our logo
Freedom is in you...
You are enough. You are your solution.  
Go Back   paxilprogress > Paxil > News / Research / Articles / Books
User Name
Password
Register Moderation Guidelines Members List Calendar Search Today's Posts Mark Forums Read

News / Research / Articles / Books Helpful resources for books, news, research and more. If you find a book article or research paper interesting, mention it here please.

Adverse Drug Reaction Reporting    FDA Warnings    Published Withdrawal Studies    Pregnancy Warnings    Forum Psychology

Reply
 
Thread Tools
Old 04-03-2005, 03:46 PM   #1
elisa
 
elisa's Avatar
 
Join Date: Jul 2004
Location: Ontario, Canada
Posts: 11,470
Paxil CR versus Immediate-Release Paxil

A comparison of the two follows below.
__________________________________
♦Paxil versus Paxil CR. This is a case for pharmacokinetics. The difference in formulation between Paxil
and Paxil CR is a degradable polymeric matrix called Geomatrix. Due to this matrix formulation, Paxil
CR is released more slowly into the body than the immediate release formulation. Here are the facts:
• Time to maximum drug concentration is extended by 0.8 to 4.8 hours.
• The half-life of Paxil is equivalent to, if not longer than Paxil CR. (21 hrs vs. 15-20 hrs)
• Immediate release Paxil appears to reach steady state concentration at the same time, if not
sooner than Paxil CR.
• Although the main selling point of Paxil CR is improved tolerability, here is a look at the
side effect profiles for both of these drugs when used to treat major depression as
compared to placebo. They do not appear to be much different.

SIDE EFFECT PAXIL CR PLACEBO PAXIL PLACEBO
Headache 27% 20% 18% 17%
Asthenia 14% 9% 15% 6%
Nausea 22% 10% 26% 9%
Diarrhea 18% 7% 12% 8%
Constipation 10% 4% 14% 9%
Somnolence 22% 8% 23% 9%
Insomnia 17% 9% 13% 6%
Decreased Libido 7% 3% 3% 0%
Abnormal Ejaculation 26% 1% 13% 0%
Female Genital Disorder 10% <1% 2% 0%

http://pharmacy.oregonstate.edu/drug...dbits/tb25.pdf
__________________
On A/D's since 1995, switching due to side-effects on 30 different brands of TCA's, SSRI's, SNRI's, Antipsychotics, Benzo's & Imovane. 6 ECT's. Tapering from 225 mg Effexor XR May 17, 2004. (Equiv. to 60 mg Paxil) Last taper Effexor XR Jan 17, 2006 down to ZERO. Currently protracted withdrawal. Sept 2006: 25 mg Doxepin. March 13/09: 10 mg Desipramine
elisa is offline   Reply With Quote
Old 04-03-2005, 04:17 PM   #2
elisa
 
elisa's Avatar
 
Join Date: Jul 2004
Location: Ontario, Canada
Posts: 11,470
Re: Paxil CR versus Immediate-Release Paxil

Here is some follow-up. It is calculated that 25 mg of Paxil CR is equivalent to 20 mg of regular Paxil.

