(breakingnews.iol.ie) - An investigation into a hospital blunder has been launched after the newborn twins of US actor Dennis Quaid and his wife Kimberly were reportedly given an overdose of a blood thinner.The celebrity website TMZ.com said yesterday that the actor's children, Thomas Boone and Zoe Grace, were given vials of heparin, used to prevent clotting, that were 1,000 times stronger than what was prescribed.Citing unnamed sources, the site said the babies were in Cedars-Sinai Medical Centre's neonatal intensive care unit in Los Angeles. A hospital spokeswoman said she could not comment on the report because of patient confidentiality laws.The California state Department of Public Health was investigating reports of an incident involving newborn twins at the hospital, department spokeswoman Suanne Buggy said.Quaid, 53, is best known for roles in a string of hit films during the 1980s including 'Great Balls of Fire' and 'Innerspace'.More recently he starred in the 2004 disaster movie 'The Day After Tomorrow'.