Exploring glycosuria as a mechanism for weight and fat mass reduction. A pilot study with remogliflozin etabonate and sergliflozin etabonate in healthy obese subjects.

Inhibitors of sodium-dependent glucose co-transporter 2 (SGLT2) increase glucose excretion in the urine and improve blood glucose in Type 2 diabetes mellitus. Glycosuria provides an energy and osmotic drain that could alter body composition. We therefore conducted a pilot study comparing the effects on body composition of two SGLT2 inhibitors, remogliflozin etabonate (RE) 250 mg TID (n = 9) and sergliflozin etabonate (SE) (1000 mg TID) (n = 9), with placebo (n = 12) in obese non-diabetic subjects. Both drugs were well tolerated during 8 weeks of dosing, and the most common adverse event was headache. No urinary tract infections were observed, but there was one case of vaginal candidiasis in the RE group. As expected, RE and SE increased urine glucose excretion, with no change in the placebo group. All the subjects lost weight over 8 weeks, irrespective of treatment assignment. There was a reduction in TBW measured by D2O dilution in the RE group that was significantly greater than placebo (1.4 kg, p = 0.029). This was corroborated by calculation of fat-free mass using a quantitative magnetic resonance technique. All but one subject had a measurable decrease in fat mass. There was significant between-subject variability of weight and fat loss, and no statistically significant differences were observed between groups. Despite a lack of a difference in weight and fat mass loss, the leptin/adiponectin ratio, a measure of insulin resistance, was significantly decreased in the RE group when compared to placebo and SE, suggesting that this SGTL-2 inhibitor may improve metabolic health independent of a change in fat mass.

Reduced T2* values in soleus muscle of patients with type 2 diabetes mellitus.

Tissue water transverse relaxation times (T2) are highly sensitive to fluid and lipid accumulations in skeletal muscles whereas the related T2* is sensitive to changes in tissue oxygenation in addition to factors affecting T2. Diabetes mellitus (DM) affects muscles of lower extremities progressively by impairing blood flow at the macrovascular and microvascular levels. This study is to investigate whether T2 and T2* are sensitive enough to detect abnormalities in skeletal muscles of diabetic patients in the resting state. T2 and T2* values in calf muscle of 18 patients with type 2 DM (T2DM), 22 young healthy controls (YHC), and 7 age-matched older healthy controls (OHC) were measured at 3T using multi-TE spin echo and gradient echo sequences. Regional lipid levels of the soleus muscle were also measured using the Dixon method in a subset of the subjects. Correlations between T2, T2*, lipid levels, glycated hemoglobin (HbA1c) and presence of diabetes were evaluated. We found that T2 values were significantly higher in calf muscles of T2DM subjects, as were T2* values in anterior tibialis, and gastrocnemius muscles of T2DM participants. However, soleus T2* values of the T2DM subjects were significantly lower than those of the older, age-matched HC cohort (22.9±0.5 vs 26.7±0.4 ms, p<0.01). The soleus T2* values in the T2DM cohort were inversely correlated with the presence of diabetes (t = -3.46, p<0.001) and with an increase in HbA1c, but not with body mass index or regional lipid levels. Although multiple factors may contribute to changes in T2* values, the lowered T2* value observed in the T2DM soleus muscle is most consistent with a combination of high oxygen consumption and poor regional perfusion. This finding is consistent with results of previous perfusion studies and suggests that the soleus in individuals with T2DM is likely under tissue oxygenation stress.

Assessment of acute and chronic pharmacological effects on energy expenditure and macronutrient oxidation in humans: responses to ephedrine.

Evidence of active brown adipose tissue in human adults suggests that this may become a pharmacological target to induce negative energy balance. We have explored whole-body indirect calorimetry to detect the metabolic effects of thermogenic drugs through administration of ephedrine hydrochloride and have assessed ephedrine's merits as a comparator compound in the evaluation of novel thermogenic agents. Volunteers randomly given ephedrine hydrochloride 15 mg QID (n = 8) or placebo (n = 6) were studied at baseline and after 1-2 and 14-15 days of treatment. We demonstrate that overnight or 23-hour, 2% energy expenditure (EE) and 5% fat (FO) or CHO oxidation effects are detectable both acutely and over 14 days. Compared to placebo, ephedrine increased EE and FO rates overnight (EE 63 kJ day 2, EE 105 kJ, FO 190 kJ, day 14), but not over 23 h. We conclude that modest energy expenditure and fat oxidation responses to pharmacological interventions can be confidently detected by calorimetry in small groups. Ephedrine should provide reliable data against which to compare novel thermogenic compounds.