Why then the side-effects of switching??
______________________________________


Pharmacy and Therapeutics Committee
Formulary Review
Paxil CRTM (Paroxetine)
Jami L. Butz, Pharm.D.
GENERIC NAME Paroxetine
BRAND NAME Paxil CRTM
THERAPEUTIC CLASS Antidepressant: SSRI
SIMILAR DRUGS None
INTRODUCTION
During treatment with an SSRI, many patients experience nausea within the first few
weeks of therapy. For some patients, this nausea leads to the discontinuation of
treatment. It is postulated that a controlled-release formulation would result in a lower
incidence of nausea, thereby leading to fewer patients discontinuing therapy.
INDICATION
Paxil CRTM is indicated for the treatment of major depressive disorder and panic disorder.
CHEMISTRY
Each enteric, film-coated tablet contains paroxetine hydrochloride embedded in a
hydrophilic matrix. Due to incomplete dissolution from the wax matrix, the dose of Paxil
CRTM is 25% higher than the dose of Paxilâ. Thus, 25 mg of Paxil CRTM is equivalent to
20 mg of Paxilâ.
PHARMACOLOGY
The mechanism of action through which Paxil CRTM exerts its therapeutic activity is
presumed to relate to its ability to inhibit neuronal uptake of serotonin in the central
nervous system.
PHARMACOKINETICS
Absorption: Paxil CRTM is formulated using an enteric-coating, which delays drug
release until the tablets have passed through the stomach. Paroxetine is
released from the degradable matrix over a period of 4 to 5 hours. The
Tmax (6-10 hours) indicates a reduced absorption rate compared to the
immediate-release formulation of paroxetine. Food does not affect the
bioavailability of Paxil CRTM.
http://www.dhmh.state.md.us/mha/rx%2...df/PaxilCR.pdf
__________________
On A/D's since 1995, switching due to side-effects on 30 different brands of TCA's, SSRI's, SNRI's, Antipsychotics, Benzo's & Imovane. 6 ECT's. Tapering from 225 mg Effexor XR May 17, 2004. (Equiv. to 60 mg Paxil) Last taper Effexor XR Jan 17, 2006 down to ZERO. Currently protracted withdrawal. Sept 2006: 25 mg Doxepin. March 13/09: 10 mg Desipramine
elisa is offline   Reply With Quote
Old 04-03-2005, 04:24 PM   #3
Bern
 
Bern's Avatar
 
Join Date: Oct 2004
Location: NJ
Posts: 3,424
Re: Paxil CR versus Immediate-Release Paxil

Quote:
Originally Posted by elisa
Here is some follow-up. It is calculated that 25 mg of Paxil CR is equivalent to 20 mg of regular Paxil.

Why then the side-effects of switching??
I had absolutely no problems going from 10mg of Paxil to 25mg of Paxil CR. That might have been becuase I was going from an uneffective dose of Paxil to an effective dose of Paxil CR.
__________________
PAXIL FREE SINCE 2009!!! Spent a total of 11 years on Paxil.

I have been taking Anafranil since 2005.

Alcohol free since 1/1/08.......Last drink was 12/31/07
Bern is offline   Reply With Quote
Old 04-03-2005, 04:25 PM   #4
elisa
 
elisa's Avatar
 
Join Date: Jul 2004
Location: Ontario, Canada
Posts: 11,470
Re: Paxil CR versus Immediate-Release Paxil

Quote:
Originally Posted by Yanks1083
I had absolutely no problems going from 10mg of Paxil to 25mg of Paxil CR. That might have been becuase I was going from an uneffective dose of Paxil to an effective dose of Paxil CR.
Yanks - I'm glad you didn't. Other people however, do.......
__________________
On A/D's since 1995, switching due to side-effects on 30 different brands of TCA's, SSRI's, SNRI's, Antipsychotics, Benzo's & Imovane. 6 ECT's. Tapering from 225 mg Effexor XR May 17, 2004. (Equiv. to 60 mg Paxil) Last taper Effexor XR Jan 17, 2006 down to ZERO. Currently protracted withdrawal. Sept 2006: 25 mg Doxepin. March 13/09: 10 mg Desipramine
elisa is offline   Reply With Quote
Old 04-03-2005, 04:32 PM   #5
scotty
Administrator
 
scotty's Avatar
 
Join Date: Feb 2004
Location: new jersey
Posts: 49,899
Re: Paxil CR versus Immediate-Release Paxil

Yanks going up in dose you wouldn't notice a significant difference, going down in dose is a whole other story. Interesting stuff Elisa, the fact that these two supposedly different "forms" of paxil are basically the same speaks volumes. By getting approval for the CR version GSK got a patent extension when in reality its the same as regular paxil. More bucks for GSK when no generic can be sold of the CR version!
__________________
AKA Laurie

"Faith is taking the first step even when you don't see the whole staircase."
MLK
scotty is offline   Reply With Quote
Old 04-03-2005, 05:05 PM   #6
elisa
 
elisa's Avatar
 
Join Date: Jul 2004
Location: Ontario, Canada
Posts: 11,470
Re: Paxil CR versus Immediate-Release Paxil

