The star's newborns are hospitalized after a reported accidental overdose.

ET confirms DENNIS QUAID's newborn twins have been placed in an intensive care unit in an L.A.-area hospital after they were given an accidental drug overdose.

10,000-unit doses of the anticoagulant Heparin were administered twice on Sunday by mistake to the babies, when normally they would only receive just 10 units per dose. The California Department of Public Health said that it is investigating the incident. Further reports say the babies were given an antidote to reverse the effects of the drug.

The actor and his wife, KIMBERLY, welcomed the twins -- THOMAS BOONE and his sister, ZOE GRACE -- into the world on November 8 via a gestational carrier (which means the twins are Dennis and Kimberly's biological children, but they were carried by another woman).

The couple's publicists tell ET, "Dennis and Kimberly appreciate everyone's thoughts and prayers and hope they can maintain their privacy at this difficult time."

The following statement was issued by MICHAEL L. LANGBERG, MD, chief medical officer of Cedars-Sinai Medical Center:

On November 18, three patients who were receiving intravenous medications as part of their treatment had their IV catheters flushed with a solution containing a higher concentration of heparin (a medication used to keep IV catheters from clotting) than normal protocol. As a result of a preventable error, the patients IV catheters were flushed with heparin from vials containing a concentration of 10,000 units per milliliter instead of from vials containing a concentration of 10 units per milliliter.

The error was identified by Cedars-Sinai staff, who immediately performed blood tests on the patients to measure blood clotting function. Four additional patients in the unit were tested as a precaution. The tests indicated that four of the seven patients had normal blood clotting function, and three had tests indicating prolonged blood clotting function. In one of the three patients, the clotting tests returned quickly to normal. The other two patients were given protamine sulfate, a drug that reverses the effects of heparin and helps restore blood clotting function to normal. Additional medical tests and clinical evaluation conducted on the two patients indicated no adverse effects from the higher concentration of heparin or from the temporary abnormal clotting function. Doctors continue to monitor the patients.

I want to extend my deepest apologies to the families who were affected by this situation, and we will continue to work with them on any concerns or questions they may have. This was a preventable error, involving a failure to follow our standard policies and procedures, and there is no excuse for that to occur at Cedars-Sinai. Although it appears at this point that there was no harm to any patient, we take this situation very seriously. We are conducting a comprehensive investigation, cooperating fully with the Los Angeles County Department of Health Services and will take all necessary steps to ensure that this never happens here again.