Do Medications Expire?
by Imogen Davis & Luitgard Holzleg
Do the medications and supplements in your cabinet actually expire? In 1979, a law was passed in the US requiring drug manufacturers to stamp an expiration date on their products. This date guarantees the full potency and safety of the medicine.
At the military’s request, various studies conducted by the Food and Drug Administration have resulted in most of what we know about medicine expiration dates. The „Shelf-Life Extension Program“, a cooperation with the US Department of Defense, aims at extending the expiry dates of medications. Since its launch, expiry dates were extended by on average 66 months, so approx. 5.5 years. It was concluded that 90% of 100 different tested drug varieties were still safe to use 15 years after their date of expiry. Lucky for the programme was the find of unopened medications that had been expired for 28 to 40 years. The medications included the pain killers, acetyl salicin acid, phenobarbital, codeine or amphetamine. Of the fifteen active ingredients found, twelve were still as effective as when manufactured.
The ability for a drug to have an extended shelf life depends on the drug’s ingredients, preservatives, temperature changes, light, humidity, and other storage conditions. For example, many creams and ointments have a limited shelf-life once opened. Active ingredients might react with oxygen, others react to light. One example for the reaction to light are calcium-antagonists, a drug used to treat high blood pressure; they should only be stored within their blister packaging. In many cases, storing a medicine in the fridge delays its potency decline.
A decrease in drug potency after expiry is usually harmless with the exception of antibiotics. Sub-potent antibiotics used to treat infections can easily create resistance. Other notable exceptions to the original potency still being present are nitroglycerin, a medication used to treat angina pectoris, insulin to treat Diabetes, and liquid antibiotics. Degraded tetracycline, another antibiotic, might even be linked to renal kidney damage. Medications containing preservatives, such as eye drops, may be dangerous past their expiration date because they might allow bacterial growth in their solutions. Other medications known to be unsafe after they have been degraded include vaccines and medicines that appear powdery, dried up or crumbled.
Pharmaceutical manufacturers rely on their own studies to set expiry dates. However, these studies usually run over a limited period only, and thus expiry dates are typically 2 to 3 years after opening a medication. Critics see this as very convenient for manufacturers. Medications are able to be introduced to the market quicker this way, as stability and potency testing must be completed before approval to it on the market.
The published expiry date hence ensures full effectiveness. We need to keep in mind that no tests check potency and stability afterwards. So our medicines may only begin to lose potency many years after the stamped date (as approved by the FDA in the US or other approval agencies).
So, does that mean I should return medications to a pharmacy once it has expired or may I still use it? In my role as a physician in a hospital or a practice, I would indeed have to dispose of such medications but at home, I use a common sense approach. We should be much more careful with the temperatures we currently have to endure. Warmth and humidity speed up the decay process. Maybe you need to move some of your medications from the bathroom cupboard into the fridge.
We currently have no answers to the questions that arise from the necessity of drug expiration awareness: are drug manufacturers trying to keep our medicine cabinets be restocked? Or are they simply ensuring we receive exactly what we paid for?
Posted on June 28, 2019 by Luitgard Holzleg
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