10.1 Product Selection: Generic Substitution (ORS 689.515) & Biologic Interchange (ORS 689.522)

Why this matters

Area 4.4 covers "conditions for permitted or mandated product selection." Oregon's generic substitution statute (ORS 689.515) and biologic interchange statute (ORS 689.522) have features that differ from many states: a mandatory sign, a no-cost-increase condition, a dosage-form substitution option, and an exception for out-of-state prescriptions. Older materials often misstate the biologic rules.

Generic substitution (ORS 689.515)

When a pharmacist may substitute

Unless the purchaser instructs otherwise, and subject to the prescriber's instructions and the cost rule, a pharmacist may substitute:

1. A drug product with the same generic name, strength, quantity, dose and dosage form that is, in the pharmacist's professional opinion, therapeutically equivalent (ORS 689.515(2)(a)). Therapeutically equivalent means FDA-approved for interstate distribution and determined by FDA to have essentially the same efficacy and toxicity at the same dosage regimen. In practice this means an "A"-rated product in FDA's Orange Book.
2. When the prescriber is not reasonably available and the drug does not use a unique delivery-system technology, an oral tablet, capsule or liquid form of the prescribed drug with the same strength, dose and schedule that is therapeutically equivalent (ORS 689.515(2)(b)). Oregon's statute expressly allows this kind of dosage-form substitution.

Limits on substitution

• Prescriber prohibition: the prescriber may specify in writing, by telephone or electronically that there may be no substitution (ORS 689.515(3)). Under OAR 855-041-1105(5), acceptable notations on written or oral orders are:
  • "No substitution."
  • "N.S."
  • "Brand medically necessary."
  • "Brand necessary."
  • "Medically necessary."
  • "D.A.W."
  • Words with similar meaning. An electronic prescription must carry the text "brand medically necessary," or similar words, plus the matching electronic indicators. These instructions may not be default values on the prescription.
• Cost: substitution is allowed only when there will be a savings in, or no increase in, cost to the purchaser (ORS 689.515(5)).
• Purchaser's choice: the patient may decline substitution.
• Out-of-state prescriptions: generic substitution does not apply unless the prescription authorizes it (ORS 689.525(3)).

Duties when substituting or dispensing generically

A substitution made within reasonable and prudent practice, or using a drug in a recognized formulary or government list, is not evidence of negligence. Substitution is not the practice of medicine (ORS 689.515(9)–(10)).

Reading the Orange Book

• "A" codes are therapeutically equivalent. AB means bioequivalence issues were resolved with studies. AA, AN, AO, AP and AT are for conventional forms, aerosols, injectable oils, injectable aqueous solutions and topicals.
• "B" codes are not considered therapeutically equivalent. Don't substitute them under ORS 689.515.
• Multiple reference drugs carry numbered codes (AB1, AB2, AB3...). A generic is substitutable only for a reference product with the same code. Levothyroxine and extended-release products are classic examples. Some generics carry more than one code, so check the specific listing.

Biologic interchange (ORS 689.522)

A pharmacy or pharmacist may substitute a biological product for the prescribed biological product only if:

1. FDA has determined the substitute is interchangeable with the prescribed product, as shown in the Purple Book.
2. The prescriber has not designated that substitution is prohibited.
3. The patient is informed of the substitution in a manner reasonable under the circumstances.
4. The pharmacy or pharmacist keeps a record of the substitution for at least three years.

The Board keeps a link to FDA's list of interchangeable products. Oregon's current statute does not require the pharmacist to notify the prescriber within a set number of days after substituting. Some states and older Oregon materials describe such a notification. A biosimilar that FDA has not designated interchangeable may not be substituted. It may be dispensed only if prescribed. Insurers may still require prior authorization for any biologic (ORS 689.524).

Exam scenario

Three prescriptions arrive:

1. "Lipitor 40 mg #30" from an Oregon physician, no DAW. The pharmacy stocks AB-rated atorvastatin that costs the patient less. The pharmacist may substitute, label "atorvastatin 40 mg" with the manufacturer, and record it. The 1-inch sign must be posted.
2. The same prescription from an Idaho physician. Under ORS 689.525(3), substitution requires authorization on the prescription. Without it, dispense Lipitor or contact the prescriber.
3. A reference insulin, with the pharmacy stocking an FDA-designated interchangeable insulin. The pharmacist may substitute if the prescriber didn't prohibit it, tells the patient, and keeps the record 3 years.