A downtown Spokane site has joined a statewide drug-checking network aimed at reducing overdoses. It's also a glimpse into what's new in illicit drug supplies. In recent months, fentanyl powder has shown up as a substance more potent than fentanyl pills. Hints showed last summer of the powerful veterinary sedative xylazine, sometimes mixed with illegal fentanyl. Compassionate Addiction Treatment, a barrier-free drug treatment center, began nearly a year ago to test small samples of drugs, anonymously and voluntarily given by people who come to the center. The statewide network is led by the Addictions, Drug & Alcohol Institute at the University of Washington.