Herpes 1 and 2 & Zoster Flashcards
Discuss the MOA of Acyclovir
> Guanosine analog is monophosphorylated in the cell by the herpes virus by the enzyme thymidine thus viruses are susceptibility
Monophosphate analog are converted to di- and tri- phosphate form by the host cell kinase
Acyclovir triphosphate competes with deoxyguanosine as a substrate for dna polymerase and when it is incorporated in the viral dna it causes premature termination of dna synthesis
Discuss the pharmacokinetics of acyclovir
> Can administered orally ,iv and topically
excreted by urine
good penetration into CNS by IV
discuss Valacyclovir
*Prodrug of acyclovir
*Undergoes first order metabolism in intestines’ / liver
> better absorption orally Particularly useful in herpes zoster
Same MOA as Acyclovir
T/F : There is no treatment for HVB
t, treatment is used to reduce viral replication to cirrohosis / cancer ,thus treatment must be taken for life
List the drugs used herpitis B
> Tenofovir(adenosine analog) ,lamivudine(cytosine analog) and Entecavir (guanine analog)
tenofovir is usually administered with lamivudine
Treatment is required if VL> 2000 copies per ml / abnormal liver enzymes
1 pill a day
What is the difference between HVB and HVC
> B is a dsDNA and C is a ssRNA
B transmission is usually from MTC and sexually especially between MSM and C is usually by shared needles and can also be sexually transmitted
How is Chronic hepatitis C treated
by directly acting drugs
Discuss the 3 directly acting drug classes
Class 1 : Protease inhibitors previr drugs
*High potency but low barrier to resistance and limited genotype coverage
class 2 : Replication complex inhibitor : asvir drugs *high potency but low barrier to resistance and multigenotypic
Class 3 : Nucleoside/Nucleotide inhibitors : buvir drugs
*Intermediate potency but high barrier to resistance and pan genotypic
Directly Active Antiretroviral uses
- Used as a combination therapy
* choice depends on genotypic degree of liver damage and presence renal impairment
