The billionaire founder of INSYS Therapeutics Inc John N. Kapoor, has resigned from the company's board of directors, the company said in a statement on Sunday. Kapoor was arrested on Thursday on U.S. charges he participated in a scheme to bribe doctors to prescribe a fentanyl-based cancer pain drug, marking a step by authorities to fight the opioid epidemic.

Kapoor has denied the allegations, according to a statement.