Suprofen-induced uricosuria. A potential mechanism for acute nephropathy and flank pain

The Pharmacodynamics, Pharmacokinetics, and Safety of Arhalofenate in Combination with Febuxostat When Treating Hyperuricemia Associated with Gout

Objective.

Arhalofenate (ARH), in development for gout, has uricosuric and anti-flare activities. ARH plus febuxostat (FBX) were evaluated in subjects with gout for serum uric acid (SUA) lowering, drug interaction, and safety.

Methods.

Open phase II trial in gout volunteers (NCT02252835). Cohort 1 received ARH 600 mg for 2 weeks, followed by sequential 1-week co-administration of FBX 80 mg followed by 40 mg. FBX 40 mg was continued alone for 2 weeks. Cohort 2 received ARH 800 mg for 2 weeks, followed by sequential 1-week co-administration of FBX 40 mg followed by 80 mg. FBX 80 mg was continued alone for 2 weeks. SUA, its fractional excretion (FEUA), and plasma oxypurines were assessed. Pharmacokinetics of FBX and ARH were determined alone and in combination for cohort 2.

Results.

Baseline mean SUA was 9.4 mg/dl for cohort 1 (n = 16) and 9.2 mg/dl for cohort 2 (n = 16). The largest SUA decrease (63%) was observed with ARH 800 mg + FBX 80 mg, with all subjects reaching SUA < 6 mg/dl and 93% < 5 mg/dl. The area under the curve (AUC)(0-t)of ARH acid + FBX/ARH acid was 108%. The AUC(0-t)of FBX + ARH acid/FBX was 87%. As expected, FBX increased oxypurines and increases were unaffected by ARH co-administration. Baseline FEUA were low (3.5%–4.6%) and ARH increased them toward normal without overexcretion of UA. ARH was well tolerated and appeared safe.

Conclusion.

ARH and FBX lowered SUA by complementary mechanisms. The combination provided greater decreases than each drug alone. The combination was well tolerated and appeared safe. Trial registration:NCT02252835.

Comparison of iothalamate clearance methods for measuring GFR

STUDY OBJECTIVE

To evaluate the bias and precision of three methods of measuring glomerular filtration rate (GFR) relative to a standard method.

DESIGN

Prospective, outpatient study.

SETTING

University-affiliated general clinical research center.

PATIENTS

Twenty-six patients with various degrees of renal function (GFR range 25-151 ml/min/1.73 m2).

INTERVENTIONS

Each patient received iothalamate twice during the study visit, first as a bolus injection and then as a priming dose followed by a constant-rate infusion for 2.5 hours.

MEASUREMENTS AND MAIN RESULTS

Plasma (ClpIVB) and renal clearances (ClrIVB) after bolus injection and plasma clearance during constant-rate infusion (ClpINF) were compared with standard renal clearance during constant-rate infusion (ClrINF). All three measures were highly correlated with ClrINF (r>0.90, p<0.001). The mean ClrIVB was not significantly different from ClrINF (106.3+/-30.4 vs 104.2+/-28.5 ml/min/1.73 m2) and provided a precise (8.8%, 95% CI 6.5-11.1%) and unbiased measure of GFR. Both ClpIVB and ClpINF were positively biased; values exceeded ClrINF by 11.8+/-11.1 (p=0.0001) and 10.5+/-12.5 ml/min/1.73 m2 (p=0.0003), respectively. Use of a nonrenal correction factor of 9.8 and 10.5 ml/min/1.73 m2 for infusion and bolus plasma clearance values, respectively, eliminated bias and improved the precision of these methods.

CONCLUSIONS

Iothalamate renal clearance after bolus injection is a simple, accurate, and precise measurement of GFR and may be a useful alternative to the standard infusion method in clinical investigations. The corrected plasma clearance provides a simple index of GFR for clinical practice.

