Topiroxostat is a non-purine selective xanthine oxidase inhibitor that exerts a uric acid-lowering effect by inhibiting uric acid production.

I. Indications and Target Population

1. Approved Indications

(1) Topiroxostat is indicated for the treatment of gout and hyperuricemia.

(2) It is suitable for patients with hyperuricemia requiring pharmacologic intervention. Clinical studies have shown that the target attainment rate of serum uric acid reduction to below 6.0 mg/dL after treatment can reach more than 70%.

2. Patient Characteristics

(1) Indicated for adult patients with confirmed gout or asymptomatic hyperuricemia who require pharmacologic therapy.

(2) Use should be guided by the latest treatment guidelines and reserved for patients with a definite need for pharmacologic intervention. Clinical experience in female patients is limited, requiring careful evaluation.

II. Contraindications and Usage Restrictions

1. Absolute Contraindications

(1) Hypersensitivity: Contraindicated in patients with a history of hypersensitivity to any ingredient of this product.

(2) Concomitant use of specific medications: Absolutely contraindicated in patients receiving mercaptopurine hydrate or azathioprine. Inhibition of xanthine oxidase by topiroxostat may increase blood concentrations of the above drugs, leading to severe myelosuppression.

2. Comorbidities Requiring Caution

(1) Severe renal impairment: Use is not recommended in patients with eGFR <30 mL/min/1.73m² due to lack of clinical trial data.

(2) Hepatic impairment: Use with caution in patients with ALT or AST ≥100 IU/L due to insufficient data.

(3) Patients with cardiovascular diseases: Although not an absolute contraindication, large-scale studies of similar drugs (febuxostat) have shown an increased risk of cardiovascular death. Cardiovascular events should be closely monitored during treatment.

3. Notes on Contraindicated Foods

No specific foods are contraindicated. However, patients with hyperuricemia should avoid the following dietary items:

(1) High-purine foods: animal offal, concentrated meat soups, seafood, shellfish.

(2) Alcohol: especially beer, which significantly elevates uric acid levels.

(3) High-fructose beverages: fructose promotes uric acid production and should be strictly restricted.

The above dietary recommendations are based on general principles of gout management, not direct drug-food interactions.

III. Key Considerations for Special Populations

1. Patients with Renal Impairment

(1) Mild to moderate renal impairment (eGFR 30–90 mL/min/1.73m²): pharmacokinetic studies show no significant differences compared with patients with normal renal function; use is permissible.

(2) Severe renal impairment (eGFR <30 mL/min/1.73m²): use is not recommended due to lack of supporting clinical data.

(3) Renal tubular injury markers including urinary α1-microglobulin, β2-microglobulin, and NAG should be regularly monitored during treatment.

2. Patients with Hepatic Impairment

(1) Use with caution in patients with hepatic impairment (ALT/AST ≥100 IU/L) due to lack of clinical data.

(2) Hepatic enzymes including AST, ALT, and γ-GTP should be regularly monitored. Treatment should be discontinued promptly if marked elevations or jaundice occur.

3. Geriatric Patients

(1) Physiological function generally declines in elderly patients, with potential subclinical deterioration of hepatic and renal function.

(2) Treatment should be initiated at a low dose with close monitoring of response to avoid gout flares induced by excessive uric acid reduction.

4. Pregnant and Lactating Women

(1) Pregnancy: Use only if the therapeutic benefit clearly outweighs potential risks. Animal studies have shown placental transfer of the drug.

(2) Lactation: Animal studies have shown excretion into breast milk. A decision should be made between continuing breastfeeding and discontinuing the drug, balancing therapeutic necessity and the benefits of breastfeeding.

5. Pediatric Patients

Clinical trials have not been conducted in the pediatric population. Safety and efficacy have not been established; use is not recommended in patients under 18 years of age.

6. Female Patients

Limited numbers of female patients were enrolled in clinical trials, resulting in restricted usage experience. Enhanced monitoring is advised during administration.