Supressive therapy with Valtrex

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Mary Ng - 26 Sep 2004 04:42 GMT

I know that by using Valtrex daily, it can decrease the frequency of
outbreaks down to a minimum of once a year. However, I was reading about
the product datasheet from GSK, and one interesting point that it kept
bringing up about advising patients with renal disorder that it may cause
futher kidney failure or renal complications. I also read in the Canadian
Pharmaceutical Guide about Valtrex and the same caution appeared. Now, I am
wondering whether Valtrex is known to deteriorate a person's renal system
because I know one day I would like to go on the daily supressive therapy
for the fact that it reduces the chances of transmission to a sexual
partner. So, if any of you are on it daily or have discussed with your
doctor about this, what is the information about it? My doctor just
shrugged, mumbled and said "no, not really..." when I asked about it.

Thanks,
Mary

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M.L.S. - 26 Sep 2004 12:23 GMT

>I know that by using Valtrex daily, it can decrease the frequency of
>outbreaks down to a minimum of once a year. However, I was reading about
[quoted text clipped - 8 lines]
>doctor about this, what is the information about it? My doctor just
>shrugged, mumbled and said "no, not really..." when I asked about it.

>Thanks,
>Mary

Hi, Mary.

The way I understand it: No, Valtrex doesn't contribute to renal
problems, it just might behave badly in the presence of them.
Clearing the drug from the blood doesn't put any strain on the
kidneys, but a weak or slowly functioning kidney might not be able
to clear the drug in an ongoing manner. An existing renal disorder
might mean that your Valtrex dosage would have to be lowered.

The Valtrex page below refers to "significantly impaired renal
function".

Scroll down to 'Dosage in the elderly'.

http://emc.medicines.org.uk/emc/assets/c/html/displaydoc.asp?documentid=2185

Hope that helps,

Mike

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maree - 26 Sep 2004 12:51 GMT

Hi Mary,

Most drugs have to be used with caution in patients with known renal
failure, as this can result in increased blood concentrations of the drug. I
checked out the drug database at the hospital where I work, and renal
impairment caused by Valtrex is extremely rare. In fact, you are more likely
to damage your kidneys from many over the counter medications.

Your doctor was right, Valtrex is a very safe drug.

Regards, Maree

> I know that by using Valtrex daily, it can decrease the frequency of
> outbreaks down to a minimum of once a year. However, I was reading about
[quoted text clipped - 11 lines]
> Thanks,
> Mary

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Tim Fitzmaurice - 28 Sep 2004 11:20 GMT

> I know that by using Valtrex daily, it can decrease the frequency of
> outbreaks down to a minimum of once a year. However, I was reading about
[quoted text clipped - 3 lines]
> Pharmaceutical Guide about Valtrex and the same caution appeared. Now, I am
> wondering whether Valtrex is known to deteriorate a person's renal system

Valtrex releases acyclovir as its active component, that is excreted as is
through the kidneys. If you aren't hydrated enough or there is enough
acyclovir in you then it can come out of solution and crystallise in the
kidneys. This is unsurprisingly considered a bad thing. Its not an issue
of the drug attacking the kidney chemically so far as I can see in the
literature though Valtrex does interact with certain renal proteins that
acyclovir does not (but it has to get there in volume first and the liver
conversion of the drug seems pretty efficient first pass). The issue with
such papers is how clinically relevant the information is (cats may well
be relevant, but we aint felines) as if you dig hard enough anything
becomes toxic....I could dig out papers on people dying from drinking
water if I wanted (yes lots of caveats - heat exhaustion and
massive electrolyte loss needed ror that one)

Now in most people this is considered an issue really only if you are on
IV drugs and its considered reversible by restoring the individuals
hydration.

But the fact it can happen immediately flags a renal disease cautionary.
If the kidneys aren't working it may be much more likely to happen, and of
course if you do get the crystals forming and you have kidney problems
already then you are going to be more likely to suffer problems from it,
and a quick look in the database suggests a set of follow-on problems are
possible in people with significant kidney disease which don't seem to
appear for the average person. There are some papers suggesting this is
more likely with valacyclovir (Valtrex) than with basic acyclovir due to
the improved bio-availability getting more into you, but its at the level
of suggestions only so far as I can see rather than hard data.

The stuff is certainly used to some degree in and around renal transplants
which is pretty much as renal disease as you can get...

So from that its be cautious in kidney disease patients...which is whats
on the label...I'll do a double check to see if anything on direct
toxicity has dropped out into the literature but it may well be a while
before I get the chance....

