AstraZeneca ( AZN) will pay $335 million to settle federal charges related to the sales and marketing practices of its prostate cancer treatment Zoladex. The company pleaded guilty to having induced physicians to submit reimbursement claims to Medicare, Medicaid and other government-funded programs for samples the doctors had obtained for free from the drugmaker. AstraZeneca had announced in its 2002 results that it had set apart $350 million to cover the costs related to the settlement, one of the largest ever related to health insurance fraud. "We accept responsibility for any improper sampling conduct that took place in the mid 1990s, and have taken steps within our new company to prevent such activities from happening again," AstraZeneca said in a statement late Friday. The drug representatives had aimed to secure future business with urologists by attracting them with the extra profit they would get from billing the government fraudulently. Doctors could reap some $300 for each one-month regimen of Zoladex per patient. Three physicians were charged, two of which have pleaded guilty. The investigation didn't find evidence of any involvement by AstraZeneca's top executives, revealing instead that the system was implemented by its sales representatives. Shares of the company were down 2.1% at $42.32 in early trading Monday.