SACRAMENTO — Almost 13 years after a driver hooked on prescription painkillers drove into Bob Pack’s two young children on a sidewalk, killing them both, the Danville father on Tuesday finally got the call he has been waiting so long to receive.

Gov. Jerry Brown signed into law Senate Bill 482, which will require doctors to check a database for a patient’s prescription history before prescribing opioids and other potentially dangerous drugs.

“It was a like a deep sigh of relief for me, and it hit me kind of tearfully at the same time,’’ Pack, a 61-year-old tech entrepreneur, said of the call from Brown’s office.

“Because, you know, not only has it been a long effort, but it just immediately made me think of my two children and their little faces. And the loss.’’

On that fateful Oct. 26 night in 2003, Pack’s wife Carmen, their 10-year-old son, Troy, and 7-year-old daughter, Alana, were walking on a sidewalk on their way to get Slurpees when out of nowhere, Jimena Barreto’s car plowed into them. At the time of the accident, she had alcohol, Vicodin and muscle relaxants in her system.

The 49-year-old woman had three previous DUI convictions and was driving with a suspended license. She’d managed to obtain Vicodin prescriptions from six different Kaiser Permanente doctors, all unaware of each other’s prescriptions. Barreto was convicted of second-degree murder and sentenced to 30 years in prison.

The tragedy spurred Pack to work for years to persuade lawmakers to pass legislation that might prevent others from having to live through his nightmare, something he acknowledged Tuesday.

“I know that this is so meaningful for so many families that also have been harmed when they lost a relative or a child due to drug overdoses,’’ Pack said.

“I want to just express my sympathies for those families, and let them know we are all on the same journey together, and that there are so many families that are going to be spared this grief that we have had to endure’’ because of the new law, he said.

The law, which goes into effect Jan. 1, comes at a time when the U.S. is confronting a nationwide opioid epidemic that has resulted in more than 1,000 emergency room visits and 78 deaths every day across the country.

“I applaud Gov. Brown for signing SB 482,” said Gary Mendell, founder and CEO of Shatterproof, a national drug control group that supported the bill, authored by Sen. Ricardo Lara, D-Bell Gardens. “More than 4,000 Californians are dying every year from opioid addiction, and this law will help turn the tide.”

California now joins two-dozen states that already require prescribers to check a state-based prescription drug monitoring system. New York reported a 75 percent reduction in “doctor shopping” for opiates after one year, while Kentucky saw opioid prescriptions fall by 8 percent.

Since September 2009, doctors have been able to voluntarily check the database online before writing prescriptions for controlled substances such as painkillers, muscle relaxants and amphetamines.

But the Packs and other advocates realized that few doctors took advantage of the database and this law makes it mandatory.

Still, there is no guarantee that doctors will follow the mandate, a weakness even Pack and the bill’s advocates acknowledge. They say one of the only ways the state Medical Board could learn that a doctor has not complied is if it finds out that a patient died from an overdose or an incident occurred like the one that led to the Packs’ tragedy. In such a case, doctors would face administrative action by the California Medical Board.

Advocates say it’s a step in the right direction.

“I’m very optimistic that California physicians will embrace this system and use it to effectively halt our prescription pain killer epidemic,” said Eric Bailey, spokesman for the Consumer Attorneys of California, which also supported the law.

If they don’t use it and tragedy ensues, Bailey believes they would open themselves up to problems.

Pack said Brown’s office has invited him and his family, wife Carmen and daughter Noelle, to meet personally with the governor on Wednesday.

“I know that he has 100 percent wanted this to become law and he has backed it very strongly … since he was the attorney general,’’ said Pack. “So I know how dedicated he has been with this.”

And he knows Troy and Alana are proud of all his efforts.

“I can only just imagine them hugging me and saying, ‘Way to go, Daddy!”’