Erythromycin Zinc Solution 4% NF VI

Cfr. Question 1220 in demand box Prof. Kinget Question An erythromycin solution with Zn acetate in ethanol shows precipitation: R/erythromycin 4g Zinc acetate 1g Propylene glycol 10g Ethanol 65 ° 45ml WATER AD 100ML [We dissolve erythromycin in ethanol, zinc acetate in water with propylene glycol and add ammonium acetate, when mixing 2 solutions we get a cloudy thick liquid. How is this and is that normal? When preparing according to TMF (isopropanol) We get a clear liquid, is this better?] Answer The precipitation has to do with the formation of Zn (OH) 2, which must be brought back in solution by complexation of Zn + + with ammonium. Perhaps more ammonium acetate solution should be added in the case of ethanol? It is clear that preference should be given to the TMF formula, which was validated. COMMENT (S) [Send a comment] To what extent is the zinc effective if it is to be complexing??? Furthermore, there is also an economic side note: Ammonium acetate solution consists only in 1 litre bottles at €80 A.P. I have to use 10 Dr of this for a preparation that occurs every so many years. Is there any other way/form to process the zinc???