Question
Posted on: April 6 2013A solution with Tetracaine hydrochloride crystallizes out in the refrigerator
R/Tetracain HCl 2%; Epinephrine 0.01%; Physiologically WATER AD 100ml
As soon as this preparation is stored in the refrigerator, this solution crystallizes completely. From the fridge this solves itself again.
Can you also tell me how long this preparation can be stored? We have a reference from Am. J Health-Syst Pharm. 53, 659 (1996) which says that such a solution is stable for 26 weeks when stored in a red-brown vial and in the refrigerator
We have already acidified this preparation as previously suggested in one of the previous questions, but this has no effect. What can we do to avoid this crystallization?
Answer
REPLY (at 20130405)
I would think we have to do with a salt-out of tetracaine. HCl but this product is listed as being very well soluble in water, so at first sight this seems rather unlikely.
Now the wonders are the world not out???
I can only give you the advice to replace physiologically water with glucose 5%.
As far as stability is concerned, I have read the article and noticed that the concentration on Nametabisulfite, the anti oxidance for epinephrine, was increased and adapted to the total volume!