Two Holyoke men have been arrested on drug charges after an investigation into heroin distribution in that city, State Police said. The Hampden County Narcotics Task Force has been investigating heroin distribution in Holyoke for several months. Over the course of the investigation, more than 3,700 bags of heroin were seized, State Police said. Julio Rosado, 20, and Armando Vega, 27, were arrested Tuesday, State Police said. Rosado faces two counts of trafficking of a Class A drug. Vega is charged with trafficking a Class A drug and possession with intent to distribute a Class B drug, oxycodone.