Objectives: Drug diversion is a growing problem in numerous countries. Some laboratories have developed tamper-resistant formulations. The problem for healthcare authorities is now to assess new formulations developed to limit the risk of diversion for administration by another mode and intended mode. It would be helpful to have a pertinent panel of in vitro tests allowing assessment of how a formulation may be altered, both for healthcare authorities and for laboratories, so as to implement adequate sanitary measures. We designed a methodology/tool allowing assessment, in a standardized manner, of the formulation's resistance to drug diversion. We present the various steps leading to the construction of the scale and to its first use.
Methods: Creating a Steering Committee - Choosing assays or parameters - standardized by a monograph of the European Pharmacopoeia and pragmatic assays related to users' behaviors - for the assessment of formulation resistance to drug diversion. Designing a scale: i) applying all these tests to a panel of formulations; ii) applying a score by drug and by test; and iii) attribution of weighting per test and calculating the total score for a drug.
Results: Eight tests or parameters and 14 drugs (diverted drugs and controls) were chosen. Buprenorphine Subutex® had the lowest score and flunitrazepam Rohypnol® the highest.
Conclusions: Our tool allowed classification of the various drugs selected. This classification correlated with results of postmarketing authorization assessment. Rohypnol®, which was the object of many measures, including formulation changes, obtained the highest score in our study.
Keywords: abuse; assessment tool; diversion; drug formulation; tampering.