Lotion Definitions and Applications

Lotion Definition

• Liquid preparations applied externally to the skin
• Used to treat local conditions like inflammation, acne, infections (bacterial, fungal, viral, parasitic)
• Often used in washes, gargles, and solutions for urethral or vaginal irrigation
• Most lotions are suspensions or emulsions, so labels should state "shake before use" and "for external use only"

Lotion Components

• Alcohol: Acts as a coolant due to evaporation and co-solvent
• Humectants: Retain moisture on the skin after application, glycerol is a common example
• Vehicle: Lotions are aqueous formulations and contain purified water
• Preservatives: Common examples include phenol (0.2–0.5%), chlorocresol (0.075–0.12%), and benzoic acid (0.1–0.3%)
• Stabilizers: Help stabilize the suspended therapeutic agent

Lotion Applications

• Medicinal: Antiseptic, germicidal, treatment of skin diseases, cooling and mild anesthetic applications for skin irritation
• Cosmetic: Applied to hair, scalp, face, hands, and widely used in sunblock preparations

Sunlight and Skin

• Composed of visible light, infrared rays, and ultraviolet (UV) radiation
• Infrared rays produce a sensation of heat
• UV radiations are responsible for therapeutic and toxic effects on the skin
• UV penetrates the skin causing histidine degeneration, which is converted to histamine
• Histamine causes:
  • Dilatation of blood vessels
  • Local irritation with severe itching and burning
• Excessive UV exposure leads to excessive melanin biosynthesis in the skin to protect against UV radiation

Lotion Preparation: Calamine Lotion

• Ingredients:
  • Calamine: 8g
  • Zinc oxide: 8g
  • Glycerin: 6 ml
  • Water: to 100 ml

Lotion Properties

• Alcohol in lotions increases drying and cooling effects
• Glycerol keeps the skin moist due to its hygroscopic nature
• Highly viscous suspending agents like gum tragacanth are not ideal for lotions due to their stickiness
• For hydrophobic substances like sulfur and magnesium stearate, a wetting agent should be added to aid in wetting with water (examples: glycerin or mineral oil)

Explore the essential definitions, components, and applications of lotions. This quiz covers the medicinal and cosmetic uses, key ingredients, and important preparation details of lotions used for skin treatments. Test your knowledge on how lotions are formulated and applied effectively.