HARRISBURG — Pennsylvania is launching its database on prescription drug dispensing in an effort to prevent their abuse.

Starting Thursday, state law requir+es physicians to review the prescription histories of first-time patients before putting them on opioid painkillers and other controlled substances.

The legislation also allows doctors to go online to see if a patient is getting prescription drugs from more than one doctor in a practice known as doctor shopping. The electronic database maintained by pharmacists who fill prescriptions is also intended to show prescribing patterns that could be a sign of over-prescribing by doctors.

But some caution that the database could cause some addicts to switch to heroin.

Pennsylvania is now the 49th state to operate such a database.