Guidelines and Drug Analysis for Safe Medication Use During the Intercritical and Chronic Phases of Gout

Management during the intercritical and chronic phases of gout:

During the intercritical and chronic phases of gout, the main treatment involves using uricosuric or uric acid-inhibiting drugs to control hyperuricemia and maintain serum uric acid levels at or below 0.36 mmol/L (6 mg/dL).

1. Uric Acid-Inhibiting Drugs
Uric acid-inhibiting drugs primarily lower serum uric acid levels through the following pathways:

(1) Inhibiting glomerular reabsorption of uric acid.

(2) Increasing tubular secretion of uric acid.

(3) Increasing glomerular filtration rate of uric acid.

The main pathway is inhibiting uric acid reabsorption and increasing its excretion. These drugs are suitable for patients with elevated serum uric acid and relatively good renal function. The efficacy begins to decrease when the patient's creatinine clearance rate is below 80 ml/min, and becomes ineffective at 30 ml/min. These drugs are not suitable for patients over 60 years of age with daily urinary uric acid excretion >4.1 mmol and suspected urinary tract stones. In addition, when using uricosuric drugs for treatment, it is important to ensure adequate urine output and urine alkalization.

Commonly used uricosuric drugs include probenecid, sulfinpyrazone, and benzbromarone.

Probenecid (carboxybenzylsulfonamide): Generally, start with 0.25g twice daily, increasing to 0.5g three times daily within two weeks, with a maximum daily dose not exceeding 3.0g. It is completely absorbed in the gastrointestinal tract, with a serum half-life of 6–12 hours. 70% disappears from circulation within 24 hours, but its metabolites still have a uricosuric effect, so its maximum effect occurs several days after administration. Approximately 5% of patients experience rash, fever, and gastrointestinal reactions; occasionally, it can cause acute gout attacks, which can be treated with colchicine. This drug belongs to the sulfonamide class and is contraindicated in patients with sulfonamide allergies.

Sulfamethoxazole: Start with a low dose of 50 mg twice daily, gradually increasing to 100 mg three times daily, with a maximum daily dose not exceeding 800 mg. This product is a derivative of phenylbutazone, with a stronger uricosuric effect than probenecid, and also has a weak anti-inflammatory and analgesic effect. It has a synergistic effect when used in combination with probenecid and is suitable for some refractory patients. Side effects are similar to probenecid, but it has higher gastric mucosal irritation and bone marrow toxicity.

Benzbromarone (Benzbromarone, Gout-Relieving, Gout-Relieving Licensing): Generally, 25–100 mg once daily. 90% of patients can control hyperuricemia.

This product is a potent uricosuric drug with low toxicity, suitable for patients who cannot use probenecid and allopurinol or have extensive gouty tophi.

Uric acid synthesis inhibitor: Allopurinol. The usual dose is 100 mg twice to four times daily. The maximum dose is 200 mg three times daily.

Allopurinol is the most commonly used uric acid inhibitor in clinical practice. It competitively inhibits xanthine oxidase, preventing the oxidation of hypoxanthine to xanthine, and thus preventing the conversion of xanthine to uric acid. It is suitable for patients with excessive uric acid production who are allergic to or ineffective with uricosuric drugs.

Concomitant use of allopurinol with uricosuric drugs can enhance efficacy, especially suitable for patients with severe tophi but good renal function. Side effects of allopurinol include rash, fever, epidermal necrosis and lysis, liver and bone marrow damage, etc., which are more common in patients with renal insufficiency. Therefore, the dose of allopurinol should be halved in patients with significant renal insufficiency. If uric acid-transferring gout attacks occur during medication, colchicine can be used as an adjunct treatment.

Tongyifengning Tablets: One tablet once daily. This product is a compound preparation of allopurinol 100 mg and benzbromarone 20 mg. Reports indicate satisfactory efficacy with fewer severe side effects compared to treatment with the two drugs mentioned above alone.

3. Other: Physical therapy and exercise can be used to treat joint mobility impairments. Larger tophi or those that have ruptured percutaneously can be surgically removed.