Stability of an intravesical installation.

Lidoca ï ne is found stable in a wide pH area of pH 3 to 6. In a solution of NaHCO3 at a pH of 6.8 no loss occurred for a period of 1 month. At pH 7.2 was no noticeable loss for three weeks but after 1 month the concentration was dropped to 88% and a crystalline precipitate arose. At pH 7.4, a loss of 25% with the formation of a crystalline precipitate was detected after 2 weeks. Precipitation seems to occur around pH 7.5.

between the data for after-heparin more contradiction is found. On the one hand, it is recommended not to freeze heparin solutions and not to store at a temperature above 40 ° C. Heparin would retain its activity after autoclaving at 120 ° C. Another study mentions a heparin solution with 10 to 35,000 IU per ml at pH 7 à 8 A stability of 15 years at 4 ° C and 7 years at 18 ° C.

added substances such as glucose and NaCl can have an influence on the stability of heparin. In a solution of Dextrose 2.5% together with 0.45% NaCl the stability at 4 ° C is 12 months; Are the respective concentrations 3.75 and 0.2% then the stability is 1 year at 4 and 22 ° C.

CONCLUSION: Very important is the pH.