(AP)—The Federal Trade Commission says it is mailing refund checks to 13,000 Medicare beneficiaries who were overcharged for drugs because a CVS Caremark Corp. business understated the price of the products.

The FTC says its redress administrator Rust Consulting Inc. began mailing the checks Tuesday. The checks are valid for 60 days from the date they were issued and they must be cashed within that time.

CVS Caremark agreed to pay $5 million in January to resolve allegations that RxAmerica understated the price of medications that treat epilepsy and symptoms of , among other drugs. CVS Caremark said RxAmerica accidentally published incorrect drug price information on a Medicare site.

The inaccurate prices appeared before CVS bought RxAmerica and appear to have ended shortly after CVS bought the company.