By Matt Sloane, CNN
Some families got more than they bargained for at a New Jersey CVS drugstore when their childrens' prescriptions for fluoride pills were filled with a popular breast cancer drug instead.
"We believe that, as a result of a single medication restocking issue at our Chatham, New Jersey pharmacy, 13 families had similar incidents in which a few tamoxifen pills were mixed in with their prescriptions for 0.5 mg fluoride pills," said Mike DeAngelis, a CVS Caremark spokesman.
DeAngelis went on to say that the company is doing a full investigation into how the switch could have occurred.
"As soon as we heard of this problem, we took immediate action to contact any family that could possibly have been affected and removed the one affected stock bottle that we believe to be the source of this issue," he said.
Tamoxifen, the drug mistakenly given to the kids, is a popular estrogen-blocking drug, used to treat many breast cancer patients with estrogen-receptor-positive cancers.
Dr. Otis Brawley, Chief Medical Officer for the American Cancer Society says the drug, in small doses for short periods of time, should not do any lasting damage to the kids.
"We got lucky with this one, because in kids this young, you're unlikely to see the major side effects like blood clots or stroke," said Brawley. But, he added, if a young girl who is about to start her period takes tamoxifen, the estrogen-blocker may delay the onset of menstruation for several weeks.
CVS' Caremark says a vigilant parent brought the concern to their attention, and the company is reaching out to any families that may have gotten the pills.
"Out of an abundance of caution we reached back 60 days," DeAngelis said. "Most families informed us that they did not receive any incorrect pills."
Several pharmacists told CNN that the errors like this are uncommon, and that several safeguards are in place in most pharmacies to help prevent mix-ups like this.
"Most of us keep our products alphabetically on the shelves," said Ira Katz, an Atlanta pharmacy owner. "Tamoxifen should have been with the 'T's' and fluoride should have been with the 'F's,' which is why this is so surprising."
Katz also said the tamoxifen bottles look very different from the sodium fluoride tablet bottles, even further reducing the possibility of confusing the two.
He went on to say that many large pharmacies use robotic filling systems, also in an effort to reduce these types of errors. It's not clear whether the CVS in Chatham had such a system.