Drug plan prices touted during Medicare open enrollment can rise within a month

Retiree Donna Weiner shows some of the daily prescription medications for which she pays more than $6,000 per year through a Medicare prescription drug plan. She supports giving Medicare authority to negotiate drug prices. (Phelan M. Ebenhack / AP)

Something strange happened between the time Linda Griffith signed up for a new Medicare prescription drug plan during last fall's enrollment period and when she tried to fill her first prescription in January.

She picked a Humana drug plan for its low prices, with help from her longtime insurance agent and the Medicare Plan Finder, an online pricing tool for comparing a dizzying array of options. But instead of the $70.09 she expected to pay for her dextroamphetamine, used to treat attention-deficit/hyperactivity disorder, her pharmacist told her she owed $275.90.