     One problem that occurs when manufacturing patches, and in particular non-occlusive patches, is undesired spreading of medication-containing ointment when the ointment is heated to a low viscosity for application to a porous backing sheet of a patch. Ointments are not water/solid emulsions and therefore have different properties than a hydrogel and react in a different manner than a hydrogel when heated and cooled. The term “ointment” as used in this application is used in a conventional sense in pharmacy and refers to a material that is semi-solid at room temperatures and softens, but not necessarily melts, at higher temperatures (e.g., when applied to the skin). The term medication is used in the sense of any bioactive agent. 
     Since an applied ointment fills the pores of a porous backing sheet in the area over which it is spread, the greater the surface area covered by the ointment, the less porous the backing sheet. A less porous backing sheet is undesirable because it makes the patch more occlusive and allows less moisture evaporation from the patient&#39;s skin. Lessening moisture evaporation can cause accumulation of water and could cause the patch to fall off. In addition, accumulation of water could cause the growth of bacteria beneath the patch and patient discomfort. 
     Increased heating of the medication-containing ointment lowers the viscosity of the ointment and thereby increases flow rate of the ointment through an ointment dispenser. Increased flow rate through the ointment dispenser can allow increased production speed and therefore a greater patch yield. However, increased heating of the ointment also increases undesired spreading of the ointment and decreases porosity as described above. 
     The problems identified above are not intended to be exhaustive but are among the many that reduce the effectiveness of current solutions to the problem of applying medication-containing ointment to a porous backing layer without decreasing porosity of the porous backing layer beyond a desired level; however, the problems presented above should be sufficient to demonstrate that currently known solutions are amenable to worthwhile improvement. 
     SUMMARY OF THE INVENTION 
     Accordingly, it would be desirable to provide an apparatus for making a non-occlusive patch which prevents unwanted spreading of a heated medication-containing ointment when the ointment is applied to a porous backing. 
     It would also be desirable to provide an apparatus for making a non-occlusive patch which prevents unwanted spreading of a heated medication-containing ointment using a low-cost enhancement of standard patch-making components. 
     It would also be desirable to provide a method of making a non-occlusive patch which prevents unwanted spreading of a heated medication-containing ointment, when the ointment is applied to a porous backing, using a simple procedure. 
     The present invention provides an apparatus for making a patch comprising a foam supplier for supplying a foam backing having a predetermined porosity; a dispensing device for applying an ointment to the foam backing in a predetermined pattern; and a cooling device for cooling the foam backing prior to application of the ointment, wherein the ointment thickens and cures upon contact with the cooled foam backing. 
     The present invention also provides a method of making a patch comprising the steps of providing a foam backing having a predetermined porosity; applying an ointment to the foam backing in a predetermined pattern; and cooling the foam backing prior to application of the ointment to increase thickening and curing of the applied ointment upon contact of the applied ointment with the cooled foam backing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment of the invention, and, together with the general description given above and the detailed description of the preferred embodiment given below, serve to explain the principles of the invention. 
     FIG. 1 is a schematic side view of the apparatus for making a non-occlusive patch provided by the invention; and 
     FIG. 2 is a top view of a porous backing sheet with medication-containing ointment applied thereto by the apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the figures, like numerals indicate like parts. FIG. 1 shows an improved apparatus for making a non-occlusive patch. In the apparatus, a double sided adhesive unwind  10  can consist of, for example, a constant tension unwind with an adjustable spring loaded dancer arm for adjusting the tension level. The double sided adhesive unwind  10  feeds a double sided adhesive  12  to a center cut-out punch die station  14 . Preferably, a web stop air cylinder is used to control registration of the double sided adhesive into the center cutout punch die station  14 . The center cut-out punch die station  14  cuts out a predetermined area inside the double-sided adhesive  12  for receiving a medication-containing ointment. The center cut-out punch die station  14  can be operated with, for example, a pneumatic cylinder equipped with a rode guided counter lever section for mounting top and bottom halves of the die. 
     A bottom adhesive backing rewind  16  takes up a bottom release liner  18  of the double sided adhesive  12  with controlled tension as the bottom-exposed adhesive of the double sided adhesive  12  is fed to a pressure roll station  24 . 
