Question
Posted on: March 6 2013What is the shelf life (how many days?) of a Stanford solution and what is an optimal formula for this (viscosity and flavour)?
Stanford solution:
R/lidoca ï NE 480 mgIn The Martindale I only find that this should be stored in dark bottles, but nowhere data about how long This preparation. The specialty Nystatin suspension also preserves 3 years (will of course contain preservatives). In the clinic one had worried the Pati ë NT (which used this for some time already), saying that this solution does not save longer than 3 days. We normally add a little xanthan gum excipient of Certa and a little raspberry syrup (perhaps better orange peel essence). Since nystatin tastes so bad and is incompatible with e.g. methyl cellulose, I also do not dare to add aqua Conservans to it. I would particularly like to have a directive on the shelf-life that we can recommend to the Pati ë NT.
nystatin 5.8 MU
after bicarbonate 8.4 gr
Water AD 600 ml
Answer
In quasi neutral middle pH = 7.5 the nystatin preserves well. So a pH control is appropriate here because I do not know how alkaline it gets with lidocaine and NaHCO3. The latter being in great excess I suspect that we will come out around pH 7.5. Lidocaine itself is rather stable. Perhaps the least stable product is still NaHCO3 but this will also be windfall. You can use Aqua Conservans. The other used tools seem to me OK.
now we can not compare 100% with Nystatin Labaz because this preparation only prevents nystatin. We can only know a reliable shelf-life by means of a stability study. I also don't know how long that 600 ml lasts? But all in all, I think we can still maintain a shelf life of 1 if possible 2 months. I would always recommend storing the specimen in the refrigerator.
I think they do slightly exaggerate in the hospital. But why not ask them what they are supporting.