transdermaalne

Transdermaalne refers to transdermal drug delivery, a route of administration where agents are delivered across the skin into the systemic circulation. This approach uses various systems, most commonly medicated adhesive patches, but also gels, creams, and ointments designed to release drug through the skin over time. The skin’s outer barrier, the stratum corneum, is the main obstacle to absorption, so successful transdermal delivery depends on the drug’s physicochemical properties and the formulation’s design.

Delivery relies mainly on passive diffusion through skin layers, driven by concentration gradients. To broaden applicability, technologies such as chemical enhancers, carrier matrices, and physical methods like iontophoresis (electric current) or sonophoresis (ultrasound) are used to increase penetration. Patch designs include reservoir, matrix, and drug-in-adhesive types, each balancing release rate, adhesion, and safety. Absorption rates vary with site, skin condition, age, and a drug’s lipophilicity and molecular weight. Onset is generally slower than injectable routes, with effects sustained for hours to days after application.

Common applications include chronic therapies where steady drug levels are beneficial. Nicotine for smoking cessation patches, opioid and nonsteroidal anti-inflammatory patches, and hormone replacement therapies are widely used examples. Advantages include avoidance of first-pass hepatic metabolism, improved patient convenience, and the ability to maintain steady plasma concentrations. Limitations involve limited drug candidates, potential skin irritation or dermatitis, and variability in absorption. Risks include accidental exposure to others if patches are mishandled or removed improperly.

Future directions focus on advanced transdermal systems, such as microarray patches and dissolvable microneedle technologies, aimed at expanding drug types, improving dosing control, and enhancing safety and user experience.