PACKAGING MATERIALS
The packaging process is employed to maintain the therapeutic effectiveness of pharmaceuticals as the packed products retain their potency till their consumption. The art and science of preparing the articles for their transport, storage, display, and use are termed packaging.
COMPONENTS OF PACKAGING
Container
It encloses the drug, thereby remains in direct contact with the drug. Such a container which is always in direct contact with the drug is an immediate container.
Types of Containers
- Well Closed Containers: Prevent product loss during transportation, handling, storage, or sale (e.g., ampoules and vials).
- Single Dose Containers: Used for a single parenteral medicament (e.g., ampoules, vials, prefilled syringes).
- Multi Dose Containers: Facilitate periodic removal of multiple drug doses (e.g., vials).
- Light-Resistant Containers: Protect photo-sensitive medicaments (e.g., amber coloured containers).
- Air-Tight or Hermetic Containers: Safeguard products from dust, moisture, and air (e.g., rigid metal cans).
- Child-Proof Containers: Prevent children from opening (e.g., push and turn threaded caps).
- Aerosol Containers: Used for storing aerosol products; mechanically strong to withstand pressure.
Components of Aerosol System
- Container (glass or metal)
- Valve and Actuator (regulates flow; plastic, rubber, aluminium, stainless steel)
- Concentrate containing the API(s)
- Propellant (develops pressure; fluorinated hydrocarbons)
Closure
It seals the container to eliminate oxygen, carbon dioxide, moisture, and microorganisms. Made up of cork, glass, plastic, metal, and rubber. Prevents loss of volatile substances and medicament during transport and handling.
Carton
Made up of cardboard, moulded wood pulp, or expanded polystyrene; provides secondary protection against mechanical and other environmental hazards (e.g., paperboard cartons).
Box
Made up of thick cardboard, wood, or suitable material; carries multiples of a product; provides primary protection against external hazards during transportation and handling (e.g., corrugated cardboard box).
TYPES OF PACKAGING
- Primary Packaging: Direct contact with dosage form (e.g., bottles, vials, ampoules, blister packs).
- Secondary Packaging: Contains and protects primary packing (e.g., shrink wrap, outer cartons, cardboard boxes).
- Tertiary Packaging: For handling, storing, and distributing multiple units in bulk (e.g., paper, cardboard, paperboard, pallets).
OBJECTIVES OF PACKAGING
- Physical Protection: Protects against mechanical shock, vibration, compression, temperature, etc.
- Barrier Protection: Protects from oxygen, water vapour, dust, etc.
- Containment or Agglomeration: Keeps small objects collectively for efficiency.
- Information Transmission: Provides usage, transport, recycling, or disposal information.
- Marketing: Convinces buyers to purchase the product.
- Security: Minimises security risks; tamper-evident features.
- Convenience: Aids in distribution, handling, stacking, display, sale, opening, reclosing, use, dispensing.
- Portion Control: Carries precise quantity of contents to manage usage.
IDEAL REQUIREMENTS OF PACKAGING MATERIALS
- Safety
- Protection
- Compatibility
- Stability
- Tamper-evident
- Ease of Use
- Cost-effectiveness
- Regulatory Compliance
- Environmental Impact
GLASS AS A PACKAGING MATERIAL
Composition of Glass
Glass is composed of sand (pure silica), soda-ash (sodium carbonate), limestone (calcium carbonate), and cullet (broken glass as fusion agent). Silicon, aluminium, boron, sodium, potassium, calcium, magnesium, zinc, and barium are cations; oxygen is the only anion.
Types, Properties, and Applications of Glass
| Type | Description | Properties | Applications |
|---|---|---|---|
| Type I (Borosilicate) | Highly resistant; alkali and earth cations replaced with boron | Resistant to alkali leaching, brittle, low thermal expansion, easy to clean | Containers for buffered/unbuffered aqueous solutions and injectables |
| Type II (Treated Soda-Lime) | De-alkalised by sulphur treatment | Surface alkali neutralised, resistant to water | Buffered aqueous solutions (pH below 7), dry powders, oleaginous solutions |
| Type III (Regular Soda-Lime) | Untreated, average chemical resistance | Releases comparatively more alkali | Dry powders and oleaginous solutions |
| Type IV (General Purpose) | General purpose soda-lime glass | Moderate hydrolytic resistance | Tablets, oral solutions, suspensions, ointments, liquids for external use |
Advantages of Glass
- Superior protective qualities
- Available in various shapes and sizes
- Does not deteriorate with age
- Heat resistant (can undergo heat sterilisation)
- Easily cleaned, impermeable, economical
- Enables identification of products
Disadvantages of Glass
- Fragile and brittle nature
- Heavy weight; occupies more volume
- Tensile strength is 1/20th that of steel
- Cannot undergo pressure/vacuum operations
- Cannot be re-joined once broken
- Alkaline glasses impart alkalinity and flakes
PLASTIC AS A PACKAGING MATERIAL
Types of Plastic
- Thermoplastics: Soften when heated, solidify when cooled; recyclable (e.g., Polyethylene, Polypropylene, PVC, Polystyrene, PET, Nylon).
- Thermosetting Plastics: Irreversibly harden when heated; cannot be melted or molded again (e.g., polyurethane, epoxy resin, phenolic resin).
Commonly Used Plastics
- Polyethylene (PE): Efficient moisture barrier; unaffected by most solvents, acids, alkalis. Disadvantage: lacks clarity, high oxygen permeation.
