28 Validation of a closed system for dispensing serum eye drops

NHS Blood and Transplant Tissue and Eye Services (TES) offer a serum eyedrop (SE) service to patients suffering from severe ocular surface disease. SE are prepared from serum collected at blood donation sessions; the serum is diluted 1:1 with physiological saline. Formerly, 3ml aliquots of diluted serum were aliquoted into glass bottles in a Grade B clean room. Since this service was started, Meise Medizintechnik have developed an automatic closed filling system consisting of tubing-linked chains of squeezable vials. They can be heat-sealed closed, under sterile conditions, after the vials have been filled.

TES R&D were asked to validate the Meise system to increase the efficiency and speed of SE production. Validation of the closed system consisted of a process simulation assessment, using bovine serum and simulating each step of the filling process, freezing to -80oC, checking the integrity of each vial and packing the vials into storage containers. They were then put into transport containers and shipped on a round-trip journey to simulate delivery to patients. On return the vials were thawed and the integrity of each vial re-checked visually and by squeezing in a plasma expressor.Subsequently a shelf-life study was carried out on three batches of fully consented human allogeneic SE. The serum was dispensed into vials, frozen as above and stored for set time points 0, 1, 3, 6 and 12 months in a standard domestic freezer set at -15-20oC to mimic a patient's freezer. At each time point, 10 random samples of vials were removed, and the outer containers were tested for damage or deterioration, the vials for integrity and their contents for sterility and stability. Stability was assessed by measuring serum albumin concentrations and sterility by testing for microbial contamination.

No structural damage or leakage was found in any of the vials, or the tubing evaluated, after thawing, at any time point. In addition, all samples tested negative for microbial contamination and serum albumin levels were always within the expected range (3 - 5 Dg/L) at each set time point.

These results demonstrate that Meise closed system vials can successfully dispense SE drops and the vials can be stored frozen without affecting integrity, sterility or stability. These vials have been in use in TES for 3 years saving clean room space and greatly increasing the numbers of patients that can use the SE service.