Anti-virals Flashcards
what do viruses lack? what does it have? what does it need to replicate? DNA or RNA?
cell wall and cell membrane
nucleic acids surrounded by protein capsid
viruses require host to replicate
can be DNA or RNA and single or double stranded
what few viral infxns can we tx w/drugs?
few URI viruses including influenza and RSV herpes CMV HIV HBV, HCV
flu ssxs?
fever myalgia, h/a, malaise, non-productive cough, sore throat, myalgias
genetic material of flu? what family? what types?
single stranded RNA virus
orthomyxoviridae family
types A, B, C (type A subtypes determined by hemagglutinin and neuroaminidase)
most common type of flu? which one assoc w/sporadic outbreaks? which one rarely seen?
type A: regular seasonal outbreaks, all age groups affected
type B: sporadic outbreaks, less common
type C: rarely in humans, not associated w/epidemics
two classes of meds that can treat flu?
adamantanes
neuraminidase inhibitors
characteristics of adamantanes?
amantadine, rimantadine
activity against only influenza A virus
no longer recommended for tx b/c of such high rates of resistance!!
also used for tx of parkinson’s
characteristics of neuraminidase inhibitors?
oseltamivir, zanamivir
activity against influenza A and B
doesn’t allow it to bind to cell membrane so can’t replicate
MOA of oseltamivir and zanamivir?
block active site of neuraminidase
reduce amount of viral particles released from infected cells
decrease shedding of flu A and B viruses
treatment efficacy of neuraminidase inhibitors?
reduces duration of uncomplicated flu A and B illnesses
BUT greatest benefit seen when started w/in 48 hrs of illness onset
reduction in viral shedding, fever, illness
may reduce complications, death and shorten duration of hospitalization
shortens sxs by 1 or 2 days
when would you begin early tx (w/in 48 hrs of onset)?
any w/suspected or proven flu whom:
is hospitalized
has severe, complicated or progressive illness
is at higher risk for complications (less than 2, PG, chronic med conditions, residents in nursing homes, elders, those w/AI or immunocompromised)
which of the neuraminidase inhibitors is used more often in clinical practice?
oseltamivir: 75 mg PO BID x 5 d
is chemoprophylaxis recommended? what is chemoprophylaxis?
NO b/c of increased resistance
includes post-exposure prophylaxis: treat for 7 d after last known exposure
metabolism and excretion of oseltamivir? route of administration? ADRs? recommended when?
metabolism: hepatic
excretion: renal
route: oral tablet, suspension
ADRs: n/v, transient neuropsychiatric events, limited data in children
preferred in PG!
recommended for severe or complicated illnesses
metabolism and excretion of zanamivir? route of administration? ADRs? not recommended when?
metabolism: not metabolized, minimally absorbed
excretion: renal
route: orally inhaled powder
ADRs: nausea, diarrhea, h/a, cough, bronchospasm in ppl w/pulmonary dz (not recommended in them)
route of administration of peramivir?
1 time 600 mg IV infusion over 15-30 min
which herpes viruses do we care most about treating?
HSV 1 (herpes labialis) HSV 2 (genital herpes) HSV 4 (varicella zoster virus: chicken pox and shingles)
3 main oral nucleoside analogs used to tx herpes?
acyclovir/zovirax
famciclovir/famvir
valacyclovir/valtrex (converted to acyclovir after oral administration, better bioavailability)
MOA of acyclovir? indications?
guanosine analog that is incorporated into the virus DNA and inhibits further viral synthesis
indications: HSV 1, HSV 2, less potent for VZV
when does acyclovir/zovirax work? route of administration? bioavailability? other characteristics?
only works against viruses that are actively replicating and ineffective against latent viruses
available PO, IV and topical ointment
low bioavailability
can cross BBB and thus tx herpes meningitis and encephalitis
resistance is increasing
clinical uses of acyclovir/zovirax? SEs? dose?
clinical uses: HSV 2, HSV 1 (modestly beneficial), varicella (need higher doses)
SEs: h/a, n/v, renal toxicity (need proper hydration), CNS effects, skin irritation
dosing: 200 mg 5x/d or 400 mg TID x 7-10 d
most common hepatitis viruses?
HAV
HBV
HEV
how is each hepatitis virus transmitted?
HAV: feces/oral HBV: blood/bodily fluids HCV: blood/bodily fluids HDV: blood/bodily fluids HEV: feces
which two viral hepatitis cause chronic infxn and therefore we can treat w/anti-virals?
HBV, HCV
acute viral hepatitis ssxs?
malaise fatigue nausea anorexia arthralgias low grade fever (?) ALT/AST over 500-1000 U/L