The effect for hyperuricemia inpatient of uric acid overproduction type or in combination with topiroxostat on the pharmacokinetics, pharmacodynamics and safety of dotinurad, a selective urate reabsorption inhibitor

BACKGROUND

Dotinurad, a novel selective urate reabsorption inhibitor (SURI), increases urinary uric acid excretion. The aim of this study is to examine the pharmacokinetics, pharmacodynamics, and safety of dotinurad according to the type of hyperuricemia, with or without concomitant use of xanthine oxidase inhibitor, in uric acid "overproduction type" patients.

METHODS

This open-label clinical pharmacology study was conducted in a hospital. Dotinurad 1 mg was administered for 7 days to hyperuricemic patients with uric acid "overproduction type" (overproduction group, n = 6; and combination group, n = 6) and uric acid "underexcretion type" (underexcretion group, n = 6). In the combination group, topiroxostat 80 mg was used concomitantly.

RESULTS

No significant differences were observed in pharmacokinetics and safety between overproduction group and underexcretion group, and the percent change in serum uric acid level and the amount of urinary uric acid excretion after administration were comparable. In "overproduction type" patients of combination group, the percent change in serum uric acid level significantly increased and the amount of urinary uric acid excretion significantly decreased compared to those of overproduction group. No clinically meaningful differences were observed in safety between the overproduction group and the combination group.

CONCLUSION

In inpatients, differences in hyperuricemic type did not significantly influence the pharmacokinetics, pharmacodynamics, and safety of dotinurad. Moreover, in "overproduction type", the coadministration of dotinurad and topiroxostat had an add-on serum uric acid lowering effect and suppressed urinary uric acid excretion.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02837198.

A clinical pharmacology study of the novel, selective urate reabsorption inhibitor dotinurad in outpatients

BACKGROUND

Dotinurad is a novel, selective urate reabsorption inhibitor (SURI), which reduces serum uric acid levels by selective inhibition of the urate transporter 1 (URAT1). The Japanese guideline for the management of hyperuricemia and gout recommends that drug selection should be based on classification of hyperuricemia as a fundamental principle. However, there may be some cases where this principle is not observed. We investigated the pharmacodynamics and safety of dotinurad in outpatients with uric acid overproduction or uric acid underexcretion type.

METHODS

This was a multicenter, open-label, forced titration study. Patients were classified as uric acid overproduction or underexcretion type. Study treatment was initiated at 0.5 mg/day, followed by dose titration to the estimated maximum dose of 4 mg/day over 14 weeks. The primary endpoint was urinary uric acid excretion at each 24-h urine collection.

RESULTS

A total of 26 hyperuricemic patients with or without gout were enrolled in the study and assigned to the uric acid overproduction group (overproduction group) or the uric acid underexcretion group (underexcretion group). Although urinary uric acid excretion, the primary endpoint, tended to be slightly greater in the overproduction group, no notable difference was noted between the two hyperuricemic types. Neither type had noteworthy safety concerns associated with dotinurad.

CONCLUSION

The results of the study demonstrated no relevant differences between the hyperuricemic types in terms of pharmacodynamic action and safety of dotinurad.

Dotinurad versus benzbromarone in Japanese hyperuricemic patient with or without gout: a randomized, double-blind, parallel-group, phase 3 study

Background

Dotinurad is a novel selective urate reabsorption inhibitor that reduces serum urate levels in hyperuricemic patients with or without gout by selectively inhibiting urate transporter 1. This study was conducted to compare the efficacy and safety of dotinurad with those of benzbromarone.

Methods

In this 14-week, randomized, multicenter, double-blind, parallel-group, dose escalation, benzbromarone-controlled, phase 3 study, hyperuricemic patients with or without gout were randomized to two groups that received either dotinurad 2 mg or benzbromarone 50 mg. Dotinurad or benzbromarone was administered once a day for 14 weeks. The primary endpoint was the percent change in serum uric acid level from the baseline to the final visit.

Results

A total of 201 Japanese hyperuricemic patients with or without gout (dotinurad: 102, benzbromarone: 99) received at least one dose of the study drug. The mean percent change in serum uric acid level from the baseline to the final visit in the dotinurad and benzbromarone groups was 45.9% and 43.8%, respectively. Non-inferiority of dotinurad 2 mg to benzbromarone 50 mg in lowering serum uric acid was verified by the predefined non-inferiority margin (95% CI − 1.27 to 5.37%). The incidence of adverse events and adverse drug reactions was comparable between the two groups.