- Polypropylene (PP): Resistant to strong acids, alkalis, organic materials; high melting point; good gas/vapour barrier. Disadvantage: lacks clarity.
- Polyvinyl Chloride (PVC): Easily processed; extreme clarity, rigid, good oxygen barrier. Disadvantage: poor impact resistance.
- Polystyrene (PS): Inexpensive, clear, rigid, water resistant, good shock absorbing. Disadvantage: high oxygen permeability, not for liquids.
- Polyethylene Terephthalate (PET): Exceptional impact strength; gas/aroma barrier. Disadvantage: low heat resistance, non-biodegradable.
- Nylon (Polyamide): Extremely strong; resistant to organic/inorganic chemicals; highly impermeable to oxygen. Disadvantage: high water transmission rate.
- Polycarbonate: Can be sterilised repeatedly; rigid like glass; impact strength 5x greater. Disadvantage: expensive; degraded by alkalies, amines, ketones.
- Acrylic Multipolymers: Good chemical resistance; excellent strength; safe disposability; resistant to oil and grease.
Advantages of Plastic
- Low thermal and electrical resistance
- Resistant to weak mineral acids and inorganic salts
- Resistant to slight pH changes
- Lightweight; reduces volume, warehousing, and distribution cost
- No corrosion problems
- Good resistance to mould and bacteria
Disadvantages of Plastic
- Low mechanical strength
- High expansion rate
- Not completely impermeable to moisture and gases
- Allows some light passage
- Difficult to clean; liable to attract dust
- May cause adsorption or absorption
- Difficult to form fully effective closing systems
METAL AS A PACKAGING MATERIAL
Metals Used for Packaging
- Aluminium: Highly resistant to corrosion; forms thin Al₂O₃ film when exposed to air.
- Steel (Electrolytic Tinplate – ETP): Cold-rolled low carbon mild steel coated with tin; coating weights 1-15.1 g/m².
- Steel (ECCS): Chromium/chromium oxide coated steel; used for drawn cans where welding is not required.
- Tin: Provides corrosion resistance; acts as oxygen scavenger.
Types of Metal Packaging
- Cans: Two-piece (drawn cans) and three-piece cans
- Drums and Pails: Large three-piece steel cans (100-220 litres for drums; 5-25 litres for pails)
- Aerosols: Three-piece or two-piece (monobloc) steel cans
- Tubes: Metallic tubes (mostly aluminium) for toothpaste, etc.
- Trays and Foils: Rigid and semi-rigid aluminium trays (70-300 µm)
- Closures and Lids: For sealing containers; aluminium closures on bottles
Advantages of Metals
- Durable
- Do not allow light, moisture, and gases to pass through
- Can be made into rigid resilient containers by impact extrusion
- Lighter in weight than glass containers
Disadvantages of Metals
- Costly
- May cause adulteration by shedding metal particles
RUBBER AS A PACKAGING MATERIAL
Types of Rubber
Natural Rubber
- Soft Rubber: Natural polymer of isoprene (C₅H₈)n; used as lining material for plants, tyres, tubes, conveyor belts.
- Hard Rubber: Formed by vulcanisation (mixing soft rubber with sulphur); used for gloves, bands, tubes, stoppers.
Synthetic Rubber
| Synthetic Rubber | Properties | Applications |
|---|---|---|
| Neoprene (Polychloroprene) | Does not burn readily; stable at high temperature | Insulating material, conveyor belts, rubber stoppers, cap liners, dropper assemblies |
| Nitrile rubber | Resistant to oil and solvents | Non-latex gloves, automotive belts, hoses, O-rings, gaskets, oil seals |
| Butyl rubber | Resistant to mineral acids and alkalis; low water vapour permeability | Closures for freeze-dried product containers |
| Silicon rubber (Polysiloxanes) | Resistant to high/low temperatures and aliphatic solvents | Tubing for dialysis, transfusion equipment, catheters |
| Polyisoprene | Stable at high temperature; translucent and flexible | Stoppers and closures |
Advantages of Rubber
- Soft rubber provides resistance against dilute mineral acids, dilute alkalis, and salts
- Impermeable to most common gases
- Good resistance to sunlight and odours
- Can be exposed to animal or vegetable oils or vaporisable chemicals
Disadvantages of Rubber
- Soft rubber can be attacked by oxidising media, oils, and organic solvents
- Not resistant to ozone, aromatic/halogenated hydrocarbons, ketones, and ester solvents
- Not suitable for insulating materials
SUMMARY TABLE: COMPARISON OF PACKAGING MATERIALS
| Material | Advantages | Disadvantages | Main Applications |
|---|---|---|---|
| Glass | Impermeable, heat resistant, economical, chemically inert | Fragile, heavy, cannot withstand pressure/vacuum | Injectables, aqueous solutions, dry powders, ointments |
| Plastic | Lightweight, flexible, low cost, no corrosion | Permeable to gases/moisture, low mechanical strength | Tablets, capsules, liquids, bottles, vials, blister packs |
| Metal | Durable, impermeable to light/moisture/gases, rigid | Costly, may shed metal particles | Aerosols, tubes, drums, cans, closures |
| Rubber | Impermeable to gases, resistant to dilute acids/alkalis | Attacked by oils, organic solvents, oxidising media | Stoppers, cap liners, dropper bulbs, closures |
