This week, the US Centers for Disease Control and Prevention (CDC) issued interim guidance to physicians to prioritize treatment of the flu in high-risk patients after receiving numerous anecdotal reports of shortages of the generic antiviral drug oseltamivir in some areas of the country amid a surge of respiratory illnesses.
The CDC said that oseltamivir should be prioritized for flu patients who are at the highest risk of severe disease and those who are hospitalized, using testing to determine the causative strain of the flu virus and guide treatment decisions.
Possible alternatives
In areas in which generic oseltamivir is unavailable, the Health Alert Network health advisory recommends prescribing the brand-name version, Tamiflu, if available, or oral baloxavir, inhaled zanamivir, or intravenous peramivir.
Patients derive the most benefit if the drugs are given within 2 days of symptom onset or as soon as possible for flu requiring hospitalization and to help control institutional flu outbreaks. Oseltamivir is the only antiviral indicated for hospitalized patients, the CDC said.
In areas in which generic oseltamivir is unavailable, the Health Alert Network health advisory recommends prescribing the brand-name version, Tamiflu, if available, or oral baloxavir, inhaled zanamivir, or intravenous peramivir.
"These antivirals have different formulations, routes of administration, dosing, duration of treatment, and recommendations for administration by age group," according to the guidance, which also said that baloxavir isn't recommended for pregnant women or people with impaired immune systems.
This means some alternatives may not be an option for some patients, according to David Margraf, PharmD, PhD, a pharmaceutical research scientist at the Resilient Drug Supply Project, part of the University of Minnesota's Center for Infectious Disease Research and Policy (CIDRAP), publisher of CIDRAP News.
"Each of these alternate drugs may be concerning to patients and prescribers due to increased costs and/or different safety and efficacy profiles, so there must be a different risk-to-benefit calculation for prescribing," he said.
An early flu season
In its latest FluView report, the CDC estimated that, so far this flu season, at least 13 million illnesses, 120,000 hospitalizations, and 7,300 deaths have occurred due to the flu. Flu season arrived early this fall, likely due to lower population immunity resulting from COVID-19 public health measures and flu virus interactions with other respiratory pathogens, CIDRAP Director Michael Osterholm, PhD, MPH, told Scientific American.
On Dec 2, the American Society of Health-System Pharmacists (ASHP) added some dosages of oseltamivir oral powder for suspension and capsules to its drug shortage list. Oseltamivir suspension is used in children and adults who can't swallow capsules. In areas in which the suspension is unavailable, the advisory said, clinicians can ask a pharmacist to compound one using capsules or mix the contents of the capsule with a thick, sweetened liquid such as chocolate syrup for administration.
Manufacturers Ajanta and Alembic told ASHP that they are reserving oseltamivir for their contracted customers, while Alvogen, Genentech, and Strides said they had both suspension and capsules, and Amneal, Camber, Macleod's, Teva, and Zydus didn't give a reason for the shortage. The US Food and Drug Administration hasn't listed oseltamivir in its drug shortage database, but the agency did acknowledge "localized shortages" of the drug on Dec 5.
Drug restocking date uncertain
Antiviral therapy is an important adjunct to vaccination in the prevention and control of the flu and can reduce the duration of flu symptoms and the risk of some complications, according to the advisory.
"Most people recover from influenza without serious complications or sequelae," it said. "However, influenza can be associated with serious illnesses, hospitalizations, and deaths, particularly among people at increased risk of complications such as older adults, very young children, pregnant people, and people of all ages with certain chronic medical conditions."
The CDC said that the generic oseltamivir shortage may persist in some areas as flu continues to circulate. Amneal told ASHP that it has 30-, 45-, and 75-milligram (mg) capsules on back order but can't estimate a release date, and Teva said it has 6-mg/milliliter (mL) powder for suspension in 60-mL bottles on back order and estimates a release by the end of this month.
Influenza can be associated with serious illnesses, hospitalizations, and deaths, particularly among people at increased risk of complications.
The CDC continues to recommend annual flu vaccination of people aged 6 months and older as the most important flu-fighting tool and the high-dose, recombinant, or adjuvanted vaccines for those 65 and older. "Healthcare providers should strongly encourage people who have not yet received influenza vaccination this season to get vaccinated as they can still benefit," it said.
