|
| your.name@here wrote:
Thanks for making me dig into the numbers. I learned something new that
was of immediate interest -- it changed what I was going to propose to
my Uro in next week's visit.
> LMac <lmac5491@yahoo.com> wrote:
>
>
> That's an interesting theory. Unfortunately, its not supported by any medical
> studies or the producers of said drugs. 
>
You are correct that Viagra, Levitra and Cialis each inhibit PDE5 and
operate on erectile function in the same way. It's how they interact
with the other ten PDEs and liver enzymes that make for different side
effects and durations. Add in individual tissue differences and
everyone's mileage gets different. I always sneeze violently after any
orgasm when I've taken Levitra and *no* one has ever posted that side
effect in this ng. This is "unusual." (I think the medical term is,
"remarkable." -- my wife has another term for this.)
I fumbled with Google this morning and pulled out some numbers. Viagra's
ratio of effect between PDE5 and PDE6 is 10 (NICB notes) and the ratio
for Cialis is 700 (Lilly prescribing notes). So, for a given effect on
erectile tissue, most Cialis users should be getting a small fraction of
the visual effct that Viagra users experience. There also large
differences in the ratios between PDE5 and PDE1/PDE3 for Viagra and
Cialis/Levitra. These ratios are what caused me to say, "better
engineered." Remember too that Viagra was an accidental discovery when
Pfizer was clinically testing a PDE inhibitor to help with hypertension.
Pfizer fine-tuned it, ran it through the FDA and we got Viagra.
However, now we've got a PDE11 issue and it's specific to Cialis:
Neither Levitra or Viagra have a major interaction with PDE11 -- Cialis
does. (PDE11 wasn't even on the radar when Cialis was developed.)
The hypothesis is that PDE11 is active in the canine and human prostate
and also in testes during the meiotic part of spermatogenesis when the
cell divides to eventually yield 'X' and 'Y' sperm.
In current (2006) reports on Taldafil and PDE11, mice were OK but some
marginally fertile human males under age 44 showed a further decrease in
sperm quantity and quality. Other males, age 45 and up did OK. This
caught my attention since I'm low-'T' and 'T' production is related to
spermatogenesis. (No clue on my current sperm production -- I got
'snipped' years ago.)
Problem is that the science isn't clear on PDE11 (reports speak to four
lines of PDE11, A1, A2, A3 and A4) and the sample sizes in the Cialis -
PDE11 trials look too small for statistical validity; but, were I young
with E.D. *and* a marginal sperm situation, I think I'd make a shift to
Viagra or Levitra until this issue is nailed down. Maybe not a cause
for concern but with a known safe alternative available... etc.
I've been thinking about swapping Levitra + alfa-blocker for daily
Cialis (some posts here have said good things about daily Cialis
knocking down LUTS--maybe a prostate effect from PDE11). I had planned
on proposing a short Cialis trial to my Uro next week. Based what I
read this morning, I'm not doing that--yet. Mama will just have to put
up with the sneezing and gushy nose--or inject me. (:-)
Anyway, thanks for making me dig a bit.
....Lmac
|
|