Background and Importance Chromoendoscopy involves the injection of dye into the submucosal layer of the intestine wall that enhances the injected area and facilitates the delimitation and marking of areas that are susceptible to endoscopic treatment. The classic technique consists of adding indigo carmine (IC) to the injected solution, colouring the resulting bulge, and ensuring that the injected layer is the submucosa, which reduces the risk of perforation and the feasibility of endoscopic resection. The inclusion of adrenaline in the solution, with a concentration 10 times lower than for haemostatic purposes, reduces the potential risk of haemorrhage and highlights the well-vascularised epithelia. There is no commercialised or standardised preparation for performing this technique.

Aim and Objectives Description and galenic validation of a solution of IC and adrenaline in colloid plasma for use in chromoendoscopy. Establishing the period of validity according to the Guide to Good Preparation Practices (GPP).

Material and Methods The developed formula was made of adrenaline 1 mg, IC 32 mg (4 mL of IC 0.8%) and q.s. ad 100 mL protein-based colloid derived from gelatine. The preparation added to a sterile 100 mL polyolefin bag.

The risk of the final preparation was determined according to the GPP matrix and galenic validation was carried out by evaluating the following parameters: physical stability due to colour change by qualitative assessment on a black and white background by two observers; chemical stability with pH determination by potentiometry; microbiological stability (trypticase soy agar culture). Determinations were made at 0, 15, 30 and 45 days post-preparation.

Results There was no colour change in any sample except at t45, where a marked change in colouration was observed. Regarding the pH, the following results were obtained: t0: 6.65 ± 0.02; t15: 6.83 ± 0.02; t30: 6.57 ± 0.03; t45: 6.70 ± 0.02. There was no microbiological growth in any sample. A medium risk level and a validity period of 14 days between 2–8°C were established according to the GPP.

Conclusion and Relevance The IC solution is physically, chemically and microbiologically stable for 14 days at 2–8°C. The final concentration of IC used and the association with adrenaline allow, in the opinion of the endoscopists, the adequate differentiation of the areas susceptible to endoscopic resection.

Conflict of Interest No conflict of interest