In addition, the half-life of the aspirin-cysteine conjugate in phosphate-buffered saline (PBS) was determined using a first-order decay model. The concentration of the conjugate was measured at various time points, and the rate constant (k) was calculated using the initial concentration and the concentration after 24 hours. The calculated value of k was 0.0029 h -1 . Using this value, the half-life (t 1/2 ) of the conjugate was calculated to be 239.1 hours. This indicates that the aspirin-cysteine conjugate is relatively stable under these conditions, with a long half-life compared to aspirin alone. The conjugate may have potential for sustained release applications or as a long-acting anti-inflammatory agent. Further studies are needed to investigate the pharmacokinetics and pharmacodynamics of the conjugate in vivo.