The drug naloxone is known for its ability to bring back people on the brink of death from an opioid overdose, leading emergency responders and health workers to rely on it more than ever as the U.S. opioid epidemic worsens. The drug has been a cornerstone in the fight against opioid abuse.

But the life-saving drug has also had to be rationed in some places as the price increases and demand soars. So the city health commissioner in Baltimore, Dr. Leana Wen, took the extraordinary step of giving all city residents increased access to naloxone by allowing pharmacies to dispense it without a doctor’s prescription.

“We in Baltimore have launched aggressive overdose campaign,” Wen told ABC News.

Baltimore is hardly the only city grappling with opioid abuse. U.S. deaths from heroin overdoses have spiked in recent years, tripling between 2010 and 2014, according to the U.S. Drug Enforcement Agency‘s National Heroin Threat Assessment Summary released earlier this year.

In 2014, the most recent year for which U.S. data is available, 10,574 people died, compared with 3,036 four years earlier.Baltimore’s Wen said the drug, a nasal spray, has saved at least 400 lives since the city increased access to it nearly a year ago. “This is an intervention that is safe and effective, and it’s immediately life-saving,” she said.

The city’s overall expenditure on the drug has tripled recently, Wen said, putting pressure on first responders and outreach workers. She said the city has to decide which health workers and police officers are more likely to encounter an opioid overdose and give them the drug to distribute.

Both generic naloxone and a name brand called EVZIO, produced by Kaleo, have been used by the health department, according to a spokeswoman for the Baltimore City Health Department.

Baltimore City Health Department

Earlier this year, U.S. Rep. Elijah Cummings, D-Md., called on one generic nalaxone manufacturer, Amphastar Pharmaceuticals Inc., which makes a popular version as a nasal spray, to explain the drug’s price increases.

“In May 2014, a 10-dose pack cost the Baltimore City Health Department roughly $190,” Cummings said in a released statement in March. “Guess what? Today, it costs more than $400 for a life-saving drug.”

Amphastar’s generic naloxone was listed at various prices, depending on the city and pharmacy. It was listed as $40 and $50 per dose in two Baltimore pharmacies, $185 for 10 doses at a Chicago Pharmacy and $60 for two doses at a San Francisco pharmacy. The name brand EVZIO autoinjector cost $3,900 to $4,500 at two different Baltimore pharmacies.

Amphastar President Jason Shandell said the price for its generic naloxone last increased in 2014 and was because of a variety of reasons, including increased manufacturing, spending on research and development, and increased spending on the factory where the medication is produced to increase capacity and modernize the facility.

“When considering any price change, Amphastar always strives to meet the goal of providing safe and effective drug products at an affordable price,” Shandell wrote in an email to ABC News. “It should be noted that after our last price change in October 2014, our naloxone injection price is still the lowest among four (4) other similar naloxone injection products when considering the price per milligram of naloxone.”

The pharmaceutical company Kaleo, which produces EVZIO, released a statement saying it is “dedicated to ensuring” people who need the drug are able to access it and that they have donated kits to Baltimore.

“We are extremely proud that, in addition to every day Americans, EVZIO is also able to help first responders and public health departments rescue people suffering from opioid emergencies such as an overdose,” Kaleo company officials told ABC News in a statement. “We have donated more than 10,000 doses of EVZIO to Baltimore so the city can best serve its residents. The city has never paid us for access to EVZIO.”

The company said it has donated 150,000 doses of EVZIO to more than 250 organizations in 34 states, including in Maryland, free of charge. More than 1,600 lives have been reported saved with the help of EVZIO donated through the Kaleo Cares Product Donation Program.

Private donations to Baltimore’s health department have meant that city officials did not have to cut back on the number of naloxone doses bought this year but, Wen said, they still have to be frugal.

Baltimore spent $118,236 on naloxone in fiscal year 2016, more than triple the $33,540 the city spent in 2014, a Health Department spokeswoman said.

But the city also had about 5,255 naloxone kits (two doses per kit) donated in the past year, at an estimated value of $400,000, she added.

In spite of the increased city spending and donated naloxone kits, however, the opioid epidemic in Baltimore has continued to force outreach workers to make hard choices.

City outreach worker Nathan Fields said he constantly has to decide which people should get the drug immediately at community events and which people to direct to a pharmacy.

“I think everybody deserves to have naloxone. I’m talking about Wall Street bankers, the person that is an intravenous drug user, the person on the methadone program, the moms that have the son who has started … robbing the medicine cabinet,” Fields told ABC News.

At outreach events, Fields said he will only give naloxone to those who he thinks won’t be able to get to a pharmacy. The city was able to negotiate a $1 co-pay for the drug for Medicaid patients in Baltimore, according to Wen.

Fields said, “I know that some people won’t [actually get the drug] if I give them a prescription because they don’t have the means. He makes the decision on a “case by case basis,” Fields added.

Fields was out in the city last Wednesday to provide free training on how to use naloxone for International Opioid Awareness Day. He said he has heard from families who have been affected by the opioid crisis and now want to help others dealing with addiction.

“I actually just encountered a family member today who lost someone in their family. At first, they were resistant to being trained,” Fields said, adding that he then explained the program and why it was important.

“They said, ‘My brother overdosed last week,’” Fields said.

He said the man was trained in how to use naloxone.

Dr. Shailja Mehta and Dr. Katie Horton contributed to this article. Both are residents in the ABC News Medical Unit.