The Food and Drug Administration (FDA) has approved design changes and a new programming interface for Medtronic's SynchroMed II implantable drug pump, months after federal authorities lifted sales restrictions on the pain-fighting device.

The SynchroMed II drug pump is approved to treat chronic pain and severe muscle spasticity in patients who don't get relief from drug therapies or other treatments. In 2015, sales of the pump were restricted only to extraordinary cases after FDA inspectors concluded that the company had repeatedly failed to fully investigate and correct problems that could result in older versions of the device over-infusing patients with drugs.

The sales restriction has since been lifted, and Medtronic is now marketing the device as a way to cut down on the use of oral opioid drugs. Medtronic says that for some patients, the device can reduce or eliminate the need for addictive oral opioid medications because it delivers small, targeted doses of pain drugs directly into the spinal fluid.

"With the ongoing opioid crisis, the ability to reduce the use of systemic opioids and effectively manage my patients' pain with the SynchroMed II pump system is more important than ever," Indiana University Health pain-medicine specialist Dr. Joshua Wellington said in a Medtronic news release. (Medtronic has paid Wellington more than $130,000 since 2014 for speaking engagements, consulting and meetings over meals, federal records show.)

The SynchroMed II system includes a pump that can be filled with various types of liquid medications that are administered in small doses through a thin tube surgically connected to the intrathecal space around the spinal cord. This "targeted drug delivery" method allows for much smaller doses of drugs, including opioid and non-opioid drugs.

Drug doses and delivery schedules can be programmed wirelessly in the doctor's office using the new programmer that the FDA approved. The programmer is an application that runs on a tablet computer. It shows side-by-side comparisons of therapy changes, and performs automated calculations to "help ensure accuracy and improve programming confidence," Medtronic's announcement on Wednesday said.

"Our new clinician programmer follows a series of recent SynchroMed II Pump design changes and was developed with patient safety in mind," said Charlie Covert, Medtronic Pain Therapies general manager. "Our goal was to make it intuitive and simple for clinicians to confidently tailor treatments to best meet patients' needs."

Past versions of the pump have been subject to considerable post-market scrutiny.

Medtronic CEO Omar Ishrak signed a consent decree with the Justice Department in 2015 resolving allegations that Medtronic had repeatedly failed to correct violations of the FDA's regulations on quality manufacturing processes related to the pump, including rules that say the company must thoroughly investigate device malfunctions and serious patient injuries and make validated design changes when needed.

The problems that the FDA observed with the SynchroMed II pump, during inspections between 2006 and 2013, could have resulted in an over- or under-infusion of medication for patients, according to a DOJ news release at the time.

In October 2016, the company issued an updated alert to doctors on the potential for an older version of the pump to over-infuse patients with drugs. It said an investigation had found several factors could lead to drug over-infusion, including using nonapproved drugs in the pumps, overfilling the pump reservoir, operating the pump without fluid in the reservoir, problems with the tube that delivers the drug, and stalls in the pump motor lasting more than 48 hours.

The 2015 consent decree originally included limitations on sales of the device to "extraordinary circumstances," requiring a physician to certify that the device was medically necessary for an individual patient's treatment. Prescribing doctors had to sign forms saying they had reviewed the agreement and discussed it with their patients.

On Wednesday, a Medtronic spokesman said that although the consent decree is still in place, doctors are no longer are required to submit certification forms to order the device and customer notification letters no longer need to be provided to doctors and hospitals, because the company had made significant progress in meeting its obligations under the agreement.

"This represents a major milestone under the consent decree," spokesman Justin Ihle wrote in an e-mail Wednesday. "As further evidence of our progress against consent decree commitments, the FDA has approved a newly designed version of SynchroMed II, which we've been shipping in the U.S. since July."

Joe Carlson • 612-673-4779