duloxetine

[oliva]

Hi!

I am a very desperate analyst, because I have to develop some HPLC methods (degradation and assay) for pellets which are containing duloxetine.
Please Help me In it!!!

Oliva

[Rafael Chust]

I was trying to get more info, but if you can give me a hint on its chemical structure and similarity with other stuff I might give you some ideas where to start...

[amaryl]

Hi!

I am a very desperate analyst, because I have to develop some HPLC methods (degradation and assay) for pellets which are containing duloxetine.
Please Help me In it!!!

Oliva

Don't be desperate its an antidepressant.

Duloxetine belongs to SSRIs ...paroxetine...PAXIL (GSK product) which will be recalled soon (addictive and results in suicidal behaviour in subjects taking it).

Check out its structure, pKa, all the previous work being done on it.

Regards,

Amaryl.

[jitender]

is it Domperidone? or

Structure:

pKa: 7.9
Water Solubility : 0.986 mg/L

I should mention the source.
Courtsy: http://redpoll.pharmacy.ualberta.ca/dru ... D00418.txt

or its some other molecule?



Source : http://redpoll.pharmacy.ualberta.ca/dru ... D00060.txt

I am confused....

[amaryl]

Here are some useful links.

http://en.wikipedia.org/wiki/Duloxetine

http://www.ncbi.nlm.nih.gov/entrez/quer ... med_docsum

http://www.ncbi.nlm.nih.gov/entrez/quer ... med_docsum


Regards,

Amaryl.

[Uwe Neue]

It's in the Merck index...

It is an antidepressant. It is likely to behave exactly like other antidepressants. The LC literature is full of chromatograms with amitriptyline, since everybody is suing it to brag about the quality of their packings.

My suggestion: use a packing with an embedded polar group such as SymmetryShield RP18 or XBridge RP18 at pH 7 with a mobile phase around 65 to 70% methanol for an isocratic assay. This will also be a good reference point if you need a gradient for the degradants.

[Rafael Chust]

I would follow Uwe suggestion - maybe increasing the pH a little bit, since it would benefit peak shape.

Although I would use Synergi Fusion-RP or Gemini C18 instead...

[oliva]

Thank you for your helping. .... Amaryl made me laugh
First af all......I have a problem with comparing sample solution stability. This molecule is very sensitive to acid, but in the literature suggest that a I should use ph=3 mobil phase.
I usually use the mobil phase (for example : MeOH+ buffer(ph=3)=1+9) to solve the samle or to dilute it, such as the comparing solution as well, because of the spectral quality and the peak form.

So I don't know how I can solve the sample...and so on.. because it is disintegrating...


Other: the second structure is correct in jitender's letter.
oliva

[Rafael Chust]

Your pH is certainly too high, as you are dealing with a base drug.

With low pH, your drug will be ionized and you will have problems to have a good chromatogram by reversed phase.

[amaryl]

Thank you for your helping. .... Amaryl made me laugh
First af all......I have a problem with comparing sample solution stability. This molecule is very sensitive to acid, but in the literature suggest that a I should use ph=3 mobil phase.
I usually use the mobil phase (for example : MeOH+ buffer(ph=3)=1+9) to solve the samle or to dilute it, such as the comparing solution as well, because of the spectral quality and the peak form.

So I don't know how I can solve the sample...and so on.. because it is disintegrating...


Other: the second structure is correct in jitender's letter.
oliva

Good to see I made you laugh . I was bit reluctant to state its a basic drug from structure. My weird guess would have been wrong even. You should work at basic mobile phase conditions at least 2 units away from the pKa of analyte as stated by Uwe sir and Rafael.

Regards,

Amaryl.

[Uwe Neue]

If you use the columns that I proposed, you will have no problem at pH 7. They give perfectly symmetrical peaks. A standard C18 is not very likely to do so.