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Inside the Spray Tank: information waivers

August 2009

Welcome back to Inside the Spray Tank – an informal ‘slice of life’ view of ACVM operations.

This is the second in a series of blogs by Andrew Pearson, who is currently our MRL advisor but also has experience with most of the application types we receive. Andrew provides an internal perspective on procedures/issues to give you some background to our decision making. (photo: Andrew Pearson)

The purpose of an information waiver is for an applicant to justify in technical terms any deviation at all from the ACVM information requirements. However, in practice, we do accept that some arguments are so straightforward that they can be processed as part of the application without a separate waiver. Examples of this include waiving data requirements for identical products and, to a similar degree, residue and efficacy requirements for agricultural chemicals applying as a generic to a similar registered product. A minor issue of non-compliance with a data assessment report may also be addressed by an argument in the covering letter, where it is identified that the risks are minimal.

Impacts on risk thresholds

The actual information waiver application process comes into effect when the divergence from the requirements can have major impacts against one or several of the risk thresholds under the Act. Say an argument for pharmaceutical equivalence for an oral veterinary medicine product--simply demonstrating an identical dose rate of active is not sufficient. Such basic chemical properties as particle size, dissolution rate and drug-drug interactions can all significantly affect the pharmacokinetics of the active to such an extent that efficacy is hampered or residue profile extended.

The most common information waiver requests received are either to demonstrate equivalence to a currently registered product or to address the omission or deviation of a specific data requirement from a study or report.

Demonstrating equivalence

An equivalence argument is usually based on comparison of the chemistry and or chemical properties (eg, dissolution rate) of 2 products. Note that the reference product has to be registered in New Zealand -- if a product isn’t registered there is no prior risk assessment on that product to assess against the ACVM Act risk thresholds. Thus, regardless of whether you can demonstrate equivalency, it provides no value.

A common mistake is to support an equivalency waiver with a very expansive argument but fail to concentrate on the direct comparison of properties or to simply overwhelm us with studies but with no direct tie into the studies. Simply saying that there will be no difference in properties of two excipients or between formulation types is insufficient. This needs to be demonstrated or supported.

Finally, this route shouldn’t be seen as a method of getting data assessed more rapidly. If you have actual trial results, say for residues, it is more appropriate that this data be assessed and then a waiver used to address the deficiencies than it is for it to be submitted as part or as all of an equivalency argument.

Addressing a specific deficiency

For a waiver application to address a specific deficiency we expect to receive an assurance, either through the provision of literature data or reference to similar situations, that the deficiency will not impact on the outcome of the study and thus the results can be interpreted as accurate. Examples could include a waiver to request provision of only one tissue type in a residue study or addressing a specific deficiency through providing a bridging study. For this type of waiver, if you quote specific studies or scientific literature to support the argument we would usually expect the source material to accompany the application.

No fixed timeframes

Information waiver applications do not have any fixed timeframes placed on them simply because the variety of arguments received means that appraisal can take anywhere from a week to 6 months. If an argument is on a specialised area, we may also seek input from a recognised expert. In general, however, our internal guidance is to try and turn waiver applications around within 3 months.

This uncertainty over timeframes is the reason why an application will be held from entering regulatory appraisal until the information waiver has been appraised. With only 40 days to complete regulatory appraisal and on top of the application queue that the technical appraiser may already have, a complex information waiver to assess will cause us to exceed our regulatory timeframes.

Waiver certificate

Once your application has been appraised, the waiver certificate identifying the specific argument and waiver considered, a summary of the supporting rationale, and the outcome of the appraisal with any conditions placed around the waiver will be sent to you. It is important to review these before your application is submitted as in certain circumstances only part of the waiver may be approved or conditions limiting the scope of the waiver may be implemented.

It is also worth noting that, although the waiver certificate does not have a set expiry date, circumstances and internal operational policy do change and a waiver may be rendered redundant by this. A waiver may also be considered superseded if an aspect of an application changes significantly from that considered previously. In other words, we cannot place a guarantee on accepting waiver certificates.