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Potency of medications affected by extreme temperatures

July 25, 2014

SPRINGFIELD - You wouldn’t intentionally leave a candy bar behind in a hot car to melt.

Here’s something else to consider keeping out of the summer heat – your medications, whether prescription or over-the-counter.

Whether in the high heat or freezing cold, extreme temperatures can physically change your medications and affect their potency, which can jeopardize your health,” said Mark Heelon, Pharm.D., who serves as medication safety coordinator for Baystate Health.

According to Heelon, one of the standards established by the U.S. Pharmacopeial Convention is to keep medications stored at room temperature, which is defined as between 68 to 77 degrees F. However, most pharmacists will agree that they are still safe between 58 to 86 degrees F.

“Never leave medications in a very hot or cold car, even briefly, and don’t keep them in luggage stored in the trunk,” said Heelon.

It’s best to keep all medicines with you in an air-conditioned car. If stopping for lunch, bring the medications into the restaurant. Also, consider a cool pack for medications such as insulin.

“If traveling by air, don’t pack your medications in your suitcase, instead, placing them in your carry-on luggage. Extreme temperatures when the plane reaches high altitudes could potentially impact their efficacy,” said Heelon.

Moisture can also impact the potency of medications, which should be kept out of the medicine cabinet in the bathroom and in a cool, dry place.

“Medications also don’t tolerate sunlight very well and can lost their potency if

stored on a windowsill, for example. Other areas you should avoid include placing you medications on top of electronic equipment which can often get warm,” said Heelon.

So, what’s all the fuss about?

If you have heart disease or diabetes, the insulin you take to control high blood sugars, and the nitroglycerin you take for heart disease, in particular, to treat symptoms of angina, can be rendered less effective if damaged by temperature,” said Heelon.

Thyroid, birth control and other medications that contain hormones are also especially susceptible to changes in temperature, as are lorazepam and diazepam, and even albuterol inhalers.

Heelon also cautioned about the damage that can be done to many diagnostic test strips, such as those used to monitor blood glucose, which are extremely sensitive to humidity resulting in inaccurate readings.

“The less talked about impact of medications that are improperly stored and their potential to lose potency is that infections may not be cleared up and disease may linger longer if antibiotics are involved. And, serious systemic infections can lead to hospitalization,” said Gary Kerr, chief pharmacy officer, Baystate Health.

He noted that more rarely the medication can be changed to a toxic byproduct that could injure the human body, such as the breakdown products of tetracycline, a broad spectrum antibiotic, which can result in Fanconi syndrome, a form of renal failure. Also, warm, muggy environments can result in aspirin tablets breaking down into acetic acid (vinegar) and salicylic acid, which can irritate the stomach.

Also, those living with no air conditioning in hot areas should consider storing their medications in the refrigerator. However, there are some medications, especially in liquid form, which may not be recommended for storage in the refrigerator.

“As always, check the label for storage directions or call your pharmacist if in doubt. And, be sure to always ask your pharmacist when picking up new medicines about the best way to store them, and also ask about other medications you may have at home that you are unsure about,” said Heelon.

Yet something else to consider when storing your medications – what to do when the power goes out. Some injectable medications, as well as others, which may need to be stored in the refrigerator, may have a short window of time before the warmth renders them unusable.

When it comes to sweltering temperatures and frigid weather, there are additional considerations for mail-order prescriptions, although the hot weather is often more of a concern than the cold.

It’s a good idea to consider having your medications overnighted with a signature required. Still more to consider – how long the package has been sitting in a

non-climate controlled delivery truck, as well as in your mailbox, especially if you are away from home for a couple of days or more.

Discard pills that are stuck together and “runny,” harder or softer than normal, changed in color, or that have a distinctly different odor when opening the bottle. However, it’s important to remember that even though your medication may look normal, it still could have been compromised in the extreme temperatures.

While not related to the cold or heat, many pharmacists will also tell you to keep all medications in their original containers.

“Mixing medications in different containers can be problematic because so many medications look similar, yet each work very differently and are used for specific diseases or symptoms,” said Kerr, who noted pill boxes/organizers are a different story.

“Pill boxes remain a very effective method of storing medications so that days, times of day, and other dose instructions are followed exactly as directed by the physician. They also have been proven to improve compliance and help patients to not forget their doses,” said Kerr.