@nbcsouthflorida: Hayden Panettiere's cause of death revealed. Actor Hayden Panettiere died from an accidental overdose of fentanyl and several other drugs, according to a coroner's report released Tuesday. The report listed the "Heroes" and "Nashville" star's cause of death as toxic effects of fentanyl, 4-ANPP -- used in the manufacture of fentanyl -- Alprazolam, commonly known by the brand name Xanax and used to treat anxiety, Methocarbamol, and Quetiapine. The manner of death was ruled an accident. Methocarbamol is a prescription muscle relaxant, often used to treat muscle pain. Quetiapine is an antipsychotic prescription medication. The autopsy showed no signs of injuries that would have contributed to her death. #Panettiere