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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 9 of 9. This is the beginning of the thread.
Posted by stjames on August 21, 2000, at 0:08:58
GENERIC PROZAC
For those who haven't heard it already: A ruling by a federal appeals court frees up drug manufacturers to market generic competitors to Prozac, defeating Eli Lilly's attempts to extend its patent on the drug. The new generics are likely to hit the market next summer, at about a third of the price of the name brand, which goes for $90 a month.
Eli Lilly, nevertheless, is not entirely out in the cold. Through an arrangement with a Massachusetts company, Sepracor, Eli Lilly next year will market an improved version of Prozac - with its own patent - purportedly free of many of its side effects.SUBSCRIBE/UNSUBSCRIBE
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Posted by SLS on August 21, 2000, at 10:07:07
In reply to From McMan's Depression and Bipolar Weekly2#30, posted by stjames on August 21, 2000, at 0:08:58
> Eli Lilly, nevertheless, is not entirely out in the cold. Through an arrangement with a Massachusetts company, Sepracor, Eli Lilly next year will market an improved version of Prozac - with its own patent - purportedly free of many of its side effects.I believe this new preparation consists of one of the fluoxetine stereoisomers rather than a racemate.
- Scott
Posted by dj on August 21, 2000, at 10:39:28
In reply to Re: From McMan's Depression and Bipolar Weekly2#30, posted by SLS on August 21, 2000, at 10:07:07
> I believe this new preparation consists of one of the fluoxetine stereoisomers rather than a >racemate.
???? huh ????
Posted by SLS on August 21, 2000, at 15:50:39
In reply to Translation please, SLS, posted by dj on August 21, 2000, at 10:39:28
> > I believe this new preparation consists of one of the fluoxetine stereoisomers rather than a racemate.
> ???? huh ????
I'm rusty and dusty, so I hope someone will jump in and correct me:Organic molecules often have variations in the arrangement of their atoms. Two molecules that have the same combination of atoms but that are arranged differently are called "isomers". If the differences between these molecules involve the placements of several attachments to a single hub atom three-dimensionally (chiral center), they are called stereoisomers or enantiomers. These two arrangements are mirror-images of each other. One will cause polarized light to rotate to the right (dextro-rotatory e.g. d-amphetamine); the other will rotate it to the left (levo-rotatory e.g. l-amphetamine). Not only do these two molecules rotate light differently, but they can also act differently chemically and pharmacologically.
Dexedrine (d-amphetamine, dextroamphetamine), is a drug preparation containing only one of the enantiomers of amphetamine. Adderal is a preparation containing both l- and d- isomers. A preparation in which the two enantiomers remain combined is described as being racemic, or is said to be a racemate. (A racemic mixture will not rotate polarized light). In addition to the direction in which they rotate light, enantiomers are also differentiated from each other by describing the relative order in which the atoms appear around the chiral center (R and S).
Prozac is a preparation containing fluoxetine racemate. It contains both R and S enantiomer molecules. It is hoped that one of the isomers (R) will produce less side effects while retaining its therapeutic efficacy.
I think my doctor, Jeffrey T. Apter, M.D., may be investigating isomers of various psychiatric drugs. Anyone interested may want to look into his clinical studies.New Jersey:
Princeton Biomedical Research
1-800-BIOMED7
1-800-246-6337http://members.aol.com/jtapter/index.html
- Scott
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Regarding R-fluoxetine (improved Prozac):
From
Clinical Psychiatry News
Fluoxetine Isomer May Hold Advantages Over Prozac
Elizabeth Mechcatie, Senior Writer
[Clinical Psychiatry News 27(3):7, 1999. © 1999 International Medical News Group.]Researchers are hoping that an isomer of the fluoxetine molecule may offer clinical advantages over Prozac.
A shorter half-life and effects on a cytochrome P-450 enzyme by the isomer may reduce the risk of drug interactions. Whether these potential benefits will translate to human benefits will be determined in clinical trials, which have just begun.
Fluoxetine is an enantiomer, a compound with two mirror-image forms --
S-fluoxetine and R-fluoxetine. Researchers have isolated R-fluoxetine, which is now being tested in healthy volunteers in the first phase of clinical trials.
Both the "S" and the "R" isomers of the fluoxetine molecule are active in the currently available selective serotonin reuptake inhibitor, but the "R" portion alone is being pursued as a therapeutic entity because it has a shorter half-life than fluoxetine and it appears to have less of a propensity to inhibit the P4502D6 isoenzyme, said Dr. Mark Demitrack, director of clinical development at Eli Lilly Research Labs in Indianapolis.
The latter feature has the potential to reduce the risk of drug-drug interactions with agents that are metabolized by this isoenzyme, such as the tricyclics, he said in an interview.
