PORTLAND, Ore. - A pharmacy erroneously made a drug 10 times more potent than intended, which killed three people who received it at an Oregon clinic, the state medical examiner said Friday.

ApotheCure Inc., a drug compounding pharmacy company in Texas, said an employee made a weighing error in the creation of the drug colchicine.

The drug was only sent to the Center for Integrative Medicine in Portland, where three people received injections of the defective batch to treat back pain, ApotheCure said.

All three people, two from Portland and one from Yakima, Wash., died between the end of March and beginning of April from the toxic levels of the drug, officials said.

The Food and Drug Administration said it is investigating the case, but thinks the problem is contained.

Gary Osborn, a pharmacist and certified clinical nutritionist for ApotheCure, said the situation could have been contained earlier, but the clinic did not contact ApotheCure until nearly two weeks after the first death. He said the second death occurred before the company was able to complete recalling the batch and sending them a new lot. He said this is ApotheCure's first incident of this sort.

"We are kind of the leaders in the industry," Osborn said. "But you know what people say, stuff happens."

The Portland clinic has since closed and representatives from the organization could not be reached for comment Friday.

Colchicine works by stopping cells from dividing, which reduces inflammation in conditions such as gout, said Dr. Rob Hendrickson, associate medical director for the Oregon Poison Center. But in excess doses, the drug stops all cells from dividing _ eventually leading to organ failure and death.

The medication is not commonly used anymore and the use as a back pain treatment is less common than for gout.