iAtoday

To keep pace with a rapidly evolving drug landscape, we review the medications that generate the highest spending every year. Looking closely at the top ten drugs gives us a better view of where innovation is heading and how these developments influence plan affordability and member health.

The top ten drugs accounted for 23% of the year’s spending, a decrease of 2% from 2024. A diversified drug mix, as well as the impacts of structured programs like biosimilar transitions and prior authorization, are contributors.

Top 10 drugs in focus

The following table shows the top ten drugs in descending order of total amount reimbursed in 2025, as well as their respective rankings in 2024 and 2023.

^B Biological drugs

Key movements in 2025

Here is what our drug experts mainly observed in 2025:

• Ozempic remained the top drug. Market dynamics may evolve quickly as generics and new therapies in this class become available.
• Trikafta continued to hold second place. Its position reflects consistent use for the treatment of cystic fibrosis. Newer drug Alyftrek is the next-in-class, once-daily therapy to watch next.
• Dupixent rose to third place from seventh. This shift highlights growing adoption across both dermatology and respiratory indications.
• ADHD therapies dropped in rankings. Methylphenidate-based treatments dropped into fourth place, while Vyvanse shifted to ninth following the introduction of its generics in 2024.
• Biosimilars remained a major driver of spending trends. Ustekinumab (Stelara) has shifted to fifth place following a year of biosimilar transitions, and infliximab (Remicade) and adalimumab (Humira) continued to rank lower.

“The ongoing presence of adalimumab and infliximab in the top ten signals that patients are being managed with biosimilars as recommended first-line options.”

Erika Hatherly, Pharmacist and Strategic Leader, Drug Programs
Group Benefits and Retirement Solutions

• Growth in inflammatory bowel disease therapies remained strong. Entyvio moved into sixth place. Rinvoq joined the top ten for the first time, driven by its approved use in both ulcerative colitis and Crohn’s disease, along with broader uptake across other immune‑mediated diseases.
• Freestyle Libre dropped slightly to number eleven. These glucose monitoring devices just marginally missed the top ten.

Here are some other important points that our experts have highlighted:

1. Growing use of non‑injectable treatments for inflammatory conditions

JAK inhibitors are oral medications that work by blocking certain signals in the body that trigger inflammation. They are small‑molecule drugs, not biologics. We note that use of Rinvoq (upadacitinib) continues to grow across several immunology conditions, including atopic dermatitis, rheumatoid arthritis, ulcerative colitis and Crohn’s disease.

We know that, in practice, doctors often consider JAK inhibitors for patients who have not had enough benefit from other advanced therapies, although treatment pathways are still being refined.

“As more members start these medications earlier in their treatment journey, the impact on overall plan costs is becoming more noticeable, particularly in conditions where biologics have usually been used first.”

Erika Hatherly, Pharmacist and Strategic Leader, Drug Programs
Group Benefits and Retirement Solutions

2. Next wave of biosimilars

We observe that biosimilar uptake continues to accelerate, with switching impacting the ranking of once-dominant therapies like adalimumab, infliximab and ustekinumab. Clinicians have gained more experience with biosimilars and policies further normalized switching. These developments are contributing to meaningful reductions in plan spending, particularly in inflammatory conditions where biologics have historically represented some of the highest individual claim costs. This comfort with transitions will become even more critical as biosimilars are introduced for therapies used in rare disease, ocular disease, and multiple sclerosis.

3. Incretin‑based treatments will continue to shape the diabetes market

We have no surprises regarding Ozempic and Rybelsus: they continue to dominate overall drug spend, reflecting how GLP-1s have become significant in managing diabetes. Wegovy, which contains the same active ingredient but is indicated for weight management, is tracked separately because its clinical purpose and annual cost differ.

Mounjaro (tirzepatide), another medication in the same class, entered the Canadian market in 2024. Despite strong clinical performance, it has not yet gained significant traction and remains outside the top tier for overall plan spending.

“We think that looking ahead, the competitive landscape is set to intensify. Pipeline updates point to further growth, including potential expanded indications for existing medications and new oral GLP‑1 options for weight loss, all expected to shape prescribing and cost trends over the next year.”

Erika Hatherly, Pharmacist and Strategic Leader, Drug Programs
Group Benefits and Retirement Solutions

4. ADHD market 

We also see that the ADHD landscape continues to shift as generic lisdexamfetamine gains market share. At the same time, higher priced brand products have launched in this category, providing alternative options but a greater cost to plans.

Our management strategies

We continue to deploy tools that protect plans while preserving access. These include prior authorization with clinically focused criteria, biosimilar-first strategies with guided transitions, intensive reviews for very high-cost therapies and targeted monitoring of fast-growing categories.

Our observations cover all claims processed by our Group Insurance line of business. They may not apply to every plan we administer.

We will be sending a communiqué to group plan administrators on March 23 (French version).

If you have any questions, please contact your advisor or your iA Financial Group Account Executive.