Efficacy and safety of the glucagon receptor antagonist PF-06291874: A 12-week, randomized, dose-response study in patients with type 2 diabetes mellitus on background metformin therapy.

AIMS: To conduct a dose-response assessment of the efficacy and safety of the glucagon receptor antagonist PF-06291874 in adults with type 2 diabetes (T2DM) using stable doses of metformin. MATERIALS AND METHODS: This randomized, double-blind, statin-stratified, placebo-controlled, 4-arm, parallel-group study was conducted in patients with T2DM who were receiving background metformin. After an 8-week, non-metformin oral antidiabetic agent washout period, 206 patients were randomized to placebo or PF-06291874 (30, 60 or 100 mg once daily) for 12 weeks. Glycosylated haemoglobin (HbA1c), fasting plasma glucose (FPG) and safety endpoints were assessed at baseline and post baseline. RESULTS: Dose-dependent mean reductions from baseline in HbA1c for PF-06291874 ranged from -0.67% (-7.29 mmol/mol) to -0.93% (-10.13 mmol/mol), and for FPG from -16.6 to -33.3 mg/dL after 12 weeks of dosing. The incidence of hypoglycaemia was low and was similar between groups receiving PF-06291874 and placebo. Small, non-dose-dependent increases in LDL cholesterol (<10%) and blood pressure (BP) (systolic BP > 2 mm Hg; diastolic BP > 1 mm Hg) were observed with PF-06291874. Modest non-dose-dependent median increases were observed across PF-06291874 groups at 12 weeks for alanine aminotransferase (range, 37.6-48.7 U/L vs placebo) and aspartate aminotransferase (range, 33.3-36.6 U/L vs placebo); these were not associated with bilirubin changes. Small increases were observed in body weight (< 0.5 kg) in each PF-06291874 group vs placebo. CONCLUSIONS: In patients with T2DM, PF-06291874 significantly lowered HbA1c and glucose, was well tolerated and carried a low risk of hypoglycaemia. Small, non-dose-related increases in BP, lipids and hepatic transaminases were observed.

Investigation of pharmacokinetic drug interaction between clesacostat and DGAT2 inhibitor ervogastat in healthy adult participants.

Co-administration of clesacostat (acetyl-CoA carboxylase inhibitor, PF-05221304) and ervogastat (diacylglycerol O-acyltransferase inhibitor, PF-06865571) in laboratory models improved non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) end points and mitigated clesacostat-induced elevations in circulating triglycerides. Clesacostat is cleared via organic anion-transporting polypeptide-mediated hepatic uptake and cytochrome P450 family 3A (CYP3A); in vitro clesacostat is identified as a potential CYP3A time-dependent inactivator. In vitro ervogastat is identified as a substrate and potential inducer of CYP3A. Prior to longer-term efficacy trials in participants with NAFLD, safety and pharmacokinetics (PK) were evaluated in a phase I, non-randomized, open-label, fixed-sequence trial in healthy participants. In Cohort 1, participants (n = 7) received clesacostat 15 mg twice daily (b.i.d.) alone (Days 1-7) and co-administered with ervogastat 300 mg b.i.d. (Days 8-14). Mean systemic clesacostat exposures, when co-administered with ervogastat, decreased by 12% and 19%, based on maximum plasma drug concentration and area under the plasma drug concentration-time curve during the dosing interval, respectively. In Cohort 2, participants (n = 9) received ervogastat 300 mg b.i.d. alone (Days 1-7) and co-administered with clesacostat 15 mg b.i.d. (Days 8-14). There were no meaningful differences in systemic ervogastat exposures when administered alone or with clesacostat. Clesacostat 15 mg b.i.d. and ervogastat 300 mg b.i.d. co-administration was overall safe and well tolerated in healthy participants. Cumulative safety and no clinically meaningful PK drug interactions observed in this study supported co-administration of these two novel agents in additional studies exploring efficacy and safety in the management of NAFLD.

Metabolism and Excretion of Nirmatrelvir in Humans Using Quantitative Fluorine Nuclear Magnetic Resonance Spectroscopy: A Novel Approach for Accelerating Drug Development.

