What Should be Done With Drugs That Have Passed Their Expiry Date?

Expiry dates on medicines are very important for ensuring the safety of the patients. The requirement for stating the expiry date on all medicines came into force in 1979. The expiry date is essentially a guarantee by the manufacturer that up till that date, the medicine will have full potency and be safe to consume. Moreover, upon reaching the expiry date, the medicine must retain at least 90 percent of its original potency, under standard storage conditions. The United States Food and Drug Administration (USFDA) recommends that all medications should contain 90-110 percent of the active ingredient that is claimed on the label. A drug generally expires between 1 to 5 years after its manufacture. However, it is not mandatory for the manufacturer to determine the potency of the medication post-expiration. This allows drug manufacturers the flexibility to fix expiration dates without determining actual long-term drug stability.

In other words, a drug manufacturer is only required to provide evidence that a drug has full potency up till the expiry date the company chooses to fix. The expiry date does not mean, or even indicate, that the drug will cease to be effective after that, nor become harmful to take.

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When Can Expired Medicines be Useful?

Under certain situations, outdated medicines may be required to be used in the absence of other alternatives or due to economic reasons. A study has shown that expired EpiPen auto-injectors that deliver epinephrine (a hormone secreted by the adrenal glands that increase cardiac output and elevates blood glucose levels) retains some of its potency even after the expiry. It is, therefore, recommended that in the event of non-availability of un-expired EpiPens, these could be used as long as no discoloration or precipitates are apparent, since the potential benefit of using them is greater than the potential risk of a suboptimal epinephrine dose or of no epinephrine treatment at all.

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Expiry Date vs Potency: Scientific Studies

The expiry date does not mean that the medicine loses its potency from that date and is no longer safe to take. In fact, the potency starts to decrease the moment it is manufactured and has no bearing on the expiry date. The expiry date is determined on the basis of the date from manufacture up to which its stability and shelf-life have been tested by the drug manufacturer.

A couple of studies have unequivocally established that the potency of medication is retained even after the expiry date:

• A US study found that 12 out of 14 drugs that were tested retained full potency up to 28 years after the expiry date, of which 8 drugs retained their full potency up to a staggering 40 years post-expiration!
• Another US study, under the Shelf Life Extension Program (SLEP) of the Department of Defense, USA, found that of a total of 122 different drugs that had been stored under ideal environmental conditions, as per military regulations, 107 (88%) had their expiry dates extended more than 1 year, with an average extension of over 5 years, and a maximum extension of 23 years

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Stability of Medicines

With reference to stability, as a general rule, liquid medicine preparations such as solutions or suspensions are less stable than solid forms such as tablets or capsules. The stability decreases upon exposure to light (especially sunlight), moisture, oxygen, and extremes of temperatures. Therefore, proper storage of medicines in a cool and dry place is very important for increasing the shelf-life.

Safety & Toxicity of Expired Medicines

With regard to safety and toxicity, the common belief is that expired drugs are unsafe and toxic. However, there is little scientific evidence to support this belief. Till date, only a single isolated report indicated that tetracycline degradation products can cause a reversible type of renal tubular damage, technically known as Fanconi syndrome. Although the lack of other reports of toxicity from expired medication is reassuring, it should, however, be remembered that very little research has been carried out in the area of toxicity of expired medicines.

Drugs for Which the Expiry Date is Critical

There are some drugs that have a narrow therapeutic index, meaning that even a small decrease in pharmacological activity can have drastic clinical consequences. Therefore, in case of these types of drugs, the expiry date should be strictly adhered to. Some of these drugs include the following:

• Digoxin
• Theophylline
• Warfarin
• Nitroglycerin
• Insulin
• Phenobarbital
• Paraldehyde
• Procainamide (sustained release)
• Thyroid hormones
• Oral contraceptives
• Anticonvulsants
• Ophthalmic solutions

Besides the above-mentioned drugs, antibiotics should also not be taken after the expiry date, as this can encourage antibiotic resistance.

