A pair of suspected fatal overdoses this week on the nation's largest death row is adding urgency to an effort to allow California prison guards and even inmates to carry a drug that can save the lives of those who overdose on opioids.

Starting next month, all sergeants working the 10 p.m. to 6 a.m. shift statewide will carry naloxone, the state corrections department said Thursday in a decision that predates the most recent deaths. Sergeants are generally the first responders in housing units overnight when medical workers aren't as readily available, said Lt. Sam Robinson, a spokesman at San Quentin State Prison.

Attorneys representing inmates want even broader distribution of the overdose-reversing drug. They requested earlier this year that correctional officers and inmates also carry the inhalers, said Steven Fama of the nonprofit Prison Law Office.

Forty California inmates died of drug overdoses last year, according to statistics provided to The Associated Press on Thursday in advance of their publication. That's double the number of drug-related deaths in 2014 and 2015, and the death toll continues to rise "at a very significant rate," according to an annual death review for the federal receiver who controls prison medical care under a long-running lawsuit. California's long-term drug overdose rate is more than three times the nationwide prison rate.

Prison nurses in California began carrying naloxone in 2016. It can reverse respiratory failures from opioid overdoses.

It is routinely administered when any inmate is found unconscious, no matter the cause, because there are no adverse side-effects, said Liz Gransee, a spokeswoman for the federal receiver. She and corrections officials could not immediately comment on the request to expand its availability.

Anyone can now easily obtain naloxone at a drug store after undergoing brief training in how to administer the inhaler, Fama said, so he said even inmates should be trained in its use.

Autopsies are set Friday for Joseph Perez Jr. and Herminio Serna, who died while awaiting execution at San Quentin State Prison north of San Francisco. But the Marin County coroner's office said toxicology results could take weeks.

In the meantime, prison officials are investigating how contraband may have been brought into death row and are increasing education to inmates on the dangers of abusing illicit drugs.

"Warning! Please be advised that contraband being circulated now is causing death and serious medical harm," the prison's chief medical officer said in a memo being distributed by hand to all San Quentin inmates, starting with those on death row

California officials have spent millions of dollars system-wide, with limited success, to stem the smuggling of contraband by inmates, visitors and employees. They blamed smuggled Fentanyl for killing one inmate and sickening 11 others at another Northern California prison in April.

"It's obviously extremely difficult to stop because you're talking about grains of Fentanyl that can be lethal," Fama said.

Prison officials blamed "acute drug toxicity" for the deaths of condemned inmates Emilio Avalos in November 2017 and Joe Henry Abbott in January. They are the most recent since overdoses were blamed for killing two condemned inmates in 2005.

Aside from drugs, officials are still investigating how an inmate on the highly secure death row obtained the weapon used to kill 30-year-old Jonathan Fajardo in October.

California has not executed anyone since 2006. Since 1978, when California reinstated capital punishment, 79 condemned inmates have died from natural causes. Another 25 have killed themselves and 15 have been executed.

Officials said two condemned multiple murderers apparently committed suicide within hours of each other last month, but the official cause of their deaths also is awaiting autopsy results.