PHILADELPHIA — A prescription drug that can reduce fatalities from heroin overdoses is about to become more widely available. Key provisions take effect Saturday in a law that was passed in an effort to get the drug naloxone into the hands of more people who can use it to stop overdoses. Naloxone, commonly called Narcan, reverses the effects of heroin. Although Pennsylvania had permitted paramedics and doctors to use it, police were not able to legally administer the antidote.

The law also allows physicians to prescribe naloxone to friends and relatives of addicts, who are often the first to come into contact with someone suffering an overdose.