Hyperuricemia is a very common metabolic disease today. It not only causes kidney stones, chronic kidney disease and gout in patients, but may also cause diabetes and cardiovascular and cerebrovascular diseases. Allopurinol, benzbromarone and febuxostat are the most commonly used urate-lowering drugs in clinical practice. What is the difference between the three of them?
How to choose uric acid-lowering drugs for treatment?
Febuxostat is approved only for the long-term treatment of hyperuricemia in patients with gout. In addition, due to the potential cardiovascular risks of febuxostat, it is not recommended for the treatment of patients with asymptomatic hyperuricemia.
The first-line urate-lowering drugs for patients with asymptomatic hyperuricemia are allopurinol or benzbromarone. Patients start with the lowest dose and slowly increase to the highest available dose. If the patient's blood uric acid level does not reach the target range, allopurinol and benzbromarone can be used in combination.
First-line urate-lowering drugs for patients with diagnosed gout are allopurinol, benzbromarone and febuxostat. Patients start with the lowest dose and slowly increase to the highest available dose. If the patient's serum uric acid level fails to reach the target range, allopurinol or febuxostat is used in combination with benzbromarone. In order to reduce the frequency of gout attacks, prevent tophi formation, prevent bone destruction, and reduce the risk of death in gout patients, they need to control their blood uric acid levels to <360 ΞΌmol/ml throughout their lives. Therefore, they may need to take urate-lowering medications for life.
What is the difference in the uric acid-lowering abilities of allopurinol, benzbromarone and febuxostat?
Increased blood uric acid levels are mainly due to increased uric acid synthesis or decreased uric acid excretion in the body.
- Allopurinol: It is a hypoxanthine analogue. Its active metabolites are xanthine analogs. Allopurinol inhibits the reduced form of xanthine oxidase and reduces uric acid synthesis.
- Benzbromarone: It inhibits urate transporter-1 on the renal tubules and reduces uric acid reabsorption. The excretion of uric acid will increase and the patient's blood uric acid level will decrease.
- Febuxostat: It is a non-purine analogue. It inhibits both the oxidized and reduced forms of xanthine oxidase. Therefore, its ability to inhibit uric acid synthesis will be stronger than that of allopurinol.
Uric acid-lowering intensity: febuxostat > allopurinol ≈ benzbromarone.
What are the advantages and risks of allopurinol?
Some studies have pointed out that allopurinol can improve vascular endothelial function and exercise tolerance in patients with angina pectoris. It can also reduce the morbidity and mortality of heart failure. Both systolic and diastolic blood pressure are lowered by allopurinol. Allopurinol may also increase creatinine clearance and decrease serum creatinine in patients with chronic kidney disease.
However, allopurinol can cause hypersensitivity syndromes such as fatal exfoliative dermatitis. HLA-B*5801 gene positivity is a risk factor for hypersensitivity reactions to allopurinol. Therefore, it is recommended that patients undergo HLA-B*5801 gene testing before using allopurinol. Allopurinol may cause renal damage, so the dose needs to be adjusted based on the patient's renal function.
What are the advantages and risks of febuxostat?
Febuxostat has the strongest uric acid-lowering ability among the three. Moreover, it is mainly cleared by the liver and has little impact on kidney function. Therefore, there is no need to adjust its dose for patients with CrCl ≥ 30ml/min.
However, febuxostat is associated with a greater risk of death from cardiovascular events than allopurinol. Therefore, allopurinol is a first-line treatment for gout patients with severe cardiovascular disease (such as myocardial infarction, history of stroke, or unstable angina).
What are the advantages and risks of benzbromarone?
Benzbromarone is a uricosuric drug. It is generally used as an alternative treatment to xanthine oxidase inhibitors. It is contraindicated in patients with CrCl <30 ml/min or in patients with kidney stones.
What are the drug interactions with uric acid-lowering drugs?
Allopurinol and febuxostat are xanthine oxidase inhibitors. Significant drug interactions may occur when they are combined with drugs that are metabolized by xanthine oxidase (such as aminophylline, azathioprine, mercaptopurine and theophylline).
Allopurinol: It combined with amoxicillin may increase the incidence of rash. The combination of allopurinol and captopril may result in fatal Stevens-Johnson syndrome, especially in patients with chronic renal failure. Allergy and renal failure may occur when thiazide diuretics are used with it. Aluminum hydroxide may decrease the absorption of allopurinol. It will cause iron-containing hemoglobin deposition when combined with iron, so the two cannot be taken at the same time. It will also increase the bleeding risk of anticoagulant drugs, and it is recommended to monitor the patient's prothrombin time when used together.
Benzbromarone: Diuretics can increase uric acid and reduce the effectiveness of benzbromarone. It is also not suitable for use in combination with anticoagulant drugs.
What are the indications and dosages of uric acid-lowering drugs?
Allopurinol: It is indicated for primary and secondary gout, hyperuricemia secondary to malignancy, hyperuricemia after organ transplantation, and calcium oxalate stone disease. Its initial dose is 50 to 100 mg daily, taken in 1 to 3 divided doses. Its maximum dose is 600mg daily. To prevent the formation of xanthine stones, patients should drink plenty of water while taking medication. Patients need to alkalinize their urine if necessary.
Febuxostat: It is indicated for the long-term treatment of hyperuricemia in patients with gout. Its initial dose is 20 to 40 mg once daily. Its maximum dose is 80mg daily. To prevent the formation of xanthine stones, patients should drink plenty of water while taking medication. Patients need to alkalinize their urine if necessary.
Benzbromarone: It is indicated for primary and secondary hyperuricemia, gout caused by various causes, and gouty arthritis. Its initial dose is 25 to 50 mg once daily. Its maximum dose is 100mg daily. To prevent the formation of uric acid crystals, patients should drink no less than 1.5 to 2L of water per day while taking medication. Patients need to alkalinize their urine if necessary.
