July 7, 2012— -- With heavy heat suffocating much of the country, physicians aren't just warning patients to keep themselves cool -- they also want patients to prevent their medications from overheating.
Temperatures above 86 degrees Fahrenheit can render some medications useless, according to Robert Glatter, MD, an emergency medicine physician at Lenox Hill Hospital in New York.
"I've noticed an increase in the number of ED visits related to mental illness in the recent heatwave," Glatter told MedPage Today, noting that most complaints have been related to anxiety or mood swings.
He said the effects could be tied to improper storage of medications in the heat, which may affect the bioavailability of the active agents in these drugs. The U.S. Pharmacopeia, a medication standards agency, states that drugs generally should be stored at room temperature -- between 68 and 77 degrees Fahrenheit -- with only brief excursions to temps as low as 59 degrees or as high as 86 degrees.
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Above or below that, there's no guarantee medications will work, the agency says.
Add to decreased efficacy the common problem of dehydration on high-heat days, and that makes for packed ED departments, Glatter said.
He said patients should be sure to keep their prescriptions with them in cool places, paying particular mind to where they're stored during travel. That means keeping medications in pockets or purses when luggage gets tossed into cargo holds that might overheat, he said.
But patients also have to be careful even when their medications are stored properly, Glatter added, since some drugs increase dehydration or interfere with the body's own cooling mechanisms.
Glatter says he's seen a "slight increase in the number of patients coming to the ED with migraine headaches who tend to get overheated," typically because the drugs they take to treat their condition prevent them from sweating.
In particular, the triptans, such as sumatriptan (Imitrex), along with other neurologic or psychiatric medications, can inhibit the body's natural cooling process by interfering with thermal control messaging between the brain and the rest of the body, according to David W. Claypool, MD, an emergency medicine physician at the Mayo Clinic in Rochester, Minn.
"Any medications that affect water intake or how our blood vessels work make patients particularly susceptible," Claypool told MedPage Today. Topping that list is blood pressure medications, especially beta-blockers like metoprolol (Toprol), which impact cooling through its effects on slowing heart rate, Glatter said.
Seizure medications and antihistamines like Claritin and Benadryl, as well as Parkinson's disease medications, also work to inhibit sweat production.
And diuretics, which sop up extra water in the body, are among the top drugs that lead to dehydration, Glatter added.
Patients on any of these medications "need to drink additional fluids and stay out of the sun as much as possible," he said.
Not even the anticipated severe storms sweeping across the Great Plains and Midwest later this week are expected to bring any relief from the heat, according to the National Weather Service.
Forecasts are calling for excessive heat for most of the nation through the weekend, with temperatures above 90 and some topping 100 expected to bear down on much of the U.S. during that time.
That's bad news for people living in areas that have already been ravaged by severe thunderstorms that have already left millions without power.
According to several reports, 18 people were killed since last weekend when excessive heat and storms churned across most of the country.
Older patients and those without access to resources such as air conditioning are at greatest risk of heat-induced health problems, clinicians say. These patients need to be evacuated to cooling centers or other settings that will keep them cool and hydrated.
Another important message for all patients, Glatter said: "Don't just drink water when you're thirsty. At that point, you're already behind" and at risk of serious complications of dehydration.