In computing tax there may be deducted from the measure of tax imposed by RCW 82.04.290(2) amounts received by physicians or clinics for drugs for infusion or injection by licensed physicians or their agents for human use pursuant to a prescription, but only if the amounts:
(1) Are separately stated on invoices or other billing statements;(2) do not exceed the then current federal rate; and(3) are covered or required under a health care service program subsidized by the federal or state government. The federal rate means the rate at or below which the federal government or its agents reimburse providers for prescription drugs administered to patients as provided for in the medicare, part B, drugs average sales price information resource as published by the United States department of health and human services, or any successor index thereto.Effective date-2007 c 447: "This act takes effect October 1, 2007." [ 2007 c 447 s 2.]