Proper storage of medicines is very important. Heat, moisture, light, dirt and breakages can harm all essential medicines making them unsuitable for use. medicines which are properly stored should be safe to use until their expiry date. Medicines which are not stored properly may not be safe to use even before their expiry date.
To ensure the stability of medicines for the period of its intended shelf life, the medicinal product must be stored under proper conditions. Stability, and therefore shelf lives of medicines are usually tested when the storage conditions are cool and dry. However, in a vast country (India) of ours with varied climatic conditions, the conditions are often hot and humid.
Shelf life of a medicine is the time period or duration in which the product will remain stable (90% of the label claim) when handled or stored under recommended conditions. The expiry date is related to storage conditions. For example, Aspirin tablets are required to store in container to prevent moisture uptake, when the shelf life is 2-3 years. On absorption of moisture, aspirin has a tendency to undergo hydrolysis to yield salicylic acid and vinegar (acetic acid). In this case we should not use the tablets.
The most commonly used medicines which are found to be unstable in hot and humid climates are Aspirin, Adrenaline, Aminophyline, Ampicillin, Chlorpromazine, Doxycycline, Erythromycin, Ferrous sulphate, Insulin etc. Medicines which are unstable can loose their therapeutic action and become toxic before their expiry date. This may occur if they are not stored properly.
In general solid dosage forms e.g. tablets and capsules are the most stable, then semisolid e.g. creams and ointments, and the least stable are liquids e.g. injections, suspensions and solutions.
STORAGE TEMPERATURES: The storage terms generally employed have the following meanings as defined by Pharmacopoeia including Indian Pharmacopoeia.
Cold – Any temperature not exceeding 80C & usually between 20C and 80C Cool – Any temperature between 80C and 250C Room Temperature – Temperature prevailing in a working area (Customarily between 80C and 300C) Warm – Any temperature between 30 and 400C Excessive Heat – Any temperature above 400C
CONDITIONS OF STORAGE AND LIFE PERIOD OF MEDICINES Protection of drugs from heat
- Open the windows to allow the air to move
- Put a layer of thatch on a metal roof
Protection of drugs from light & moisture
- Keep the lid on the container
- Use containers that protect the medicine from light
- Use dark plastic or dark glass bottles
- Use curtains to cover the windows
Proper storage conditions of medicines is an important issue. Schedule P to (Indian) Drugs and Cosmetics Rules specifies storage conditions of more than 150 various categories of medicines. Schedule P specifies the period in months (unless otherwise specified) the life of a medicine between the date of manufacture and date of expiry which the labeled potency period of medicine shall not exceed under the conditions of storage specified. The life period of a vaccine varies depending upon storage temperature. Polio vaccine’s life period is 24 months when stored at -200C, 6 months at 00C, and 3 months at 40C.