CORPUS CHRISTI, TEXAS - The case of 14 babies who received accidental overdoses while in intensive care has raised new questions about how a common blood-thinning medication could be given to infants repeatedly in the wrong dosage.

Unlike a previous case involving twins of actor Dennis Quaid, in this case the Texas newborns got the overdose because of an error at the hospital pharmacy, not a labeling problem.

In Corpus Christi, pharmacy workers at Christus Spohn Hospital South made what the hospital called a "mixing error." The two workers involved went on voluntary leave.

The heparin, which was 100 times as strong as recommended, was given to 14 infants in the hospital's neonatal intensive care unit July 4.

Two of the babies -- twins who were born one month premature -- have died, although the hospital said its physicians have found no direct links to the overdose. Autopsies are being performed.

In addition to the 14 infants, three other babies who were discharged shortly after the overdoses may also have received too much heparin, but they showed no ill effects.

Nurses discovered the error Sunday and immediately gave the hospitalized infants a drug to counteract the effects.

A patient safety expert said hospitals are often slow to change.

"It is frustrating to people that we have had other heparin issues," said Diane Pinakiewicz, president of the National Patient Safety Foundation.

"When you have complex systems interfacing with humans, we're never going to have perfection," she added. But "our job is to get as close to perfection at all times."

Hospitals around the nation have made changes to the way they handle heparin, which is one of the most common additives to intravenous solutions.

"You always have to go on the premise that somebody is going to make a mistake," said Dr. Eric Eichenwald, medical director of the unit. "So you have to make it really, really hard to make a mistake."