A Derby nurse practitioner was among the top 10 prescribers nationally of the most potent controlled substances in Medicare’s drug program in 2012 – an anomaly in a state where Medicare records show nurse practitioners rarely prescribe such drugs, which have a high potential for abuse. Heather Alfonso, an advanced practice registered nurse (APRN) at the Comprehensive Pain & Headache Treatment Centers, LLC, wrote out 8,705 prescriptions for opioids and other Schedule II drugs in 2012 – the most prolific prescriber among all Connecticut practitioners, including pain specialists and other physicians, according to Medicare data compiled by ProPublica. She wrote out more prescriptions for the opioid Exalgo than any other Medicare provider in the country, and was the seventh highest prescriber nationally of Oxycontin, writing out more than twice as many prescriptions for that narcotic as the next highest prescriber in Connecticut. She also was the 10th highest prescriber nationally of Avinza, a morphine product. There is no indication that Alfonso’s unusual prescribing frequency drew scrutiny from state or federal officials.