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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 6 of 6. This is the beginning of the thread.
Posted by Shelley on August 29, 2001, at 14:24:54
Hi,
Does anyone know if taking Tegretol tablets which have expired a year ago is dangerous or simply innefective?
In other words, when the drug decomposes, are there harmful substances formed ? The medication was not prescribed for seizures, by the way.Thanks.
Posted by SalArmy4me on August 29, 2001, at 15:45:38
In reply to expired meds, posted by Shelley on August 29, 2001, at 14:24:54
Posted by Cam W. on August 29, 2001, at 16:59:26
In reply to expired meds, posted by Shelley on August 29, 2001, at 14:24:54
Shelley - A tablet starts to degradate as soon as it is made. To compensate for this (and to follow Health Canada/FDA laws), drug companies are allowed batches of drugs to have a potency between 95% and 105% of stated drug weight. Most drug companies will manufacture their medications with slightly more than 100% of stated dose, so that the drug's extends time to expiry date, slightly.
The expiry date is determined by chemical testing and is reached once a drug still contains 95% active drug. Most drugs are safe to use after their expiry date, but how it effective (and potent) it will be can vary greatly. How much of the actual drug is left can only be determined by having the drug tested. Factors, such as: how the med was stored (on your shelf, in the pharmacy, and at the wholesaler); or how long the med was on the pharmacy shelf (unless there is an actual expiry date on the presription bottle). Excessive heat and cold can both degradate tablets faster, as can humidity.
Tegretol™ (carbamazepine) blood levels are monitored, because the drug has a narrow therapeutic window (which means that the blood level needs to between effective minimum effective concentration and toxic concentrations, is more narrow than most other drugs). For this reason, I would less likely to use a drug like Tegretol after it's expiry date, than many other medications.
Also, a year after expiry date is a little long, and it would be very difficult to guess how much active ingredient is left.
My thoughts - Cam
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Posted by Grouch on August 29, 2001, at 22:07:35
In reply to Re: expired meds » Shelley, posted by Cam W. on August 29, 2001, at 16:59:26
> Factors, such as: how the med was stored (on your shelf, in the pharmacy, and at the wholesaler); or how long the med was on the pharmacy shelf (unless there is an actual expiry date on the presription bottle).Another complicating factor is that the "expiration date" on the prescription bottle is probably not the real expiration date; i.e. the date on the original packaging for the medication.
Looking at my prescription bottles, for example,
they all have a "discard after" date which is arbitrarily set to one year after the date the prescription was filled. I would assume that the pharmacy doesn't want to be liable for people using expired medication so they are probably conservative with that date. Nevertheless, there's really no way of knowing for sure.
Posted by Shelley on August 30, 2001, at 3:13:40
In reply to expired meds, posted by Shelley on August 29, 2001, at 14:24:54
Posted by Ted on August 30, 2001, at 11:43:31
In reply to expired meds, posted by Shelley on August 29, 2001, at 14:24:54
Shelley,
I agree with the information presented by the others, but you also have to take into account the desire for companies to make you purchase more product. For this, they place expiration dates where they are sometimes rediculous. Examples include sodas sealed in aluminum cans and bottled water. I know, these are not meds, but they are still controlled by the same government agency in the US.
In my opinion, one never knows what the *real* expiration date is unless research has been performed.
Ted
> Hi,
>
> Does anyone know if taking Tegretol tablets which have expired a year ago is dangerous or simply innefective?
> In other words, when the drug decomposes, are there harmful substances formed ? The medication was not prescribed for seizures, by the way.
>
> Thanks.
This is the end of the thread.
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