Windsor Regional Hospital is no longer buying products from Marchese Healthcare Solutions, the company under scrutiny after nearly 1,000 cancer patients were given diluted chemotherapy medication.

The drug was somehow improperly mixed with too much saline solution. Some patients were given diluted drugs for more than a year during their cancer treatment.

"We are now not using any products from Marchese. We stopped using the chemo drug the moment we were told there was a possible issue," Windsor Regional Hospital CEO David Musyj wrote in a memo to staff. "The other drugs were not "mixed" but we still made a decision to stop all purchases from Marchese and are either "mixing" in house or found  another provider."

How and why more than 1,000 people received diluted chemotherapy will now be the focus of a third-party investigation in Ontario.

Musyj also said in the memo that 289 of the 290 patients or next of kin in Windsor have been contacted.

"It has been a very tedious and emotional process," Musyj wrote. "However, it has been done swiftly and with compassion."

Marchese was awarded a contract to supply sterile compounding services to hospitals.

"This issue involves only the volume and concentration of a high quality preparation, and those exist within very narrow boundaries of variation. Those variations were the result of the use of our preparation, which according to our current understanding was not consistent with the contract, the preparation or its labeling," Marita Zaffiro, the president of Marchese Hospital Solutions, said in a statement last week.