Conclusion

Dotinurad 2 mg was verified to have a non-inferior serum uric acid lowering effect compared with benzbromarone 50 mg, in Japanese hyperuricemic patients with or without gout.

ClinicalTrials.gov Identifier

NCT03100318.

Gout, Hyperuricemia, and Crystal-Associated Disease Network Consensus Statement Regarding Labels and Definitions for Disease Elements in Gout

OBJECTIVE

The language currently used to describe gout lacks standardization. The aim of this project was to develop a consensus statement on the labels and definitions used to describe the basic disease elements of gout.

METHODS

Experts in gout (n = 130) were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach consensus on the labeling and definitions for the basic disease elements of gout. Disease elements and labels in current use were derived from a content analysis of the contemporary medical literature, and the results of this analysis were used for item selection in the Delphi exercise and face-to-face consensus meeting.

RESULTS

There were 51 respondents to the Delphi exercise and 30 attendees at the face-to-face meeting. Consensus agreement (≥80%) was achieved for the labels of 8 disease elements through the Delphi exercise; the remaining 3 labels reached consensus agreement through the face-to-face consensus meeting. The agreed labels were monosodium urate crystals, urate, hyperuric(a)emia, tophus, subcutaneous tophus, gout flare, intercritical gout, chronic gouty arthritis, imaging evidence of monosodium urate crystal deposition, gouty bone erosion, and podagra. Participants at the face-to-face meeting achieved consensus agreement for the definitions of all 11 elements and a recommendation that the label "chronic gout" should not be used.

CONCLUSION

Consensus agreement was achieved for the labels and definitions of 11 elements representing the fundamental components of gout etiology, pathophysiology, and clinical presentation. The Gout, Hyperuricemia, and Crystal-Associated Disease Network recommends the use of these labels when describing the basic disease elements of gout.

Autosomal dominant tubulointerstitial kidney disease: diagnosis, classification, and management--A KDIGO consensus report

Rare autosomal dominant tubulointerstitial kidney disease is caused by mutations in the genes encoding uromodulin (UMOD), hepatocyte nuclear factor-1β (HNF1B), renin (REN), and mucin-1 (MUC1). Multiple names have been proposed for these disorders, including 'Medullary Cystic Kidney Disease (MCKD) type 2', 'Familial Juvenile Hyperuricemic Nephropathy (FJHN)', or 'Uromodulin-Associated Kidney Disease (UAKD)' for UMOD-related diseases and 'MCKD type 1' for the disease caused by MUC1 mutations. The multiplicity of these terms, and the fact that cysts are not pathognomonic, creates confusion. Kidney Disease: Improving Global Outcomes (KDIGO) proposes adoption of a new terminology for this group of diseases using the term 'Autosomal Dominant Tubulointerstitial Kidney Disease' (ADTKD) appended by a gene-based subclassification, and suggests diagnostic criteria. Implementation of these recommendations is anticipated to facilitate recognition and characterization of these monogenic diseases. A better understanding of these rare disorders may be relevant for the tubulointerstitial fibrosis component in many forms of chronic kidney disease.

[Definition and classification of hyperuricemia]

Hyperuricemia (serum urate level >7 mg/dL) is caused by accelerated generation of uric acid and/or impaired excretion in the kidney. It is classified into three types (overproduction, underexcretion and mixed types). The typical cases with the type of uric acid overproduction are hypoxanthine guanine phosphoribosyl transferase deficiency due to HPRT gene abnormality, excessive consumption of purine-rich diet, and cytolysis induced by chemotherapy for blood neoplasm, those with the type of underexcretion are familial juvenile hyperuricemic nephropathy due to uromodulin gene abnormality and abrupt body weight loss due to low calorie diet, and those with the mixed type are glucose 6-phosphatase deficiency due to glucose 6-phosphatase gene abnormality and excessive consumption of alcohol beverages.

[Pathophysiology and treatment of secondary hyperuricemia]

Hyperuricemia caused secondly from acquired disorders which affect production or excretion of uric acid is defined as secondary hyperuricemia. Many conditions are associated with this type of hyperuricemia and are classified into three types according to the underlying pathophysiology, including accelerated purine nucleotide degradation, ATP breakdown and purine de novo biosynthesis as overproductive type, use of drugs affecting renal urate handling and renal insufficiency as underexcretion type, or overintake of alcohol or fructose as mixed type. Determining uric acid clearance and urate excretion is important for pointing out original disorder; however, sometimes the result from correcting causal factor should be waited for to fix up a final diagnosis. Anti-hyperuricemia agents are used according to the pathophysiology.

