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Dear All,
Does anyone know of a supplier of N-desmethyl erythromycin. I
understand that one of the affiliates of Sigma used to sell it but
removed it from their catalogue in late 1997.
Thanks
Laurent P Rivory
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Only person can be of help is Dr. Paul Watkins University of Michigan.
Prasad Tata, Ph.D.
Otsuka America Pharmaceutical, Inc.
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If Sigma or Aldrich once sold it, you should call and talk to them. They
used to maintain an inventory of chemicals that they didn't list in the
catalog, but had as specialty stock. It included remains of things they
had synthesized for themselves and others, materials taken out of stock etc.
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We have a method to synthesize N-desmethyl compounds. Recently we've
used this method to synthesize N-desmethyl promethazine. And also we've got
high yield and the method is simple. This method might help solve your
problem.
The method we followed is from following reference
title: A NEW REAGENT FOR THE SELECTIVE, HIGH-YIELD N-DEALKYLATION OF
TERTIARY
AMINES
source: Olofson, R.A., J.Organic Chemistry, vol.49., pp-2081-2082, 1984.
Sreenivasa Rao( Dr.David.W.A.Bourne ), Graduate Student,
college of Pharmacy, University of oklahoma
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Dear All,
We are looking for a simple method to quantitate erythromycin and
read with interest the paper by A.S. Amin and Y.M. Issa "Selective
spectrophotometric method for the determination of erythromycin and
its esters in pharmaceutical formulations using gentiana violet"
published in J. Pharm Biomed Anal. 14 (1996) 1625-1629.
Unfortunately, our attempts at reproducing their results have been
complete failures even at high concentrations. Has anyone tried this
method? Alternatively, does anyone have a fax number or email address
for the authors?
The problem may relate to the dye. Gentiana violet does not appear
to exist,
there is either gentian violet (crystal violet) or gentiana violaceum
which also contains pentamethyl and tetramethyl-p-rosaline. May be
those extra components are required.
Thanks in advance!!
Laurent Rivory (PhD)
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Dear Dr. Rivory:
I tried to get the fax no for your but the information is not available.
Hence I am providing my input into this issue.
This is an ion pair complex formation reaction. Authors used Gentian Violet
from Aldrich hence there is no need for that extra ingredient. It is 1:1
molar complex formation. I would suggest you to follow the steps listed
below:
1. Prepare all the solution and adjust the pH of the solutions approximately
to pH 8.5 with glacial acetic acid.
2. Mix gentian violet (2.5 ml) and erythromycin (7.5 ml) and allow the
reaction for 1 minute and then add the buffer then add 15 mL of pH 8.5
borate buffer mix the solution and measure the absorbance after 30 minutes
but within 2 hrs.
Important points to remember is that maintaining pH of 8.5, % of alcohol
content not less than 40%. and the need for reaction time.
See if my suggestions work.
Please contact me if you need any additional information
Prasad NV Tata, Ph.D.
Department of Clinical PK/PD and Metabolism
Otsuka America Pharmaceutical, Inc.
2440 Research Blvd.
Rockville, MD 20850.
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Dear Dr Tata,
Tried your suggestion without success. Have you used this method?
What I don't understand is how the method can be based on the
formation of an ion pair
when both erythromycin and gentian violet are cations.
Previously only acid dyes (sulphonates) have been used to form ion
pairs with erythromycin but there are no significant colour shifts
reported for these complexes.
Regards
laurent Rivory (PhD)
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