This year, the company expects to begin phase II clinical trials of R-fluoxetine in patients with major depression and hopes to complete phase III trials and file for approval with the Food and Drug Administration by 2001, according to a statement released by Eli Lilly and Co.
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From Sepracor website:(R)-fluoxetine has potential advantages over existing therapies for treatment of psychiatric disorders. The drug has potential for improved efficacy and new indications such as depression, OCD, anxiety spectrum disorders, eating disorders such as obesity and anorexia as well as PMS. (R)-fluoxetine has the potential for increased tolerability in treating anxiety and sexual dysfuntion. In addition, it is a preferred platform for combination therapies due to its faster onset and improved efficacy. In December 1998, Sepracor and Eli Lilly and Company announced a licensing agreement, that will enable Lilly to exclusively develop and globally commercialize R-fluoxetine. R-fluoxetine, a new chemical entity patented by Sepracor, is a modified form of an active ingredient found in Prozac.
Posted by shar on August 21, 2000, at 17:32:17
In reply to Re: Translation please, SLS, posted by SLS on August 21, 2000, at 15:50:39
If the new, improved version has a shorter half-life than the old Prozac, it may not be as much help when used to alleviate withdrawal from other meds. I wonder if they will keep the old prozac available?
Shar
Posted by Phil on August 21, 2000, at 21:05:49
In reply to Re New Prozac and shorter half life, posted by shar on August 21, 2000, at 17:32:17
Shar,
With the money they are making off of Prozac, it's not going anywhere soon! It'll just be Classic Prozac.
Phil
Posted by Sunnely on August 21, 2000, at 22:37:57
In reply to Re New Prozac and shorter half life, posted by shar on August 21, 2000, at 17:32:17
> If the new, improved version has a shorter half-life than the old Prozac, it may not be as much help when used to alleviate withdrawal from other meds.
Good point. The "new, improved Prozac" (shorter half-life) will probably be just like the other SSRIs when it comes to withdrawal symptoms.
>I wonder if they will keep the old prozac available?
Probably not for long. The old Prozac will probably be relegated to oblivion in due time. FYI, a generic version of the old Prozac will be available by next year, probably as early as February 2001 or August 2001.
On August 9, 2000, a federal court ruling denied an extension to Eli Lilly's patent on the old Prozac. Lilly plans to appeal, however. If the current ruling is upheld, a generic version of the old Prozac could be available as early as February 2001 or at a later date, August 2001. (Based on this ruling, the patent on the old Prozac is set to expire in February 2001. But because Lilly is going to test the drug in pediatric cases, the patent could be extended another six months, until August 2001.)
Barr Laboratories Inc., has 2 generic versions of the old Prozac awaiting FDA approval. The price of the generic old Prozac will no doubt be much cheaper than the brand name. Typically, generic drugs are at least half the price of brand-name equivalents.
FWIW, after the news of the court decision, Lilly's stock value dropped 29%.
Posted by Cam W. on August 22, 2000, at 0:42:15
In reply to Translation please, SLS, posted by dj on August 21, 2000, at 10:39:28
> > I believe this new preparation consists of one of the fluoxetine stereoisomers rather than a >racemate.
>
>
> ???? huh ????dj - It's like your two hands. They are basically mirror images of each other, like Scott said. - Cam
Posted by stjames on August 22, 2000, at 1:43:41
In reply to Re: Translation please, SLS » dj, posted by Cam W. on August 22, 2000, at 0:42:15
> > > I believe this new preparation consists of one of the fluoxetine stereoisomers rather than a >racemate.
> >
> >
> > ???? huh ????
>
> dj - It's like your two hands. They are basically mirror images of each other, like Scott said. - CamJames here....
Isomers have the same number of atoms (or number of fingers) but arranged the oppsite
way. Isomers can have differing, no action, or same action as each other. generally
organic life seems to prefer the d isomer, but this is not a hard fast rule. Some meds
contain stereo(both) isomers or just one isomer. Patents are very specific so each isomer
can be a different patent. This is the so called "least patentable difference", the smallest
change from a patented med needed to get a new patent.It is much cheaper to modify an existing med than to make on from scratch, Like Porzac of Effexor.
Big costs happen when you make sucessful novel meds. The original sucessful AD, Tofranil, a TCA,
was developed from sedating antihistamines like Benedryl. Tofranil then spawned many other TCA's, each
slightly different from the original atomic sturcture. I suspect that Prozac was released as the more sucessful
isomer with its other isomer held in the wings till needed. i would wait till after the pre marketing
studies are done to see how the real population responds. It is safe to say at least a few people will
do better on the new isomer but the real question is as a whole is this any better than Prozac or other AD's.
james
This is the end of the thread.
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