Implantable naloxone sensor could improve opioid safety

US researchers have made an implantable device that can detect opioid overdoses and automatically respond with naloxone.

The device, called the iSOS implant, has not yet been tested in humans, but has successfully reversed the overdoses of 24 out of 25 pigs.

The study is published in Device.

“Having an automated robotic system that is able to sense and reverse opiate overdose could be transformational, particularly for high-risk populations,” says senior author Dr Giovanni Traverso, a biomedical engineer at the Massachusetts Institute of Technology and clinician at the Brigham and Women’s Hospital.

“Substance use is a fundamental disorder, and individuals who have had overdoses are at higher risk of overdosing again.”

Opioid overdose, from both prescription and illicit drug use, causes more than 125,000 deaths per year worldwide according to the World Health Organization.

In the USA, mortality has increased in the past decade and particularly during the pandemic. In 2022, the country recorded more than 80,000 opioid-related deaths.

The drug naloxone is an antidote for opioid overdose, but it has to be administered quickly – overdose can cause permanent brain damage in less than 3 minutes and death in 4-6 minutes. It also generally needs to be administered by a bystander who can recognise the symptoms, since patients rapidly lose consciousness.

“To help support this population and those at the greatest risk of overdosing, we wanted to develop an automated way of providing early detection of those events, and then couple that signal with the quick release of naloxone,” says Traverso.

The device, which currently measures 8mm × 12mm × 78mm, is designed to be implanted under the skin. It’s fitted with sensors that track heart rate, body temperature, breathing, blood pressure and oxygen saturation.

The researchers used animal studies to develop an algorithm that decides when an overdose is happening based on these factors (as opposed to other conditions that might disrupt vital signs, like sleep apnoea).

The iSOS implant is fitted with a refillable reservoir that can pump 10 milligrams of naloxone into subcutaneous tissue. It could also buzz or send an alert to a smartphone to warn a patient of overdose, or send a wider medical alert.

“The most challenging aspects of developing an engineering solution to prevent overdose mortality are addressing patient adherence and willingness to adopt new technology, minimizing false positive detections, and ensuring the rapid delivery of antidotes,” says co-first author Dr Hen-Wei Huang, a roboticist at Brigham and Women’s Hospital, Harvard Medical School, and Massachusetts Institute of Technology.

“Our proposed solution tackles these unmet needs by developing a miniaturised robotic implant equipped with multi-sensing modalities, continuous monitoring capabilities, on-board decision-making, and an innovative micro-pumping mechanism.”

Traverso tells Cosmos that the device has taken about 5 years to develop so far. The team is now working on optimising the implant and making it smaller.

“We are now focused on advancing the device further with the goal of initiating first-in-human trials within the next 3-5 years,” says Traverso.

The team also plans to learn more about patient preferences, to see how they can enhance the device’s acceptability.

“We believe that many patients would be willing to adopt the iSOS implant, especially those who are at high risk of opioid overdose and are seeking reliable, life-saving interventions,” says Traverso.

“However, we also recognise that the decision to adopt an implantable device is significant, and acceptance may vary among individuals.”

Traverso says that the team will likely run studies such as surveys, focus groups and pilot programs to find patients’ and healthcare providers’ views on the device.

“These studies will help us refine the device further, address any concerns, and ensure that it meets the needs and expectations of potential users.”