Blister Packaging Compnents

Introduction For well over four decades, the blister pack has offered a cost-effective and practical method of delivering unit dose packaging. It has proved to be one of the most enduring, versatile and adaptable pack forms, and its popularity has continue to rise unabated in the European market, some time assisted – and at other times potentially threatened – by changes in the regulatory environment. History The 1980s was perhaps the fastest period of growth in demand for blister-packed products in Europe, as governments across the continent began to advocate original pack dispensing (OPD) as the preferred means of delivering product to patients. The key benefit of OPD was that the risk of product tampering, contamination or dispensing errors was largely eliminated; since the product is deliver to the customer exactly as it leaves the packaging line, as opposed to the traditional method of pharmacist dispensing the required amount of medication from bulk supplies. In response to this market trends, machine manufacturers began to offer increase outputs: in the early 1980s 420 blister/minute was considered high speed, by the end of the decade this had doubled, and today out puts 1200 blister/minute are unknown. Blister packaging Blister pack is a term for several types of pre-formed plastic packaging used for small consumer goods, foods, and for pharmaceuticals. In other word, the primary component of a blister pack is a cavity or pocket made from a formable web, usually a thermoformed plastic. This usually has a backing of paperboard or a lidding seal of aluminum foil or plastic. A blister that folds onto itself is often called a clam shell. Blister packaging components The four basic components of pharmaceutical blister packages are the forming film, the lidding material, the heat-seal coating, and the printing ink. Forming films account for approximately 80–85% of the blister package, and lidding materials make up15–20% of the total weight of the package. Because the forming film and the lidding material form an integrated package, they must match precisely. Forming film The forming film is the packaging component that receives the product in deepdrawn pockets. One key to package success is selecting the right plastic film forthe blisters in terms of its property type, grade, and thickness. Identification  Plastic forming filmssuch as PVC, polypropylene (PP), andpolyester (PET) can be thermoformed,but support materials containing aluminum are cold-formed.  The formingfilm usually is colorless and transparent,but it can be obscured for use in child resistant packages or to protect light sensitive drugs.  The forming web for blister packs nearly always is PVC, sometimes coated or laminated with additional components that enhance the oxygen and water-vapor barrier. Difference between Thermo forming & cold forming • Thermoforming- the cavity is constructed of clear, thermoformed plastic, and the lid is formed of clear plastic or a combination of plastic, paper, or foil. • Example: Alu-PVC blister pack • Cold forming –The package contains foil as an essential component of both webs, and its cavity is created by cold stretching. • Example: Alu-Alu blister pack Table: Comparison of Forming Films Type & Thickness Of Forming Film(mil) WVTR(g/m2/day) Price Per Unit Area PVC(10) 1.1 1 PVD/PVDC(10/1.2) 0.17 2.1 PVC/CTFE(8/0.76) 0.07 2.1 PP(12) 0.20 1.3 PET(10) 2.6 1.4 PS(12) 6 1.2 OPA/aluminum/PVC(1/1.8/2.4) 0 2.9 Types of forming films Types forming film are: • Polyvinyl chloroide (PVC) • Polyvinylidene chloride (PVdC) • Chlorotrifluoroethylene (CTEF) • Polypropylene (PP) • Polyethylene terepthalate (PET) • Polystyrene (PS) • Oriented polyamide (OPA) • CTFE homopolymer Polyvinyl chloroide (PVC) PVC forming filmis called rigid PVC because it is almost freeof softening agents. Rigid PVC is a very clear, stiff material with a low WVTR. It exhibits excellent thermoformability; a high flexural strength; good chemical resistance; low permeability to oils, fats, and flavoring ingredients; easy tintability; and low cost. These properties make rigid PVC the material of choice for blister packaging, and it essentially has 100% of the market for the plastic component. PVC films that are thermoformed have a thickness of about 10-mil. Advantages  It has high clarity.  It is practically unaffected by sunlight.  It un-plasticized materials are non-toxic.  It is less permeable to gases than polythene.  Its plasticized grades are good oil resistant.  Some grades can be sterilized by autoclaving.  The surface can be printed readily. Disadvantages  It is less flexible, heavier and much more permeable to water vapour.  It adsorbs some drugs.  It require an extended sterilization time due to its heat resistant. Uses: PVC collapsible bags are used to package most infusion fluids. Recycling process of polyvinyl chloroide (PVC) The relatively new mechanical recycling process known as Vinyloop® technology, developed by Solvay Research & Technology, allows the complete separation of PVC material from the non-PVC materials that are often combined with it. The Vinyloop Process 1. Pretreatment 2. Dissolution 3. Separation 4. Precipitation 5. Drying Polyvinylidene chloride (PVdC) Although the volume of PVC in drug packaging is small, PVDC plays a critical role in blister packaging as laminations or coatings on PVC. PVDC is the most common coating in blister packaging because it can reduce the gas and moisture permeability of PVC blister packages by a factor of 5–10. Coated PVC films have a thickness of 8–10 mil; the thickness of the PVDC coat amounts to 1–2 mil.The coating is applied on one side and usually faces the product and the lidding material. Advantages  High levels of transparency offer the most attractive product presentation and display. The PVdC film can be color-toned to reduce exposure.  