8.2 Kentucky Generic Drug Substitution & Biosimilars

8.2 Kentucky Generic Drug Substitution & Biosimilars

Generic drug substitution is a vital component of healthcare cost containment and pharmaceutical care. While states vary between permissive and mandatory substitution frameworks, Kentucky is strictly a mandatory generic drug substitution state under the Kentucky Generic Drug Substitution Act (KRS 217.814 through 217.826) and Title 201 KAR 2:115. Furthermore, with the emergence of biological therapies, Kentucky enacted KRS 217.182, establishing clear statutory protocols for substituting biosimilars and interchangeable biological products.

1. Kentucky Mandatory Generic Drug Substitution Law (KRS 217.822)

Under KRS 217.822, whenever a healthcare practitioner prescribes a brand-name drug product by its trade or proprietary name, the dispensing pharmacist SHALL substitute a lower-priced, therapeutically equivalent generic drug product if one is in stock at the pharmacy.

┌─────────────────────────────────────────────────────────────────────────────┐
│            CORE PILLARS OF KENTUCKY MANDATORY GENERIC SUBSTITUTION          │
├─────────────────────────────────────────────────────────────────────────────┤
│ 1. Mandatory Duty:                                                          │
│    The statute uses mandatory language ('shall substitute'). Substitution   │
│    is not optional or discretionary for the pharmacist when an equivalent   │
│    generic product is available in stock.                                   │
│                                                                             │
│ 2. Therapeutic Equivalence Standard:                                        │
│    The generic product MUST be therapeutically equivalent to the brand     │
│    product as determined by the FDA Orange Book ('A' rated) and must not be │
│    listed on the Kentucky Nonequivalent Drug List (201 KAR 2:115).          │
│                                                                             │
│ 3. Cost Savings Pass-Through Mandate:                                       │
│    The pharmacist MUST pass the entire cost savings resulting from the      │
│    substitution on to the purchaser/patient. Retaining the generic margin   │
│    while charging brand pricing is an actionable statutory violation.       │
└─────────────────────────────────────────────────────────────────────────────┘

The Two Lawful Exceptions That Override Mandatory Substitution

Under KRS 217.822, a pharmacist must dispense the brand-name product and refrain from generic substitution ONLY under two specific legal conditions:

1. Prescriber Override (DAW 1):
   • The prescribing practitioner expressly indicates that the brand-name drug must be dispensed.
   • Written Prescriptions: The prescriber must write in their own handwriting on the face of the prescription order: "Dispense as Written" (DAW), "Do Not Substitute" (DNS), or "Brand Medically Necessary" (BMN).
   • Pre-Printed Checkbox Prohibition: A pre-printed statement, checkbox, or pre-printed "DAW" box on a prescription blank is NOT legally valid in Kentucky to prevent substitution unless the prescriber physically hand-writes the phrase or hand-signs a distinct, separate DAW signature line designated specifically by state regulations.
   • Electronic Prescriptions (EPCS / EHR): The prescriber transmits an explicit electronic DAW-1 indicator indicating brand medically necessary.
   • Oral Prescriptions: The prescriber expressly communicates orally that the brand product is medically necessary, which the pharmacist immediately documents on the prescription record.
2. Purchaser / Patient Request (DAW 2):
   • The patient (purchaser) exercises their statutory right under KRS 217.822 to request the brand-name product instead of the generic equivalent.
   • If the patient requests the brand name, the pharmacist must dispense the brand product, and the patient assumes responsibility for any price differential.

2. FDA Orange Book Therapeutic Equivalence Evaluations

The formal publication Approved Drug Products with Therapeutic Equivalence Evaluations (commonly known as the FDA Orange Book) is the official regulatory gold standard used by pharmacists to determine whether a generic product is therapeutically equivalent to a reference listed drug (RLD).

Definitions of Equivalence

• Pharmaceutical Equivalents: Drug products that contain the same active ingredient(s), are of the same dosage form and route of administration, and are identical in strength or concentration (e.g., Lisinopril 10 mg oral tablet from Manufacturer A vs. Lisinopril 10 mg oral tablet from Manufacturer B). They may differ in shape, scoring, excipients, color, and packaging.
• Pharmaceutical Alternatives: Drug products that contain the same therapeutic moiety, but differ in salt form, ester, complex, dosage form, or strength (e.g., Tetracycline hydrochloride vs. Tetracycline phosphate; Amoxicillin 250 mg capsules vs. Amoxicillin 250 mg chewable tablets). Pharmaceutical alternatives CANNOT be substituted without prescriber authorization.
• Therapeutic Equivalents: Pharmaceutical equivalents that have demonstrated bioequivalence (comparable rate and extent of drug absorption in human in vivo studies) and can be expected to produce the same clinical efficacy and safety profile.

Comprehensive Orange Book Therapeutic Equivalence (TE) Code Guide

┌─────────────────────────────────────────────────────────────────────────────┐
│                     FDA ORANGE BOOK TE CODING ARCHITECTURE                  │
├─────────────────────────────────────────────────────────────────────────────┤
│  FIRST LETTER:                                                              │
│  • 'A' = Bioequivalent & Therapeutically Equivalent -> SUBSTITUTABLE        │
│  • 'B' = Bioequivalence Problems / Inadequate Data  -> NOT SUBSTITUTABLE    │
│                                                                             │
│  SECOND LETTER:                                                             │
│  • Describes the specific dosage form or testing methodology                │
└─────────────────────────────────────────────────────────────────────────────┘

Exam Trap — Multi-Source 'AB' Sub-Codes (e.g., AB1, AB2, AB3, AB4): When multiple reference listed drugs (RLDs) exist for a complex molecule (such as Levothyroxine or Diltiazem extended-release), the FDA assigns numerical sub-codes (AB1, AB2, AB3, AB4). A generic product rated AB1 is therapeutically equivalent ONLY to other products rated AB1 (or the AB1 brand). An AB1 generic CANNOT be substituted for an AB2 or AB3 product without contacting the prescriber!

