Did you talk to the head pharmacist or to an assistant or technician? LRS is not routinely stocked at pharmacies except maybe plastic bottle used for pouring, not administering via line (e.g., subQ fluids). Thus they would have b ordered and you will likely have to order a case of them. Also, you will likely have to provide a NDC number (National Drug Code) for the bags. There is a different NDCs for LRS for each manufacturer and then for each bag size and other variations, like being DEHP-free.
http://www.zzcat.com/CRF/supplies/ndc.htm