Tim
--
When playing rugby, its not the winning that counts, but the taking apart
ICQ: 5178568

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Mary Ng - 29 Sep 2004 03:56 GMT

Thank you everyone for your information and especially Tim, quite
informative.

Tim has pointed out a drawback of taking Valtrex is that I would have to
drink lots of water to keep the drug from crystalizing in my kidneys and I
do know that I do not drink 8 full glasses of water daily. It is something
of concern for myself.

Also, the fact that the possibility of it affecting the kidneys when large
doses of Valtrex is taken. It sort of leads to the new dosing that my
doctor suggested me - four 500mg caplets of Valtrex at first symptom and
then another four 500mg caplets 12 hours later and that is it - the doctor
considers this a large dose at a time but seems to be effective for some
people. Now, such a large volume at once seems to have a higher likelihood
of affecting the kidneys to me and especially if I do no drink enough water
(small bladder just cannot handle it).

So, just my thoughts on your advice.

Much Appreciation,
Mary

>> I know that by using Valtrex daily, it can decrease the frequency of
>> outbreaks down to a minimum of once a year. However, I was reading about
[quoted text clipped - 47 lines]
> When playing rugby, its not the winning that counts, but the taking apart
> ICQ: 5178568

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Tim Fitzmaurice - 29 Sep 2004 08:27 GMT

> Thank you everyone for your information and especially Tim, quite
> informative.
[quoted text clipped - 3 lines]
> do know that I do not drink 8 full glasses of water daily. It is something
> of concern for myself.

Woah, slow up here a bit. You have to get a lot of drug and/or a loss of a
lot of water for it to happen...as I said its typically only seen in
patients being given acyclovir intravenously....this is NOT what you are
doing.

From this you could take the view that it would be sensible to keep
adequately hydrated to try to avoid the issue of dehydration completely,
thats fine. However that does not equate to saying if you don't drink lots
of water you will get problems, which is an overly strong interpretation.

I was trying to put over that there is data on kidney related issues, but
its associated with certain things happening and outside of those areas
would be rare as you lose risk factors.

> Also, the fact that the possibility of it affecting the kidneys when large
> doses of Valtrex is taken.

Again that sort of data was in the renal disease group, not the average
person....the problem I pointed out with the data that indicates it
can interact with kidney proteins (and I tried to make this point by
pointing out that it may not be clinically relevant) relies on 2 issues,
firstly that said interaction induces any side effect and scondly that it
is clincally relevant....it required valtrex itself to reach the kidney -
not the acyclovir and valtrex seems to be very efficiently converted first
time thorugh the liver.

> It sort of leads to the new dosing that my
> doctor suggested me - four 500mg caplets of Valtrex at first symptom and
> then another four 500mg caplets 12 hours later and that is it - the doctor
> considers this a large dose at a time but seems to be effective for some

'Large dose' is relative. A large dose compared to clinical norms may not
be a large dose as far as the target system/absolute measures is concerned

In this case, the dosing strategy you pointed out is a hit and run one
that was put through clinical trial by Woody Spruance and the results
released a couple of years ago. While its a large dose of pills compared
to normal it is over a much shorter than normal period of time so the
actual amount you take is not huge and only remains for a short period of
time - yet its still as effective as the normal multiple day treatment.
When that clinical trial data was described by Spruance he did not mention
a single case of kidney problems that I can remember yet he did mention a
side effect profile (extremely limited say he from memory).

What your doctor is describing is essentially a new way of using the drug
that has cropped up.

If you want to see all the details then its published in
Spruance SL, Jones TM, Blatter MM, Vargas-Cortes M, Barber J, Hill J,
Goldstein D, Schultz M.
High-dose, short-duration, early valacyclovir therapy for episodic
treatment of cold sores: results of two randomized, placebo-controlled,
multicenter studies.
Antimicrob Agents Chemother. 2003 Mar;47(3):1072-80.

Tim
--
When playing rugby, its not the winning that counts, but the taking apart
ICQ: 5178568

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davey1 - 03 Oct 2004 20:18 GMT

I've used Valtres before and it did nothing for me. I've recently bought
aviralex and it worked very well. I'd recommend it to anyone as it was
recommended to me by my doctor.

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Mary Ng - 05 Oct 2004 07:10 GMT

Is it "aviralex" or "avirex"?

Mary

> I've used Valtres before and it did nothing for me. I've recently bought
> aviralex and it worked very well. I'd recommend it to anyone as it was
> recommended to me by my doctor.

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