Local health providers using caution in prescribing antiviral drugs for flu
WILLMAR — With influenza laying siege to much of the United States, local doctors are fielding dozens of requests from sick patients for antiviral drugs.
The medication might not be right for everyone, though.
Vulnerable high-risk patients are the ones who benefit the most from antiviral medication and are the best candidates to receive it, said Dr. Ken Flowe, chief medical officer at Rice Memorial Hospital and a physician in Rice’s emergency room.
“Those people need early, aggressive therapy,” he said. “A healthy, normal, middle-aged adult doesn’t necessarily benefit.”
Local health providers are turning to guidelines from the U.S. Centers for Disease Control and Prevention to help decide whether to prescribe an antiviral or not.
CDC recommendations call for using antivirals among patients at higher risk for influenza complications. These include children younger than age 2; adults 65 and older; individuals with chronic conditions such as asthma, kidney disease or diabetes; and anyone who is immune-suppressed or extremely obese.
They also include anyone 19 and older who is on long-term aspirin therapy; women who are pregnant or within two weeks after delivery; and residents of long-term care facilities.
The CDC also recommends antivirals for people whose flu gets progressively worse.
The drug most commonly prescribed is oseltamivir, more widely known by its brand name, Tamiflu. Zanamivir, or Relenza, a nasal spray, is prescribed less often. Both drugs work by inhibiting the production of neuraminidase, an enzyme that’s found on the surface of influenza viruses.
Antibiotics work against bacteria and are of little use against influenza, which is caused by a virus. They may be prescribed, however, if someone develops a bacterial infection along with flu.
Antiviral treatment seems to lessen the likelihood of flu-related complications among high-risk patients but appears to be less helpful for healthy individuals at average or low risk, Flowe said.
And although antiviral therapy can help shorten the course of influenza, it may be by only a day or two, he said. “There’s not a huge benefit.”
“It’s not a panacea,” agreed Jo DeBruycker, manager of the Health Learning Center at Affiliated Community Medical Centers.
Timing also matters. Antiviral treatment is most effective when it’s started within two days of the onset of flu symptoms, Flowe said.
Some studies that were carried out in 2009, during the H1N1 flu outbreak, found a benefit to antiviral treatment within the first five days of illness but the effectiveness was greatest at the earlier stages of flu and diminished over time, he said.
Using antivirals appropriately is one way clinicians can help ensure the drug remains available to patients who need it the most, DeBruycker said.
Reports are emerging of Tamiflu shortages in some areas, she said. “That’s beginning to be the concern.”
Flowe said he has prescribed flu antivirals to emergency-room patients “several times” already this winter. None have reported any trouble getting the prescription filled but the liquid form of Tamiflu given to children may be a little harder to find, he said. “Some pharmacies here and there are running out.”
Another key issue is the potential for resistance to develop with misuse or overuse of influenza antivirals. Ongoing monitoring by the CDC has found minimal resistance to oseltamivir and zanamivir among currently circulating strains of flu, indicating the medications are still widely effective this season. But two older A-type strains of flu, the 2009 H1N1 and H3N2 viruses, show high levels of resistance against an older class of antivirals that includes amantadine and rimantadine.
It can be difficult to tell sick patients that they may not be a good candidate for an antiviral, Flowe said. “That’s always hard. It’s a whole different mindset from a doctor-patient mindset to a public health mindset… Antiviral resistance is a real thing.”
Local providers continue to urge people to get a flu shot. The vaccine does not confer 100 percent protection but it can help lower the risk of getting flu — and those who get sick in spite of being vaccinated may have less severe illness.
“It still may temper that course,” DeBruycker said.