Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number NDC00603-5438-21 found under Promethazine Hydroc by Par Pharmaceutical Inc. The National Stock Number assigned to this part is 6505013648557, and the Federal Supply Class is . Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like NDC00603-5438-21.