Packaging is an integral part of pharmaceutical industry. It plays important roles in product identification, convenience in handling and protection from the manufacturing centre to the end users. Selection of packaging material depends on the environmental conditions to which the product is exposed, and the characteristics of the drug formulation. Several types of packaging are used to contain and protect the drug product.

Early packaging forms for medical devices included bags, cartons, and wraps; the primary material was paper. Glass and metal containers were used to a lesser extent. Due to the availability of thermoformable materials during 1950-1960, the tray and blister packaging were developed. Due to lack of good sealing materials, the use of blister packaging was limited. But now a days, blister packaging is well accepted due to the development of sealing materials and is widely used for all sorts of pharmaceutical products for some important properties and features. These are discussed below.

Blister packaging is a pre-formed plastic packaging that uses a backing card, usually paper board which usually has some featured printing artwork on it and a clear plastic pocket or film known as the blister.  The blister film is fixed on the printed paper board through a heat sealed coated primer as shown in Figure 1. Direct roll coaters are also used widely for packaging materials: paper sizing, paper colour coating, over coating of blister packaging board, and heat seal coating. Figure 2 shows some photographs of blister packages that are used in the pharmaceutical industries for the packaging of tablets and capsules.

Preformed blisters are filled with the object, the coated paperboard is placed over the filled blister, and the assembly is heat sealed. Small hardware items and small notions are commonly packaged in this manner. Blister packaging consists of two primary components i.e., i) the cavity - made from either plastic or aluminum foil and ii) the lid made from paperboard, paper, plastic or aluminum. The cavity contains the product and the lid seals the product in the package.

In pharmaceutical industry blister packaging is used to pack tablets, pills, capsules, granules or lozenge and also to pack different goods viz. pens, pencils etc. The name derives from the fact that each item packed in blister packing is contained within its own small plastic bubble or blister. It is also called as a bubble or push-through-pack. Clear plastic is used for packing the items and aluminum foils coated with adhesive bonding are used in the film which are heated together to form a separate sealed package. Blister packs can provide barrier protection for shelf life requirements and a degree of tamper resistance. In the USA, blister packs are mainly used for packing physician samples of drug products, or for Over the Counter (OTC) products in the pharmacy. In other parts of the world, blister packs are the main packaging type since pharmacy dispensing and re-packaging are not common. Blister packs also prevent in illegal manufacturing and use of the OTC drugs.

Blister packing is also known as Push-Through-Pack (PTP). The main advantages of unit-dose blister packs over other methods of packing for pharmaceutical products are the assurance of product or packaging integrity including shelf life of each individual dose and the possibility to create a compliance pack or calendar pack by printing the days of the week above each dose.

Blister packs are created by means of a form-fill-seal process at the pharmaceutical company or designated contract packer. A blister packaging using multi-layered HDPE packaging material and selection of adequate sealing technique may help prevent moisture access into the blister system.

In blister packaging two different types of plastic materials viz. poly-vinyl chloride (PVC), PET polyethylene terephthalate (PET), amorphous polyethylene terephthalate (APET), high density poly ethylene (HDPE), acrylonitrile butadiene styrene (ABS) etc. and aluminum sheets or foils are mainly used.  In pharmaceutical industry two basic types of blister packages are used.  In the first type, the cavity is constructed of clear, thermoformed plastic and the lid is formed of clear plastic or a combination of plastic, paper, and or foil. The second type of blister package contains foil as an essential component of both webs and its cavity and is created by cold stretching.

Compliance packaging such as for fixed-dose-combination pills and unit-of-use packaging is a therapy-related interventions that is designed so as to simplify medication regimens and thus potentially improve adherence. Compliance packaging can be defined as a pre-packaged unit and provides one treatment cycle of the medication to both the pharmacist and the patient in a ready-to-use package. This innovation type of packaging is usually based on blister packaging using unit-of-one dosing. The separate dosage units and separate days are usually indicated on the dosage cards to help remind the patient when and how much of the medication to take, for example, blister-packed oral dosage forms with drug information leaflets, specifically the contraceptive pills

The most important advantage of blister packaging for the patients is the convenient and easy removal of tablets or capsules by pressing blister and forcing the contents to backing strip. The other advantages of blister packing are as follows.

• Blister packaging is very light weight; and consumes less volume compared to glass which often used for packing medicine. This saves a significant amount of transportation cost.
• Provide better sealing to the medicines need to be store in dry moisture free environment. Thus it extends the shelf life of drugs and medicines which also can be stored for a longer time without damage.
• Dose accuracy can be easily maintained in blister packing. Blister packaging of paracetamol was introduced in 1989 in UK, to prevent  overdoses.
• Blister packaging can be easily automated to maximize the protection of the safety of packaging.
• In addition to the high degree of process automation, there are a number of safety testing devices, including box and manual identification and detection that can greatly improve the safety and health of blister packing users.

Blister packaging provides good quality sealing for the tablets and capsules. It is easy to test the leak test after packaging. The ease of packaging, testing, reliability and assured quality control make the blister packaging popular and its popularity is increasing day by day.