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Background and Importance Intrathecal amikacin is prescribed for the treatment of central nervous system infections caused by Gram-negative bacteria. There is no commercially available formulation for this method of administration.Aim and Objectives To establish the aseptic preparation process of a 5 mg/ml sterile amikacin formulation in polypropylene syringes for intrathecal use, and to conduct a stability study to confirm a 48-hour shelf life.Material and Methods A systematic search was conducted in PubMed and PubChem with no data found regarding the stability of a sterile amikacin solution in polypropylene syringes. A preparation process was established, using AMIKACIN 5 mg/ml 100 ml, Luer Lock 10 ml sterile polypropylene syringes, 0.22 μm syringe filters and sterile female-to-female Luer Lock connectors.A batch of two syringes (30 mg/6 ml) was prepared under aseptic conditions. Syringes were then stored in UV-Vis light-protective steribags and refrigerated (2–8 °C). Final product samples were obtained and analysed at 0, 2, 4, 24, and 48 hours.The physicochemical stability was defined as the absence of organoleptic changes (no colour change and no precipitates), pH variation < 0.5 units, and osmolarity between 280–310 mOsm/L. Regarding chemical stability, the acceptance range was set at 90–110% recovery of the initial amikacin concentration by particle-enhanced turbidimetric inhibition immunoassay. For microbiological stability, sterility testing was performed according to the European Pharmacopoeia.Results Solutions remained clear, without precipitation or colour changes. pH values remained within the acceptable range: 4.37 ± 0.05 (0 h), 4.28 ± 0.06 (2 h), 4.21 ± 0.08 (4 h), 4.27 ± 0.07 (24 h), and 4.08 ± 0.11 (48 h). Osmolarity values were 306 ± 16.97 mOsm/L (24 h) and 292.5 ± 3.54 mOsm/L (48 h), both within the target range.Amikacin recovery percentages were 99.78 ± 0.99% (2 h), 100 ± 0.35% (4 h), 95.88 ± 0.28% (24 h), and 93.49 ± 0.49% (48 h), remaining within the 90–110% range.Microbiological cultures were negative at all time points.Conclusion and Relevance The 5 mg/ml amikacin formulation in polypropylene syringes met the stability requirements for intrathecal administration. It demonstrated physical, chemical, and microbiological stability for up to 48 hours when stored at 2–8 °C under light protection.Conflict of Interest No conflict of interest