Medicare is on pace to waste $126 million this year overpaying for one generic drug. The drug is lamotrigine ER, the extended-release version of a widely used medication for seizures and bipolar disorder. It's an old generic with several manufacturers, and its price has been coming down. If you pay through insurance, though, you'd never know it. Medicare is paying nearly $200 per prescription. At our pharmacy, a 3-month supply costs about $20 without insurance.