Shelf-life is an important criterion for all products whose properties change with time. It depends on a number of factors :
ype and integrity of packaging.
Storage conditions (open or close shelves, use of dust covers, cleanliness of area, access to insects, frequency of handling etc.)
Atmospheric conditions (temperature, humidity)
Time related physicochemical changes in the product.
For sterile drugs or medical devices two properties are of prime considerations sterility and integrity of the product.
For radiation sterilization, drugs and devices are prepacked in hermetically sealed, durable packages that are impermeable to microorganisms, and thus are not subjected to post-process contamination through handling. Then, from the sterility point of view, pre-packed, radiation sterilized items have long shelf-life, literally indefinite, provided the package is unopened or undamaged. Shelf-life dating, solely for the purpose of assuring package integrity and sterility, would appear to be redundant. But there may be a need for shelf-life or expiration date if the drug or a component of the device can deteriorate with time, e.g., loss in potency of the drug, increasing discolouration or stickiness of soft PVC devices, decrease in physical strength of PP devices, loss of power in a battery in a pacemaker, etc.
Pharmaceutical preparations like antibiotics, their ointments etc. are given a shelf-life reckoned from the date of manufacture of the formulation. The shelf-life varies from product to product depending on its stability and formulation matrix; for example 3 to 5 years for sterile powders of antibiotics, and 2 years for ophthalmic ointments.
Similarly, for sterile disposable medical products, it is desirable to fix a shelf-life and mention it on the package along with the following information commonly given :
Sterility guaranteed so long as the package is unopened or undamaged.
Date of manufacture
Date of sterilization
The information on shelf-life helps in stock rotation.
In France “the maximum duration of the storage period is two years running from the sterilization date”. In India the shelf-life is two years (reckoned from the date of sterilization) for kits containing cellullosic dressings, and three years for polyethylene drapes.