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Agvetlink Special Issue for Veterinarians March 2005

SELENIUM

Selenium products were regarded as prescription until a review in 1993, which resulted in rules allowing most to be over the counter if not required to be prescription for other reasons.

In general this applied to most boluses, injectable products and selenised vaccines for sheep and cattle in the market at the time. As the change relied on licensees making an application, some products remained on the market as PAR until picked up when updating to the ACVM Act. In at least one case a product was updated with a PAR condition that should have been deleted. Because of delays in labels being reprinted there will still be some labels in the market with a PAR requirement that no longer applies.

When the ACVM Act was introduced, the status of all oral mineral supplements including those containing selenium changed. Previously, under the Animal Remedies Act, they were not regarded as food and had to be registered. Under the ACVM Act they are exempt as oral nutritional compounds provided conditions are met and therapeutic claims are not made. Some oral selenium products remained registered because they make claims to treat clinical disease directly in the same way that calcium products making claims to treat milk fever are registered.

Dose rates

There were rules in place providing for maximum dose rates for over the counter products. However, the current regulations do not specifically state maximum acceptable levels. The old limits are still used as a guide as to whether a dose rate is acceptable on an exempt product available for general sale.

There has been a tendency for label selenium dose rates to be as high as possible without exceeding the limits, which were based on the risk of toxicity and not on the levels actually required. We are reminding companies producing selenium products of their obligations and the need to keep dose rates consistent with good practice so that the opportunity for toxicity to occur is not unnecessarily increased.

Adverse events

In setting up the ‘exemptions from registration’ process, it was recognised that reports of adverse events are needed to provide ongoing assurance the risks are being managed as required. It is important that adverse event reports are submitted where toxicity does occur, not just with selenium but with other toxic compounds (such as copper) used as nutritional supplements. These reports have a valuable role to play in making sure that the management of exempt products is adequate, just as they do for products that are registered.