You’ve just had a root canal or knee surgery — both situations that will likely require some sort of local pain medication. But instead of taking a systemic narcotic with all its side effects, what if you could medicate only the part of your body that hurts, only when needed and only as much as necessary?

That concept is today’s reality in the laboratory of Daniel Kohane, MD, PhD, professor of anesthesia at Harvard Medical School and a senior associate in pediatric critical care at Boston Children’s Hospital.

The Kohane laboratory is developing a patient-triggered drug delivery system — but not a simple time-release mechanism or one tethered to ports or pumps. Instead, around the time of an intervention, pain medication would be injected into the site, or around a nerve leading to that site. Whenever pain relief is needed, the patient triggers release of the drug with a laser-like light-emitting device. “It’s like carrying the pharmacy in your body,” explains Kohane. …