3.2: Topical Drug Delivery II

Ointment bases are categorized based on their interaction with water, including hydrocarbon, absorption, and emulsion bases.

A greasy, water-insoluble ointment base, typically anhydrous, that forms a continuous film on the skin.

A greasy, ointment base that can absorb water due to surfactants, typically forming water-in-oil emulsions.

An ointment base where water is the internal phase and oil is the external phase, often containing pre-mixed water.

The ability of an ointment base to prevent water loss from the skin.

The ability of an ointment base to soften and soothe the skin.

A common, highly refined hydrocarbon ointment base used in ointments; commonly known as Vaseline.

A water-absorbing ointment base containing petrolatum and surfactants; known as Aquaphor.

A skin moisturizer similar to Aquaphor, but with added water and preservatives. It's somewhat occlusive.

Creams where water is the external phase. They absorb varying amounts of water and can be turned into lotions.

A type of cream where water evaporates after application, leaving a protective film. Good for drug delivery.

Bases made of polyethylene glycols (PEGs). They feel greasy but are water-soluble and non-occlusive.

Ointments with a high percentage (20-50%) of fine powder, usually petrolatum. Forms a protective film.

Something that prevents or blocks the passage of something, often used for skin care products to retain moisture.

A substance that softens or smoothes skin.

The natural loss of water from the skin.

Polymers that create gel-like consistency, often used as suspending agents in higher concentrations. Examples include carbomer, tragacanth, alginic acid, and cellulose derivatives.

Most gels are designed to be both water-soluble and water-absorbing. This allows for easy application and drug release.

When applied, the solvent evaporates, leaving a porous matrix film that allows drug diffusion.

The porous matrix film efficiently releases the drug, making gels advantageous for drug delivery.

Solvents like ethanol can increase drug penetration into the skin.

Gels often have greater potency compared to other dosage forms with the same drug concentration due to efficient release and penetration enhancement.

A liquid preparation of pyroxylin dissolved in alcohol, ether, and acetone, with or without added drugs, that forms a film upon application.

The film formed by collodion can seal small wounds and protect surrounding tissue.

Lotions are liquid emulsions or suspensions applied topically. They predominantly have an aqueous continuous phase, meaning water is the main component.

Calamine lotion, Clotrimazole lotion, Selenium sulfide lotion, and Cetaphil (oil-in-water emulsion) are common examples of lotions.

Lotions evaporate upon application, leaving a thin film. This cooling effect soothes the skin and their fluidity allows easy application to various areas.

Lotions, like oral suspensions and emulsions, can experience physical instability (separation, settling), chemical instability, and microbiological instability.

Topical solutions are generally aqueous vehicles that sometimes contain alcohol.

Burrow's solution, Dakin's solution (diluted sodium hypochlorite), and tinctures are examples of topical solutions.

Gels are semi-solid systems where a liquid phase is confined within an interconnected polymeric matrix, often made from natural or synthetic gums.

Gels typically have a water based liquid phase, but can contain co-solvents like alcohol. The drug is usually suspended or dissolved in this liquid phase.

A delivery system for medicines in the form of a spray, typically using a blend of drug and propellant. Examples include: Anti-fungal powders, Sunburn products.

Aqueous solutions soaked into dressings like gauze, linens used for cleansing and promoting wound healing. Often contain astringents or antiseptic agents.

Gas-propelled liquids or solids administered as aerosols, similar in consistency to shaving cream. Used for gentle application and easier spreading without rubbing.

Substances added to topical dosage forms to prevent rancidity in hydrocarbon-containing formulations.

Substances added to water-containing dosage forms to prevent microbial growth.

A natural oil used as a plasticizer in topical dosage forms – it softens the pyroxylin and helps it stay in place.

Moisturizers that form a barrier on the skin to prevent water loss. They create a seal, keeping moisture in.

Moisturizers that attract water to hydrate the skin. They can pull moisture from the air or from deeper layers of the skin.

Substances that help dissolve medications in moisturizers, preventing the medicine from separating out.

A way to measure the correct amount of moisturizer to apply, about the size from your fingertip to the first crease.

Estimates the amount of moisturizer needed for both sides of one hand, about one fingertip unit.

The best time to apply moisturizer is right after bathing or showering, when your skin is still damp.

Always wash your hands before and after applying moisturizer to prevent spreading germs.

Apply moisturizer in a thin layer, usually enough to cover the area without being too thick.