[Molecular basis of primary renal hyperuricemia : role of the human urate transporter hURAT1]

Lesinurad: A significant advancement or just another addition to existing therapies of gout?

Gout is a metabolic disorder that usually presents as recurrent episodes of acute arthritis due to deposition of crystals in joints and cartilages. Despite the availability of several drugs for gout, its management is still less than adequate. There is always a search for newer, safer, and more potent urate-lowering therapies for treating patients inadequately controlled with available drugs. Lesinurad in combination with a xanthine oxidase inhibitor provides an effective mode of therapy in the management of hyperuricemia associated with gout. Lesinurad is a selective uric acid transporter 1 (URAT1) inhibitor. URAT1 is responsible for the majority of uric acid absorption from kidneys to the circulation. Lesinurad was granted marketing approval based on three randomized, double-blind, placebo-controlled; phase III clinical trials. It is devoid of interaction with organic anion transporters (OATs) such as OAT1 and 3, responsible for drug-drug interactions, an undesirable property associated with probenecid. On-going research is more focused on reducing inflammation consequent to deposition of crystals rather than production and excretion of urate. Various targets are being explored, and interleukin-1 beta inhibition seems to be one of the most promising approaches.

[Gout as a systemic disease. Manifestations, complications and comorbidities of hyperuricaemia]

Of all inflammatory rheumatic diseases gout has the highest prevalence. Patients with intermittent acute gout attacks are usually treated by primary care physicians. However, in cases of insufficient long-term control of serum uric acid levels, complications or atypical clinical manifestations may necessitate consultation with a rheumatologist in the further course of the disease. An oligoarticular or polyarticular presentation can give rise to the initial suspicion of rheumatoid or psoriatic arthritis. In these cases a careful clinical work-up supported by laboratory and imaging investigations is necessary and synovial fluid analysis is usually required. As in other rheumatic diseases extra-articular manifestations are of utmost importance for morbidity and mortality. Gout is a complex metabolic and inflammatory disease and besides articular symptoms the renal and cardiovascular effects of hyperuricemia are particularly relevant for the overall prognosis.

Gout--current diagnosis and treatment

BACKGROUND

Because of the changing dietary habits of an aging population, hyperuricemia is frequently found in combination with other metabolic disorders. Longstanding elevation of the serum uric acid level can lead to the deposition of monosodium urate crystals, causing gout (arthritis, urate nephropathy, tophi). In Germany, the prevalence of gouty arthritis is estimated at 1.4%, higher than that of rheumatoid arthritis. There are no German guidelines to date for the treatment of gout. Its current treatment is based largely on expert opinion.

METHODS

Selective literature review on the diagnosis and treatment of gout.

RESULTS AND CONCLUSIONS

Asymptomatic hyperuricemia is generally not an indication for pharmacological intervention to lower the uric acid level. When gout is clinically manifest, however, acute treatment of gouty arthritis should be followed by determination of the cause of hyperuricemia, and long-term treatment to lower the uric acid level is usually necessary. The goal of treatment is to diminish the body's stores of uric acid crystal deposits (the intrinsic uric acid pool) and thereby to prevent the inflammatory processes that they cause, which lead to structural alterations. In the long term, serum uric acid levels should be kept below 360 micromol/L (6 mg/dL). The available medications for this purpose are allopurinol and various uricosuric agents, e.g., benzbromarone. There is good evidence to support the treatment of gouty attacks by the timely, short-term use of non-steroidal anti-inflammatory drugs (NSAID), colchicine, and glucocorticosteroids.