FDA Approves New Interchangeable Biosimilar of Insulin Glargine, Expanding Substitution Authority for Pharmacists

The FDA has approved Langlara (insulin glargine-aldy; Lannett Company), a biosimilar to Lantus (insulin glargine; Sanofi), for the treatment of adults and pediatric patients with type 1 diabetes and adults with type 2 diabetes. Critically, the FDA has also granted Langlara an interchangeable designation, meaning pharmacists may substitute it for Lantus at the point of dispensing without intervention from the prescribing health care provider in states that permit such substitution.¹

The approval arrives as the burden of diabetes in the US remains substantial. According to the CDC, an estimated 40.1 million Americans have diagnosed or undiagnosed diabetes, representing approximately 12% of the US population. More than 7 million individuals with diabetes, including all patients with type 1 diabetes and a significant proportion of those with type 2 diabetes, require daily insulin therapy.²

Approval Basis and Clinical Profile

The FDA approval of Langlara was based on a comprehensive analytical, preclinical, and clinical program. According to Lannett, the data package confirmed the pharmacokinetic and pharmacodynamic (PK/PD) profile, efficacy, safety, and immunogenicity of Langlara as comparable to Lantus in patients with both type 1 and type 2 diabetes.¹

Insulin glargine is a long-acting basal insulin analogue administered once daily by subcutaneous injection. It provides relatively constant glucose-lowering activity over approximately 24 hours, with no pronounced peak, making it a widely used component of basal-bolus insulin regimens. For pharmacists counseling patients on Langlara, the clinical profile—including administration technique, injection site rotation, storage requirements, hypoglycemia risk, and the management of missed doses—mirrors that of Lantus. Patients transitioning from Lantus to Langlara, whether through pharmacist substitution or prescriber direction, should be advised that dose adjustments are generally not required but that blood glucose monitoring remains essential during any transition period, as individual responses can vary.³

The Interchangeable Designation: What It Means for Pharmacy Practice

The interchangeable designation represents a regulatory distinction that carries direct, practical implications for pharmacists. Under federal law, a biosimilar that earns this designation has satisfied additional FDA requirements demonstrating that it can be expected to produce the same clinical result as the reference product in any given patient and, for products administered more than once, that the risk in terms of safety or reduced efficacy of alternating or switching between the biosimilar and the reference product is not greater than the risk of using the reference product without such alternation or switching.⁴

Not all biosimilars achieve this status. Manufacturers must specifically seek FDA approval for an interchangeable product through a separate regulatory pathway. The FDA's updated draft guidance, issued in June 2024, eliminated the prior requirement for repeated clinical switching studies, instead permitting manufacturers to provide an assessment of why their existing comparative analytical and clinical data satisfy the statutory switching standard. This policy shift has been associated with a meaningful acceleration in interchangeable biosimilar approvals.⁵

For pharmacists, the practical significance is immediate: an interchangeable designation confers the legal authority to substitute Langlara for a dispensed Lantus prescription—or vice versa—without first obtaining a new prescription or authorization from the prescriber. This positions the pharmacist as a direct decision-maker in supporting patient access to a potentially lower-cost insulin option at the point of dispensing.⁴

State Substitution Laws Govern Pharmacist Authority

Although the FDA’s interchangeable designation establishes federal eligibility for pharmacist substitution, the actual scope of that authority is governed state by state. All 50 states and Puerto Rico have enacted statutes or regulations addressing biosimilar substitution, but the requirements vary considerably. In some states, pharmacists may substitute an interchangeable biosimilar without any prior notification to the prescriber or patient. In others, the pharmacist must notify the prescriber, the patient, or both—either before or after dispensing—and may be required to document the substitution in a manner accessible to the prescriber for a defined period. In a small number of states, substitution requires prescriber consent prior to dispensing.^6,7

Pharmacists should review their state’s current biosimilar substitution statute before dispensing Langlara under an automatic substitution framework. This review should encompass whether patient or prescriber notification is required, the timing of any such notification, documentation and record-keeping obligations, and whether patient consent is a prerequisite in their jurisdiction.^6,7

Implications for Patient Counseling and Formulary Considerations

For pharmacists managing patients on long-acting insulin, the availability of a new interchangeable insulin glargine biosimilar introduces both an opportunity and an obligation. The opportunity lies in expanding access to an agent that may carry lower acquisition costs, particularly for uninsured or underinsured patients for whom insulin affordability remains a persistent barrier. The obligation lies in ensuring that any substitution, whether automatic or prescriber-directed, is accompanied by clear, patient-centered counseling.

When counseling patients who are switched to Langlara, pharmacists should explain the basis of biosimilarity and interchangeability in accessible terms; confirm that the delivery device and concentration are identical to what the patient has been using; address any patient concerns about the efficacy or safety of the transition; and reinforce the importance of consistent monitoring during the initial weeks following a product change. Pharmacists should also be prepared to address patient questions driven by misinformation or confusion about biosimilars, as unfamiliarity with the regulatory framework can generate hesitancy among patients who have been stable on Lantus for years.

REFERENCES

1. Lannett Company, Lanexa Biologics and Sunshine Lake Pharma announce FDA approval of Langlara, an interchangeable biosimilar of Lantus (insulin glargine). News release. Lannett. May 4, 2026. Accessed May 4, 2026. https://www.businesswire.com/news/home/20260504761789/en/Lannett-Company-Lanexa-Biologics-and-Sunshine-Lake-Pharma-announce-FDA-Approval-of-LANGLARA-an-Interchangeable-Biosimilar-of-Lantus-insulin-glargine

2. National Diabetes Statistics Report. CDC. January 21, 2026. Accessed May 4, 2026. https://www.cdc.gov/diabetes/php/data-research/index.html

3. American Diabetes Association Professional Practice Committee. Standards of care in diabetes—2025. Diabetes Care. 2025;48(suppl 1):S1-S337. doi:10.2337/dc25-SINT

4. Biosimilar and interchangeable biologics: more treatment choices. FDA. Updated August 17, 2023. Accessed May 4, 2026. https://www.fda.gov/consumers/consumer-updates/biosimilar-and-interchangeable-biologics-more-treatment-choices

5. Considerations in demonstrating interchangeability with a reference product: update. FDA. Updated June 20, 2024. Accessed May 4, 2026. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/considerations-demonstrating-interchangeability-reference-product-update

6. Niazi SK. No two classes of biosimilars: urgent advice to the US Congress and the FDA. J Clin Pharm Ther. 2022;47(9):1352-1361. doi:10.1111/jcpt.13743

7. Kwon Y, Sarpatwari A, Dusetzina SB. State substitution laws and uptake of an interchangeable insulin biosimilar. JAMA Health Forum. 2025;6(4):e250406. doi:10.1001/jamahealthforum.2025.0406