Dispensing of prescription medication expiration dating
SLEP has found that 88% of 122 different drugs stored under ideal conditions should have their expiration dates extended more than 1 year, with an average extension of 66 months, and a maximum extension of 278 months.Recently researchers investigated samples of 8 medications that had expired 28 to 40 years earlier and contained 15 different active ingredients in all.Injectable medications, which have become cloudy or discolored or show signs of precipitation should not be used.Certain medications have a narrow therapeutic index and little decreases in the pharmacological activity can result in serious consequences for patients.The expiration date is only an assurance that the labeled potency will last at least until that date.Ongoing research shows that stored under optimal conditions, many drugs retain 90% of their potency for at least five years after the labeled expiration date, and sometimes longer.Drugs prepared by addition of a solvent before dispensing or administration (such as suspensions of antibiotics for oral use or lyophilized drugs in vials for parenteral use) tend to be relatively unstable in the liquid state.
This date is required by Health Canada to be displayed on a manufacturer’s package: it is a ‘consumer-use-by’ date, and for dispensing purposes pharmacists and practitioners must calculate the prescription’s supply to ensure that, if used as directed, the prescription will be completed prior to the stated expiry date.For example, if a company chooses a three year expiration date, it does not have to test beyond that for prolonged effectiveness.In fact, medication's potency gradually decreases starting from the moment of its manufacture.The active ingredients tested for were: aspirin, amphetamine, phenacetin, methaqualone, codeine, butalbital, caffeine, phenobarbital, meprobamate, pentobarbital, secobarbital, hydrocodone, chlorpheniramine, and acetaminophen.The results showed that 11 (79%) of the 14 drug compounds were always present in concentrations of at least 90% of the amount indicated on the drug label, which is generally recognized as the minimum acceptable potency.
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by e Med Expert staff Medical references reviewed: August, 2018 Many medications are very expensive and people hate to waste them.