Blister packs cold forming

Blister Packs. Two basic types can be found in use for pharmaceuticals today—hot formed and cold formed. 

All the above processes can also be used in a form fill seal process with, for example, thermoforming and cold forming blister packs. Rommelag type bottle pack systems use an extrusion process where the container is formed by either blowing or vacuum (smaller sizes). Immediately after this, containers are filled, and the pack is sealed (welded) by using the residual heat in an extension to the main body of the container. 

Other special features include shrink films, stretch films and cling films. These features are, however, unlikely to be used in combination materials although oriented plastics are used in cold formed blister packs. 

Combined with polythene to give various thermoformed packs for cheese, bacon, etc. Also used as an outer ply for boil-inbag applications and as an outer ply in some cold formed blisters. 

A broad summary can be made of machines, materials, outputs, costs, etc. in comparison with glass and plastic bottles, metal cans, and strip packs as shown by the general costings. As the requirement for a unit dose or multiple unit dose increases, both blister and strip packs are ensured of a significant increase. Blisters may gain in space and cost saving but lose out in climatic protection, unless cold formed foil, a foil tropicalised blister, or an overwrapping system is used. 

Two basic types exist, i.e. hot formed and cold formed. The filling and closing operations are covered in detail in Chapter 13. Most blister packs will need to be collated and cartoned, with a leaflet, as they are not robust enough to survive the rigours of transport and distribution unprotected. 

In addition to catering for conventional thermoformed blisters using a plastic tray and a foil-based lid, most blister machine manufacturers now offer facilities to increase moisture protection, by use of either a tropicalised blister (by an additional foil over cover) or a cold formed, foil-based tray. Considerable competition is expected between these and similar options, where a high level of climatic protection is required. The other options include blisters in sachets and overwraps to cartons. Output speeds, climatic protections achieved, overall cost and patient/marketing preference, will influence the final pack choice. 

Strip packs present an alternative form of pack for a unit dosage. Strips can be produced from single or multi-ply materials, provided the two inner plies can be sealed by heat or pressure (e.g. cold self-adhesive seal). Materials can range from relatively permeable plies to those which incorporate a foil ply of sufficient thickness (and effectiveness of seal) that an individual hermetic seal is produced for each dosage. To date strip packs are usually produced at lower speeds and also occupy greater volume than blisters. The break-even cost with glass containers largely depends on the material used, output speed, and item size. 

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