     The pressure roll station  24  laminates the bottom-exposed adhesive of the double sided adhesive  12  to a foam backing  26  at a predetermined laminator nip roll pressure. The pressure roll station  24  can be driven, for example, by a servo motor or by the foam web. After the bottom-exposed adhesive of the double sided adhesive  12  has been laminated to the foam backing  26 , a top adhesive backing rewind  20  takes up the top release liner  22  of the double sided adhesive  12  with controlled tension. The foam backing  26  is supplied to the pressure roll station  24  by a foam backing unwind  28 . The foam backing unwind  28  may consist of, for example, a constant tension unwind with an adjustable spring loaded dancer arm for adjusting the tension level. 
     The laminated foam backing  30  is then fed to a cooling device  32  positioned just before a dispensing die  34 . The cooling device  32  may comprise, for example, a cooling plate which lies below the laminated foam backing  30  and provides cooling by pumping chilled water or other cooling media through an aluminum plate. A stream of Nitrogen or any other inert gas directed through a manifold positioned adjacent, above, beneath or around the laminated foam backing  30  could also be used either in conjunction with a cooling plate or separately. Other possible embodiments of the cooling device  32  include an air blower provided above, below or around the laminated foam backing  30  to supply cool air, a refrigeration unit through which the laminated foam backing  30  is fed, or any other like means of cooling the laminated foam backing  30 . 
     The dispensing die  34  dispenses medication-containing ointment through, for example, a predetermined slot pattern in a dispensing head. The dispensing die  34  may be used, for example, in conjunction with an IVEK metering pump  36  having a temperature control system to dispense a controlled pattern of medication-containing ointment onto the laminated foam backing  30  within the cut-out section of the double sided adhesive now laminated to the foam backing. The exact location of the ointment may be controlled by, for example, a predetermined program written for a programmable controller. 
     Before being dispensed by the dispensing die  34 , the medication-containing ointment is heated to a desired viscosity, for example to a temperature of between 55 and 65 degrees Celsius by a blend hopper  38  to decrease viscosity of the ointment. This decreased viscosity enables the dispensing die  34  to dispense an accurate and controlled amount of medication-containing ointment through the predetermined slot pattern onto the laminated foam backing  30 . 
     The cooling device  32  pre-cools the laminated foam backing  30  to help prevent undesired spreading of the medication-containing ointment and to control the ointment pattern on the laminated foam backing  30 . 
     The cooling plate may be provided with, for example, a vertical adjuster to adjust the height of the laminated foam backing  30  in relation to the dispensing head of the dispensing die  34 . Adjustment of the foam backing height in relation to the dispensing head allows for further control of the pattern of medication-containing ointment dispensed onto the laminated foam backing  30  and further prevents undesired spreading of the ointment. 
     As can be seen in FIG. 2, one embodiment of the ointment pattern can be plural lines  100  of droplets of ointment dispensed by the slots of the dispensing head onto the laminated foam backing  30 . Any number of lines may be used, and the droplet thickness may vary depending on the desired amount of medication to be applied. The droplets may be applied with little or no gap between successive droplets. The lines of droplets may further be cross-hatched. Other possible shapes could be circles, a series of concentric circles, ovals, etc. It must be recognized, though, that whatever predetermined pattern is chosen for application of the medication-containing ointment, a minimal surface area should be covered by the medication-containing ointment to maintain a high porosity of the foam backing and therefore avoid occlusiveness of the patch in order to decrease moisture build-up under the resulting patch and therefore increase patient comfort and safety from bacteria, and ensure patch adhesiveness. 
     When the foam backing is cooled, the temperature of the dispensed medication-containing ointment is decreased upon contacting the foam backing  30  and therefore the viscosity of the dispensed medication-containing ointment is increased. Increasing viscosity of the ointment decreases spreading of the ointment over the surface area of the foam backing  30 . Upon contacting the cooled foam backing  30 , the outer sides of the dispensed medication-containing ointment are cured and therefore spreading of the ointment over the surface area of the foam backing  30  is further decreased. Decreased spreading helps maintain a maximum porosity of the foam backing  30 , and therefore precludes occlusiveness of the patch in order to increase patient comfort and safety from bacteria, and ensure patch adhesiveness. 
