Antibiotics for unapproved indications

Editor, – I would like to revisit the use of various antibiotics for 'orphan' indications. One example is rifampicin for deep infections due to methicillin-resistant Staphylococcus aureus (MRSA). There are few oral antibiotics available for the treatment of MRSA infections, but the combination of rifampicin and fusidic acid is commonly used and is recommended in Therapeutic Guidelines: Antibiotics.

In 1994, Australian Prescriber published a response to a query (Aust Prescr 1994;17:95)asking why rifampicin was not subsidised for osteomyelitis. The response said that no application had been submitted for the use of rifampicin for this indication.

Would it be possible for the Therapeutic Goods Administration to approve an 'orphan' indication for well-known drugs where they are recommended by recognised guidelines? Perhaps for such indications, a simplified application to the Australian Drug Evaluation Committee could be made by clinicians or their representative bodies.

Allen Cheng
Infectious diseases physician
Geelong Hospital
Menzies School of Health Research
Geelong, Vic.

Dr Leonie Hunt, Director, Drug Safety & Evaluation Branch, Therapeutic Goods Administration, comments:

The Therapeutic Goods Administration (TGA) is able to approve indications for extensions of use of medicines, including antibiotics, after it has received an application from a sponsoring company, supported by data to establish quality, safety and efficacy for the intended use.

For an extension of indication, quality will usually have been established and the focus is on safety and efficacy. In order to facilitate the lodgement of applications for the treatment of rare conditions, which may otherwise not be cost-effective, the TGA has introduced an Orphan Drug Scheme, whereby all evaluation fees are waived provided the sponsor obtains designation for the product for the indication. The usual criteria for determining a disease is rare are the orphan criteria that it is not likely to affect more than 2000 people.

The TGA has also adopted a number of modifications to data packages to facilitate applications for older, off-patent or orphan products. These include literature based submissions, whereby companies can submit published papers as the basis for an approval of a product or an extension of use of a product. Unfortunately, the TGA has no power to approve products for new indications in the absence of an application, but it is always happy to discuss with sponsors the modified data requirements for products where there is a demonstrated clinical need.