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(Reuters) - Health insurer Anthem Inc ANTM.N filed a lawsuit against Insys Therapeutics Inc INSY.O on Wednesday, alleging the drugmaker fraudulently obtained reimbursements for its opioid painkiller Subsys.

The lawsuit alleges that Insys had paid kickbacks to doctors and lied to Anthem about patients’ diagnoses for reimbursements, which would otherwise have not been covered. The lawsuit was filed in federal court in Arizona.

Two former Insys sales representatives, including the wife of its ex-chief executive pleaded guilty on Tuesday to engaging in schemes to pay kickbacks to medical practitioners to prescribe Subsys.

The pleas came amid ongoing investigations of Insys related to Subsys, an under-the-tongue spray intended for cancer patients that contains fentanyl, a highly addictive and regulated synthetic opioid.

Federal prosecutors in Boston in December announced charges against six former Insys executives and managers in connection with the probes.