Prescription Drug Monitoring Programs in New Jersey and Pennsylvania are now fully reciprocal, allowing physicians and pharmacists to check whether patients are doctor-shopping for painkiller prescriptions or picking them up at multiple pharmacies. Both are signs that they may be addicted to opioids or are selling them illegally on the street.

The databases are seen as key tools in reducing the epidemic of opioid addiction by alerting physicians that they may need to wean their patients off the drugs or get them into treatment programs. Simply cutting off their supply can lead them to purchase pills like Percocet and OxyContin on the street or buy heroin as a cheaper substitute. Meanwhile, overdose fatalities have risen sharply as dealers mix their heroin with far more powerful fentanyl.

Gov. Christie on Wednesday announced the data-sharing with Pennsylvania and four other states. Trenton's monitoring database was launched in 2011; Pennsylvania's program was overhauled last summer, becoming the 49th in the country to allow access by medical providers (Harrisburg's old program was limited to law enforcement).