I would like to test the susceptibility of Helicobacter pylori against clarithromycin (Sigma) and levofloxacin (Sigma) using broth dilution method. I have bought the antibiotics in the lyophilized form. Based the manufacturer, the suggested solvents are acetone and chloroform respectively. Due to the little amount of the antibiotics that's available, I dare not to test on various solvents. May i know any alternative solvent which is highly recommended or should I used the suggested solvent?
Main advantage of acetone and chloroform is their volatility.
If you don't like the way those solutions behave, you can always speedvac
them away. Besides that, DMSO is my favourite (but it is not easy to get rid of).
Hi Xinsheng
You probably do not have to use any solvent if you apply the antibiotics in salt form.
allmost every Antibiotic has an ionic charge cationic or anionic, where you are able to attach a salt and you have the possibilty like in your case, form hydrochlorides that have dramatically higher solubilty in water the the original, non-dissociated form.
http://www.scbio.de/datasheet-202693-levofloxacin-hydrochloride.html
Clarythromycin is not so common, it has less Ionic groups and will be a les soluble, but maybe you can perform the hydrochlorid-forming for yourself according to a pharmacological protocoll
http://www.kilomentor.com/2008/04/making-the-hydrochloride-pharmaceutical-salt-of-basic-drug-substances
maybe in your case it might be enough to dissolve in excess of HCl-Ethanol or HCl-Methanol and evaporate the solvent. The residues should be white powders with increased water solubility.
Good luck
What is the solubility of your antibiotics in the solvents recommended by the manufacturer ? And what is the concentration of solvent (e.g. acetone) that is toxic to H. pylori ? It may well be that you could make concentrated solutions such that after dilution into the culture medium, the concentration of solvent becomes irrelevant. Also, regarding chloroform, it is volatile poorly miscible with water and will evaporate if you preincubate your medium with aeration (note that this may create an occupational hazard, though; i would prefer acetone).
2 categories of solvents. Water soluble or Organic soluble.
Since the manufacturer suggested acetone or chloroform, an organic solvent. I think it's organic soluble.
DMSO is soluble in both organic and water. It is highly used solvent for organic soluble antibiotics preparation. Maybe you can refer to a antibiotics susceptibility testing manual for more information on how to prepare it.
I'd go ahead and use the recommended solvent. Acetone has a very low toxicity. Chloroform is a bit worse, but I doubt that It will do any harm at the concentrations you're likely to be using. If you're worried about this, try doing a broth dilution with just the solvents, without the antibiotics.
I have successfully dissolving levofloxacin using 1% acetic acid and the outcome is good.
Dissolving it in small amount of acetic acid and top up with water to the required volume will be better
maybe you could try with methanol (10% in the final solution), or DMSO and PEG 400 (2:1)
I have a lot of protocols if you want write to me..
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