(a) In formulating the maximum allowable cost price for a drug, a health benefit plan issuer or pharmacy benefit manager may only use the price of that drug and any drug listed as therapeutically equivalent to that drug in the most recent version of the United States Food and Drug Administration’s Approved Drug Products with Therapeutic Equivalence Evaluations, also known as the Orange Book.
(b) Notwithstanding Subsection (a), if a therapeutically equivalent generic drug is unavailable or has limited market presence, a health benefit plan issuer or pharmacy benefit manager may place on a maximum allowable cost list a drug that has:
(1) a “B” rating in the most recent version of the United States Food and Drug Administration’s Approved Drug Products with Therapeutic Equivalence Evaluations, also known as the Orange Book; or
(2) an “NR” or “NA” rating or a similar rating by a nationally recognized reference.

(c) A health benefit plan issuer or pharmacy benefit manager must, in accordance with Subsection (d), disclose to a pharmacist or pharmacy the sources of the pricing data used in formulating maximum allowable cost prices.
(d) The information described by Subsection (c) must be disclosed:
(1) on the date the health benefit plan issuer or pharmacy benefit manager enters into the contract with the pharmacist or pharmacy; and
(2) after that contract date, on the request of the pharmacist or pharmacy.