Excellent barrier qualities extend the shelf life and conservation of foods, while at the same time reducing the need for preservatives, which in turn enhances the appeal of the product to the consumer.  Outstanding heat sealing properties help materials such as paper, cellophane and other plastics to seal themselves effectively. This means that packaging can be easily and rapidly sealed during processing, so that high film speeds and throughputs can be achieved.  Highly flexible characteristics allow the PVdC to perform across a very wide range of applications Disadvantages While extremely useful as a food packaging agent, the major disadvantage of Saran is that it will undergo thermally induced dehydrochlorination at temperatures very near to processing temperatures. Recycling process of Polyvinylidene chloride (PVdC) Due to the fact that you need such a small amount of PVdC to achieve your barrier needs, there is very little in the post consumer stream especially compared to polymers like PET. If PVdC could be easily segregated, it could be easily recycled. Therefore, PVdC typically can only be recycled in a general non-specific plastic recycling program. Chlorotrifluoroethylene (CTFE) Advantages  Films made from PVC and CTFE have the lowest water-vapor permeability of all films used for blister packaging.  When compared with the water-vapor permeability of 10-mil PVC, the permeability of 8-mil PVC/0.76-mil CTFE is lower by a factor of 15.  However, the environmental concerns regarding PVC also apply to PVC/CTFE films. Disadvantages Extremely expensive. Attacked by esters & aromatic hydrocarbons. Polypropylene (PP) There is an increasing trend toward using PP as a support material for blister packages. The water-vapor permeability of uncoated PP is lower than that of PVCand is comparable to that of PVDC-coatedPVC. The thickness of PP films used in the thermoforAdvantages  Easy recyclability,  No release of toxins during incineration, and  Good moisture-barrier properties. Disadvantages PP has some drawbacks. One problem is thermoforming. The temperatures required for thermoforming PP and for the subsequent cooling process must be controlled precisely. Warping also can occur, in which case the packages must be straightened before cartoning. Other difficulties associated with the use of PP include its thermal instability, higher rigidity than PVC, and susceptibility to post processing shrinkage. Polyethylene terepthalate (PET) Advantages  Bottles for beverages such as soft drinks, fruit juices, mineral waters. It is especially suitable for carbonated drinks, cooking and salad oils, sauces and dressings and detergents.  Wide mouth jars and tubs for jams, preserves, fruits & dried foods.  Trays for pre-cooked meals that can be re-heated in either microwave or conventional ovens. Pasta dishes, meats and vegetables.  Foils for 'boil-in-the-bag' pre-cooked meals, snack foods, nuts, sweets, long life confectionery.  Other PET products with an extra oxygen barrier are ideal for containing beer, vacuum packed dairy products e.g., cheese, processed meats, 'Bag in Box' wines, condiments, coffee, cakes, syrups. Disadvantage The disadvantage is that PET becomes increasingly brittle and opaque at increasing crystallization levels. Extremely crystalline PET is effectively white. This can be clearly seen on the neck of some returnable bottles already in the market. ming process ranges from 10 to 12 mil. Recycling process of Polyethylene terepthalate (PET) Mechanical recycling is a method of recovery a material from waste by means of mechanical processing. In order to be recycled, PET bottles have to be collected from astore and baled. Polystyrene (PS) Advantages  It is light and cheap material & easy to mould  It is odorless, tasteless, and available in transparent.  It has excellent dimensional stability that assure to fine limits of accuracy.  It soften at a lower temperature  Good tensile strength Disadvantages  It is hard & rigid material  It is brittle to cold or when dropped or flexed.  It permits the permeability of water vapor than other plastics.  It tends to be electrostatic and very permeable to aromatic flavoring. Uses: As foam or expanded material Recycling process of Polystyrene (PS) The low cost of polystyrene manufacturing deters recycling. Polystyrene recycling is generally similar to other forms of recycling. Large trucks carry polystyrene, collected in various locations, to polystyrene recycling facilities, similar to the Dart recycling operation in Mason, MI. According to the Concord, CA, website, polystyrene takes up more space in these large trucks than is profitable to recycle. Oriented polyamide (OPA) Advantages  OPA are intriguing. With a laminate structure consisting of 1-mil OPA, 1.8-mil aluminum, and 2.4-mil PVC it is possible to eliminate water-vapor permeability almost entirely.  Moreover, because of the large proportion of aluminum in the laminate, recycling this material has become feasible (particularly because most lidding materials also contain aluminum).  Enormous efforts are being made to replace PVC with PP in such laminates to comply with environmental standards. Disadvantages  Like other laminates containing aluminum, the OPA/aluminum/PVC laminate is cold-formed.  Its cost per square meter can stand any critical comparison with PVDC-coated PVC.  