Influenza Flashcards
Overview
Negative stranded, enveloped, RNA virus
May infect humans, birds, pigs, horses
Harder to transmit from person to person if animal origin but more deadly
New virus strains created by mixing of RNA segments
Prevention: vaccination, only covers A and B
Type A
Infects humans and different animals
H: hemagglutinin (1-16)
- binds to terminal sialic acid residues via glycolytic bond
N: neurominidase (1-9)
- enzyme located in viral membrane allowing detachment or release by cleaving glycolytic bonds between terminal sialic acid and sugars from infected cell
Each virus has 1 H and 1 N
Type B
only humans
Type C
mild disease
Neurominidase inhibitors
Structurally mimic sialic acid (transition state analog)
Oseltamivir activation
PRODRUG
contains 3-pentyloxy and COOC2H5 (improved oral bioavailability)
Converted by hepatic esterases to oseltamivir coboxylate
Oseltamivir spectrum
Flu A and B
Oseltamivir PK
Readily absorbed via GI tract and NG tube
Renally eliminated via glomerular filtration and tubular secretion
- dose adjust if CrCl is < 30 mL/min
- removed by dialysis/CRRT
Oseltamivir treatment regimen
≥ 2 weeks of age who have been symptomatic for NO MORE THAN 2
DAYS
Prophylaxis for ≥ 1 year of age
Oseltamivir SE
N/V/D, abdominal pain
Neuropsychiatric events–>japenese
Oseltamivir pearl
Do not administer live vaccine (intranasal) flu vaccine within 2 weeks before or 48 hours after
Oseltamivir drug interaction
probenecid–>decreases renal clearance by 50%
Oseltamivir resistance
mutation of active site of neurominidase (more in oseltamivir > zanamivir)
cannot bind after 1 mutation
Zanamivir
prodrug
INHALER
Flu A and B
Zanamivir PK
4-17% of inhaled dose systemically absorbed
- 15% in lower respiratory tract
- 85% in oropharynx
Renally excreted unchanged by kidneys
Zanamivir regimen
≥ 7 years who have been symptomatic for NO MORE THAN 2 DAYS
Prophylaxis for ≥ 5 years of age
Zanamivir
Bronchospasm
Worsening COPD
Neuropsychiatric events
Bronchitis, nasal signs/symptoms
Zanamivir pearl
Do not administer live vaccine (intranasal) flu vaccine within 2 weeks
before or 48 hours after
Do not use with asthma or COPD
