after joining the study you will be assigned to one of two groups in a double‑blind manner. one group receives tigulixostat 300 mg taken by mouth once daily and matching placebo capsules, the other group receives allopurinol 800 mg taken by mouth once daily and matching placebo tablets. the assignment is performed by the study staff using a computer‑generated randomization list.

in addition to the study drug you will take background medicines. colchicine 1.8 mg is taken by mouth once daily to help prevent gout attacks. naproxen 1000 mg is taken by mouth once daily to manage pain and inflammation. these medicines are given to all participants regardless of the group you are in.

each day you will swallow the assigned study tablet or capsule with water. the dosing schedule is once daily, every day, for the entire study period of twelve months. the matching placebo is taken in the same way as the active drug to keep the study blind.

throughout the study you will attend regular clinic visits for safety monitoring. at each visit blood samples are taken to measure sua (serum uric acid) levels, vital signs are recorded, and you will be asked about any adverse events such as nausea, skin reactions, or kidney problems. these visits occur approximately once each month.

at the end of month 4, month 5, and month 6 a blood test is performed to determine whether your sua level is below 6.0 mg/dL. the primary goal of the study is to have this level sustained at each of these three time points.

from month 6 through month 12 you will keep a diary of any gout attacks (known as gout flares). the study staff will review the diary entries at the month 12 visit to calculate the proportion of participants who experienced at least one flare during this period.

at month 12 a physical examination is performed to assess the status of any existing tophus (deposits of uric acid crystals under the skin). the evaluation looks for complete resolution of at least one target tophus, no new tophi, and no progression of existing ones.

after the month 12 assessments you will have a final study visit. the visit includes a summary of safety findings, a review of all adverse events, and instructions for stopping the study medication. study participation ends after this visit.