First human dose-escalation study with remogliflozin etabonate, a selective inhibitor of the sodium-glucose transporter 2 (SGLT2), in healthy subjects and in subjects with type 2 diabetes mellitus.

BACKGROUND: Remogliflozin etabonate (RE) is the prodrug of remogliflozin, a selective inhibitor of the renal sodium-dependent glucose transporter 2 (SGLT2), which could increase urine glucose excretion (UGE) and lower plasma glucose in humans. METHODS: This double-blind, randomized, placebo-controlled, single-dose, dose-escalation, crossover study is the first human trial designed to evaluate safety, tolerability, pharmacokinetics (PK) and pharmacodynamics of RE. All subjects received single oral doses of either RE or placebo separated by approximately 2 week intervals. In Part A, 10 healthy subjects participated in 5 dosing periods where they received RE (20 mg, 50 mg, 150 mg, 500 mg, or 1000 mg) or placebo (4:1 active to placebo ratio per treatment period). In Part B, 6 subjects with type 2 diabetes mellitus (T2DM) participated in 3 dose periods where they received RE (50 mg and 500 mg) or placebo (2:1 active to placebo per treatment period). The study protocol was registered with the NIH clinical trials data base with identifier NCT01571661. RESULTS: RE was generally well-tolerated; there were no serious adverse events. In both populations, RE was rapidly absorbed and converted to remogliflozin (time to maximum plasma concentration [Cmax;Tmax] approximately 1 h). Generally, exposure to remogliflozin was proportional to the administered dose. RE was rapidly eliminated (mean T½ of ~25 min; mean plasma T½ for remogliflozin was 120 min) and was independent of dose. All subjects showed dose-dependent increases in 24-hour UGE, which plateaued at approximately 200 to 250 mmol glucose with RE doses ≥150 mg. In T2DM subjects, increased plasma glucose following OGTT was attenuated by RE in a drug-dependent fashion, but there were no clear trends in plasma insulin. There were no apparent effects of treatment on plasma or urine electrolytes. CONCLUSIONS: The results support progression of RE as a potential treatment for T2DM. TRIAL REGISTRATION: ClinicalTrials.gov NCT01571661.

Toxicity and toxicokinetics of metformin in rats.

Metformin is a first-line drug for the treatment of type 2 diabetes (T2D) and is often prescribed in combination with other drugs to control a patient's blood glucose level and achieve their HbA1c goal. New treatment options for T2D will likely include fixed dose combinations with metformin, which may require preclinical combination toxicology studies. To date, there are few published reports evaluating the toxicity of metformin alone to aid in the design of these studies. Therefore, to understand the toxicity of metformin alone, Crl:CD(SD) rats were administered metformin at 0, 200, 600, 900 or 1200 mg/kg/day by oral gavage for 13 weeks. Administration of > or =900 mg/kg/day resulted in moribundity/mortality and clinical signs of toxicity. Other adverse findings included increased incidence of minimal necrosis with minimal to slight inflammation of the parotid salivary gland for males given 1200 mg/kg/day, body weight loss and clinical signs in rats given > or =600 mg/kg/day. Metformin was also associated with evidence of minimal metabolic acidosis (increased serum lactate and beta-hydroxybutyric acid and decreased serum bicarbonate and urine pH) at doses > or =600 mg/kg/day. There were no significant sex differences in mean AUC(0-24) or C(max) nor were there significant differences in mean AUC(0-24) or C(max) following repeated dosing compared to a single dose. The no observable adverse effect level (NOAEL) was 200 mg/kg/day (mean AUC(0-24)=41.1 microg h/mL; mean C(max)=10.3 microg/mL based on gender average week 13 values). These effects should be taken into consideration when assessing potential toxicities of metformin in fixed dose combinations.

An automated method for the determination of montelukast in human plasma using dual-column HPLC analysis and peak height summation of the parent compound and its photodegradation product.