Cold-forming, however, requires more packaging material than doe’s thermoforming to package the same number of the same size of tablets or capsules. CTFE homopolymer Recently introduced a 3-mil CTFE homopolymer barrier film (AclarUltRx 3000) that can be thermoformed easily and that exhibits the highest moisture barrier of clear films. This reflects the trend toward the use of higher-barrier materials. Various Aclar products have allowed wider use of blister packaging because they can be thermoformed into clear or tinted blister cavities and exhibit barrier properties close to those of the near-perfect barrier offered by foil. Lidding materials The lidding material provides the base ormain structural component upon whichthe final blister package is built. It mustbe selected according to the size, shape,and weight of the product as well as thestyle of the package to be produced. Lidding materials range in caliper or thickness from 0.36 to 0.76 mm, but 0.46–0.61mm is the most popular range. Characteristics The lidding material canbe clear plastic, but in pharmaceuticalpackaging it is either plain or printed 1-mil foil (for push-through blister types)or paper/foil or paper/PET/foil laminations (for child-resistant peel–push types). Types of lidding materials Hard aluminum Identification Hard aluminum isthe most widely used push-through liddingmaterial. The foil usually has a thickness of 0.8-mil. There are endeavors,however, to reduce the thickness of this foil to 0.6-mil. The hardness of the aluminumfacilitates push-through opening.Usually, only the print primer side features a printed design, but occasionally theside with the heat-sealing coating also canbe printed. Advantages  A double coat of heat-sealingcoating (a heat-sealing primer and the actual heat-sealing coating) has become thestandard for lidding materials.  The heat-sealing primer ensures optimum adhesion of the heat-sealing coatingto the aluminum foil.  If the heat-sealing primers are colored, applying the heat-sealing coating overthe primer can protect the packaged product from coming in contact with the pigments. Soft aluminum Identification Soft aluminum (1 mil) frequently is usedfor child-resistant push-through foils. Withthe exception of the type of aluminumused, the structure of this lidding material corresponds to that of hard aluminum(0.8- mil). Advantages  The softness and thickness ofthis type of aluminum help prevent children from pushing tablets through it.  Thismaterial also is supplied with a perforation along the sealed seams so that it cannot be peeled off the formed film in onepiece. Paper/aluminum Identification In combinations of paper and aluminum, the weight of the paperamounts to 40–50 g/m2. In Europe, thethickness of the aluminum typically is0.28–0.48 pm, but in the United States ithas a thickness of 0.6–1 mil. Characteristics Lidding material made of a paper/PET/aluminum laminate is often called peel off–push through foil. This kind of material is used predominately in the United States. Advantages • In the United States, this type of materialis used as a peel-off foil, so the foil mustbe relatively thick for effective peeling. Because printing is applied to the side withthe paper, no print primer is required. • The concept is to first peel off the paper/PET laminatefrom the aluminum and then to push thetablet through the aluminum. The Recycling Process of Aluminum: Five stage process 1. Collection 2. Sorting 3. Reprocessing 4. Rolling 5. Converting Heat-seal coatings Identification  A successful heat-sealcoating for blister packages must exhibitgood gloss, clarity, abrasion resistance, andhot tack and must seal to various blisterfilms.  Although heat-seal coatings used forblister packaging still are predominantly solvent-based vinyls (because of their superior gloss), water-based products aremaking some inroads.  In addition, the heat-seal coating mustprecisely match the lidding material andthe plastic material of the forming films.  Theheat-seal coating also protects the printedarea and provides a glossy finish. Mostimportantly, the heat-seal coating must comply with FDA recommendations. Printing inks Identification Printing inks must resist heatsealing temperatures as high as 300 8Cwithout showing any discoloration ortackiness (blocking). In addition, they mustsufficiently resist abrasion, bending, andfading and must be safe for use with theintended product. Printing inks should not contain excessive amounts of hydrocarbonlubricants, greases, oils, or release agents. Advantages  Printing inks provide graphics and aesthetic appeal.  They can be applied to thelidding material by letterpress, gravure, offset, flexographic, or silk-screen printingprocesses. Cold-formed foil/foil Identification One element of the foil/foil blister pack comprises a lamination of plastic film (PVC or PE), adhesive,foil, adhesive, and an outer plastic film.The outer film, which can be PET or PVC,supports the thin aluminum layer and actsas the heat-seal layer. The aluminum layerusually consists of several very thin layersrather than a single thick one. Advantages  The multiple layers help ensure that pinholes do not go all the way through the foil.  They also increase the stretch ability of the metal and facilitate the cold-stretching process. Disadvantage  Is that the cavities must bemade larger in the cold-forming processthan during thermoforming, thus increasing the overall area of the packageand often allowing the product to shiftinside the blister.  Even so, the brittleness of cold-formed aluminum means that foil/foil blisters cannot be made as formfitting as plastic ones Conclusion Packaging engineers have been called upon to develop creative solutions for meeting the Consumer Product Safety Commission’s child-resistant and senior-friendly requirements. With additional regulatory developments such as the International Conference of Harmonization’s testing guidelines and FDA’s rule on iron supplements, a large increase in blister packaging use, along with the use of innovative materials and designs, is expected.