Mayne Pharma International Pty Ltd and Minister for Health

Mayne Pharma International Pty Ltd sought judicial review of a decision by the Minister for Health to refuse the registration of its sustained-release oxycodone tablets in the Australian Register of Therapeutic Goods. The proposed product, Mayne Pharma Oxycodone MR, was intended as a generic version of a modified-release oxycodone product, OxyContin AU, which was no longer marketed. The Administrative Appeals Tribunal considered the appeal against the initial decision made under section 25 of the *Therapeutic Goods Act 1989* (Cth).

The core legal issues before the Tribunal concerned the interpretation of the *Therapeutic Goods Act 1989* and associated guidelines, specifically in relation to the demonstration of bioequivalence for the registration of generic medicines. The Tribunal was required to determine whether the comparative testing methods used by Mayne Pharma adequately established the safety and efficacy of its proposed product, particularly in light of the unavailability of the original reference product, OxyContin AU, and its Canadian equivalent, OxyContin CA, which had also been reformulated. The Tribunal had to consider the TGA's adopted guidelines, including the "Guideline on the investigation of bioequivalence" and "Guidance 15 of the Australian Regulatory Guidelines for Prescription Medicines (ARGPM)".

The Tribunal's reasoning focused on the inadequacy of the bioequivalence studies presented by Mayne Pharma. It was found that the studies did not satisfactorily demonstrate that the plasma levels of oxycodone during the onset of treatment were similar between Mayne Pharma Oxycodone MR and the reference product. This lack of similarity raised concerns about potentially different requirements for supplementary analgesia, increased difficulty and variability in dose titration, and consequently, heightened risks of opioid-related side-effects or reduced pain control. The Tribunal affirmed that bioequivalence studies are crucial for establishing that a generic product is essentially similar to an approved reference product, thereby validating its safety and efficacy without requiring a full suite of studies.

The Tribunal upheld the initial decision to reject the registration of Mayne Pharma Oxycodone MR. The application was remitted to the original decision-maker for further consideration, implying that the applicant may have an opportunity to provide further information or conduct additional studies to address the identified deficiencies.