Review on: THE PHARMACEUTICAL PACKAGING
The end –folder wrapper is formed by pushing the product into a sheet of over wrapping film, which forms the film around the product and folds the edges in a gift-wrap fashion. The folded areas are sealed by pressing against a heated bar. Because of the overlapping folding sequence of the seals, the film used must be heat –sealable on both surfaces. Materials commonly used for this application are cellophane and polypropylene. Cellophane, which is regenerated cellulose ,is not inherently heat-sealable but requires a heat-seal coating to impart heat-sealing characteristics to the film. This is usually accomplished by coating the cellophane with either polyvinylidene chloride (PVDC)or nitrocellulose. . The PVDC provides a durable moisture barrier , PVDC coated cellophane is often used for the over wrapping of products that are sensitive to moisture . To be tamper-resistant, the over wrap must be well sealed and must be printed or uniquely decorated. If the print of the carton being over wrapped is coated with a heat-sensitive varnish, it causes the over wrap to bond permanently to the paperboard carton during the sealing of the over wrap.
PHOTO 5.2: END FOLDED WRAPPER
5.3.3-Fin seal wrapper:
Unlike the end folded wrapper configuration, fin seal packaging dose not require the product to act as a bearing surface against which the over wrap is sealed. The seal are formed by crimping the film together and sealing together the two inside surface of the film, producing a "fin" seal Since the seals are formed by compressing the material between two heater bars rather than sealing against the package. When more consistent and greater sealing pressure is applied, better seal integrity can be accomplished .For this reason, fin sealing has primarily been used when protective packaging is critical . Since the surface of the heat seal dose not come in contact with the heated sealing bars on the packaging equipment, much more tenacious heat sealants such as polyethylene can be used. With good seal integrity, the over wrap can be removed or opened only by tearing the wrapper.
PHOTO 5.3: FIN SEAL WRAPPER
Film over wrapping can also be accomplished with the use of a shrink wrapper .The shrink wrap concept involves the packaging of a product in a thermoplastic film that been stretched and oriented during its manufacture and that has the property of reverting back to its un-stretched dimension once the molecular structure is "unfrozen " by the application of heat. The shrink wrap concept has a diversity of uses in packaging, one of which is its use as an over wrap .In this case ,the shrink film is usually used in roll form ,with the center folder in the direction of winding .As the film unwinds on the over wrapping machine ,a pocket is formed in the center fold of the sheet ,into which the product is inserted .An L-shaped sealer seals the remainder of the over wrap and trims off the excess film .The loosely wrapped product is then moved through a heated tunnel ,which shrink the over wrap into a tightly wrapped unit The material commonly used for this application are heat –shrinkable grades of polypropylene, polyethylene, and poly vinyl chloride. Since the various heat-shrinkable grades of film have different physical characteristic such as tear and tensile strength, puncture resistance, and shrinking forces, selection of the particular material used must be based upon specific product consideration so that the shrink wrap provides suitable integrity without crushing or damage the product. The major advantages of this type of wrapper are the flexibility and low cost of the packaging equipment required.
PHOTO 5.4: SHRINK WRAPPER
When one thinks of unit dose in pharmaceutical packaging, the package that invariably comes to mind is the blister package. This packaging mode has been used extensively for pharmaceutical packaging for several good reasons. It is a packaging configuration capable of providing excellent environmental protection, coupled with an esthetically pleasing and efficacious appearance. It also provides user functionality in terms of convenience, child resistance, and now, tamper resistance.6
The blister package is formed by heat-softening a sheet of thermoplastic resin and vacuum-drawing the softened sheet of plastic into a contoured mold. After cooling, the sheet is released from the mold and proceeds to the filling station of the packaging machine. The semi-rigid blister previously formed is filled with product and lidded with a heat-sealable backing material. The backing material, or lidding, can be of either a push-through or peelable type. For a push-through type of blister, the backing material is usually heat-seal-coated aluminum foil. The coating on the foil must be compatible with the blister material to ensure satisfactory sealing, both for product protection and for tamper resistance. Peelable backing materials have been used to meet the requirements of child-resistant packaging. This type of backing must have a degree of puncture resistance to prevent a child from pushing the product through the lidding and must also have sufficient tensile strength to allow the lidding to be pulled away from the blister even when the lidding is strongly adhered to it. To accomplish this, a material such as polyester or paper is used as a component of the backing lamination. Foil is generally used as a component of the backing lamination if barrier protection is a critical requirement; however, metallized polyester is replacing foil for some barrier applications. A peelable sealant compatible with the heat-seal coating on the blister is also required since the degree of difficulty of opening is a critical parameter for child-resistant packaging. The use of peelable backing materials for blister packaging must be carefully evaluated to ensure that peelstrengths are sufficient to meet tamper-resistance objectives.
