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Hi all,
It will be great if anybody gives the answer to my
doubt regarding the Rifampicin solubility. Rifampicin
is slightly soluble in water. But its solubility in
water increases in presence of sodium hydroxide, Is it
due to formation of Rifampicin sodium. If so kindly
send me an any authentic evidence / reference to
support that.
Thanks,
TN Rao
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Hello
Rifampicin being a zwittor ion its solubility increases both in acid as
well as basic solution. This work was done as a part of PhD thesis and
you may be able to see a publication very soon. Meanwhile you may note
its pH dependent solubility values.
pH 1: 125.5 mg/ml, pH2: 11.4, pH 3: 1.15, pH 3.5: 0.75, pH 4: 0.99, pH
4.5: 1.25, pH 5.2, 1.5, pH 6.8: 2.5, pH 7.4: 3.4, pH 8: 5.4.
Hope this helps
Shruti
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Dear TN Rao
If you look at the chemical structure of rifampicin. There are phenolic
groups that
can be ionized in the alkali solution. Also rifampicin can dissolve in
acidic medium,
since there are amines in the structure.
Srirat
Dept. of Pharmaceutical Chemistry
Prince of Songkla University
Thailand
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Dear Rao,
I'm afraid I've lost the original mail you sent. If it concerns
rifampicin
solubility, it is fairly soluble in methanol and you can easily change
the
pH thereafter. At 25 mg/mL, it is over the solubility limit, at 20
mg/mL it
may take some time but if fully dissolves. At 10 mg/mL it dissolves
fast. Do
use gloves! Hope it's of any help.
Goncalo
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