Multiple-dose pharmacokinetics and pharmacodynamics of sergliflozin etabonate, a novel inhibitor of glucose reabsorption, in healthy overweight and obese subjects: a randomized double-blind study.

Sergliflozin, the active entity of sergliflozin etabonate, is a selective inhibitor of the sodium-dependent glucose cotransporter-2 in the renal tubule. The pharmacokinetics and pharmacodynamics of sergliflozin were examined during administration of sergliflozin etabonate (500 or 1000 mg) or placebo 3 times daily (tid) for 14 days in healthy overweight or obese human volunteers (n = 18). At the doses tested, sergliflozin showed less than dose-proportional pharmacokinetic characteristics. Mean half-life of the active entity was approximately 2 hours; there was no evidence of drug accumulation. Sergliflozin etabonate produced rapid and sustained suppression of renal glucose reabsorption, resulting in a dose-related glucosuria, and a transient increase in urinary electrolyte and fluid loss; plasma glucose, insulin, and electrolyte levels were unchanged. Sergliflozin etabonate produced a rapid, dose-related reduction in body weight (mean changes of -0.09, -1.55, and -1.74 kg from baseline to day 15 with placebo, sergliflozin etabonate 500 mg, and sergliflozin etabonate 1000 mg, respectively), apparently through increased urinary calorie loss rather than through osmotic diuresis. Sergliflozin etabonate 500 or 1000 mg tid was generally well tolerated; no clinically significant adverse events were identified. Renal function (creatinine clearance) was not affected by sergliflozin etabonate, although urinary microalbumin, N-acetyl-beta-D-glucosaminidase, and beta(2)-microglobulin levels tended to increase.

Single-dose pharmacokinetics and pharmacodynamics of sergliflozin etabonate, a novel inhibitor of glucose reabsorption, in healthy volunteers and patients with type 2 diabetes mellitus.

Sergliflozin, the active entity of sergliflozin etabonate, is a selective inhibitor of sodium-dependent glucose cotransporter 2 (SGLT2). The pharmacokinetics and pharmacodynamics of sergliflozin were evaluated following single oral dose administration of sergliflozin etabonate (5-500 mg) in healthy volunteers (n = 22) and patients with type 2 diabetes mellitus (n = 8). The prodrug was rapidly and extensively converted to sergliflozin; the latter displayed linear kinetics, reached maximum plasma concentrations at approximately 30 to 45 minutes postdose (t(max)), and had a plasma elimination half-life (t(1/2)) of approximately 0.5 to 1 hour. Both prodrug and active entity showed low glomerular filtration and/or extensive renal tubular reabsorption, with <0.5% of the administered dose being recovered in the urine. In both populations, sergliflozin etabonate produced a dose-related glucosuria under fasting conditions and following glucose loading but did not appreciably affect urinary electrolyte excretion or fluid balance. The magnitude and duration of the glucosuric effect closely paralleled plasma sergliflozin concentrations. Sergliflozin did not significantly affect fasting plasma glucose levels but produced transient attenuation of the plasma glucose AUC following glucose challenge. Single doses of sergliflozin etabonate 5 to 500 mg were well tolerated, and there were no clinically significant adverse laboratory findings.

Quantitative magnetic resonance (QMR) for longitudinal evaluation of body composition changes with two dietary regimens.

