Arizona's Naloxone Coprescribing Law Worked on Prescribing. A New Study Can't Yet Say It Saved Lives

Arizona's requirement that clinicians prescribe naloxone alongside high-dose opioid prescriptions produced an immediate, measurable jump in naloxone prescribing — and then settled at roughly twice its previous level — according to a new University of Arizona study that tracked every opioid prescription dispensed in the state over six years.

The analysis, published in the American Journal of Preventive Medicine and released by University of Arizona News on October 7, used data from the Arizona Controlled Substances Prescription Monitoring Program — the state's mandatory database of dispensed controlled-substance prescriptions — covering 2017 through 2022. Because the program records prescriptions when they are filled rather than when they are written, the data capture naloxone that patients actually picked up, not just prescriptions their clinicians wrote.

The researchers found that coprescribing of naloxone among patients on the highest opioid doses spiked between 331% and 360% in the first two months after the law took effect, then declined but stabilized at roughly double the pre-law rate. The team also documented an effect the law did not require: naloxone prescribing rose for patients on moderate doses the statute did not cover, and pharmacist dispensing rose sharply across every dose category, including low doses.

What the study could not determine is whether any of that translated into fewer overdoses or fewer deaths. The authors say so plainly, and that gap is the most important caveat in the paper.

What the law required

Arizona's coprescribing requirement took effect in April 2018. It applied to patients receiving more than 90 morphine milligram equivalents (MME) per day — a threshold that functions as a rough marker of elevated overdose risk in opioid prescribing. Clinicians writing prescriptions above that level were required to also prescribe naloxone, the opioid-overdose reversal medication sold over the counter as Narcan and in generic forms.

Arizona already had a second, separate door to naloxone: statewide standing orders allowing pharmacists to dispense the medication to a patient without an individual prescription. That mechanism predated the coprescribing law and was not what the statute changed.

What the data showed

Led by James Cunningham, a professor in the Department of Family and Community Medicine at the University of Arizona College of Medicine – Tucson, the research team analyzed statewide dispensing records and compared prescribing behavior before and after April 2018.

Among patients on high-dose opioids, coprescribing behavior changed fast:

• For patients receiving 90 to 119 MME per day, naloxone coprescribing rose 331% in the first two months.
• For patients receiving 120 MME per day or more, it rose 360%.
• After the initial spike, coprescribing settled at levels 97% and 123% above the pre-law baseline, respectively — roughly twice as high as before.

By the end of 2022, about 2.3 naloxone prescriptions were being coprescribed for every 100 opioid prescriptions among patients at 90 to 119 MME per day, and about 1.5 per 100 among those at 120 MME or more. Before the law, that rate was roughly 0.5 per 100 high-dose prescriptions. The study notes that no optimal coprescribing level has been established, partly because a new naloxone prescription is not needed every time an opioid prescription is filled.

The spillover the authors didn't expect

Two findings went beyond what the statute required.

Patients receiving 50 to 89 MME per day — a moderate dose, below the legal threshold — also saw coprescribing rise by 215% in the first two months, settling at a level 72% higher than before the law. "The increase wasn't limited to patients covered by the law," Cunningham said. "Naloxone prescribing also increased for patients receiving moderate doses of opioids."

Pharmacists moved too. Dispensing under Arizona's standing orders increased by at least 111% in every opioid-dose category, including among patients on low doses, and stayed elevated for about two years before tapering. "Pharmacists also sharply increased naloxone dispensing to patients who had opioid prescriptions but had not been prescribed naloxone, even though pharmacist dispensing wasn't addressed by the law," Cunningham said.

The authors also point to who got reached. Community harm-reduction programs distribute naloxone widely, but they tend to focus on people using illicit opioids. "The coprescribing law helped provide naloxone to patients who might not have gotten it through community organizations," Cunningham said — people with a legitimate prescription who are nonetheless at risk.

Why a prescription still matters after over-the-counter naloxone

Naloxone became available over the counter nationwide in March 2023, after the study period ended. That changed the access picture, but it did not make prescriptions irrelevant. Patients who need high-dose opioids often face financial strain, and a prescription can route the cost through insurance rather than a cash purchase of roughly $30 to $40.

Cunningham also argues the requirement has a behavioral function that an over-the-counter product does not: it keeps the subject in the room. "You're in the doctor's office for 10, 15 minutes, and then you're out the door," he said. "Clinicians have a lot of things competing for their attention, but the regulation helps keep naloxone in the conversation."

The limit the study states plainly

The paper measured prescriptions. It did not measure outcomes. The study, in the authors' own words, could not determine whether the increase in naloxone prescribing translated into fewer overdoses or deaths — a question they say requires additional research.

Arizona's own mortality data show why that question is not academic. According to CDC National Center for Health Statistics provisional counts, Arizona recorded 2,807 drug overdose deaths in the 12 months ending May 2026, down from 2,922 in the 12 months ending January 2026. Of those, 2,072 involved opioids, and 1,862 involved synthetic opioids other than methadone — a category dominated by illicitly manufactured fentanyl. Nationally, the same series shows 65,351 deaths in the 12 months ending May 2026, down from 69,671 in the January figure.

Those counts are not adjusted for population. Using Census Bureau population estimates, Arizona's count works out to roughly 37 overdose deaths per 100,000 residents against roughly 19 per 100,000 nationally — an approximation, not an age-adjusted rate, but one that shows the state's per-capita burden remains close to double the national figure even as the trend line bends downward.

In other words: the law changed what clinicians and pharmacists do, in a way that is measurable and durable. What it did for survival is still an open question.

What it means for Arizona patients and families

The practical takeaways do not depend on the outcome question being settled.

If you or a family member is prescribed opioids at or above 90 MME per day, Arizona law requires the prescriber to also prescribe naloxone. Ask. If the answer is no, ask why — and note that pharmacists in the state can dispense naloxone under standing orders without an individual prescription.

If someone in your household has a take-home naloxone kit, the people around them should know where it is and how to use it. Our guide to getting naloxone for a family member walks through prescriptions, pharmacies, insurance and free sources, and safe medication storage and disposal covers what belongs locked up when opioids are in the house.

Naloxone reverses an overdose. It does not treat opioid use disorder. The medications that do — buprenorphine, methadone and naltrexone — remain underused nationwide, and starting medication for opioid use disorder is still the intervention with the strongest evidence behind it.

What's next

Three things to watch.

Outcome research. The Arizona paper is a prescribing study; the mortality question it leaves open is the one policymakers need answered. Expect follow-up work linking coprescribing mandates to overdose and death data.

Whether other states copy the model. Arizona is one of a small number of states that tied naloxone to high-dose opioid prescriptions by statute. Its measurable prescribing effect is an argument for the approach — and the unresolved mortality question is the counterargument.

How the over-the-counter era changes the calculus. Arizona's data end in 2022, before naloxone moved to pharmacy shelves without a prescription. Whether mandates still add reach now that anyone can buy naloxone — and whether they still help with cost — is a different study than the one just published.

If you or someone you know needs help now, the SAMHSA National Helpline is 1-800-662-4357, free and confidential, 24 hours a day. The 988 Suicide & Crisis Lifeline takes calls, texts and chats. FindTreatment.gov lists licensed treatment options by location and payment type, and Poison Help (1-800-222-1222) advises on suspected poisoning and medication exposure.