What are transdermal dosage forms?
Transdermal dosage forms are dosage forms in which the product is applied to the skin and is diffused through the layers of the skin at a controlled speed, reaching the systemic circulation and being distributed through the tissues until it reaches its site of action. Transdermal dosage forms can be patches, creams, gels, ointments, lotions, gel-creams, plasters and any other pharmaceutical form that allows the active pharmaceutical ingredient (API) to permeate (spread through) the layers of the skin, resulting in a therapeutic effect. The transdermal technology enabled the production of effective systems to promote the absorption of drugs through the skin. The skin covers the surface of the body and represents 16% of the body’s weight. It has a complex structure, being formed by the epidermis (of ectodermal embryonal origin) and dermis (of mesodermal origin), which means that the API needs to cross multiple barriers, in order to gain systemic circulation. Therefore, developing a transdermal dosage form with proven transdermal permeation is a complex task, which can be challenging to the compounding pharmacies worldwide – reason why ready-to-use vehicles like Pentravan® are so important and beneficial.