PBS Guide · 8 min read

Biosimilars on the PBS

How biosimilars enter the PBS, the 35% mandatory price reduction policy, brand substitution rules, and what clinicians need to know about switching patients. This guide also covers biosimilar regulatory approvals across the TGA and FDA, including recent biosimilar FDA approval developments that inform global interchangeability standards.

BiosimilarsBrand substitutionPBS price policyBiologics

TGA approval and PBS listing

Before a biosimilar can be listed on the PBS, it must first be approved by the Therapeutic Goods Administration (TGA) ↗ via its dedicated biosimilar regulatory pathway. TGA approval requires:

Analytical characterisation — extensive physicochemical and biological comparison of the biosimilar with the reference product

Non-clinical studies — in vitro receptor binding, pharmacology, and toxicology comparisons

Clinical PK/PD studies — bioequivalence demonstrated for key PK parameters in an appropriate population

Clinical safety and efficacy — confirmatory trial in at least one sensitive indication; extrapolation to other indications if justified

After TGA approval, the manufacturer applies to the PBAC ↗ for PBS listing. The PBAC assesses cost-effectiveness, and the PBPA negotiates the listing price.

Biosimilar regulation: global context

Biosimilar regulatory frameworks vary by region. In Australia, the TGA evaluates biosimilars through its dedicated pathway. In the United States, the FDA ↗ has approved numerous biosimilars under the BPCIA (Biologics Price Competition and Innovation Act), with interchangeability designations allowing pharmacy-level substitution in many states. Recent biosimilar FDA approvals continue to expand the available biosimilar portfolio globally, influencing TGA and PBS policy on pricing and substitution. In the EU, the EMA ↗ has the longest track record, with biosimilars approved since 2006.

The 35% mandatory price reduction

Reference biologic price (before biosimilar listing)

$X per pack

→ −35%

Reference biologic price (after first biosimilar listed)

$0.65 × X

When the first biosimilar of a reference biologic is listed on the PBS, the reference product's PBS price is automatically reduced by 35% on the date of biosimilar listing. This policy was designed to generate PBS savings while maintaining access to both the reference product and biosimilar. For adalimumab alone, biosimilar listing generated over $650 million in projected PBS savings over 5 years.

Exemptions from the 35% reduction exist in limited circumstances — for example, where there is only one listed brand and the PBPA determines that the reduction would jeopardise supply. Manufacturers can apply for an exemption.

Biosimilar substitution at the pharmacy

A PBS-dispensing pharmacist may substitute a prescribed biologic with a biosimilar (or vice versa) when:

The PBS listing includes the "a" brand substitution flag (biosubstitutable designation)
The prescriber has not marked "brand substitution not permitted" on the prescription
The pharmacist informs the patient of the substitution

Clinical note: For patients who are stable on a reference biologic, switching to a biosimilar is generally considered safe based on robust pharmacovigilance data. However, for biologics with complex immunogenicity profiles (e.g., adalimumab anti-drug antibodies), some clinicians prefer to continue the established product. This is a clinical — not regulatory — decision.

Not all PBS biosimilar listings are yet biosubstitutable. Check the PBS Schedule ↗ for the "a" flag on each item. The list of biosubstitutable biosimilars is expanding as TGA and DoH review each product pair.

Frequently asked questions

What is a biosimilar and how is it different from a generic medicine?

A biosimilar is highly similar — but not identical — to its reference biologic. Unlike generics (chemically identical small molecules), biosimilars are large proteins from living cells with natural variation. TGA approves biosimilars via a dedicated biosimilar regulatory pathway ↗ requiring analytical, PK/PD, and clinical comparability. See biosimilars and interchangeability guide for full scientific detail.

What is the mandatory 35% PBS price reduction when a biosimilar is listed?

When the first biosimilar enters the PBS, the reference biologic's PBS price is cut by 35% on the listing date. Policy objective: encourage biosimilar uptake and reduce PBS expenditure. Manufacturers of the reference product can apply for exemptions in limited circumstances. The PBS biosimilar price policy ↗ and PBPA manage this process. Related: biosimilar interchangeability.

Are biosimilars automatically substituted at the pharmacy like generics?

Automatic biosimilar substitution requires the PBS listing to carry the "a" flag (biosubstitutable) and the prescriber NOT to mark "brand substitution not permitted". The pharmacist must counsel the patient. Not all PBS-listed biosimilars are yet flagged as biosubstitutable. Check the PBS Schedule ↗ for individual items. Prescribers may restrict substitution for narrow-TI biologics or during initiation. See how to read a PBS listing for flag definitions.

Which biologics currently have biosimilars listed on the PBS?

PBS-listed biosimilars (2026) include: adalimumab (many biosimilars — largest driver of PBS savings), etanercept, infliximab, trastuzumab, rituximab, bevacizumab, filgrastim, epoetins, insulin glargine, pegfilgrastim. Full list: PBS biosimilar medicines ↗ and TGA biosimilar register ↗. See also biosimilars guide.