Biosimilar Interchangeability: 5 Questions to Ask Your Pharmacist Before Trying a Biosimilar

Medications can be pricey. That’s old news. But the ability to access life-changing medications at the pharmacy remains a long-standing problem for many people.

At the same time, when there’s a problem, there’s often a solution to consider. For example, many biologic medications now have biosimilar alternatives that are FDA approved and available for use.

Biologics themselves are complex medications that come from natural and living organisms. A biosimilar is like a generic version of a “brand-name” biologic. The two medications are expected to offer the same clinical results, but biosimilars are often available at a lower cost. Most biosimilars require a separate prescription. But some biosimilars — dubbed interchangeable biosimilars — can be automatically substituted by your pharmacist.

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Here, we’ll highlight what you should know about biosimilar interchangeability and how to talk to your pharmacist about it.

Are all biosimilars interchangeable?

No. Not all biosimilars are interchangeable with their reference biologic. In fact, the large majority of biosimilars aren’t interchangeable.

This difference means one of two things:

1. If your healthcare provider sends a prescription for a biologic to your pharmacy and there's an interchangeable biosimilar available, your pharmacist can usually dispense the biosimilar without asking for your provider's permission.

2. If your provider prescribes a biologic that only has a non-interchangeable biosimilar, your pharmacist will need to confirm it's OK to dispense the biosimilar and likely get a new prescription. Depending on how busy your pharmacy and provider are, this can lead to delays.

This doesn’t mean interchangeable biosimilars are safer or more effective than other biosimilars. In fact, it has nothing to do with medication quality. It’s just a legal definition the FDA gives to certain biosimilars based on extra data they receive from drug manufacturers.

Good to know: The interchangeable biosimilar designation is mostly relevant for biosimilars that are dispensed at a community pharmacy, such as CVS or Walgreens. It’s less applicable for biosimilars that are administered at a hospital or infusion center.

How many interchangeable biosimilars are FDA approved?

As of December 2023, the FDA has approved seven interchangeable biosimilars:

• Cyltezo (adalimumab-adbm), a biosimilar to Humira (adalimumab)

• Abrilada (adalimumab-afzb), another biosimilar to Humira

• Semglee (insulin glargine-yfgn), a biosimilar to Lantus (insulin glargine)

• Rezvoglar (insulin glargine-aglr), another biosimilar to Lantus

• Cimerli (ranibizumab-eqrn), a biosimilar to Lucentis (ranibizumab)

• Byooviz (ranibizumab-nuna), another biosimilar to Lucentis

• Wezlana (ustekinumab-auub), a biosimilar to Stelara (ustekinumab)

5 questions to ask your pharmacist about interchangeable biosimilars

Biosimilars haven’t been around for too long. The first biosimilar in the U.S. was approved in 2015. The first interchangeable biosimilar wasn’t even approved until 2021. It’s natural and expected to have questions about biosimilars if you haven’t been exposed to one yet.

Here are five questions to ask your pharmacist if you’re curious about interchangeable biosimilars.

1. Will my insurance cover an interchangeable biosimilar?

Like many things related to insurance, it depends. That’s why it’s important to ask.

All health insurance plans have a formulary. This is essentially a list of medications your plan prefers to cover. Every insurance plan’s formulary is different — and there are currently close to 1,000 health insurers in the U.S.

After your pharmacist receives your prescription, they’ll submit a claim to your insurance to see if they’ll cover it. Your insurance will tell your pharmacist if they prefer to cover the reference biologic or an interchangeable biosimilar. They may also require a prior authorization or even prefer to cover another drug altogether, including a non-interchangeable biosimilar.

While biosimilars are priced around 50% lower than reference biologics on average, many plans still prefer reference biologics. This trend is starting to shift in biosimilars’ favor, but the most cost-effective choice for you will depend on which medication your insurance prefers.

2. Does your pharmacy keep biologics and biosimilars in stock?

Once you know that your insurance plan will cover your medication, the next step is to purchase it and take it home. You should ask your pharmacist when you can expect to pick up your prescription.

Why is this? It’s more expensive for your pharmacy to keep biologics and biosimilars in stock compared to more traditional, small molecule medications (like blood pressure pills). What’s more, since some reference biologics have several biosimilars, it’s hard to keep every option in stock.

If your pharmacy doesn’t have your preferred product in stock, they’ll need to order it for you. It often takes 1 or more business days for an out-of-stock medication to arrive at the pharmacy. But this can take longer if you need a speciality medication or your medication is on back order, among other reasons.

Your pharmacy’s staff can tell you what time frame you can expect.

3. If I fill an interchangeable biosimilar prescription today, will I continue to receive it in the future?

Clinically speaking, switching back and forth between an interchangeable biosimilar and reference biologic shouldn’t cause any problems. But if you’re switching to a biosimilar, it’s a good idea to ask your pharmacist if it's a temporary change or if the biosimilar will be your new medication going forward. It’s always reassuring to know what to expect and to avoid surprises at the pharmacy counter.

Some changes are inevitable though. These are some situations that may prompt you to switch products:

• Your insurance plan’s formulary changes, such as after the start of a new year

• The pharmacy isn’t able to order your prescription due supply chain issues

• Your symptoms change and you need a different medication to treat them

• You experience a new or worsening side effect

4. Does our state have laws about interchangeable biosimilars?

Pharmacy is a highly regulated industry. Alongside federal pharmacy laws, every U.S. state has its own pharmacy laws, too. Some states have laws that impact your pharmacist’s ability to fill an interchangeable biosimilar. These state laws are generally more strict than federal laws.

For example, some states (Alabama, Indiana, South Carolina, Washington) don’t allow pharmacists to automatically substitute interchangeable biosimilars at the pharmacy. They need your healthcare provider’s authorization to do so. And many states only allow it if your expected out-of-pocket cost for the interchangeable biosimilar is lower than it would be for the reference product.

If you’re having issues switching to an interchangeable biosimilar, ask your pharmacist for details. The pharmacist that's working in your pharmacy is required to be licensed in your state. They should be familiar with your state’s laws regarding interchangeable biosimilars.

5. If I want a biosimilar, when should I contact my prescriber instead of the pharmacy?

In some cases, it’s more efficient to direct questions to the healthcare provider who prescribed your medication. If you prefer to receive a biosimilar, you should talk to your provider before they send the prescription to the pharmacy.

This is especially true if the biosimilar you want isn’t considered interchangeable. Your provider can add a note to the prescription that proactively tells your pharmacist that biosimilar substitutions are OK. They can even add a note that says a biosimilar must be dispensed — with no exceptions.

The opposite is also true. If you prefer to receive a reference biologic over a biosimilar (no matter if it’s interchangeable), your provider can add a note to the prescription saying the original product must be dispensed. The pharmacy is required to follow these instructions.

Good to know: If the biosimilar you want isn’t initially covered, your provider can submit a formulary exception request to your insurance plan. This will likely grant you access to your preferred medication, but in some cases, this process can take days or weeks to complete.

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Written by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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