Infectious Diseases I

Agent

Influenza

Activity

Bioavailability

Half-life

(hr)

Treatment

Dosage

Adverse

Effects

Comments

Zanamivir

Neuraminidase

inhibitor;

A and B

Inhaled: Up to

17%

2.5–5

10 mg twice a

day for 5 daysa

Allergic

reactions,

diarrhea,

nausea,

headache,

dizziness

Not

recommended

in patients

with chronic

lung disease

or severe

influenza;

not available

for delivery

through

mechanical

ventilator

circuit

because of

bronchospasm

Baloxavir

marboxil

Polymerase

acidic

endonuclease

inhibitor; A

and B

Tablet, oral:

Prodrug con-

verted almost

completely

to active

baloxavir;

bioavailability

not formally

established

79%

(53%–96%);

primary

hepatic

metabolism

(80% of

dose)

Weight 40–79.9

kg: 40 mg orally

once; weight ≥

80 kg: 80 mg

orally once

Generally

minimal (< 5%

of patients):

Diarrhea,

bronchitis,

nausea,

sinusitis,

headache

93% protein

binding;

limited data for

hospitalized

patients with

severe influenza

Amantadine

Adamantane;

A only

70%–100%

15–17

100 mg twice

a day

Nausea,

dizziness,

insomnia,

lower seizure

threshold,

anticholinergic

effects

High resistance

to current

influenza A

strains

Rimantadine

Adamantane;

A only

> 90%

24–35

100 mg twice

a day

Dizziness,

nausea,

vomiting;

anticholinergic

effects

High resistance

to current

influenza

A strains;

limited market

availability

aLonger durations of up to 14 days may be needed for severely ill patients.

IV = intravenous(ly); NG = nasogastric; OG = orogastric.

symptoms of infection. Development of oseltamivir resistance during therapy has been reported, but

this is rare. If suggested through local surveillance, therapy should be switched to zanamivir by the

appropriate administration route. Improvement in infectious and noninfectious complications may be

delayed, despite resolution of primary influenza infection. ARDS, in particular, may persist for days

beyond primary influenza.