Pharm: Influenza Flashcards
What is the MOA of neuraminidase inhibitors?
Completely inhibit neuraminidase enzymes
Prevent viral reproduction by budding from host cell
Neuraminidase usually cleaves the sialic acid found on glycoproteins on human cells
What are the neuraminidase inhibitors?
oseltamivir (oral)
zanamivir (inhaled)
peramivir (IV)
When should you use oseltamivir?
Uncomplicated influenza A and B
Patients who report sx started within 48 hrs
What are the contraindications for oseltamivir?
hypersensitivity
End-stage renal dz
Suicidal thoughts, confusion, delirium
What are the warnings associated with oseltamivir?
Serious bacterial infections (may coexist with influenza infection)
Do not give live influenza vaccine (intranasal) within 2 weeks before or 48 hrs after oseltamivir is given –> interferes with vacceine effectiveness
What is the limitation of oseltamivir?
not a substitute for flu vacceine –> should continue to get annually
Can you give oseltamivir to really young or really old?
Not indicated in children younger than 2 weeks
Not given to prevent flu in children less than 1 yo
Can give to geriatric population
Can you give oseltamivir in women breastfeeding/pregnant?
Benefits may outweight risks in breastfeeding moms
No controlled data in human pregnancy, however, drug does cross placenta at high doses
Can you take oseltamivir with warfarin?
What about clopidogrel?
Warfarin: Yes
Evidence supports inhibition of activating enzyme when taking with clopidogrel, may decrease effectiveness
What is the active metabolite of oseltamivir?
Does this have an effect on CYP450 or UGT?
oseltamivir carboxylate = OC
Does not affect CYP450 or UGT enzymes
What is the indication for zanamiviruse?
influenza A or B infection within 48 hrs of sx onset
Benefits overall appear to be small (cost outweights benefits in most healthy patients)
What are contraindications for zanamivir?
Allergy to lactose or milk proteins
Brain dz
mental illness
Seizures - use with caution
Lung disease (asthma, COPD) - not recommended
What are some warnings of zanamivir?
Should not recieve live flu vacciene 2 wks before or 48 hrs after med given
Doesn’t prevent bacterial infections that present with flu-like sx
May cause SOB & bronchospasm in pts with lung dz
Can you use zanamivir in young kids or elderly?
Not recommended in kids younger than 12
Can give to elderly, however, monitor closely for side effects
Can you use zanamivir in breastfeeding/pregnant women?
Benefits may outweight risks
Relatively safe for use by pregnant and breastfeeding women
How is zanamivir eliminated from body?
almost exclusively eliminated by kidney
Not a substrate for CYP450 –> no clinically significant drug interactions
What is the indication for peramivir use?
Tx of acute uncomplicated influenza patient 18 or older who have been symptomatic for no more than 2 days
given IV (peramIVir)
What are the contraindications for peramivir?
hypersensitivity
More evidence for effectiveness against influenza type A
No efficacy established in serious flu cases requiring hospitalization
What is the most common adverse effect of peramivir?
diarrhea (>2%)
What are some warnings for peramivir?
Serious skin/hypersensitivity rxns: SJS, erythema multiforme
Neuropsychiatric events (increases risk of hallucinations, delirium and abnormal behavior)
Risk of bacterial infections
Can you use peramivir in pregnant/breastfeeding women?
Pregnancy catergoy C
No evidence available
Use in pregnant women only if clearly needed
Can you use peramivir in kids and elderly?
Dont use in those younger than 18
Not enough evidence to determine elderly response
Reduce dose in those with creatinine clearance below 50 mL/min
How is peramivir metabolised?
Not significantly metabolized in humans - major route of elimitation is kidney but 90% of drug is elimiated unchanged
Not a CYP450 substrate
What is the MOA of baloxavir?
inhibits virus mRNA replication
What are the indications for baloxavir?
given in pts 12 or older who have been symptomatic for no more than 48 hrs
What are the contraindications for baloxavir?
hypersensitivity
What are some adverse effects of baloxavir?
diarrhea
bronchitis
nasopharyngitis
HA
nausea
What are the warnings associated with baloxavir?
serious bacterial infections presenting with flu-like sx
What are the metabolic pathways of baloxavir?
Prodrug that gets almost completely converted to active metabolite
UGT1A3
CYP3A4
80% excreted in feces
rest excreted in urine
What is the MOA of amantadine?
Unknown
Inferfering with fxn of viral M2 protein?
What are the indications for amatadine?
infection with influenza A
Parkinson’s dz
What are some adverse effects of amatadine?
What are some side effects of withdrawl?
falling asleep during ADLs
Suicidality & depression
Hallucinations & psychotic behavior
Dizziness & orthostatic hypotension
Withdrawl:
Emergent hyperpyrexia & confusion
Impulse control & compulsive behaviors
What are some warnings associated with amantadine?
Deaths reported from overdose (lowest lethal dose reported was 1 gram)
Increases seizure activity in those with history
Don’t give to pts with untreated angle closure glaucoma
Suicide attempts in pts who recieved short courses for flu tx or prophylaxis
Do not discontinue abruptly in pts with Parkinson’s (abrupt mental deterioration)
Accumulates in plasma of pts with renal dz
May elevate liver enzymes
What is the half life of amantadine?
How does this change in pts with renal dz?
Mean t1/2: 10-14 hrs
Renal dysfuntion t1/2: 7-10 days!
