Conference Coverage
WASHINGTON – A single injected dose of the neuraminidase inhibitor peramivir safely alleviated flu-like symptoms in adults when administered within 48 hours of onset of illness, an analysis of phase II and phase III clinical trial data indicates.
No single-dose treatment for influenza is currently available in the United States. Approval of the investigational drug would help protect those for whom influenza poses a higher than average risk, such as the elderly, the very young, and those who have other underlying illness such as chronic obstructive pulmonary disease, according to Dr. Richard Whitley, distinguished professor of pediatrics and microbiology at the University of Alabama, Birmingham.
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A new single-dose influenza vaccine could prove hugely beneficial to those who are very young, very old, or otherwise more likely to contract the illness.
"Historically, we would have said the disease only afflicts [certain populations], but what we learned in the H1N1 pandemic was that ... we can’t ignore influenza. It’s here to stay." He made his comments during a media conference at the annual Interscience Conference on Antimicrobial Agents and Chemotherapy.
In two placebo-controlled, multicenter studies of a combined 427 adults with acute, uncomplicated influenza, peramivir 300 mg reduced flu symptoms within a median of 22 hours, and resolved fever within 24 hours, compared with placebo (both findings were significant). Symptoms included lethargy, cough, sore throat, headache, and myalgia. Though for time-to-symptom reduction, statistical significance fell away (P = .161), after adjustment for smoking behavior, influenza season, and virus type, the peramivir did significantly reduce nasal viral shedding within 48 hours following treatment, compared with placebo, Dr. Whitley reported
Results were based on patient-reported data using a four-point severity scale recorded over 14 days. Prior to injection, all patients were confirmed to have flu using rapid antigen detection testing, and none had any underlying illnesses or compromised autoimmunity. The drug was administered intramuscularly within 48 hours of onset of illness.
"If you ask me to put that into perspective with the other neuraminidase inhibitors, the level of benefit is virtually identical," said Dr. Whitley.
Currently, only two neuraminidase inhibitors are approved by the Food and Drug Administration: oral oseltamivir and inhaled zanamivir. Both are administered twice daily over 5 days.
Peramivir was determined to be generally safe, well tolerated, and with rates of adverse events such as mild to moderate diarrhea and dizziness similar in both the treatment and placebo arms. A separate study of the drug in a pediatric population is underway, said Dr. William Sheridan, chief medical officer of BioCryst, maker of peramivir.
"Influenza is associated with significant mortality and morbidity," Dr. Whitley said. In addition to annual immunization, "we need antivirals to keep people out of hospitals and to keep people from dying."
Annually, about a quarter million Americans are hospitalized with influenza, and nearly 36,000 die from it, according to the Centers for Disease Control and Prevention.
Peramivir has been approved in Japan and Korea since 2010. If approved by the FDA, it would be the first neuraminidase inhibitor approved in this country in more than a decade.
Pain and practicality
According to Dr. Sheridan, a New Drug Application to the FDA is currently under review with an assigned Prescription Drug User Fee Act action date of December 23, 2014. The indication, if approved, will be for influenza in adults. Dr. Sheridan also spoke during the media briefing.
Dr. Sheridan said that the application to the FDA is for an intravenous infusion that is the bioequivalent of the intramuscular version used in the trials because of the lack of practicality of intramuscular delivery.
"It hurts to get an intramuscular injection. In fact, it hurts a fair bit. We had to have our study subjects lay flat because if you stand up and feel faint after an injection like that, it’s probably a bad thing.
‘Real-world issues’ remain
If approved, the drug could also benefit underserved communities, the panelists agreed.
Richard Whitley, M.D.
"If you see the patient once, you’re lucky," said Dr. Whitley. "If you give him a prescription, and you expect him to get it filled, the probability of that happening is maybe 20%-25%. So, if you’re worried about that individual, direct-observed therapy in the health care provider’s office is a good way to help solve this problem."
The shelf life of the drug, according to Dr. Sheridan, is about 5 years, if stored at room temperature.
Because there is less work for the end user, including finding a drug store that has sufficient supplies of the antiviral, "this drug, from a public health perspective, sounds even better than the oral medication," said the media briefing’s host, Dr. Michael Schmidt, professor and vice chair of immunology at the Medical University of South Carolina in Charleston.