Question
Posted on: April 11 2017In a W/O cream are prescribed after thiosulfate crystals. Why crystals?
Answer
I find no indication of a variant with 6 AQ but with 5 aq. This is crystalline and soluble 1 part in 0.6 parts water.
In A cream one would normally expect the powder but here it is intended to dissolve the thiosulfate in water.
Whether there is a difference in solubility between powder and crystalline is not reflected. Both are listed as soluble in water. I don't know which thiosulfate can be purchased.
I cannot express my opinion on the shelf life. Thiosulfate is not very stable in water anyway and here ZnO will inevitably make the water phase Alcalisch. So????
We could recommend a storage in the fridge but here we run the risk of crystallization. So just keep it cool. I think that as a magistal preparation with a retention period of 2 months, the shelf life should not cause any major problems. So do not store in the closet and after x months top up again.