Introduction to Cosmetics, Aerosols & Packaging Materials
The final unit covers three diverse but industrially critical areas. Cosmetics — the formulation of everyday products like lipsticks, shampoos, creams, and sunscreens that apply pharmaceutical science to personal care. Aerosols — sophisticated pressurized systems that deliver drugs as fine sprays or mists (MDIs for asthma). Packaging Materials — the science of selecting appropriate glass, plastic, metal, or rubber containers that protect the drug product throughout its shelf life while meeting all regulatory requirements.
Syllabus & Topics
- 1Cosmetics – Introduction: Products applied to the human body for cleansing, beautifying, promoting attractiveness, or altering appearance without affecting body structure or function. Regulated differently from drugs (cosmetics do not claim therapeutic effects).
- 2Lipsticks: Waxy sticks applied to lips for color and protection. Formulation: Castor oil (~65%, glossy base), Beeswax + Carnauba wax (hardness, structure), Ozokerite (binding), Certified colorants (D&C Red), Fragrance, Antioxidants. Manufacturing: melting waxes/oils → adding pigment → pouring into molds → cooling → flaming for gloss.
- 3Shampoos: Liquid or gel cleansers for hair/scalp. Types: clear (simple), conditioning (with silicones), anti-dandruff (Zinc pyrithione/Ketoconazole), baby (tear-free, amphoteric surfactants). Primary surfactant: Sodium Lauryl Sulfate (SLS) or Sodium Laureth Sulfate (SLES). Conditioning agents: Dimethicone, Polyquaternium. pH 5-7.
- 4Cold Cream & Vanishing Cream: Cold cream = W/O emulsion (cooling effect due to water evaporation) – Beeswax + Mineral oil + Borax + Water. Vanishing cream = O/W emulsion using Stearic acid + Alkali (Potassium hydroxide → potassium stearate soap = emulsifier). Vanishing cream absorbs into skin and ‘vanishes’. Used as a base for sunscreens and medicated creams.
- 5Tooth Pastes: Semi-solid for cleaning teeth. Key ingredients: Abrasive (Calcium carbonate, Silica – 30-50%), Humectant (Glycerin, Sorbitol – prevent drying), Binder (CMC, Xanthan gum), Surfactant (SLS – foaming + cleansing), Therapeutic agent (Fluoride NaF 1000-1500 ppm – anti-caries), Flavoring (Peppermint), Preservative, Sweetener (Saccharin).
- 6Hair Dyes: Temporary (color molecules sit on surface, wash out in 1 shampoo), Semi-permanent (penetrate partially, last 6-8 washes), Permanent/Oxidative (para-phenylenediamine + H₂O₂ → oxidative polymerization inside hair cortex → permanent color change). Safety concern: PPD can cause severe contact dermatitis – mandatory patch test before use.
- 7Sunscreens: Protect skin from UV radiation. UVB (290-320 nm) causes sunburn. UVA (320-400 nm) causes aging/cancer. Chemical sunscreens absorb UV: PABA esters, Oxybenzone, Octinoxate. Physical sunscreens reflect UV: Zinc oxide, Titanium dioxide (broad spectrum, opaque). SPF (Sun Protection Factor) = MED with sunscreen / MED without. SPF 30 blocks ~97% UVB.
- 8Pharmaceutical Aerosols – Definition: Pressurized dosage forms that release drug as fine spray/mist/foam upon actuation of a valve. Components: (1) Product concentrate (drug + solvents). (2) Propellant (provides pressure). (3) Container (tin-plated steel, aluminum, glass). (4) Valve (metering or continuous). (5) Actuator.
- 9Aerosol Propellants: Liquefied gases: CFCs (Freon – banned, ozone depleting), HFAs (HFA-134a, HFA-227ea – current replacement, non-ozone depleting), Hydrocarbons (propane, butane – flammable). Compressed gases: CO₂, N₂ (constant spray rate as pressure drops – foam aerosols). Vapor pressure determines spray characteristics.
- 10Types of Aerosol Systems: (1) Solution systems (drug dissolved in propellant – finest spray). (2) Suspension/Dispersion systems (drug suspended – Metered Dose Inhalers/MDIs). (3) Foam systems (emulsion-type – shaving cream, vaginal foams). (4) Intranasal sprays. (5) Topical sprays (first-aid, wound dressing).
- 11Aerosol Manufacture & Evaluation: Cold filling (chilled propellant added to concentrate in open container) or Pressure filling (propellant forced through valve under pressure into sealed container – preferred). Evaluation: Weight check, Leak test (water bath), Spray pattern/rate, Particle size (cascade impactor for MDIs), Dose uniformity, Delivered dose per actuation.
- 12Packaging Materials – Glass: Type I (Borosilicate – highest resistance, parenterals), Type II (Treated soda-lime – aqueous solutions), Type III (Regular soda-lime – oral/topical). Amber glass reduces photodegradation. Tests: Powdered glass test, Water attack test, Arsenic limit test. Advantages: inert, transparent, impermeable. Disadvantage: fragile, heavy.
Learning Objectives
Frequently Asked Questions (FAQs)
Q1. What Is the Difference Between Cold Cream and Vanishing Cream?
Cold cream is a water-in-oil (W/O) emulsion that produces a cooling sensation due to slow evaporation of water from the skin surface. It is greasy and occlusive, making it useful as a cleanser and emollient. Vanishing cream is an oil-in-water (O/W) emulsion typically prepared using stearic acid and an alkali. It spreads easily and is rapidly absorbed by the skin, leaving a non-greasy matte finish, which makes it suitable as a base for day creams, sunscreens, and medicated creams.
Q2. Why Were CFC Propellants Banned in Aerosols?
Chlorofluorocarbon (CFC) propellants such as Freon-11 and Freon-12 were widely used because they are non-toxic and non-flammable with suitable vapor pressure. However, they were found to cause depletion of the stratospheric ozone layer by releasing chlorine radicals when exposed to ultraviolet radiation. The Montreal Protocol mandated the global phase-out of CFCs, which were replaced by hydrofluoroalkane propellants such as HFA-134a and HFA-227ea that have zero ozone depletion potential.
Q3. What Is SPF in Sunscreens and How Is It Measured?
Sun Protection Factor (SPF) indicates the ability of a sunscreen to protect the skin against UVB radiation responsible for sunburn. It is calculated as the ratio of the minimal erythemal dose (MED) with sunscreen to the MED without sunscreen. For example, SPF 30 theoretically allows a person to stay in sunlight about 30 times longer before developing sunburn. SPF values mainly measure UVB protection, while UVA protection is evaluated using other rating systems such as PA or star ratings.
Q4. What Is the Difference Between Type I and Type III Glass?
Type I glass is borosilicate glass containing boron trioxide, which provides high chemical resistance and excellent resistance to thermal shock. It is commonly used for parenteral containers such as vials and ampoules. Type III glass is ordinary soda-lime glass containing sodium and calcium oxides and has lower chemical resistance. It may release small amounts of alkali into solutions and is therefore generally used only for non-parenteral products such as oral liquids or topical preparations.
Q5. What Are Extractables and Leachables in Packaging?
Extractables are chemical substances that can potentially be extracted from packaging materials under exaggerated laboratory conditions such as high temperature or aggressive solvents. Leachables are compounds that actually migrate from packaging materials into the drug product under normal storage conditions. Examples include plasticizers like Di-2-ethylhexyl phthalate, antioxidants, and rubber additives. Regulatory agencies require identification and toxicological assessment of these substances to ensure product safety.