Prescription opioid drug abuse has been the focus of significant media attention in recent months. The Minister of Health recently stated that she has asked her staff to work on a range of options to address Canada's epidemic of opioid abuse, including setting up a national surveillance system to monitor drug overdoses.
Back in December 2014, Health Canada sought stakeholder consultation on a draft guidance tamper-resistant formulations of opioid drug products, and that guidance has now been finalized with the release of Health Canada's guidance document: Tamper-resistance Formulations of Opioid Drug Products (the "Opioid Drug Guidance"). The Opioid Drug Guidance applies to all drug submissions for sponsors seeking authorization to include tamper-resistance statements in the product monograph ("PM") of a controlled-release opioid drug. The Opioid Drug Guidance sets out specific criteria and data requirements for demonstrating the tamper-resistance characteristics of a human drug product for the purpose of reducing the likelihood of prescription opioid drug abuse. The Opioid Drug Guidance became effective on March 30, 2016.
The Opioid Drug Guidance defines "tamper-resistance formulations" as including those products that are manufactured with measures intended to reduce the likelihood of abuse, as demonstrated by appropriate in vitro and clinical studies. As defined in the Opioid Drug Guidance, such formulations may contain, for example:
- physical/chemical barriers rendering the product more difficult to manipulate or less rewarding if administered;
- an added opioid antagonist which would become active if the product is tampered with, thereby defeating the euphoric effect of the product;
- an aversive agent rendering an unpleasant effect if the product is tampered with; or
- a delivery system in which drug release designs can offer resistance to abuse.
The Opioid Drug Guidance notes that a change in formulation to an existing marketed product, to add a tamper-resistance feature, requires the filing of an SNDS, SANDS, or NDS, depending on the circumstances.
Submissions seeking to obtain an approval for the inclusion of scientific statements and claims of tamper resistance in PMs are to be supported by appropriate studies such as in vitro manipulation and extraction studies, pharmacokinetic studies and clinical trial data demonstrating a reduction in "drug liking". For new products submitted by way of NDS, sponsors wishing to include statements, or label claims of tamper-resistance, should provide evidence from in vitro laboratory, pharmacokinetic and clinical abuse liability studies.
In the case of ANDSs, namely generic drug products, the Opioid Drug Guidance requires that the generic tamper-resistant opioid drug product establishes equivalent tamper-resistance properties and performance of the product in comparison to the Canadian Reference Product. The comparative studies provided in support of the tamper-resistance features are to provide sufficient evidence to support equivalent performance of the proposed product to the CRP with respect to the tamper-resistance properties. Depending on the design of the product, in vitro laboratory manipulation and extraction studies, and/or pharmacokinetic studies may be required.
In terms of in vitro laboratory studies, the Opioid Drug Guidance sets out a variety of suggested studies for assessing tamper-resistance, including: particle size distribution testing, dissolution testing, extractability testing, injectability testing, vaporization testing, and insufflation testing.
Regarding pharmacokinetic studies, the Opioid Drug Guidance states that the tamper-resistance feature of the product must not affect dosage, absorption, distribution and elimination of the drug product, as shown by pharmacokinetic studies of the controlled release properties, aversive agent for deterring abuse, or the effect of food and alcohol on the formulation.
In terms of clinical abuse-liability studies for tamper-resistance, the Opioid Drug Guidance states that such studies are to evaluate relative abuse potential and provide data in demonstrating a significant decrease in the measure of abuse liability compared to a positive control. The positive control should be a product that has the same active ingredient as the test product, but without tamper-resistant properties.
The Opioid Drug Guidance states that Health Canada will allow the inclusion of explicit statements stating the product is formulated with tamper-resistance properties. Studies supporting the tamper-resistance claim will be described in the PM only if a claim is sought by a sponsor and authorized by Health Canada. The status of a product claiming to deter abuse can change with various factors such as demographics, availability of tools to overcome the tamper-resistance properties, availability of non-tamper-resistant prescription opioids, ease of accessibility to illicit drugs, and so forth; therefore, the Opioid Drug Guidance states that Health Canada states that no claims of real world abuse-deterrence will be included in the PM.
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