BOSTON >> The Massachusetts Senate has joined the House in approving a bill aimed at cracking down on fentanyl, a powerful narcotic often added to heroin.

Senators passed the bill unanimously on Wednesday as part of an effort to fight a deadly opioid abuse epidemic in Massachusetts.

The measure would create the new crime of trafficking in fentanyl for amounts greater than 10 grams and set a punishment of up to 20 years in prison.

Under existing law, drug traffickers can only be charged with manufacturing, dispensing, or possessing fentanyl — a drug experts say is more potent than heroin.

The House approved the bill last month. Routine final votes are now needed in both chambers to send the measure to Gov. Charlie Baker's desk.