Trial of Chitogel/Deferiprone patch to assess post operative epidural fibrosis in patients undergoing lumbar spinal surgery

Methodology Ethics This study was approved by the Central Adelaide Local Health Network Human Research Ethics Committee (CALHN HREC), approval number 2022/HRE00088. Clinical trial notification through the Therapeutic Goods Administration number CT-2023-CTN-03907-1. All participants provided written informed consent prior to enrolment, and the study was conducted in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice guidelines. Surgical Procedure The procedure would involve a decompressive lumbar laminectomy at the affected level/s with rhizolysis of the affected nerve root/s with consideration for microdiscectomy if indicated. Materials Chitogel The current commercially produced formulation of Chitogel® (Chitogel, Wellington, NZ) was used. Chitogel is made up of a combination of three components; 5% succinyl-chitosan, 0.3% phosphate buffer which includes glycerol and 3% dextran aldehyde. The components are manufactured and sterilized by Chitogel. All stocks were stored at room temperature. Deferiprone European Pharmacopoeia grade Deferiprone (3-hydroxy-1,2-dimethylpyridin-4(1H)-one) (Sigma-Aldrich, St Louis, USA) was stored at room temperature. Royal Adelaide Hospital Pharmacy compounded 4mM of sterile Deferiprone. Preparation of Chitogel and Deferiprone Preparation involved opening a sterile Chitogel kit on the operating table by the scrub nurse at the beginning of the surgery. The Chitogel and Deferiprone were prepared by the scrub nurse. A sterile study kit was compounded by the Royal Adelaide Hospital Pharmacy in advance and contained the following: 12ml 0.3% Sodium Phosphate buffer solution (Vial A), 350mg Dextran Aldehyde powder (Vial B), 12ml 5% Chitosan Succinamide solution (Vial C) and 4ml Deferiprone 4mM sterile solution. The preparation steps were as follows: Using a mixing cannula and 20 mL syringe, remove and discard 8.8 mL of chitosan succinamide from Vial C. Mix Vial A into Vial B together and shake for 20 seconds. Draw 8.8ml of the newly mixed Vial A/B solution and add to Vial C. Transfer 4ml of Deferiprone solution into vial C, making 16ml of 1% Deferiprone and 1% chitosan. Draw up the required volume based on the number of levels (~3ml per operative level) and allow to set as a gel for 5 minutes, then administer. Preparation of the Chitogel-Def gel commenced once the operation was finished while the surgeon was achieving haemostasis prior to closure. The neurosurgeon performing the procedure applied the gel at the conclusion of the operation. The gel was applied onto the dura and nerve root, aiming for at least 3ml of gel per level.