(Reuters Health) - Opioid prescriptions may decline when states legalize marijuana, two U.S. studies suggest.

FILE PHOTO: Marijuana is seen for sale at Harborside, one of California's largest and oldest dispensaries of medical marijuana, on the first day of legalized recreational marijuana sales in Oakland, California, U.S., January 1, 2018. REUTERS/Elijah Nouvelage/File Photo

One study focused on older adults with Medicare drug benefits. In each state, in an average year, doctors prescribed 23 million daily doses of opioids. Compared to states where cannabis was banned, states where medical marijuana was legal averaged 3.7 million fewer opioid doses annually, while states that permitted only home cultivation of marijuana had 1.8 million fewer doses.

A separate study of adults insured by Medicaid, the U.S. health program for the poor, found medical marijuana laws associated with an almost 6 percent decline in opioid prescriptions.

“These findings suggest that cannabis may play a role in fighting the opioid crisis by reducing some patients’ need for opioids,” said Dr. Kevin Hill, coauthor of an accompanying editorial and director of addiction psychiatry at Beth Israel Deaconess Medical Center in Boston.

“The evidence thus far does not suggest that cannabis should be a first-line or even a second-line treatment for pain,” Hill said by email. “But if a patient has tried to treat pain using multiple modalities without success, a trial of medical cannabis may make sense.”

Each day, 90 Americans die from opioid overdoses, Hill notes in JAMA Internal Medicine, where both studies were published. While some deaths may be due to illegal narcotics like heroin, others are caused by opioid medications like oxycodone, fentanyl, hydrocodone, morphine, and methadone.

In the Medicare study, conducted from 2010 to 2015, researchers didn’t find cannabis legalization associated with a meaningful reduction in prescriptions for fentanyl or oxycodone.

But annual hydrocodone use declined, on average, by 2.3 million daily doses in states with legal marijuana dispensaries and by 1.3 million daily doses in states that legalized only home growth of marijuana.

Legal dispensaries were also associated with an average of 361,000 fewer daily doses of morphine prescriptions each year, the study found.

“Patients and physicians seem to be responding to the introduction of medical cannabis as if it were medicine - in many ways as they would with the introduction of a new FDA-approved medical treatment,” said study coauthor W. David Bradford, a researcher at the University of Georgia in Athens.

“Of course, there may be diversion from medical cannabis sources to recreational purposes - our research can’t really speak to that,” Bradford said by email.

The study of Medicaid patients examined the association between opioid prescribing rates and state marijuana laws implemented from 2011 to 2016.

In states without medical marijuana laws, the annual opioid prescription rate was about 670 for every 1,000 people enrolled in Medicaid, the study found.

When states implemented medical marijuana laws, however, the annual opioid prescription rate declined by almost 6 percent, or approximately 39 fewer prescriptions for every 1,000 people enrolled in Medicaid each year.

Neither study proves that legalizing marijuana causes a decline in opioid prescriptions. Also, it’s unclear from the studies exactly how much marijuana use was for medical versus recreational purposes or how much people might have relied on other non-opioid painkillers.

“Marijuana is one of the potential, non-opioid alternatives that can relieve pain at a relatively lower risk of addiction and virtually no risk of overdose,” said Hefei Wen, co-author of the Medicaid study and a researcher at the University of Kentucky College of Public Health in Lexington.

“The potential of these marijuana (legalization) policies to reduce the use and consequences of addictive opioids deserves consideration especially in states that have been hit hard by the opioid epidemic,” Wen said by email.

SOURCE: bit.ly/2uIwdEI, bit.ly/2uGnCT1 and bit.ly/2uLErMo JAMA Internal Medicine, online April 2, 2018.