We have recently reported a validation study of a prototype low-field strength quantitative magnetic resonance (QMR) instrument for measurement of human body composition (EchoMRI-AH). QMR was very precise, but underreported fat mass (FM) by 2-4 kg when compared to a 4-compartment (4C) model in this cross-sectional study. Here, we report the performance of an updated instrument in two longitudinal studies where FM was decreasing. Healthy obese volunteers were given a modest energy deficit diet for 8 weeks (study A) and obese patients with heart failure and/or at high cardiovascular risk were prescribed a low energy liquid diet for 6 weeks (study B). FM was measured at the start and end of these periods by QMR, dual-energy X-ray absorptiometry (DXA) and 4C. A higher proportion of the weight lost came from fat in study A compared with study B, where loss of total body water (TBW) played a greater part. The intraclass correlation between QMR and 4C estimates of FM loss (DeltaFat) was 0.95, but 20 of 22 estimates of DeltaFat by QMR were lower than the corresponding estimate by the 4C model. Bland-Altman analysis demonstrated that estimates of FM loss by QMR were ~1.0 and 0.7 kg lower than those obtained with 4C (P = 0.0008) and DXA (P = 0.049), respectively. Measurement precision remained high. QMR measurement should prove valuable for quantifying modest changes of FM in small trials.

Regional hemodynamic effects of the N-(2-benzoylphenyl)-L-tyrosine peroxisome proliferator-activated receptor-gamma ligand, GI 262570 [(S)-2-(2-benzoylphenylamino)-3-[4-[2-(5-methyl-2-phenyl-2-oxazol-4-yl)ethoxy]phenyl]propionic acid], in conscious rats.

This study provides novel data on the regional hemodynamic effects of the peroxisome proliferator-activated receptor-gamma activator, GI 262570 [(S)-2-(2-benzoylphenylamino)-3-[4-[2-(5-methyl-2-phenyl-2-oxazol-4-yl)ethoxy]phenyl]propionic acid], in conscious, male Sprague-Dawley rats. Administration of GI 262570 twice daily for 4 days caused a slowly developing, modest fall in mean arterial blood pressure, associated with a progressive, hyperemic hindquarters vasodilatation, but with no consistent changes in renal or mesenteric hemodynamics. The hindquarters vasodilator effect of GI 262570 was not inhibited by the beta2-adrenoceptor antagonist, ICI 118551 ((+/-)-1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxy]-3-[(1-methylethyl) amino]-2-butanol hydrochloride), and was still apparent in the presence of the alpha-adrenoceptor antagonist, phentolamine. Neither the latter, nor antagonism of angiotensin (AT1) and endothelin (ETA and ETB) receptors unmasked vasodilator responses to GI 262570 in the renal or mesenteric vascular beds. In the presence of GI 262570, vasodilator responses to acetylcholine and vasoconstrictor responses to methoxamine were normal. Furthermore, the cardiovascular responses to nonselective nitric-oxide synthase inhibition were not influenced by GI 262570. Collectively, these results indicate that the vasodilator action of GI 262570 is specific to the hindquarters vascular bed (of those studied), does not involve alpha- or beta2-adrenoceptors, and is not associated with a change in basal or stimulated nitric oxide release.

alpha-Tropomyosin mutations Asp(175)Asn and Glu(180)Gly affect cardiac function in transgenic rats in different ways.

To study the mechanisms by which missense mutations in alpha-tropomyosin cause familial hypertrophic cardiomyopathy, we generated transgenic rats overexpressing alpha-tropomyosin with one of two disease-causing mutations, Asp(175)Asn or Glu(180)Gly, and analyzed phenotypic changes at molecular, morphological, and physiological levels. The transgenic proteins were stably integrated into the sarcomere, as shown by immunohistochemistry using a human-specific anti-alpha-tropomyosin antibody, ARG1. In transgenic rats with either alpha-tropomyosin mutation, molecular markers of cardiac hypertrophy were induced. Ca(2+) sensitivity of cardiac skinned-fiber preparations from animals with mutation Asp(175)Asn, but not Glu(180)Gly, was decreased. Furthermore, elevated frequency and amplitude of spontaneous Ca(2+) waves were detected only in cardiomyocytes from animals with mutation Asp(175)Asn, suggesting an increase in intracellular Ca(2+) concentration compensating for the reduced Ca(2+) sensitivity of isometric force generation. Accordingly, in Langendorff-perfused heart preparations, myocardial contraction and relaxation were accelerated in animals with mutation Asp(175)Asn. The results allow us to propose a hypothesis of the pathogenetic changes caused by alpha-tropomyosin mutation Asp(175)Asn in familial hypertrophic cardiomyopathy on the basis of changes in Ca(2+) handling as a sensitive mechanism to compensate for alterations in sarcomeric structure.