[Transdermal therapeutic systems]

Transdermal therapeutic systems (TTS) gain continuously increasing importance in therapy due to their advantageous properties. They assure constant concentration of the active substance in the blood, a lower amount of the drug compared to the orally administered dose is sufficient, side effects decrease, and the therapy is painless. Since the appearance of the first products many TTSs have been developed containing a wide variety of active substances including hormonal, antihypertensive, antianginal, and analgesic plasters. Nowadays TTSs belong to the most advanced formulations. There is ongoing research in the field of regulating the active substance release with electric current or ultrasound. There are systems containing insulin, cytostatics, antiparkinsonians, contraceptives, and anxiolytics under development.