More than 160 Lawrence and Douglas County residents disposed of more than 450 pounds of unused prescription drugs during this weekend’s National Prescription Drug Take-Back Day, Lawrence police and Douglas County Sheriff’s Department officials said.

Residents were invited to drop off the unused or unwanted drugs at one of two locations in Lawrence on Saturday. It was part of an event that takes place twice a year in conjunction with the Federal Drug Enforcement Administration.

The Douglas County Sheriff’s Department also began an ongoing take-back service in July. Residents can dispose of unwanted medications Monday through Friday at the Judicial and Law Enforcement Center, 111 East 11th St. The free, anonymous service is available from 8 a.m. to 5 p.m. via a drop-box just inside the building’s west main doors.