[Primary hyperuricemia due to decreased renal uric acid excretion]

Hyperuricemia reflects extracellular fluid supersaturation for uric acid. Although dietary, genetic, or disease-related excesses in urate production underlie hyperuricemia in some cases, impaired renal excretion of uric acid is the dominant cause of hyperuricemia. This type of hyperuricemia may be primary (idiopathic) and unassociated with an identifiable disorder. Two important candidates that may affect renal urate excretion were identified recently. One is an organic anion transporter (OAT) family member called urate transporter (URAT) 1. URAT1 has highly specific urate transport activity, exchanging this anion with others including most of the endogenous organic anions and drug anions that are known to affect renal uric acid transport. Another is uromodulin (UMOD), which is the key protein for the pathogenesis of familial juvenile hyperuricemic nephropathy that is characterized by early onset of hyperuricemia and renal failure. The role of these proteins in the cause of hyperuricemia is under investigation.

[Historical review of gout and hyperuricemia investigations]

Historical development of gout and hyperuricemia investigations was reviewed. Gout has been a recognized disease since the fifth century B.C. In 1683, Sydenham described the detailed clinical features of the disease based on his own condition. Leeuwenhoek (1679) first described crystals in a gouty tophus, which were identified as uric acid by Wollaston (1797). Since uric acid clearance of hyperuricemia was markedly lower than that in normal controls, early investigators considered that the main cause of hyperuricemia was urate underexcretion. However, in the 1940s, studies on uric acid metabolism using isotope tracer techniques demonstrated that a part of hyperuricemia resulted from urate overproduction, which was detected in approximately one-third of all gouty patients. In the 1970s, micropuncture, microinjection and microperfusion methods as well as stop-flow methods demonstrated that uric acid transports in nephron were suspected to consist of four steps, that were glomerular filtration, reabsorption, secretion and postsecretory reabsorption. The majority of filtrated uric acid was almost completely reabsorbed, followed by secretion and postsecretory reabsorption at a proximal site in the tubulus. Each proportion of transports to the glomerular filtration(100%) was estimated approximately 99%, 50% and 40%, respectively. Subsequently, about 10% of the filtrate was excreted in the urine. The authors (1999) suggested that the secretion rate of hyperuricemic patients was significantly lower than that of normal controls but postsecretory reabsorption was not. Therefore, the decrease in the secretion rate was suspected to be the main cause of underexcretion. Dunkan (1960) reported a family demonstrating hyperuricemia associated with severe renal damage that progressed rapidely. Currently, this disease is called familial juvenile hyperuricemic nephropathy (FJHN), and was recently found to be the result of a variation in uromodulin. Enomoto (2002) found a number of urate transporters in the cell surface of the tubulus, among which URAT1 was the most effective in reabsorbing urate from the tubulus lumen to the cells. The urate was released to the blood vessel side by the other transporter OAT. Therefore, URAT1 was suspected to be a cause of underexcretion. As the mechanism underlying overproduction of uric acid, de novo purine nucleotide synthesis has been shown to be increased. In some cases, the increase in de novo synthesis is the result of gene mutation in purine nucleotide synthesis enzymes, such as PRPP synthetase (Sperling, 1973) as well as hypoxanthine guanine phosphoribosylpyrophosphate synthetase (Seegmiller, 1967). However, the mechanism in majority of the overproduction has not yet been clarified and is currently under investigation.

[Uricosuric agent]

Urate lowering treatment is indicated in patients with recurrent acute attacks, tophi, gouty arthropathy, radiographic changes of gout, multiple joint involvement, or associated uric acid nephrolithiasis. Uricosuric agents like benzbromarone and probenecid are very useful to treat hyperuricemia as well as allopurinol (xanthine oxidase inhibitor). Uricosuric agents act the urate lowering effect through blocking the URAT1, an urate transporter, in brush border of renal proximal tubular cells. In order to avoid the nephrotoxicity and urolithiasis due to increasing of urinary urate excretion by using uricosuric agents, the proper urinary tract management (enough urine volume and correction of aciduria) should be performed.