Expiry Dates: Is There a Commercial Angle?

Could the stamping of expiry dates be a marketing strategy by pharmaceutical companies, encouraging us to keep buying new medicines, throwing away unused ones, thereby ensuring that their coffers are filled regularly? This is one way of looking at it.

The other way is that the expiry dates are very conservative to ensure that medicines have their full potency. Moreover, if a pharmaceutical company had to do shelf-life and drug stability testing for longer periods; it would slow down its pipeline of new and improved formulations due to obvious logistic reasons.

What Should You Consider Before Taking Expired Medicines?

The following factors should be taken into consideration before deciding to take expired medication:

• Appearance of the Medicines: The actual appearance of the medicine is very important in the decision-making process – whether to take or not. Medicines should not be taken under the following circumstances:
  • If tablets are brittle, have lost their sheen or have become discolored
  • If an injectable becomes cloudy or a precipitate forms
  • In expired ophthalmic solutions, the drug itself does not degrade, but the preservative degrades, thereby encouraging microbial growth. So, if the solution becomes cloudy (indicating microbial growth), it should be immediately discarded
• Length of Time From Manufacture: The lesser the time between the date of manufacture and time of final use, the better will be the potency of the medication
• Storage Conditions: If the medicines are stored properly in a cool and dry place, and kept unopened, the stability of the medicines will be higher
• Package Type: The type of package will also determine the stability and longevity of the medicines. In this regard, an air-tight strip of tablets or capsules will be far superior to an opened screw-cap container
• Formulation: The formulation is a critical factor in the stability of the drug. Generally, liquid formulations are less stable than solid formulations

Expired Medicines – To Take or Not to Take?

So, what should be the ‘bottom line’ or ‘take home’ message? From the foregoing discussion, it is evident that expired medicines are, by and large, not harmful and retain their potency close to 90 percent of the original potency at the time of manufacture. Therefore, under normal circumstances, i.e. for mundane symptoms such as headaches, muscle pain, sprains, stomach cramps, constipation and others, expired medicines may be taken as none of these conditions are life-threatening. However, for conditions on which your life is at stake, and for which 100 percent potency is desirable, it is best to go for new medicines and discard the expired ones. After all, “It’s better to be safe than sorry”.

 
References:

1. Sandford-Smith J. Outdated Drugs May be Useful.  Br Med J. 2003; 326(7379): 51.
2. Simons FE, Gu X, Simons KJ. Outdated EpiPen and EpiPen Jr Autoinjectors: Past Their Prime? J Allergy Clin Immunol. 2000; 105(5): 1025-30.
3. Cantrell L, Suchard JR, Wu A, Gerona RR. Stability of Active Ingredients in Long-expired Prescription Medications. Arch Intern Med. 2012; 172(21): 1685-7.
4. Courtney B, Easton J, Inglesby TV, SooHoo C. Maximizing State and Local Medical Countermeasure Stockpile Investments Through the Shelf-Life Extension Program. Biosecur Bioterror. 2009; 7(1): 101-7.
5. Lyon RC, Taylor JS, Porter DA, Prasanna HR, Hussain AS. Stability Profiles of Drug Products Extended Beyond Labeled Expiration Dates. J Pharm Sci. 2006; 95(7): 1549-60.
6. Khan SR, Kona R, Faustino PJ, Gupta A, Taylor JS, Porter DA, Khan M. United States Food and Drug Administration and Department of Defense Shelf-Life Extension Program of Pharmaceutical Products: Progress and Promise. J Pharm Sci. 2014; 103(5): 1331-6.
7. Frimpter GW, Timpanelli AE, Eisenmenger WJ, Stein HS, Ehrlich LI. Reversible “Fanconi syndrome” caused by degraded tetracycline. JAMA. 1963; 184(2): 111-3.

 

Source-Medindia