Limit potential dangers by restricting problem drugs on formulary
Are metformin, tramadol, and others worth keeping on the list?
Here’s another way to protect patients and save money: Clean up your formulary of "dangerous" drugs. That’s what the Fairview Health System in Minneapolis did, eliminating five drugs from the hospital formulary and putting restrictions on several others. It was all part of an effort by the hospital to reduce adverse drug reactions and medication errors.
What is a dangerous drug? The answer, Drug Utilization Review found, really depends on what institution you’re talking about. Danger, when it comes to drug products, goes beyond intrinsic toxicity. There are "systems" issues to consider with some drugs. For example, can a hospital ensure that food or milk will be available for elderly patients taking anti-inflammatories? If not, stomach bleeding is a risk. Can the hospital ensure careful blood glucose monitoring for a patient taking an extended-release sulfonylurea? If not, the patient is at risk of developing hypoglycemia.
Thus, a dangerous drug isn’t always easily defined. Take metformin. Fairview has concluded that the new antidiabetic is too risky for hospitalized patients. Metformin failed to make the cut because, says assistant director of pharmacy Steven Miesel, PharmD, no fail-safe mechanism existed to screen out patients at risk of developing lactic acidosis from its use. At-risk patients include those with renal dysfunction, those undergoing radiographic tests with contrast agents, and hypoxic patients.
"With patients as sick as they are, it’s an unpredictable risk. Patients could become hypoxic with pneumonia," Miesel says. "You just never know what a patient will need during the course of a hospital stay contrast media studies, for example."
Miesel agrees that banning metformin is an unusual formulary position, but he says the drug’s benefits just don’t measure up during a short hospital stay. It’s far safer, he says, to give sliding-scale insulin.
Metformin can be safe if monitored
Other hospitals don’t share Fairview’s take on metformin. At the Chambersburg (PA) Hospital, Evans Prieston, PharmD, assistant director of clinical services, says it’s mostly outpatients who undergo radiographic procedures, and the pharmacy has helped implement a warning system for X-ray candidates on metformin. The radiographic checkoff sheet now includes a metformin alert, and signs posted in each X-ray examining room warn patients and technicians of the danger of lactic acidosis from combining metformin and an intravenous contrast agent.
Regarding inpatients, Prieston says the hospital doesn’t use much metformin but keeps it on the formulary for patients who are admitted on the drug. Additionally, the pharmacy’s computer system has been programmed to flag metformin use in the renally impaired.
A similar checkoff sheet keeps X-ray patients safe at The Medical College of Georgia in Augusta. Rusty May, PharmD, associate director of pharmacy, says the institution has had good experiences using metformin.
The antihistamine terfenadine is one common "dangerous" formulary deletion these days. The Food and Drug Administration recently proposed to withdraw terfenadine’s approval because of a long history of problematic and potentially deadly drug interactions involving certain antifungals and macrolide antibiotics. Chambersburg and Fairview didn’t wait for the FDA, however; both banned the drug months ago and replaced it with loratadine. In the meantime, Fairview also eliminated the antihistamine astemizole from the formulary because of its similarity to terfenadine.
Oral ketorolac, a non-steroidal anti-inflammatory (NSAID), is another drug that failed to find a place in many hospital pain-killing arsenals for various reasons. At Chambersburg, it was cost. At Fairview, it was safety. "The parenteral (ketorolac) has a very important niche," says Miesel. "But the PO version is the riskiest of all the NSAIDs for causing gastrointestinal bleeding. There’s no other IV choice, but on a PO basis there are plenty to choose from."
The intramuscular (IM) version of ketorolac also found a home on the Medical College formulary, but May says fear of side effects kept ketorolac tablets out of the hospital. IM ketorolac may have some serious compe-tition soon, if the results of an Italian study are true. Investigators in Rome found a new oral formulation of diclofenac diclofenac dispersible relieved pain better and faster than IM ketorolac.
Tramadol did not measure up
Miesel says the niche for another drug quickly faded after it was introduced. Its manufacturer billed tramadol (Ultram) as a non-addicting painkiller as effective as a strong narcotic. For Fairview, the important niche tramadol was supposed to occupy that is, a strong painkiller without addictive risk began to fade once the FDA informed prescribers the drug carried a risk of seizures and chemical dependency.
Tramadol never found a niche at the Medical College. "We evaluated it, and it just didn’t look that impressive," May says. Sales representatives sampled the product heavily at the hospital, and some physicians were disappointed the drug didn’t make it onto the formulary, he says, but the pharmacy thought the drug’s potential problems outweighed its benefits.
Humalog the ultra-rapid onset insulin product while not banned at Fairview, is carefully controlled. "We took the position to restrict Humalog to only those patients who can self-administer," Miesel says. That way, if dietary is late delivering a tray of food, the patient can hold off on an injection. Plus, it decreases confusion for the nursing staff over who’s on regular insulin and who’s on rapid onset.
One place hospitals want rapid onset and more importantly, rapid clearance is in the choice of a sleeping medication. "Flurazepam has seen its day," Miesel says of the veteran benzodiazepine. The problem with flurazepam was, of course, its long half-life a persistence that caused some patients to fall and hurt themselves when getting up from bed. Fairview has switched to temazepam, a benzodiazepine that induces sleep without a morning-after hangover.
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