In a previous article I discussed the treatment of acute gouty arthritis (GA). In this article I'll focus on treatment of chronic disease. The aims of chronic GA treatment are to prevent recurrent attacks by lowering the serum uric acid (UA) below 6mgs/dl, and addressing other associated medical conditions that could be aggravating GA. These include obesity, high blood pressure, diabetes, drugs the patient may be taking that can elevate UA such as diuretics, and osteoarthritis.
With chronic GA, patient can develop long term problems including the formation of tophi (deposits of UA under the skin and inside internal organs), joint destruction, kidney stones, and kidney failure.
The treatment of chronic GA involves dietary counseling, medication adjustment, and specific medicines to treat GA.
GA medicines lower serum UA. They do this through various mechanisms including reducing the production of uric acid, increasing the excretion of uric acid through the kidneys, and finally, with newer agents converting UA to less damaging substances. The choice of therapy depends on the severity of disease as well as the medical condition of the patient.
The mainstay of chronic GA treatment has been a drug called allopurinol. It reduces UA by blocking an enzyme that allows uric acid production.
Usually this drug is started at a low dose and slowly increased over time.
Allopurinol is associated with a number of potential side effects including rash, vasculitis (blood vessel inflammation), life-threatening hypersensitivity reactions, hepatitis, kidney damage, and bone-marrow abnormalities.
Allopurinol dosing needs to be adjusted in patients with kidney damage.
Febuxostat is a new medicine that hits the same target as allopurinol but it appears to have fewer side effects. Because it's metabolized in the liver, less reduction of dose is needed in patients with kidneys that aren't functioning normally.
Uricosuric drugs are medicines that make patients get rid of UA via the kidneys. They shouldn't be used in patients with a history of kidney stones and also don't work for patients with kidney insufficiency. The most commonly used drug in this category is probenicid.
Another new class of drug are the uricolytics. These convert urate, the substance that eventually becomes UA into allantoin, a relatively inert ingredient that is easily excreted from the body. The drug that is primarily used in this category is PEG uricase (Krystexxa). This drug is given intravenously. The most common side effects of PEG-uricase are an acute flare of gout and infusion reactions. Infusion reactions consist of nausea, vomiting, dizziness, breathing problems, muscle aches, and rash.
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