When treating gout, both allopurinol and febuxostat can reduce uric acid production. What is the difference?

A friend left a message to Huazi, asking that among the drugs for treating gout, allopurinol and febuxostat have the same effect of inhibiting the production of uric acid, so what is the difference in specific use? Huazi said that both can inhibit the production of uric acid, and febuxostat is more effective. In terms of adverse reactions, both have their own characteristics.

Hyperuricemia is the cause of gout, and there are two reasons for the increase in blood uric acid levels: one is increased uric acid production, and the other is reduced uric acid excretion. Allopurinol and febuxostat are both drugs that reduce uric acid production.

1. Reducing uric acid production requires drugs. Hyperuricemia will precipitate crystals in joints, soft tissues and other parts, forming tophi, leading to gouty arthritis. There are two sources of uric acid in the human body. One is from purine-containing foods, accounting for about 20% to 30%; the other is from the body's own metabolism, accounting for about 70% to 80%.

In other words, dietary control can only affect a small part of the uric acid level. Patients often complain to Huazi, "I feed myself like a rabbit, eating grass every day, but the uric acid level still can't be reduced." If you want to significantly reduce the production of uric acid, you can't rely on dietary control alone, you need to use drugs.

2. Mechanism of allopurinol and febuxostat The production of uric acid in the human body is synthesized using hypoxanthine and xanthine as raw materials under the action of reduced xanthine oxidase and oxidized xanthine oxidase.

Allopurinol and its metabolites are similar in structure to hypoxanthine and xanthine in the "uric acid raw materials" and can inhibit reduced xanthine oxidase and reduce the synthesis of uric acid.

Febuxostat is not a xanthine analogue, and it can inhibit not only reduced xanthine oxidase, but also oxidized xanthine oxidase. Therefore, compared with allopurinol, Febuxostat has a stronger effect in inhibiting uric acid.

3. Differences between usage and safety How to use:

The effect of allopurinol is equivalent to using "false raw materials" to combine with urate synthase to reduce the production of uric acid, so there is a competitive relationship between it and the "normal raw materials", and usually a larger dose is required to play a better role. However, the half-life is short, and taking a large amount of medicine at one time is prone to adverse reactions. Therefore, when the daily dose of allopurinol exceeds 200 mg, it is necessary to take the medicine 2 to 3 times a day to reduce adverse reactions.

Febuxostat can directly inhibit urate synthase and reduce the synthesis of uric acid. It also has a long half-life, so taking Febuxostat once a day can effectively inhibit the production of uric acid.

Security:

Allopurinol may cause hypersensitivity reactions, leading to life-threatening exfoliative dermatitis. This reaction is associated with HLA-B-5801 gene positivity, which is about 2% in Caucasians and 6% to 8% in Chinese. Therefore, before using allopurinol, it is recommended to do a genetic test. If you are HLA-B-5801 positive, allopurinol is prohibited.

Febuxostat does not cause hypersensitivity reactions, but in the US FDA's study, the cardiovascular risk of Febuxostat is greater than that of allopurinol. Febuxostat is slightly higher in terms of liver damage and the incidence of common adverse reactions than allopurinol. Therefore, both drugs need to be used under the guidance of a doctor and weighed.

Both drugs may cause liver dysfunction, so if you experience fatigue, decreased appetite, aversion to greasy food, darker urine color, etc. during medication, you should seek medical attention in time. Both drugs will not increase uric acid excretion in urine, but will increase xanthine excretion in urine. In order to avoid the formation of xanthine stones, you need to drink a lot of water to maintain urine volume (more than 3000ml per day) and alkalize urine during medication.

Allopurinol may cause a rash before a hypersensitivity reaction occurs, so if a rash occurs, stop taking the drug and seek medical attention immediately. If you experience chest pain, chest tightness, headache, and other symptoms while taking febuxostat, be alert to cardiovascular and cerebrovascular diseases and seek medical attention immediately.

In summary, Febuxostat is more effective in lowering uric acid than allopurinol, and Chinese people are more likely to have hypersensitivity reactions when using allopurinol, so Febuxostat is more commonly used in China. However, during use, be alert to the cardiovascular effects of Febuxostat. Drugs must be used under the guidance of a doctor. If you have any questions about medication, please consult a doctor or pharmacist in time. I am pharmacist Huazi, welcome to follow me and share more health knowledge.