     The blend hopper  38  is provided for maintaining the medication-containing ointment at a controlled temperature and supplying the medication-containing ointment to the IVEK metering pump  36 . A top cap of the blend hopper  38  may be provided with a port (not shown) for charging ointment to the blend hopper  38 . 
     After the medication-containing ointment has been dispersed onto the laminated foam backing  30  by the dispensing die  34 , the laminated foam backing  30  is led to a backing unwind  40  that provides a release liner  42  at a controlled tension for covering the area of dispensed medication-containing ointment on the laminated foam backing  30 . Slight pressure is provided to help adhere the release liner  42  to the laminated adhesive on the foam backing  30 . The release liner may comprise, for example, silicon. 
     Prior to applying pressure to adhere the release liner  42  to the laminated foam backing  30 , a tear notch is cut into the release liner  42  using a tear notch station  44 . The tear notch station  44  consists of a blade mounted at a 45 degree angle to the release liner  42 . The tear notch station  44  may be operated, for example, with a pneumatic cylinder equipped with a rod-guided counter-lever section for holding the tear notch blade. 
     After application of the release liner  42 , the laminated foam backing  30  is led to a patch drive station  46 . The patch drive station  46  pulls the laminated foam backing, which at this point includes the applied medication-containing ointment and the release liner, through a packaging machine. The driving force may be provided, for example, by rubber drive rolls positioned to lie on either side of the laminated foam backing  30 . 
     After the laminated foam backing  30  passes through the patch drive station  46 , a foam backing liner rewind  48  pulls a paper liner  50  from the laminated foam backing  30  at a constant tension which may be provided, for example, by a pneumatic break clutch. 
     After removal of the paper liner  50 , the laminated foam backing  30  is led to a unit die cut station  52 . The unit die cut station  52  cuts a finished unit out of the laminated foam backing, which at this point includes the applied medication-containing ointment and the release liner. The unit die cut station  52  comprises a male part of the die and a female part of the die. The male part of the unit die  52  cuts the unit from the bottom to introduce the unit to a pick and place station  54 . The unit die cut station  52  may be operated with, for example, a pneumatic cylinder equipped with a rod-guided counter-levered section for holding the male and female parts of the die. 
     Prior to introduction to the pick and place station  54 , a scrap rewind  56  takes up an unused portion  58  of the foam web at a constant tension. The scrap rewind  56  maintains the foam web position at the unit die cut station  52  prior to and after the unit is die cut from the foam web. 
     The pick and place station  54  picks the die cut unit from the top of the male part of the die and transfers it to a bottom pouch foil  60 . The pick and place station  54  may be operated, for example, with a stepper motor drive operating a reciprocating pick arm with a vacuum suction cup attached. 
     A bottom foil unwind  62  provides the bottom pouch foil  60 . A top foil unwind  64  provides the bottom pouch foil  66 . The bottom and top pouch foils  60 , 66  provide a foil pouch with the die cut unit inside. The bottom and top foil unwinds  62 , 64  may use, for example, pneumatically controlled tension clutches for maintaining controlled tension to the pouch foils  60 ,  66 . 
     The foil pouch is led to a pouch seal station  68  which hermetically seals the top pouch foil  66  to the bottom pouch foil  60  with the die cut unit inside using a seal die. A rubber base may be provided beneath the seal die for forming a seal area around the pouch. The pouch seal station  68  may be operated, for example, with a pneumatic cylinder equipped with a rod-guided counter-levered section for holding the seal die and the rubber base in place. 
     A foil drive station  70  pulls the pouch foil through the pouch seal station  68  and to a pouch cut station  72 . The foil drive station  70  can be driven, for example, by a servo motor. The foil drive station  70  provides registration needed to ensure that the finished units are not located in the seal area of the pouch. If the finished units get caught in the seal area of the pouch, a hermetic seal cannot be achieved by the pouch seal station  68 . 
     The pouch cut station  72  cuts the sealed and registered pouches into a finished pouch system (finished product) and comprises a male die part and a female die part. The die may be operated, for example, with a pneumatic cylinder equipped with a rod-guided counter-levered section for holding the male and female die parts in place. 
     The finished product falls from underneath the pouch cut station  72  into, for example, a box or a registered conveyor section. 
     Other embodiments of the method and apparatus for making a non-occlusive patch will be apparent to those skilled in the art from consideration of the specification disclosed herein. It is intended that the specification be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.