What Is Merilog?

Merilog (Insulin Aspart-szjj) is a rapid-acting biosimilar insulin made by Sanofi, approved by the FDA to improve blood sugar control in adults and children with type 1 and type 2 diabetes.

If that one-liner covers your question, great. But if you want the full picture — what it's used for, how to take it, what it costs, and how it compares to other rapid-acting insulins — keep reading. This is everything you need to know about Merilog in 2026.

The Basics: Brand Name, Generic Name, and Drug Class

• Brand name: Merilog
• Generic name: Insulin Aspart-szjj
• Drug class: Rapid-acting insulin analog (biosimilar)
• Manufacturer: Sanofi (sanofi-aventis U.S. LLC)
• FDA approval date: February 14, 2025
• Market launch: July 2025
• Controlled substance: No
• Reference product: NovoLog (Insulin Aspart) by Novo Nordisk

Merilog is a biosimilar to NovoLog. That means it's been shown to be highly similar to NovoLog in terms of safety, effectiveness, and quality, with no clinically meaningful differences. Think of it like a generic version of a biologic medication — not an exact copy, but functionally equivalent.

What Is Merilog Used For?

Merilog is FDA-approved to:

• Improve glycemic control in adults with type 1 and type 2 diabetes mellitus
• Improve glycemic control in pediatric patients with type 1 and type 2 diabetes mellitus

It's a mealtime insulin — you inject it before eating to cover the blood sugar spike that comes with food. Merilog is typically used alongside a longer-acting basal insulin (like Lantus, Basaglar, or Toujeo) that handles background blood sugar control throughout the day.

Some doctors also use Insulin Aspart off-label for gestational diabetes, diabetic ketoacidosis (DKA) management in hospitals, and hyperkalemia treatment.

How Is Merilog Taken?

Dosage Forms

Merilog comes in two formulations:

• 10 mL multiple-dose vial — 100 units/mL, used with insulin syringes
• Merilog SoloStar prefilled pen — 3 mL per pen (100 units/mL), sold in cartons of 5 pens. The pen dials in 1-unit increments and delivers up to 80 units per injection.

How to Inject

• Inject subcutaneously (under the skin) 5-10 minutes before a meal
• Injection sites: abdomen, thigh, buttocks, or upper arm
• Rotate injection sites within the same region to prevent lipodystrophy (changes in fat tissue)
• Do not mix Merilog with any other insulin
• Do not inject into a vein or use in an insulin pump (unless specifically directed)

Dosing

There's no one-size-fits-all Merilog dose. Your doctor will individualize your dose based on:

• Your blood sugar readings
• Your A1C level
• Your meal patterns and carbohydrate intake
• Your activity level
• Other medications you're taking

If you're switching from NovoLog to Merilog, the conversion is typically 1:1 — the same dose applies.

Storage

• Unopened: Refrigerate at 36-46°F until the expiration date
• Opened/in use: Store at room temperature (up to 86°F) and use within 28 days
• Do not freeze. Do not use if the insulin has been frozen.
• Keep out of direct sunlight and heat.

Who Should Not Take Merilog?

Merilog is contraindicated in two situations:

• During episodes of hypoglycemia — Do not inject Merilog when your blood sugar is already low.
• Known hypersensitivity — If you've had an allergic reaction to Insulin Aspart or any of the inactive ingredients in Merilog.

Special caution is needed for people with kidney or liver impairment (higher risk of hypoglycemia), those taking thiazolidinediones (risk of heart failure), and pregnant or breastfeeding patients (monitor blood sugar closely). For a full list of interactions, see our Merilog drug interactions guide.

How Much Does Merilog Cost?

Here's the pricing landscape for Merilog in 2026:

• Sanofi Insulins Valyou Savings Program: $35 per 30-day supply for any combination, type, or quantity of Sanofi insulins — including Merilog. Available to all patients regardless of income or insurance status.
• Sanofi Insulins Copay Savings Program: Commercially insured patients pay no more than $35 for a 30-day supply.
• Medicare: Under the Inflation Reduction Act, insulin copays are capped at $35/month for Medicare Part D beneficiaries.
• Retail price (without discounts): Estimated $100-$150 for a 10 mL vial; $140-$200 for a carton of 5 SoloStar pens.
• Patient assistance: Sanofi Patient Connection provides Merilog at no cost to eligible uninsured or underinsured patients. Apply at sanofipatientconnection.com or call 1-888-847-4877.

For a complete breakdown of every savings option, read our guide to saving money on Merilog.

How Does Merilog Compare to Other Rapid-Acting Insulins?

Merilog enters a market with several established options:

• NovoLog (Insulin Aspart) — The reference product. Same active ingredient as Merilog. Novo Nordisk cut the NovoLog vial price to ~$72 in 2024.
• Humalog (Insulin Lispro) — A rapid-acting insulin by Eli Lilly. Different molecule but same drug class. Available as vials and KwikPen.
• Admelog (Insulin Lispro) — Another Sanofi product, this one is a biosimilar to Humalog.
• Apidra (Insulin Glulisine) — A rapid-acting insulin by Sanofi with slightly different onset characteristics.
• Fiasp (Insulin Aspart) — An ultra-rapid formulation of Insulin Aspart by Novo Nordisk. Currently experiencing supply shortages.

For a detailed comparison, see our guide to Merilog alternatives.

Final Thoughts

Merilog is a welcome addition to the rapid-acting insulin market in 2026. As a biosimilar to NovoLog, it offers the same clinical effectiveness with strong cost-savings options — especially the $35/month Valyou Savings Program that's available to virtually everyone. If you have diabetes and use mealtime insulin, Merilog is worth discussing with your doctor.

Need to find Merilog at a pharmacy near you? Search Medfinder to check availability and pricing in your area.