How Drug Expiry Dates are Created, Explained for Students in Drug Safety Courses

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When a manufacturer stamps a medication bottle with an expiration date, this date reflects the period of time the drug is known by the manufacturer to be stable. The stability refers to the length of time the drug should retain its quality, potency, and purity when stored in recommended conditions and in its original packaging. 

To understand more about how Health Canada works with drug manufacturers to regulate the expiration dates of medications in Canada, and shed some light on some new thinking on the accuracy of these dates, let’s examine the issue more closely. 

Drug Expiration as Governed Under Canadian Law

Those taking pharma courses should know that all manufacturing and distribution of dosage drugs and medications in Canada is regulated by the government. According to Health Canada, an expiration date of a drug in dosage form should represent the last date a drug has been deemed to maintain its labelled potency, purity, and physical characteristics. 

Health Canada specifies that the date should be expressed at a minimum as a year and a month. The maximum tends to reach the two to three-year limit on the majority of dosage drugs.

How the Potency and Purity of the Drug Is Determined

With the potency and the purity of the drug dictating the assumed expiration date, it’s important for anyone taking drug safety courses to understand the process for determining these characteristics. Health Canada works together with drug manufacturers to ensure that quality control best practices are adhered to in an effort to maintain the safety and efficacy of all products released to the public.

Drug manufacturers must meet basic quality control requirements detailing, among other things, the proven potency and purity of the drug in question. Some quality control requirements that must be met include:

  • Ensuring the right environment, trained personnel, and approved procedures are maintained for sampling raw materials
  • Validation of testing methods
  • Keeping records to show that all sampling, testing, and inspecting requirements were met
  • Ensuring finished products contain active ingredients that comply with the qualitative and quantitative composition stated in the marketing or clinical trial authorization.
  • Ensuring the finished product is of the required purity, and correctly labelled to include the expiration date
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Drug manufacturers must conduct testing with government oversight to propose an expiration date

Manufacturers must provide stability testing under the above conditions to propose an expiration date and storage conditions for the drug in question awaiting approval. All testing should provide sufficient evidence-based data to provide Health Canada with the confidence that the drug will meet its required purity and strength for the duration of its proposed shelf-life. 

Research Over Expiration Dates Students of Drug Safety Courses Should Know About

While the Canadian health authority mandates expiration dates to comply with well-established industry requirements, researchers behind a recent study say these dates do not necessarily indicate the point at which a drug can become dangerous, and that the efficacy of some drugs may last far longer than the indicated shelf-life.

The UK-based study tested five types of drugs returned from a British Antarctic survey mission, varying from one to four years past their expiration date. The drugs included:

  • Naproxen, a commonly used NSAID painkiller
  • Bendroflumethiazide, a diuretic for hypertension treatment
  • Fucloxacillin, an antibiotic similar to penicillin
  • Atropine, used to treat pesticide or nerve agent poisoning
  • Nifedipine, a treatment to relax the heart and blood vessels for high blood pressure and chest pain

All five drugs were deemed to be theoretically as effective as fresh samples of the same medications, with tests revealing they had retained their chemical stability and active ingredient. 

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Expired drugs returned from an Antarctic survey mission were found to have retained their stability

While acknowledging that doctors should always recommend that consumers adhere to expiry recommendations, the researchers believe the findings warrant further study on the true longevity of medications. People living in remote communities are an example of those they say could benefit from more knowledge on drug stability, with doctors in those underdeveloped areas often faced with the ethical dilemma of whether to give a seriously ill person an expired drug or not treat them at all. 

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Research has revealed that many drugs may be effective long after their expiration dates are reached

Even environments with wide drug availability stand to gain from such research, as mass amounts of drugs may be getting discarded unnecessarily, with the cost ultimately passed onto the public in medical bills, taxes, and insurance.

Whether or not such research is pursued, drug expiration dates remain an important aspect of a drug’s government-mandated labelling. 

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