DENVER — The mother of a child with a double lung transplant said she is worried that accessing a critical drug for her daughter’s care will be challenging if  the drug’s manufacturer and Walgreens do not reach an agreement on a contract.

Jenna Parker’s daughter Portia Opichka received a double lung transplant two years ago.

Now, Portia is on 17 medications and Parker said the most critical is immunosuppressant Prograf.

Parker said she called to request a refill at the Walgreens at Children’s Hospital Colorado and was told the prescription could not be filled after April 1.

Parker said she was told by a pharmacist that Walgreens and the drug’s manufacturer, Astellas Pharma U.S., have not been able to reach an agreement on a new contract so it’ll expire at midnight March 31.

“This is probably one of the biggest hurdles I have had to face because this is the most important drug these kids can be on,” Parker said.

Parker said the Walgreens at Children’s Hospital Colorado is the only pharmacy in the Denver area that carries Prograf and can compound it, the process of turning the pill into a liquid form that can be inserted into Portia’s feeding tube.

“This is a very serious situation,” Parker said.

If the companies can’t reach an agreement, Parker said she’ll have to have the medication flown in from out of state.

She worries about the reliability of this option as well as making sure Medicaid will cover the out-of-state medication.

“Why would I want to rely on an airplane to deliver her life-saving medicines on time? My heart can’t deal with that, that’s too stressful,” Parker said.

“Astellas cares about the patients who need our products,” Astellas Pharma U.S. said in a statement. “We are unaware of any business dispute with this retailer. Retailers make their own decisions about which products to carry.”

Walgreens could not be reached for comment.