Materials commonly used for the thermo-formable blister are poly vinyl chloride (PVC), PVC/polyethylene combinations, polystyrene, and polypropylene. For commercial reasons and because of certain machine performance characteristics, the blisters on most unit dose packages are made of polyvinyl chloride. For added moisture protection, polyvinylidene chloride (saran) or polychlorotrifluoroethylene (Aclar) films may be laminated to PVC. The moisture barrier of PVC/Aclar is superior to that of saran-coated PVC, especially under prolonged and extremely humid storage conditions.
PHOTO 5.5: BLISTER PACKAGING MACHINE
A strip package is a form of unit dose packaging that is commonly used for the packaging of tablets and capsules. A strip package is formed by feeding two webs of a heat-sealable flexible film through either a heated crimping roller or a heated reciprocating plate. The product is dropped into the pocket formed prior to forming the final set of seals. A continuous strip of packets is formed, generally several packets wide depending on the packaging machine's limitations. The strip of packets is cut to the desired number of packets in length. The strips formed are usually collated and packaged into a folding carton. The product sealed between the two sheets of film usually has a seal around each tablet, with perforations usually separating adjacent packets. The seals can be in a simple rectangular or "picture-frame" format or can be contoured to the shape of the product. Since the sealing is usually accomplished between pressure rollers, a high degree of seal integrity is possible. The use of high-barrier materials such as foil laminations or saran-coated films, in conjunction with the excellent seal formation, makes this packaging mode appropriate for the packaging of moisture-sensitive products.
Different packaging materials are used for strip packaging based on their properties. Few examples are cited below:
For high-barrier applications, a paper/polyethylene/foil/polyethylene lamination is commonly used. When the visibility of the product is important, heat-sealable cellophane or heat-sealable polyester can be used. In some cases the the material used on either sides of the strip package varies and the choice of material used depends on both the product and the equipment.
PHOTO 5.6: STRIP PACKAGING MACHINE
5.3.6- Bubble Pack:
The bubble pack can be made in several ways but is usually formed by sandwiching the product between a thermoformable, extensible, or heat-shrinkable plastic film and a rigid backing material. This is generally accomplished by heat-softening the plastic film and vacuum-drawing a pocket into the film in a manner similar to the formation of a blister in a blister package. The product is dropped into the pocket, which is then sealed to a rigid material such as heat-seal-coated paperboard. If a heat-shrinkable material is used, the package is passed through a heated tunnel, which shrinks the film into a bubble or skin over the product, firmly attaching it to the backing card.7
PHOTO 5.7: SHRINK TUBING
5.3.7- Shrink Banding:
The shrink band concept makes use of the heat-shrinking characteristics of a stretch-oriented polymer, usually PVC. The heat-shrinkable polymer is manufactured as an extruded, oriented tube in a diameter slightly larger than the cap and neck ring of the bottle to be sealed. The heat-shrinkable material is supplied to the bottler as a printed, collapsed tube, either pre-cut to a specified length or in roll form for an automated operation. The proper length of PVC tubing is slid over the capped bottle far enough to engage both the cap and neck ring of the bottle .The bottle is then moved through a heat tunnel, which shrinks the tubing tightly around the cap and bottle, preventing the disengagement of the cap without destroying the shrink band. For ease of opening, the shrink bands can be supplied with tear perforations.
PHOTO 5.7: SHRINK TUBING
5.3.8-- Foil, Paper, or Plastic Pouches:
The flexible pouch is a packaging concept capable of providing not only a package that is tamper-resistant, but also, by the proper selection of material, a package with a high degree of environmental protection. A flexible pouch is usually formed during the product filling operation by either vertical or horizontal forming, filling, and sealing (f/f/s) equipment.