Typically human absorption, distribution, metabolism, and excretion (ADME) studies are executed using radiolabeled (e.g., carbon-14) material, the synthesis of which is a time-consuming activity. In this study, we were able to assess the metabolism and excretion of unlabeled nirmatrelvir (PF-07321332) within the first-in-human study via a novel application of quantitative fluorine (19 F) nuclear magnetic resonance (NMR) spectroscopy in place of a standard radiolabel ADME study. Six healthy participants received a single 300-mg oral dose of nirmatrelvir (in combination with ritonavir), and excreta were collected up to 10 days. Virtually all drug-related material was recovered within 5 days, and mass balance was achieved with 84.9 ± 8.9% (range = 70.7-95.5%) of the administered dose recovered in urine and feces. The excretion of fluorine-containing material in urine and feces was 47.0% and 33.7%, respectively. Unchanged nirmatrelvir represented 82.5% of the normalized drug-related material with a carboxylic acid metabolite M5, derived from hydrolysis of the P2 amide bond, present at 12.1% of dose. Nirmatrelvir was the only drug-related entity observed in plasma. Approximately 4.2% of the dose was excreted as metabolite M8 (measured by liquid chromatography-mass spectrometry), which was 19 F NMR silent due to hydrolysis of the trifluoroacetamide moiety. Hydrolysis of nirmatrelvir to M5 and M8 was shown to occur in cultures of human gut microflora. This successful demonstration of quantitative 19 F NMR spectroscopy to establish the mass-balance, excretion, and metabolic profile of nirmatrelvir offers an advantageous means to execute human ADME studies for fluorine-containing compounds early in drug development.

Evaluation of pharmacokinetic parameters and dipeptidyl peptidase-4 inhibition following single doses of sitagliptin in healthy, young Japanese males.

AIMS: Sitagliptin is a selective inhibitor of dipeptidyl peptidase-4 (DPP-4) used to treat type 2 diabetes. The present aim was to evaluate pharmacokinetic (PK), pharmacodynamic (PD) and safety characteristics of sitagliptin following single doses in healthy, young Japanese males. METHODS: In this alternating two-panel, randomized, controlled double-blind study, six healthy Japanese male subjects (aged 20-46 years) in each panel received single oral doses of 5-400mg sitagliptin and two received placebo. Plasma and urine drug concentrations were measured from 0-48h post dose and plasma DPP-4 inhibition from 0-24h post dose. The results were compared with historical data from young, healthy non-Japanese males. RESULTS: Plasma concentrations of sitagliptin increased approximately in proportion to dose; maximum concentrations occurred 2-6h post-dose. The mean apparent terminal half-life for plasma sitagliptin was 9-14h, with the half-life slightly decreasing as the dose increased. The mean dose fraction excreted unchanged in the urine was 0.73-1.00. Ingestion of a traditional Japanese breakfast prior to dosing had only a minor effect on PK parameters. After correction for dilution and competition effects during assay, doses of sitagliptin ≥50mg resulted in weighted average DPP-4 inhibition from 0-24h post-dose >94% (without correction, >78%). No clinically meaningful differences in PK and DPP-4 inhibition parameters were found between Japanese and non-Japanese subjects. Sitagliptin was generally well tolerated and there were no serious adverse experiences or episodes of hypoglycaemia. CONCLUSIONS: The PK and PD findings from this study are consistent with once daily dosing of sitagliptin in Japanese patients with type 2 diabetes.

Inhibition of ketohexokinase in adults with NAFLD reduces liver fat and inflammatory markers: A randomized phase 2 trial.

BACKGROUND: Increased consumption of the lipogenic sugar fructose promotes the current epidemic of metabolic disease. Ketohexokinase (KHK) catalyzes the first committed step in fructose metabolism. In animal models, KHK inhibition decreases hepatic de novo lipogenesis and steatosis and corrects many metabolic abnormalities associated with insulin resistance. The consequences of inhibiting fructose metabolism in humans have not been tested. This randomized, double-blind, placebo-controlled, phase 2a study (NCT03256526) assessed the effect of the reversible KHK inhibitor PF-06835919 on metabolic parameters in participants with non-alcoholic fatty liver disease (NAFLD). METHODS: Adults with NAFLD (>6% whole liver fat [WLF] by magnetic resonance imaging-proton density fat fraction) received once-daily oral placebo or PF-06835919 75 mg or 300 mg for 6 weeks. Randomization (1:1:1) was via computer-generated randomization code with random permuted blocks. Endpoints included WLF (primary endpoint), safety/tolerability, and metabolic parameters. FINDINGS: Overall, 158 participants were screened and 53 randomized; 48 completed the trial (placebo, n = 17; PF-06835919 75 mg, n = 17; PF-06835919 300 mg, n = 14). Compared with placebo, significant reductions in WLF were observed in participants receiving PF-06835919 300 mg (difference of -18.73%; p = 0.04), but not with 75 mg. In addition, inhibition of KHK resulted in improvement in inflammatory markers. The incidence of treatment-emergent adverse events (AEs) was low and similar across treatment groups (26.3%, 23.5%, and 29.4% of participants in the placebo and PF-06835919 75 mg and 300 mg groups, respectively). No serious AEs were reported. CONCLUSIONS: Data suggest that KHK inhibition may be clinically beneficial in the treatment of adults with NAFLD and insulin resistance. FUNDING: This study was sponsored by Pfizer Inc.

