Transdermal Drug Delivery Concepts

The merging or fusing of individual droplets within an emulsion.

The ability of the stratum corneum to allow the drug to pass through it.

The outermost layer of the skin that acts as the primary barrier for drug penetration during transdermal delivery.

Drugs with low solubility and high permeability.

The application of a direct electrical current to enhance drug delivery through the skin.

An emulsion where oil droplets are dispersed in a continuous water phase. This is commonly used for oral drug delivery due to its ability to mask the taste of lipophilic drugs.

An emulsion where water droplets are dispersed in a continuous oil phase. This type is ideal for delivering lipophilic drugs with poor water solubility, as the oil phase can encapsulate them.

A thickening agent added to emulsion formulations to increase viscosity. It improves emulsion stability by preventing droplet aggregation and separation. It increases the overall thickness.

A phenomenon where small droplets merge to form larger ones, leading to phase separation. It's a common stability problem in emulsion formulations.

A combination of two or more emulsions, which can enhance drug delivery. For example, an O/W/O emulsion consists of oil droplets dispersed in water droplets that are further dispersed in an oil phase.

A spherical structure formed by a phospholipid bilayer, with an aqueous interior. Think of a tiny sphere filled with water, with the phospholipids forming the wall of the sphere.

The process where phospholipids spontaneously arrange into bilayers when placed in water. The hydrophobic tails face inward, and the hydrophilic heads face outward, forming a stable structure.

A type of liposome characterized by high flexibility and deformability, allowing them to pass through small pores. Imagine a deformable balloon that can squeeze through small openings.

A unique type of nanoparticle designed to deliver drugs through the skin. They primarily consist of phospholipids and water, forming small, flexible vesicles that can penetrate the skin.

The process by which nanoemulsions release their encapsulated drug over an extended period, providing a sustained therapeutic effect. Think of a time-release capsule gradually releasing its medicine.

Surfactants that have a stronger affinity for water than oil. They gather at the interface of oil and water, creating a protective layer around the oil droplets, aiding in the formation of oil-in-water (O/W) emulsions.

The potential difference between the surface of a charged particle (like an emulsion droplet) and the liquid surrounding it. It's a measure of the electrostatic repulsion between droplets, influencing emulsion stability.

The tendency of droplets in an emulsion to rise to the top, due to density differences between the dispersed and continuous phases. This is a common issue, especially in emulsions with low-density dispersed phases.

A measure of a surfactant's ability to form an emulsion. It's a scale from 0 to 20, with higher values representing better O/W emulsifiers and lower values indicating better W/O emulsifiers.

A theory that explains emulsion stability by the formation of a strong and flexible film around the dispersed droplets, created by surfactants. This film acts as a barrier against droplet coalescence.