Pregna-4,20-dien-3,6-dione

Pregnadienedione (PDD), or pregna-4,20-dien-3,6-dione, is a steroid and pherine, or synthetic pheromone. PDD has been found to activate the vomeronasal organ in men. Moreover, inhalation by men has been found to affect autonomic and central function and to lower luteinizing hormone and testosterone levels, while inhalation by women has few or no effects.