Metabolism and excretion of anacetrapib, a novel inhibitor of the cholesteryl ester transfer protein, in humans.

Anacetrapib is a novel cholesteryl ester transfer protein inhibitor being developed for the treatment of primary hypercholesterolemia and mixed dyslipidemia. The absorption, distribution, metabolism, and excretion of anacetrapib were investigated in an open-label study in which six healthy male subjects received a single oral dose of 150 mg and 165 microCi of [(14)C]anacetrapib. Plasma, urine, and fecal samples were collected at predetermined times for up to 14 days postdose and were analyzed for total radioactivity, the parent compound, and metabolites. The majority of the administered radioactivity (87%) was eliminated by fecal excretion, with negligible amounts present in urine (0.1%). The peak level of radioactivity in plasma (approximately 2 microM equivalents of [(14)C]anacetrapib) was achieved approximately 4 h postdose. The parent compound was the major radioactive component (79-94% of total radioactivity) in both plasma and feces. Three oxidative metabolites, M1, M2, and M3, were detected in plasma and feces and were identified as the O-demethylated species (M1) and two secondary hydroxylated derivatives of M1 (M2 and M3). Each metabolite was detected at low levels, representing

Mini-Review: Comprehensive Drug Disposition Knowledge Generated in the Modern Human Radiolabeled ADME Study.

The human radiolabeled absorption, distribution, metabolism, and excretion (ADME) study offers a quantitative and comprehensive overall picture of the disposition of a drug, including excretion pattern and metabolite profiles in circulation and excreta. The data gathered from the ADME study are highly informative for developing a cohesive strategy for clinical pharmacology studies. Elements of standard ADME study designs are described. An exciting new development in human ADME studies is the application of accelerator mass spectrometry (AMS) as the detection technique for carbon-14, in replacement of radioactivity measurements. This technology permits administration of 100-fold to 1,000-fold lower amounts of carbon-14, and thus opens the door to the application of new study designs. A new ADME study design, termed the AMS-Enabled Human ADME study, is described. In this design, both oral and intravenous administration are assessed in a single clinical study with a two-period crossover. In addition to all of the standard ADME study end points (e.g., mass balance and quantitative metabolite profiles), the AMS-Enabled ADME study can provide the fundamental pharmacokinetic parameters of clearance, volume of distribution, absolute oral bioavailability, and even estimates of the fraction of the dose absorbed. Thus, we have entered a new era of human ADME study design that can yield vastly more informative and complete data sets enabling a superior understanding of overall drug disposition.

Assessment of the CYP3A-mediated drug interaction potential of anacetrapib, a potent cholesteryl ester transfer protein (CETP) inhibitor, in healthy volunteers.

In this study, midazolam was used as a probe-sensitive CYP3A substrate to investigate the effect of anacetrapib on CYP3A activity, and ketoconazole was used as a probe-inhibitor to investigate the effect of potent CYP3A inhibition on the pharmacokinetics of anacetrapib, a novel cholesteryl ester transfer protein inhibitor in development for the treatment of dyslipidemia. Two partially blinded, randomized, 2-period, fixed-sequence studies were performed. Safety, tolerability, and midazolam and anacetrapib plasma concentrations were assessed. All treatments were generally well tolerated. The geometric mean ratios (90% confidence interval) of midazolam with anacetrapib/midazolam alone for AUC0-infinity and Cmax were 1.04 (0.94, 1.14) and 1.15 (0.97, 1.37), respectively. Exposure to anacetrapib was increased by ketoconazole--specifically, the geometric mean ratios (90% confidence interval) of anacetrapib with ketoconazole/anacetrapib alone for AUC0-infinity and Cmax were 4.58 (3.68, 5.71) and 2.37 (2.02, 2.78), respectively. The study showed that anacetrapib does not inhibit or induce CYP3A activity. Furthermore, anacetrapib appears to be a moderately sensitive substrate of CYP3A.

