How is the shelf life of a medicine determined?

In order for a medicine to be approved, the manufacturer must conduct studies to find out how long the medicine can be stored and how it must be stored.
The shelf life can be as short as a few months or as long as several years.

A “specification” is created for each medicinal product. This specifies, for example, how much active ingredient may still be present in order for the medicine to retain its effect.
These studies also examine how many degradation products may be produced so that no undesirable effects occur.
In addition, there are tests that depend on the type of drug: e.g., for tablets, how quickly the active ingredient is released, or for injections/infusions, whether the sterility is given.

There are international guidelines on how such shelf-life tests should be conducted:

• Real-time studies at, for example, 25 °C and 60 % humidity.
• Accelerated studies at, for example, 40 °C and 75 % humidity (imitating “worst-case” conditions, e.g. during transport).
• Light sensitivity is also tested.

As a result of these tests, two things are determined and must be approved: the shelf life (i.e. how long the medicine is valid) and any special storage instructions. This information must be included in the package leaflet and on the packaging, along with the expiry date. If a medicine comes in a multi-dose package (e.g. oral liquid or ointment), it must be tested to determine how long it can be kept after opening/first use. In other words: not only ‘after opening’, but also ‘after first use’.  The same applies if a medicine is only ‘made ready for use ’ shortly before administration (e.g. solution or mixed infusion): in this case, a shelf life is specified for both the unopened medicine and the medicine that has already been prepared.

Storage

Unfortunately, with most medicines, it is not possible to tell whether they can still be used after incorrect storage.
In the case of solutions, for example, discolouration or the precipitation of substances may be an indication that the medicine has already been damaged — unless the package leaflet states that such a change is normal.

Three main factors can have a negative impact on shelf life:

• high temperatures
• high humidity
• light

A typical unsuitable storage location is the bathroom, where there is usually high humidity and high temperatures. A cooler room, such as the bedroom, is better. Always make sure that the medicine is  out of reach of children.

If light protection is required, this is usually provided by the outer packaging – therefore, the medicine should be stored in its original packaging. The package leaflet should also be kept with the medicine, as it contains important information on its use.

Storage at room temperature:
Most medicines can be stored at room temperature (up to 25 °C). Refrigerated storage is only  necessary if this is stated on the packaging or in the package leaflet (e.g. for vaccines or insulin).

In general, it is not recommended to store medicines in the refrigerator – this can even impair their quality. For example: active ingredients in solutions can precipitate when exposed to cold, and the consistency of ointments can change. Freezing vaccines also often destroys their active ingredients and weakens their effect.

Dry powders for antibiotic syrups  can often be stored at room temperature for long periods of time. However, once the suspension ( has been prepared, i.e. after the powder has been mixed with water, the medicine usually needs to be refrigerated and can often only be used for a few days.

Very important: Never leave medicines in the car! Especially in summer, temperatures in the car can quickly rise to over 60 °C or 70 °C. This can destroy almost any medicine. 

Storage of vaccines

Vaccines are usually provided by pharmacies. If they are not injected immediately afterwards, it is essential to adhere to the temperature specified in the product information for transport and storage.
Vaccines are sensitive to light and heat. Incorrect storage can impair their efficacy and tolerability.

When transporting vaccines, the following applies: if a cool bag is used, frozen ice packs (-20 °C) must not be placed directly on the vaccine packaging, as this could cause the vaccine to freeze.

For vaccines that do not need to be kept refrigerated at all times, the following applies: they can be transported or stored outside the refrigerator for a few hours.
Temperatures above +25 °C and direct sunlight must be strictly avoided.