The FDA has approved Merilog (insulin-aspart-szjj), the first rapid-acting insulin biosimilar. The biosimilar to Novolog (insulin aspart) is indicated for glycemic control in both adult and pediatric patients with diabetes mellitus.

The approval encompasses both a 3-mL single-patient-use prefilled pen and a 10-mL multiple-dose vial formulation. Merilog represents the third FDA-approved insulin biosimilar product, following two long-acting insulin biosimilars approved in 2021.

"Today's approval highlights our continued efforts to improve the efficiency of the biosimilar approval process to help support a competitive marketplace and increase options for costly treatments, like insulin," said Peter Stein, MD, director of the Office of New Drugs in the FDA's Center for Drug Evaluation and Research.

Clinical Implementation

The administration protocol for Merilog mirrors that of Novolog, requiring subcutaneous injection 5 to 10 minutes before meal initiation. Approved injection sites include the stomach, buttocks, thighs, and upper arms. Clinicians should note that dosing requires individualization based on patient-specific requirements.

Sarah Yim, MD, director of the Office of Therapeutic Biologics and Biosimilars, highlighted the potential impact on the estimated 8.4 million Americans who depend on insulin therapy: "Having a biosimilar option for their rapid-acting insulin injection can truly make a difference, as biosimilar products have the potential to increase access to these life-saving medications."

Safety Profile

The adverse event profile includes:

• Serious adverse events:
  • Hypoglycemia
  • Severe allergic reactions
  • Hypokalemia
• Common adverse events:
  • Injection site reactions
  • Pruritus
  • Rash
  • Lipodystrophy at injection sites
  • Weight gain
  • Peripheral edema

Regulatory Context

This approval brings the total number of FDA-approved biosimilar products to 65 across various therapeutic areas. As defined by the FDA, a biosimilar must demonstrate high similarity to and no clinically meaningful differences from its reference product, with patients expected to experience equivalent safety and efficacy outcomes.

The manufacturer of record is Sanofi-Aventis U.S. LLC.

Reference:

U.S. Food and Drug Administration. FDA Approves First Rapid-Acting Insulin Biosimilar Product for Treatment of Diabetes [press release]. Silver Spring, MD: FDA; February 14, 2025.