Background Calciphylaxis (calcific uremic arteriolopathy) is the ischemic ulceration of the skin caused by the disseminated calcification of the subcutaneous tissue and small arteries as a consequence of hyperparathyroidism in uremic patients.

Purpose To describe the method of preparation and checking of an injectable solution of 25% sodium thiosulfate for the treatment of intradialytic calciphylaxis in renal patients.

Materials and Methods Sodium thiosulfate is an antioxidant, vasodilator and calcium chelator. The preparation process for the solution of 25% sodium thiosulfate is: Ingredients: Sodium thiosulfate pentahydrate: 25 g, water for injection (WFI): qs 100 ml. Preparation: Weigh the amount of sodium thiosulfate in a sterile beaker. Then, working in a horizontal laminar flow hood, boil WFI to eliminate CO₂. Dissolve the thiosulfate in about 80 ml of boiled water. Check that the pH of the solution is between 6 and 9.5, if it is not, adjust with HCl or NaOH. Flush into a 100 ml volumetric flask and make up to volume. Filter with a double 0.22 micron philtre. Finally pack with 50 ml syringe into a sterile glass bottle and label.

Results The result is a solution of 100 ml of 25% sodium thiosulfate, transparent, sterile and stable for 30 days in refrigerator. For QC a visual particulate sterility cheque is performed by sowing in aerobic and anaerobic cultures and a bubble point test to verify the integrity of the philtres.

Conclusions Proper preparation and checking of the 25% solution of sodium thiosulfate has guaranteed its parenteral administration is safe. The treatment is effective and well tolerated, helping patients and improving their quality of life.

No conflict of interest.