Magazine article Drug Topics

Many Medical Myths Should Be Debunked, Say Experts

Magazine article Drug Topics

Many Medical Myths Should Be Debunked, Say Experts

Article excerpt

Peak and trough serum levels should be measured for patients on vancomycin, right? Well, sort of. According to Sharon See, Pharm.D., BCPS, associate clinical professor at St. John's University College of Pharmacy in New York, only trough levels are necessary. And in most cases, no levels are needed at all. That was one medical myth that was exploded at the recent American College of Clinical Pharmacy (ACCP) annual meeting in St. Louis in October.

In an interesting and lively presentation entitled "Medical Myths and Clinical Controversies," speakers had only 10 minutes each to either prove their clinical controversy to be true or to debunk the myth completely. Ideas and beliefs that pharmacists have known as "truths" for years-for no reason other than "that's just the way it has been"-were put to this test, and this is what resulted.

According to see, "If a patient has normal renal function, most physicians will not get a level even if a patient is on the drug for 14 days," although some studies show that levels are a good idea when treatment continues for more than five days. For patients on high-dose vancomydn, concomitant nephrotoxic drugs, hemodialysis, or those with altered volumes of distribution (burn patients, trauma, and IV drug abusers) or rapidly changing renal function, only trough levels need to be measured. Trough levels should be taken 30 minutes before the next dose and should be four to five times the minimum inhibitory concentration (MIC), currently set at 1 mcg/ml.

For years, pharmacists have been monitoring vancomycin levels based on the belief that both ototoxicity and nephrotoxicity, two adverse effects of the drug, were linked to blood levels. Well, that's not really the case, said See. In fact, the actual incidence of ototoxicity is extremely rare, with only 53 documented cases in 30 years of use. Also, only 17 of those were patients receiving vancomycin as a monotherapy, without concomitant toxic drugs. To boot, there haven't been any controlled studies that show a correlation between vancomycin levels and ototoxicity. Even nephrotoxicity is rare, with about a 5% incidence when the antibiotic is used as a monotherapy.

Cari Brackett, Pharm.D., BCPS, clinical associate professor at Ohio State University College of Pharmacy, demystified the long-believed myth that beta-blockers should be avoided in patients with chronic airway disease. …

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