3. The Kentucky Formulary / Nonequivalent Drug Product List (KRS 217.819 / 201 KAR 2:115)

Under KRS 217.819, the Kentucky Board of Pharmacy is charged with maintaining the Kentucky Formulary for Generic Drug Products, which includes the Nonequivalent Drug Product List codified in Title 201 KAR 2:115.

Negative Formulary Mechanism

• Kentucky operates under a negative formulary approach: Any multi-source drug product approved by the FDA with an 'A' rating in the Orange Book is automatically approved for generic substitution in Kentucky, EXCEPT those specific drugs or dosage forms explicitly designated by the Kentucky Board of Pharmacy as nonequivalent.
• If a drug product exhibits significant narrow therapeutic index (NTI) characteristics or documented bioequivalence disparities, the Board places it on the Nonequivalent Drug Product List.
• Legal Consequence: Pharmacists are strictly prohibited from substituting generic versions of any medication on the Nonequivalent Drug Product List unless the prescribing practitioner provides explicit authorization.

4. Biosimilars & Interchangeable Biological Products (KRS 217.182 & FDA Purple Book)

Biologics are complex, high-molecular-weight molecules derived from living biological systems (e.g., monoclonal antibodies, fusion proteins, insulins, growth hormones). Unlike traditional small-molecule chemicals, exact molecular replication of a biologic is impossible. The Biologics Price Competition and Innovation Act (BPCIA) and Kentucky statute KRS 217.182 govern their regulation and pharmacy dispensing.

The FDA Purple Book

The FDA publication Lists of Licensed Biological Products with Reference Product Exclusivity and Biosimilarity or Interchangeability Evaluations (the Purple Book) serves as the official registry for biological products.

The Two Regulatory Tiers of Follow-On Biologics

1. Biosimilar:
   • A biological product that is highly similar to the FDA-approved reference biologic notwithstanding minor differences in clinically inactive components, with no clinically meaningful differences in terms of safety, purity, and potency.
   • CRITICAL DISPENSING RULE: A standalone biosimilar rating DOES NOT authorize pharmacist substitution at the pharmacy counter. A prescription written for reference Humira (adalimumab) cannot be substituted with a biosimilar (e.g., Amjevita) unless the biosimilar has attained the additional designation of Interchangeable!
2. Interchangeable Biological Product:
   • An FDA-approved biosimilar that meets additional rigorous statutory criteria: it must produce the same clinical result as the reference product in any given patient, and for a product administered multiple times, the risk of alternating or switching between the biosimilar and reference product is not greater than the risk of using the reference product alone.
   • PHARMACIST SUBSTITUTION PERMITTED: An interchangeable biologic MAY be substituted by a pharmacist without prior prescriber consultation, subject to Kentucky state law.

┌─────────────────────────────────────────────────────────────────────────────┐
│                     BIOLOGIC SUBSTITUTION LEGAL SPECTRUM                    │
├─────────────────────────────────────────────────────────────────────────────┤
│ Reference Biologic (e.g., Lantus, Humira, Neupogen)                        │
│       │                                                                     │
│       ├──> Biosimilar (e.g., 'Highly Similar', No Clinical Differences)     │
│       │    └─> CANNOT substitute at retail pharmacy counter without new Rx  │
│       │                                                                     │
│       └──> Interchangeable Biologic (Meets Switching & Efficacy Studies)    │
│            └─> Pharmacist MAY substitute at counter under KRS 217.182       │
│                └─> MANDATORY: 5-Day Prescriber Communication Protocol!      │
└─────────────────────────────────────────────────────────────────────────────┘

Kentucky Interchangeable Biologic Dispensing & 5-Day Prescriber Notification (KRS 217.182)

Under KRS 217.182, a pharmacist may substitute an interchangeable biological product for a prescribed reference biologic only if:

1. The product is rated Interchangeable by the FDA in the Purple Book;
2. The prescriber has not indicated in handwriting or electronic DAW that the reference product is medically necessary; and
3. The patient does not refuse the substitution.

Mandatory 5-Business-Day Communication Mandate

• Communication Deadline: Within five (5) business days following the dispensing of an interchangeable biological product, the dispensing pharmacist or their designee SHALL communicate to the prescribing practitioner the specific product provided to the patient, including the brand name or generic name and the specific manufacturer.
• Permissible Methods of Communication:
  1. An entry into an interoperable electronic health records (EHR) system, electronic prescribing technology, or pharmacy management portal that is directly accessible by the prescriber (satisfies requirement automatically);
  2. Facsimile (fax);
  3. Telephone / verbal communication;
  4. Electronic transmission or secure electronic mail.
• Statutory Exemptions to the 5-Day Communication Rule:
  • No communication is required if there is no FDA-approved interchangeable biological product for the product prescribed;
  • No communication is required for a refill prescription where the product dispensed is identical to the product dispensed on the immediate prior fill.