transdérmicas

Transdermal patches, known in Spanish as “transdérmicas,” are medical devices designed to deliver a drug through the skin into the systemic circulation. The technology exploits the skin’s ability to act as a reservoir, allowing for controlled, sustained release of medication over periods ranging from several hours to weeks. Transdermal systems are composed of an adhesive backing, a drug-containing matrix or reservoir, and a rate-controlling membrane in some designs. The adhesive ensures intimate contact with the skin, while the matrix or reservoir holds the active pharmaceutical ingredient (API) and any excipients needed to modulate release.

The primary advantages of transdérmicas include improved patient adherence, avoidance of gastrointestinal degradation or first‑pass hepatic metabolism, and the ability to maintain relatively constant plasma drug concentrations. They are employed for a variety of therapeutic indications such as nicotine replacement for smoking cessation, analgesia (e.g., fentanyl or buprenorphine patches), hormonal therapy (e.g., estradiol or testosterone), and treatment of motion sickness (scopolamine). Recent developments have expanded their use to vaccines, hormonal contraception, and anti‑emetic agents.

Drug selection for transdermal delivery depends on physicochemical properties: low molecular weight (generally < 500 Da), moderate lipophilicity (log P between 1 and 4), and adequate potency to achieve therapeutic levels with the limited amount that can be transferred through the skin. Enhancers such as ethanol, oleic acid, or iontophoresis may be incorporated to increase permeability.

Safety considerations involve skin irritation, allergic reactions, and potential for overdose if patches are applied improperly. Regulatory agencies require rigorous testing of adhesion, drug release kinetics, and stability. Proper disposal is also important to prevent accidental exposure, especially for potent opioids. Transdermal patches remain a valuable alternative to oral and injectable routes, offering a non‑invasive method for sustained drug delivery.