It is a legal requirement that all pharmaceutical products must carry the date of manufacture and date of expiry on their label. The period between the two dates is called the ‘life period’ or ‘shelf-life’ of the drug.
EXPIRY DATE OF PHARMACEUTICALS
It is a legal
requirement that all pharmaceutical products must carry the date of manufacture
and date of expiry on their label. The period between the two dates is called
the ‘life period’ or ‘shelf-life’ of the drug. Under specified storage
conditions, the product is expected to remain stable (retain >95% potency)
during this period. In India, the schedule P (Rule 96) of Drugs and Cosmetics
Act (1940) specifies the life period (mostly 1–5 years) of drugs and the
conditions of storage. The expiry of other medicines has to be specified by the
manufacturer, but cannot exceed 5 years, unless permitted by the licencing
authority on the basis of satisfactory stability proof.
The shelf-life of a
medicine is determined by real time stability studies or by extrapolation from
accelerated degradation studies. The expiry date does not mean that the
medicine has actually been found to lose potency or become toxic after it, but
simply that quality of the medicine is not assured beyond the expiry date, and
the manufacturer is not liable if any harm arises from the use of the product.
Infact, studies have shown that majority of solid oral dosage forms (tablets/capsules,
etc.) stored under ordinary conditions in unopened containers remained stable
for 1–5 years (some even 25 years) after the expiry date. Liquid formulations
(oral and parenteral) are less stable. Suspensions clump by freezing.
Injectable solutions may develop precipitates, become cloudy or discoloured by
prolonged storage. Adrenaline injection (in ampoules) has been found to lose
potency few months after the expiry date of 1 year (it gets oxidized).
There is hardly any
report of toxicity of expired medicines. The degradation product of only one
drug (tetracycline) has caused toxicity in man. Outdated tetracycline capsules
produced renal tubular damage resembling Fancony syndrome in the early 1960s.
The capsules have now been reformulated to minimize degradation.
Loss of potency beyond
the ‘life period’ of the formulation depends on the drug as well as the storage
conditions. High humidity and temperature accelerate degradation of many drugs.
Though, majority of medicines, especially solid oral dosage forms, remain safe
and active years after the stated expiry date, their use cannot be legally
allowed beyond this date.
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