The effects of eprosartan, an angiotensin II AT1 receptor antagonist, on uric acid excretion in patients with mild to moderate essential hypertension

The effects of antihypertensive agents, including angiotensin II receptor antagonists, on urine uric acid excretion may have important clinical consequences. Therefore, the effects of single and repeated doses of eprosartan on uric acid excretion were evaluated in 57 male patients with mild-to-moderate essential hypertension in a double-blind, randomized, placebo-controlled, repeated dose, dose-rising, two-period, period-balanced, crossover study conducted in two parts. In part 1 (n = 33), the effects of eprosartan dose regimens of 50 mg, 100 mg, and 350 mg once daily and 150 mg every 12 hours on uric acid excretion were assessed. In part 2 (n = 24), the effects of eprosartan dose regimens of 600 mg, 800 mg, and 1,200 mg once daily on uric acid excretion were assessed. Eprosartan was well tolerated. There were no appreciable changes from predose values in fractional excretion of uric acid (FEua), urine uric acid excretion, urine uric acid to creatinine (Uua/Ucr) ratios, or serum uric acid concentrations after single or repeated doses of eprosartan. Mean Uua/Ucr ratios for eprosartan doses of 50 mg, 100 mg, or 350 mg daily or 150 mg every 12 hours were comparable to those for placebo. Mean FEua values and Uua/Ucr ratios for eprosartan doses of 600 mg, 800 mg, or 1,200 mg daily also were comparable to those for placebo. Single and repeated oral doses of eprosartan ranging from 50 mg to 1,200 mg daily had no effect on serum uric acid concentrations or urine uric acid excretion in patients with mild-to-moderate essential hypertension.

Effects of suprofen on the isolated perfused rat kidney

Although suprofen has been associated with the development of acute renal failure in greater than 100 subjects, the mechanism of damage remains unclear. The direct nephrotoxic effects of a single dose of 15 mg of suprofen were compared in the recirculating isolated rat kidney perfused with cell-free buffer with or without the addition of 5 mg/dL of uric acid. There were no significant differences in renal sodium excretion, oxygen consumption, or urinary flow rates in kidneys perfused with suprofen compared with the drug-free control groups. In contrast, a significant decline in glomerular filtration rate was found after the introduction of suprofen to the kidney perfused with uric acid; no changes were found with suprofen in the absence of uric acid. A significant decrease in the baseline excretion rate of uric acid was found in rats given suprofen, compared with drug-free controls. However, the fractional excretion of uric acid was unchanged between the groups over the experimental period. In summary, suprofen causes acute declines in renal function, most likely by directly altering the intrarenal distribution of uric acid.

The effects of lovastatin in hyperlipidemic patients with the nephrotic syndrome

Hypercholesterolemia may pose a substantial risk for cardiovascular disease. The present investigation was designed to evaluate the safety and efficacy of the cholesterol synthesis inhibitor, lovastatin, in 13 nephrotic patients with 5.6 +/- 0.7 g/24 h of albuminuria. All patients were maintained on a low cholesterol diet throughout the study. After a 4-week placebo period, lovastatin was administered, 20 mg twice daily for 6 weeks. Lovastatin reduced total cholesterol by 27% from 8.6 +/- 0.6 mmol/L (331 +/- 24 mg/dL) to 6.3 +/- 0.4 mmol/L (242 +/- 17 mg/dL) (P less than 0.01), low-density lipoprotein cholesterol by 27%, from 5.8 +/- 0.5 mmol/L (223 +/- 20 mg/dL) to 4.2 +/- 0.6 mmol/L (163 +/- 22 mg/dL) (P less than 0.01), and apolipoprotein B by 29%, from 153 +/- 12 mg/dL to 109 +/- 8 mg/dL to 109 +/- 8 mg/dL P less than 0.01). Triglycerides and very-low-density lipoprotein (VLDL) cholesterol levels were also reduced by 30% and 37%, respectively (P less than 0.01). High-density lipoprotein (HDL) cholesterol, and apolipoproteins A-1 and A-2 were not significantly altered. Renal function and urine protein excretion were not affected by lovastatin. Although one patient developed diarrhea and discontinued treatment before completing 6 weeks of lovastatin, the other 12 patients had no adverse effects. In this short-term study, lovastatin therapy had few side effects and had favorable effects on the lipoprotein profile of nephrotic syndrome patients.