Quote:
Originally Posted by scotty
Yanks going up in dose you wouldn't notice a significant difference, going down in dose is a whole other story. Interesting stuff Elisa, the fact that these two supposedly different "forms" of paxil are basically the same speaks volumes. By getting approval for the CR version GSK got a patent extension when in reality its the same as regular paxil. More bucks for GSK when no generic can be sold of the CR version!
Scotty, I saw that too - that's one of the reason I posted it and not just a "link". Interesting that the coating (CR) is some sort of "wax"
__________________
On A/D's since 1995, switching due to side-effects on 30 different brands of TCA's, SSRI's, SNRI's, Antipsychotics, Benzo's & Imovane. 6 ECT's. Tapering from 225 mg Effexor XR May 17, 2004. (Equiv. to 60 mg Paxil) Last taper Effexor XR Jan 17, 2006 down to ZERO. Currently protracted withdrawal. Sept 2006: 25 mg Doxepin. March 13/09: 10 mg Desipramine
elisa is offline   Reply With Quote
Old 04-03-2005, 05:15 PM   #7
scotty
Administrator
 
scotty's Avatar
 
Join Date: Feb 2004
Location: new jersey
Posts: 49,899
Re: Paxil CR versus Immediate-Release Paxil

Time to maximum drug concentration is extended by 0.8 to 4.8 hours.
• The half-life of Paxil is equivalent to, if not longer than Paxil CR. (21 hrs vs. 15-20 hrs)
• Immediate release Paxil appears to reach steady state concentration at the same time, if not sooner than Paxil CR.


So the CR version slows the release by .8-4.8 hours?? Amazing that they got an extension on these numbers, but then again it is the FDA!!
__________________
AKA Laurie

"Faith is taking the first step even when you don't see the whole staircase."
MLK
scotty is offline   Reply With Quote
Old 04-03-2005, 05:31 PM   #8
elisa
 
elisa's Avatar
 
Join Date: Jul 2004
Location: Ontario, Canada
Posts: 11,470
Re: Paxil CR versus Immediate-Release Paxil

Quote:
Originally Posted by scotty
Time to maximum drug concentration is extended by 0.8 to 4.8 hours.
• The half-life of Paxil is equivalent to, if not longer than Paxil CR. (21 hrs vs. 15-20 hrs)
• Immediate release Paxil appears to reach steady state concentration at the same time, if not sooner than Paxil CR.


So the CR version slows the release by .8-4.8 hours?? Amazing that they got an extension on these numbers, but then again it is the FDA!!
So now that we know that the half life of Paxil CR is minimal, the withdrawl effects of Paxil CR can be just as severe as with the regular Paxil.

And the docs think ofcourse that Paxil CR has a much longer half-life than in reality.

As a result of that thinking, the docs would advise patients to take the CR every other day....... thinking it would cover 2 days. GGRRRRRR

That's my view on it.
__________________
On A/D's since 1995, switching due to side-effects on 30 different brands of TCA's, SSRI's, SNRI's, Antipsychotics, Benzo's & Imovane. 6 ECT's. Tapering from 225 mg Effexor XR May 17, 2004. (Equiv. to 60 mg Paxil) Last taper Effexor XR Jan 17, 2006 down to ZERO. Currently protracted withdrawal. Sept 2006: 25 mg Doxepin. March 13/09: 10 mg Desipramine
elisa is offline   Reply With Quote
Old 04-06-2005, 06:12 PM   #9
SuSu
 
SuSu's Avatar
 
Join Date: Feb 2005
Location: California
Posts: 778
Re: Paxil CR versus Immediate-Release Paxil

The more I read about all the ways the governments and big business effectively dupe us time and again, the more I'm starting to think we really do live in The Matrix!!!
SuSu is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Forum Jump


All times are GMT -6. The time now is 01:23 PM.


We are not in any way affiliated with Paxil's manufacturer GlaxoSmithKline.
Our ideas and suggestions are anecdotal, inspirational, and they work.

Get the best web browser, FireFox

Powered by vBulletin® Version 3.6.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.