The importance of the expiration date
Many pet owners would choose to skip their vacation or the purchase of a new television set if it was a choice between those things and the health of their pet. Everything seems so costly these days: dinner out, movies, clothes, even water which should really be free is on the shelves everywhere for sale in plastic bottles. Those of us with pets quickly come to realize that pet ownership is very costly under ordinary circumstances, and an unexpected illness could easily lay ruin to the most carefully planned out budget. Shopping around to decrease some of the costs associated with healthcare is generally not a bad idea, but sometimes I get calls from pet owners who want to cut costs in ways that are potentially harmful, such as trying to avoid bringing the pet to the veterinarian when the pet is not well. Another example of a bad idea is to use medication that is past its expiration date. While having a sick pet and not bringing him or her to the veterinarian for proper examination is obviously a very bad idea, many might not so easily recognize other dangers such as using expired medication.
Drug manufacturers are required to put expiration dates on drug products. These dates for a particular product are not chosen randomly, but are assigned after the manufacturer has performed stability testing. Other factors are also taken into consideration, such as chemical degradation in a particular environment or the effects a particular combination of chemicals when placed together. Another thing to note is that the manufacturer’s expiration date is sometimes different than the “beyond use” date given by the pharmacist filling the prescription. When a medication is removed from the pharmacy and stored at home, many times the conditions are less than ideal for maintaining drug and chemical stability. The medicine cabinet in the bathroom is an example of a location that is generally bad for drug storage because of humidity and temperature extremes.
What happens to medications when they pass their expiration date? Well that depends. In some cases the medication may begin to lose its potency, and in other cases the medication can degrade in such a way as to become more concentrated. Let’s look at the following example: A 100 ml bottle of liquid medication that is formulated to provide 10mg per 1ml will become 20 percent more concentrated if four teaspoonfuls of the liquid evaporated over time. The original 10mg dose will now be providing 12mg of active ingredient. Needless to say, increasing the dose of medication in such a manner for a small cat or dog can have potentially harmful consequences.
The flip side of that coin would be the futility of giving a medication that has lost rather than gained potency and therefore is providing the pet with little more than a “placebo” effect. A placebo is what the old-time pharmacist used to call the “sugar pill” which contained no active ingredient at all and was often prescribed for the treatment of some psychologically based illnesses. Since our pets, however, do not know what the original purpose of the medication was, we certainly can’t expect the placebo to exert a psychological effect on them like it does in some of us “complicated” humans.
The bottom line is that medication can and does go through chemical changes over time, and these changes are not always predictable. The expiration dates that the manufacturers put on the bottle are there for a reason, and have in many cases been carefully selected after doing chemical analysis and taking other factors into consideration. Since there is potential harm in keeping and using expired medication, let’s all take a few minutes and read our old medication bottles (both prescription and non-prescription) and begin doing some healthy “feel good” spring cleaning. Be sure to properly dispose of any expired medications.
As always, if you have any questions about dosing, expiration dates, or other medication related concerns please feel free to call your 1800PetMeds pharmacist who will be happy to help answer those for you.