RCW 69.41.125: Interchangeable biological product may be substituted for biological product—Exception—Wholesale price less.

Unless the prescribed biological product is requested by the patient or the patient's representative, if "substitution permitted" is marked on the prescription as provided in RCW 69.41.120, the pharmacist must substitute an interchangeable biological product that he or she has in stock for the biological product prescribed if the wholesale price for the interchangeable biological product to the pharmacist is less than the wholesale price for the biological product prescribed.