Acyclovir vs Ganciclovir - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-14-2010
b.abid's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS+3
Posts: 167
Threads: 56
Thanked 90 Times in 43 Posts
Reputation: 100
Drug Acyclovir vs Ganciclovir

While I was reading about Antiviral therapy, I noticed a difference between FA and Microbiology MRS ...

In FA, it is said that Ganciclovir is monophoshorylated by HSV\VZV thymidine kinase and then bi and tri phosphorylated by the cellular kinases so that it has a preferential action against viruses since our cells don't have this thymidine Kinase ..

Now in MRS, it is said that Ganciclovir does not need the viral thymidine kinase to be monophosphorylated and can be mono, bi and triphosphorylted by the cellular enzymes

I think MRS makes more since on this since it explains why Ganciclovir is more toxic to the kidneys and the bone marrow than Acyclovir, which needs the viral Kinases for sure

So what do you guys think??

P.S. I am studying from MRS 2004 edition and FA 2008 edition
Reply With Quote Quick reply to this message



  #2  
Old 08-14-2010
USMLE Forums Guru
 
Steps History: 1 + CK
Posts: 373
Threads: 30
Thanked 375 Times in 160 Posts
Reputation: 385
Correct Answer

Quote:
Originally Posted by b.abid View Post
While I was reading about Antiviral therapy, I noticed a difference between FA and Microbiology MRS ...

In FA, it is said that Ganciclovir is monophoshorylated by HSV\VZV thymidine kinase and then bi and tri phosphorylated by the cellular kinases so that it has a preferential action against viruses since our cells don't have this thymidine Kinase ..

Now in MRS, it is said that Ganciclovir does not need the viral thymidine kinase to be monophosphorylated and can be mono, bi and triphosphorylted by the cellular enzymes

I think MRS makes more since on this since it explains why Ganciclovir is more toxic to the kidneys and the bone marrow than Acyclovir, which needs the viral Kinases for sure

So what do you guys think??

P.S. I am studying from MRS 2004 edition and FA 2008 edition
Both Acyclovir & Ganciclovir are Guanosine analogs (nucleosides) so would require conversion to the triphosphate form to be effective.

For Ganciclovir, first phosphorylation is viral specific & requires TK in
HSV & a phosphotransferase (ul97) in CMV.


*Source. Kaplan lecture notes Pharmacology 2009.

If u still have any doubts google "UL97 mutation & Ganciclovir resistance" u well get ur answer
Reply With Quote Quick reply to this message
  #3  
Old 08-14-2010
b.abid's Avatar
USMLE Forums Addict
 
Steps History: 1+CK+CS+3
Posts: 167
Threads: 56
Thanked 90 Times in 43 Posts
Reputation: 100
Default

Thank you

So I guess this has to be corrected in MRS
Reply With Quote Quick reply to this message



Reply

Tags
Microbiology-, Pharmacology-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)