Silicon Valley's favorite drug helped kill Heath LedgerMedical examiners have released results of Heath Ledger's toxicology report earlier today. The young star died of an accidental overdose — an "acute intoxication" — from the combined effects of hydrocodone, diazepam, temazepam, alprazolam, doxylamine and oxycodone. The latter is the active substance in Silicon Valley's drug of choice, OxyContin.