Antivirals Flashcards
how viruses work?
- Attach
- enter
- uncoat
- synth proteins
- synth nucleic acids
- package and assembly
- viral release
Basic concepts
- viruses are intracellular
- depend on host machinery
antivirals do 3 things: only on active replicators
1. block entry into cell
2. block exit from cell
3. interfere with virus specific proteins once translated in cytosol
DO NOT HAVE ANY EFFECT ON VIRUSES IN LATENT STATE
agents specific to certain viruses or viral classes
Viruses currently tx
- Herpes
- Hepatitis B&C
- HPV
- influenza A&B
- RSV
- HIV
Herpes virus
DNA enveloped virus
six types:
1. herpes simplex virus 1
2. herpes simplex virus 2
3. varicella-zoster virus
4. cytomegalovirus
5. epstein barr virus
6. human herpes virus 8- HIV
Herpes antivirals:
anti hsv and vzv
* Valacyclovir
* penciclovir
* acyclovir
* famciclovir
* trifluridine
anti-cmv
* Ganciclovir
* Valganciclovir
* Foscarnet
* Cidofovir
interact with protein synth
Acyclovir
zovirax
synthetic quanosine analogue which leads to terminaiton of viral replication
Activity: HSV1, HSV2, VZV
low bioavailability
can take with food but give frequently bc of short half life=5x daily=low pt compliance
renal adjustment
monitor pts on zidocudine (hiv meds) and acyclovir-> increase somnolence and lethargy
Acyclovir activation and Clinical uses
activation: must have active infection-> viral thymidine kinase requried-> leads to chain termination by competing in dna polymerase
Uses:
* primary genital herpes
* secondary tx for genital herpes
* suppression therapy
* primary oral herpes
* shingles
white plaques w/ erythematous base, herpetic gingiiostomatatis
IV- serious
Topical-initial type 2 infection- not curative but may help with symptoms->prevention of recurrence during pregnancy @ 36 wks gestation
IV acyclovir clinical uses
almost only one thats IV
- herpes simplex encephalitis
- neonatal hsv infxn
- serious hsv or vzv in immunocomp host
Caution:
reversible renal toxicity
neurologic effects-> seizures
need adequate hydration
other anti hsv agents
Valacyclovir- more bioavail, SE: NVRash, suppressive therapy in pregnant woman
Famciclovir- good bioavail and expensive
Penciclovir cream- only topically
Trifluridine- used topically by opthalmologists
TX of varicella or cutaneous zoster
get picture
Tx decreases:
* total # of lesions
* duration of sxs
* viral shedding
* risk of post herpetic neuralgia
w/in 24 hours of rash (varicella-chkn pox) onset or 72 for cutaneous zoster
Cytomegalovirus
common virus infects all age groups
infants and HIV- vulnerable
over half of adults by age 40 have been infected- w/out sxs
Congenital cmv- 1 out of 200 born with it
* 15% develop progressive hearing loss
Transmission: person to person-> kissing, intimate contact, vertical transmission-mother child, blood transfusions, stem cell transplantation
Anti CMV AGENTS
-
Ganciclovir- older used IV for CMV- also for CMV volitis, esophagitis, pneumonitis
* SE: myelosuppresion and peripheral nueropahty - Valganciclovir- great oral bioavail- prophyl for transplant or AIDS pt
- Foscarnet- poor bioavail- used for cmv and acyclovir resistant HSV
* electrolyte abnormalities, renal impairment - Cidofovir- IV for CMV retinitis
* renal impairment, uveitis
Anogenital warts
Condyloma acuminatam
caused by HPV types 6 or 11, 16 or 18 are occasional
Goal: remove wart and ameliorate sxs
patient applied tx:
1.Imiquimod cream-> stim interferon
2.Sinecatechins-> upreg apop genes
Provider administration:
1. Cryotherapy with liquid nitrogen
2. Surgical removal
Hepatitis A
Vaccine preventable liver infxn
* stool and blood of infected
* very contagious by fecal/oral or person to person
* SXS: fatigue, nausea, vomiting, anorexia, stomach pain, then jaundice
* Not usually long lasting over a few months and self limiting
VACCINE VACCINE VACCINE- Hepatitis A virus ag 25 units/0.5 ml, inactivated
Ig vacc= for short term prevention
Hepatitis B
DNA virus infects hepatocytes
DX of acute HBV infxn= HBsAG and antiHBc
DX of chronic HBV= persistence of HBsAG for greater than 6 months
Goal of therapy: NOT CURABLE, suppress hbv replication to prevent progression to CIRRHOSIS AND HEPATOCELLULAR CARCINOMA or prevent reactivaiton
Cirrhosis
Hepatocellular injury-> fibrosis and regenerative nodules
Causes: Chronic viral hep, alcohol, drug toxicity, non alcoholic fatty liver disease
End stage chronic liver disease
SXS: ascites, jaundice, variceal hemorrhage, hepatic encephalopathy- altered mental status
Hepatocellular carcinoma
another progressionof Hep B
When should we treate Hepatitis B?
Active HBV + altered liver function +/- cirrhosis
Pharmacologic therapy for Hep B
1.immune mediating-Pegylated interferon alpha
2.Antiviral agents- BBW for lactic acidosis= preferred agents due to barrier of resistance
* entecavir, tenofovir, diprovoxil