Many medical myths should be debunked, say experts

December 11, 2006
Heidi Belden, PharmD

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 vancomycin, 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.

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. "This is one of our most cherished tenets," she told the audience. But only a handful of patients with COPD have been documented as having acute bronchospasm induced byº any beta- blocker. In fact, more recent journal articles have actually shown beta-blockers to benefit patients with COPD. In 2002, in an article published in Annals of Internal Medicine, the authors concluded that patients with COPD are generally at greater risk for ischemic heart disease and therefore may benefit more from the use of beta-blockers.

"COPD patients may actually need beta-blockers more than the average Joe," said Brackett. "But we still under use them because we're afraid of bronchospasm." Brackett went on to explain that the most recent guidelines established by the American College of Cardiology and the American Heart Association suggest that beta-blocker therapy after acute myocardial infarction is appropriate for many patients with COPD or other relative contraindications.

What is the proper form of vitamin K to use in patients requiring reversal of anticoagulation? Is it intravenous (IV), oral (PO), or subcutaneous (SC)? According to a presentation given by Thomas G. Vondracek, Pharm.D., BCPS, that depends. The preferred route is oral, except in cases of serious bleeding with elevated international normalized ratios (INRs) or when reversal is needed in less than 12 hours. Subcutaneous vitamin K is only for very limited situations, he said.

"Some tweaking has occurred over the years and the recommendations for management of a nontherapeutic INR have changed from IV to SC to PO," said Vondracek, a clinical specialist at Exempla Saint Joseph Hospital in Denver. In 1992, IV vitamin K was recommended for all categories. By 2004, IV had become the therapy of choice for bleeding. And still today, the same recommendations hold true: IV is the therapy of choice for bleeding, and higher-dose PO is recommended for urgent surgery and for those with INR > 9.

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