In the vertical forming, filling, and sealing (f/f/s) operation, a web of film is drawn over a metal collar and around a vertical filling tube, through which the product is dropped into the formed package. The metal filling tube also acts as a mandrel, which controls the circumference of the pouch and against which the longitudinal seal is made. The formation of this seal, which can be either a fin seal or an overlap seal, converts the packaging film into a continuous tube of film. Reciprocating sealers, orthogonal to the longitudinal seal, crimp off the bottom of the tube, creating the bottom seal of the package. The product drops through the forming tube into the formed package. The reciprocation sealer moves up the film tube a distance equal to the length of the package and forms the top and final seal of the package.
The top seal of the package becomes the bottom seal of the next package and the process repeats itself. Since vertical f/f/s machines are gravity-fed, they are primarily used for liquid, powder, and granular products.
The horizontal forming, filling, and sealing (f/f/s) system is generally used for products of smaller volume, which are more amenable to the flatter format of the packages. In this system, the web of film is folded upon itself rather than around a tube. As the folded film is fed horizontally through the equipment, a reciprocating platen creates pockets in the film by making vertical separation seals. The product is then placed into each pocket and the final top seal is made. Packages formed on horizontal f/f/s equipment typically have a three-sided perimeter seal, but other variations are possible, depending on the type of equipment used. For moisture- and oxygen-sensitive products, foil is commonly used as part of the film lamination. Now a days foil is replaced by metallized polyester which is used in the lamination for high barrier application and includepaper/polyethylene/foil/polyethyleneand polyester/polyethylene/foil/polyethylene. They offer some advantages that they are of lower cost, excellent appearance, and flexural endurance.
5.3.9- Bottle Seals:
A bottle may be made tamper-resister by bonding an inner seal to the rim of the bottle in such a way that access to the product can only be attained by irreparably destroying the seal. Various inner seal compositions may be used, but the structures most frequently encountered are glassine and foil laminations. Typically, glassine liners are two-ply laminations using two sheets of glassine paper bonded together with wax or adhesive. The inner seals are inserted into the bottle cap and held in place over the permanent cap liner by either by applying friction or by the a slight application of wax which temporarily adheres the seal to the permanent cap liner. If glue-mounted inner seals are to be used, glue is applied to the rim of the bottle prior to the capping operation. The application of the cap forces the inner seal into contact with the glued bottle rim and maintains pressure during glue curing and until the cap is removed. When the bottle cap is removed, the inner seal is left securely anchored to the bottle rim.
Pressure-sensitive inner seals can also be used. The pressure-sensitive adhesive is coated on the surface of the inner seal as an encapsulated adhesive. During the capping operation, the torque pressure ruptures the encapsulated adhesive, which then bonds the inner seal to the rim of the bottle. One type of pressure-sensitive inner seal is constructed of thin-gauge styrene foam inner seal material coated on one side with a specially formulated torque-activated adhesive. The adhesive has minimal surface tack, but when applied with a properly torqued cap, it provides excellent adhesion to both glass and plastic bottles.
A third method of application uses a heat-sensitive adhesive that is activated by high-frequency induction. This type of application requires the use of aluminum foil as part of the inner seal composition. Once the cap is applied, the bottle is passed under an induction coil, which induces high-frequency resonation in the foil. The frictional heat that is generated activates the heat-seal coating and bonds the liner to the bottle. This type of seal can only be used with plastic caps since metal caps would interfere with the induction sealing of the inner seal. To meet the tamper-resistant criteria, the inner seals must be printed or decorated with a unique design. The seal must also be bonded sufficiently to ensure that its removal would result in destruction of the seal.
Tape sealing involves the application of a glued or pressure-sensitive tape or label around or over the closure of the package, which must be destroyed to gain access to the packaged product. The paper used most often is a high-density lightweight paper with poor tear strength. Labels made of self-destructing paper are available; these cannot survive any attempt at removal once they have been applied. To reduce further the possibility of removing the label intact, perforation or partial slitting of the paper can be made prior to application so that the label tears readily along those weak points if any attempt is made to remove it.
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