Tex. Occ. Code § 562.014
(a) Except as provided by this section, drug selection as authorized by this subchapter does not apply to the refill of a prescription for a narrow therapeutic index drug. The board, in consultation with the Texas Medical Board, shall by rule establish a list of narrow therapeutic index drugs to which this subsection applies. A prescription for a narrow therapeutic index drug may be refilled only by using the same drug product by the same manufacturer that the pharmacist last dispensed under the prescription, unless otherwise agreed to by the prescribing practitioner. If a pharmacist does not have the same drug product by the same manufacturer in stock to refill the prescription, the pharmacist may dispense a drug product that is generically equivalent if the pharmacist, before dispensing the generically equivalent drug product, notifies:
Acts 1999, 76th Leg., ch. 388, Sec. 1, eff. Sept. 1, 1999.
Acts 2007, 80th Leg., R.S., Ch. 385 (S.B. 625), Sec. 1, eff. June 15, 2007.