Extreme temperatures have the potential to alter the effectiveness of medications. Drugs should not be stored in areas where the temperature may exceed 86 degrees or drop below 58 degrees. Both prescription and over-the-counter medications are at risk for loss of potency and changes in chemical structure if not stored properly. Besides temperature extremes, other conditions can alter medications such as moisture, light, and time.
Most medications degrade slowly and lose potency over months to years but do not become harmful, but there are a few medications that can cause harm once they begin to degrade. An example is the tetracycline family. The tetracycline family of medications may cause kidney damage due to a change in their chemical structure. Nitroglycerin becomes inactive when heated. Liquid medications such as antibiotics degrade fairly rapidly usually within one to two weeks depending on the drug. Insulin is a protein and can be altered by both heat and cold. Insulin can also be altered by bacterial growth that breaks down the protein making the drug ineffective. Different types of insulin vary in the time degradation occurs. Insulin contained in pen cartridges breaks down sooner than those in vials. Consultation with a pharmacist about storage and expiration dates is important due to the many available forms of insulin. The protection of diabetic patients’ insulin supply is important to their health and well-being.
Moisture can decrease the effectiveness of drugs. An example is aspirin. Aspirin breaks down even in low moisture environments; therefore, care should be taken to store aspirin in dry, temperature-controlled areas. Do not use tablets or capsules that are adhered to each other or have changed in color or texture. Areas that are not ideal for storing medications include the bathroom and kitchen due to moisture and heat fluctuations.
Light is another aspect of the environment that effects medications. If a medication is stored in an amber bottle, it should remain stored in the bottle to prevent degradation. UV light can change the chemical structure of sensitive medications such as potassium iodide and tinctures.
Some common signs of medication degradation are creams or ointments that are discolored or have changed in texture. Also, a cream or ointment that has cracked or become separated indicates degradation. Tablets that have broken, become chipped, changed in color, or have an unusual smell should be discarded. Aspirin has a strong vinegar smell when degraded.
Precautions should be made when traveling with medications. Medications should be stored in a purse or separate bag that can be carried to prevent degradation by exposure to hot or freezing temperatures such as in a car trunk or airline baggage compartment. For hot temperatures, a pharmacist can suggest a cool pack that would be appropriate for the specific medication being used.
To prevent water supply contamination, expired medications should not be flushed down a toilet. If a drug collection program is not available, placing the medications either in coffee grounds or cat litter before discarding should make them unpalatable to animals and children.