Over the years that I’d been a member of the CQM (Canadian Quality Milk) and now ProAction Food Safety technical committee, questions have come up over various statements made on drug and vaccine labels. The most recent one was, “How important is it to follow the storage instructions?”
There are not many good answers that I can give to a general question like that. Sometimes, I can give a good answer but I need to know what specific drug or vaccine is involved and what the specific storage conditions were. Even then it could be difficult to provide an answer because most people don’t know what happened to the drug itself. I got a call about a farmer who left an expensive drug outdoors in a shed. It was supposed to be stored at room temperature. In the morning, it was -7 C outside. Was it that cold in the shed where he left the bottle? Not a great opportunity to provide a quality answer.
A similar situation happens when I get a call from someone who left a vaccine out on the counter overnight. Without knowing how warm the vaccine became and for how long, it is difficult to predict whether the vaccine will still work.
Everyone makes mistakes, especially when there is more than enough to do all the time. Fortunately, these are special situations that don’t occur all the time. The more common situation is that people store drugs and vaccines in ways that are convenient for them but not in the conditions recommended on the product label. Not storing light-sensitive products in the dark and not storing at the recommended temperature appear to be really common situations. Does it matter when drugs or vaccines are stored improperly? There is no way to know in a general sense — storage conditions can be really important for some drugs and vaccines and not so important for others. Even still, unless you know how long the drug or vaccine has been stored that way, it is difficult to judge if storage has reduced its effectiveness or even made it dangerous. Because farmers are producing food, it becomes important to consider whether improper storage has affected the withdrawal times for milk or for meat. Those are even more difficult questions to answer.
Most people understand that vaccines should be refrigerated but I suspect that many drugs are not stored properly because people don’t read the product label. It is a good idea, especially if you are using a new (and likely expensive) drug for the first time.
Sometimes farmers do intend to store drugs properly, especially vaccines, but their fridge doesn’t actually work the way they thought it did. There have been a few studies on how well farm fridges work, most in the U.S. and, last month, one in Britain. I have not seen a study for Canadian farm fridges but I don’t have good reason to suspect that they would be too different. The most recent study showed results similar to the previous studies; almost none of the fridges stayed inside their intended temperature range. Most also had different temperatures on different shelves, including some fridges with shelves where the temperature went below freezing. The only way to know if the fridge works properly is to have a thermometer with a regulated minimum/maximum temperature and a sensor located where the drugs or vaccines are actually stored.
As you read the label, it may be worthwhile to check other information that is likely important. One piece of information on the label that is often missed is that many drugs have TWO expiry dates. The first expiry date is obvious; the second one is less obvious but labels on lots of drugs have a time period when they should be used after they are opened. A second piece of information is that many drugs, especially antibiotics, have a maximum amount that can be given at one site. This maximum amount per site is really important to know and follow because it may affect the drug’s withdrawal.
Dr. Robert Tremblay is a veterinarian for Boehringer-Ingelheim and lives near Guelph.