Brand Substitution

Page last updated: 13 July 2018

Where are the 'a' and 'b' flags?

The concept of "bioequivalence flags" (also known as 'a'-flagging) has been replaced with Brand Substitution Groups. Brand Substitution Groups allow the specification of brand substitutable products across different PBS Item Codes. This was not possible with 'a'-flagging.

Brand Substitution in PBS XML v3.0

Brand Substitution Groups

A brand substitution group is included in the v3.0 PBS XML as a <p:brand-substitution> element within the <rdf:RDF> element. The <p:brand-substitution> element includes a rdf:about attribute that identifies the group. For example:

<p:brand-substitution rdf:about="http://pbs.gov.au/brand-substitution/GRP-14639">
   <db:title>Brand Substitution Group</db:title>
   <p:code>14639</p:code>
</p:brand-substitution>

One or more <product-listing> elements may be a member of the group. This is indicated by the <product-listing> element containing a <member-of> element that references the group using its rdf:resource attribute. For example:

<product-listing>
  <member-of-list>
    <member-of rdf:resource="http://pbs.gov.au/brand-substitution/GRP-14639">
      <code rdf:resource="http://pbs.gov.au/code/group">14639</code>

   </member-of>
  </member-of-list>
  …
</product-listing>

A <product-listing> element occurs in a prescribing rule and gives the TPP that is listed for that prescribing rule. All product listings that are members of the same brand substitution group are substitutable, even if they are in different prescribing rules.

Determining the Flag

If for some reason you need to determine an 'a' or 'b' flag for display purposes then the following guidelines may help.

  1. Start with a prescribing rule (PBS Item Code).
  2. Find all of the product listings in that prescribing rule.
  3. Find all of the brand substitution groups for the product listings.
  4. Sort the groups by their rdf:about attribute.
  5. The first group will be marked with 'a', the second with 'b', and so on.
  6. For each product listing, if there is more than 1 product listing in the brand substitution group and the same prescribing rule then display the flag (determined above) for that group.

Brand Substitution in PBS XML v2.12

Brand Substitution Groups

A Brand Substitution Group is included in the PBS XML as a pbs:group element with child pbs:type element having the content group:brand-substitutable. This type of group may have pbs:prescribing-rule and pbs:tpp elements as its members.

Group membership is indicated by the presence of a pbs:member-of element in the pbs:member-of-list element for the prescribing rule or TPP. The pbs:member-of element has an xlink:href attribute that hyperlinks to the pbs:group element.

Both pbs:prescribing-rule and pbs:tpp elements may be members of one or more Brand Substitution Groups.

Substitutable Products

All TPPs that are members of a Brand Substitution Group are substitutable with other members of that group, within the context of the prescribing rules that are also members of that group.

If a prescribing rule is a member of just one Brand Substitution Group then all of the TPPs in that group may be substituted with each other. In other words, they would all have an 'a' flag.

If a prescribing rule is a member of more than one Brand Substitution Group then these define separate groups of products that may be substituted. These would be indicated using 'a' and 'b' flags in the Schedule.

A TPP is substitutable with other products that are members of the same Brand Substitution Group only for the prescribing rules that are also members of that group.

If a TPP is a member of more than one Brand Substitution Group then this means that there are separate contexts in which the TPP is substitutable. The prescribing rules that are members of those Brand Substitution Groups define the context.

Determining the Flag

If for some reason you need to determine an 'a' or 'b' flag for display purposes then the following guidelines may help.

  1. Start with a prescribing rule (PBS Item Code).
  2. Find all of the Brand Substitution Groups that the prescribing rule is a member of.
  3. Sort the groups by their pbs:name child element.
  4. The first group will be marked with 'a', the second with 'b', and so on.
  5. For each group, find all of the TPP members of that group.
  6. For each TPP, if it is listed in the current prescribing rule and there is more than 1 TPP in the brand substitution group then display the flag (determined above) for that group. If the TPP is not listed in this prescribing rule then it is still substitutable (the Schedule currently includes notes to indicate this).