Lotion Definitions and Applications

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@HumaneMinotaur8554

Study Notes

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"

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

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

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

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

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)