PURPOSE: To develop an assay to evaluate the bioequivalence of overcoated and marketed montelukast formulations, the former to be used for future blinded clinical studies. METHODS: The method used automated 96-well sample preparation and dual-column HPLC analysis for increased throughput. Regression analysis was performed using the total peak height of montelukast and its photodegradent, a cis-ethenyl geometric isomer. This approach successfully compensated for montelukast's light sensitivity, allowing both clinical specimen handling and bioanalytical laboratory analysis to be conducted without extensive precautions being taken to protect samples from UV light. To ensure a molar equivalent fluorescence response between the cis (Z) and trans (E) isomers, the emission wavelength and detector attenuation were both increased just prior to the elution of the montelukast peak (i.e., the trans isomer), effectively dampening the response of the stronger fluorophore. Plasma proteins were precipitated using acetonitrile, and 50 microl of supernatant was injected onto an HPLC system consisting of two C18 analytical columns connected to a 10-port switching valve. Injections were overlapped on alternating columns allowing twice as many samples to be processed during each analytical run. RESULTS: The calibration curve was linear from 5 to 2000 ng ml(-1). The inter-day and intra-day precision expressed as coefficient of variation (%CV), were 1.1-6.1% and 3.1-6.7%, respectively. The accuracy, reported as percentage bias, was less than or equal to +/-9.1%. The absolute recovery was determined to be 94.3% and 98.1% at 15 and 1500 ng ml(-1), respectively. CONCLUSIONS: This assay represents a rapid, accurate, and sensitive method for the determination of montelukast in human plasma. The method has been successfully used to demonstrate the bioequivalence of the overcoated montelukast formulations to their equivalent marketed tablets.

Equivalent steady-state pharmacokinetics of lamivudine in plasma and lamivudine triphosphate within cells following administration of lamivudine at 300 milligrams once daily and 150 milligrams twice daily.

Once-daily administration of 300 mg of lamivudine in combination with other antiretroviral agents has been proposed as a possible way to optimize anti-human immunodeficiency virus (HIV) treatment and to facilitate adherence. A single-center, randomized, two-way, crossover study was conducted in 60 healthy subjects to compare the steady-state pharmacokinetics of lamivudine in plasma and its putative active anabolite, lamivudine 5'-triphosphate (lamivudine-TP), in peripheral blood mononuclear cells (PBMCs) following 7 days of treatment with lamivudine at 300 mg once daily and 7 days of the standard regimen of 150 mg twice daily. Serial blood samples were collected over 24 h for determination of plasma lamivudine concentrations by liquid chromatography-mass spectrometry and intracellular lamivudine-TP concentrations in peripheral blood mononuclear cells by high-performance liquid chromatography/radioimmunoassay methods. Pharmacokinetic parameters were calculated based on lamivudine and lamivudine-TP concentration-time data. Regimens were considered bioequivalent if 90% confidence intervals (CI) for the ratio (once daily/twice daily) of geometric least-squares (GLS) means for lamivudine and lamivudine-TP pharmacokinetic values fell within the acceptance range of 0.8 to 1.25. Steady-state plasma lamivudine pharmacokinetics following the once- and twice-daily regimens were bioequivalent with respect to the area under the drug concentration-time curve from 0 to 24 h at steady state (AUC(24,ss)) (GLS mean ratio, 0.94; 90% CI, 0.92, 0.97) and average plasma lamivudine concentration over the dosing interval (C(ave,ss)) (GLS mean ratio, 0.94; 90% CI, 0.92, 0.97). Steady-state intracellular lamivudine-TP pharmacokinetics after the once- and twice-daily regimens were bioequivalent with respect to AUC(24,ss) (GLS mean ratio, 0.99; 90% CI, 0.88, 1.11), C(ave,ss) (GLS mean ratio, 0.99; 90% CI, 0.88, 1.11), and maximum lamivudine concentration (C(max,ss)) (GLS mean ratio, 0.93; 90% CI, 0.81, 1.07). Lamivudine-TP trough concentrations were modestly lower (by 18 to 24%) during the once-daily regimen; the clinical importance of this is unclear, given the large intersubject variability in values that was observed (coefficient of variation, 48 to 124%). Once-daily lamivudine was as well tolerated as the twice-daily regimen. Overall, the results of this study suggest that for key AUC-related parameters, lamivudine at 300 mg once daily is pharmacokinetically equivalent to lamivudine at 150 mg twice daily.