A thorough QTc study to assess the effect of sitagliptin, a DPP4 inhibitor, on ventricular repolarization in healthy subjects.

A randomized, double-blind, placebo-controlled, 4-period crossover study was performed with a single oral dose of sitagliptin (100 mg, 800 mg), moxifloxacin (400 mg), and placebo in order to provide a rigorous assessment of the effect of sitagliptin on ventricular repolarization based on the ICH E14 guidance. The clinical dose of sitagliptin 100 mg was not associated with an increase in QTc interval, corrected using the Fridericia correction (QTcf), at any time point. The supratherapeutic 800-mg dose of sitagliptin was generally well tolerated and was associated with minimal, clinically insignificant prolongation of the QTcf interval at concentrations approximately 11-fold higher than maximal concentrations following the 100-mg clinical dose. The PK/QTc model demonstrated a shallow relationship between the plasma concentration of sitagliptin and the placebo-subtracted QTcf change from baseline, with a 0.59-millisecond increase in QTc for every 1000-nM increment in sitagliptin plasma concentration. The sensitivity of the assay to detect modest increases in QTc interval was established with the active control moxifloxacin. In conclusion, at clinically relevant concentrations, sitagliptin is not associated with clinically meaningful QTcf prolongation.

Single-dose pharmacokinetics and pharmacodynamics of anacetrapib, a potent cholesteryl ester transfer protein (CETP) inhibitor, in healthy subjects.

AIMS: Anacetrapib is an orally active and potent inhibitor of CETP in development for the treatment of dyslipidaemia. These studies endeavoured to establish the safety, tolerability, pharmacokinetics and pharmacodynamics of rising single doses of anacetrapib, administered in fasted or fed conditions, and to preliminarily assess the effect of food, age, gender and obesity on the single-dose pharmacokinetics and pharmacodynamics of anacetrapib. METHODS: Safety, tolerability, anacetrapib concentrations and CETP activity were evaluated. RESULTS: Anacetrapib was rapidly absorbed, with peak concentrations occurring at approximately 4 h post-dose and an apparent terminal half-life ranging from approximately 9 to 62 h in the fasted state and from approximately 42 to approximately 83 h in the fed state. Plasma AUC and C(max) appeared to increase in a less than approximately dose-dependent manner in the fasted state, with an apparent plateau in absorption at higher doses. Single doses of anacetrapib markedly and dose-dependently inhibited serum CETP activity with peak effects of approximately 90% inhibition at t(max) and approximately 58% inhibition at 24 h post-dose. An E(max) model best described the plasma anacetrapib concentration vs CETP activity relationship with an EC(50) of approximately 22 nm. Food increased exposure to anacetrapib; up to approximately two-three-fold with a low-fat meal and by up to approximately six-eight fold with a high-fat meal. Anacetrapib pharmacokinetics and pharmacodynamics were similar in elderly vs young adults, women vs men, and obese vs non-obese young adults. Anacetrapib was well tolerated and was not associated with any meaningful increase in blood pressure. CONCLUSIONS: Whereas food increased exposure to anacetrapib significantly, age, gender and obese status did not meaningfully influence anacetrapib pharmacokinetics and pharmacodynamics.

Effect of the cholesteryl ester transfer protein inhibitor, anacetrapib, on lipoproteins in patients with dyslipidaemia and on 24-h ambulatory blood pressure in healthy individuals: two double-blind, randomised placebo-controlled phase I studies.

BACKGROUND: The inhibition of cholesteryl ester transfer protein (CETP) is considered a potential new mechanism for treatment of dyslipidaemia. Anacetrapib (MK-0859) is a CETP inhibitor currently under development. We aimed to assess anacetrapib's effects as monotherapy on low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) and on 24-h ambulatory blood pressure. METHODS: We did two double-blind, randomised, placebo-controlled phase I studies. In the first study, 50 patients with dyslipidaemia (LDL-C 100-190 mg/dL; 40 active, 10 placebo) aged 18-75 years received anacetrapib doses of 0, 10, 40, 150, or 300 mg orally once a day with a meal for 28 days. Standard lipid and lipoprotein monitoring, safety monitoring, and anacetrapib concentrations for pharmacokinetics were done. In the second study, 22 healthy participants aged 45-75 years received either 150 mg of anacetrapib once a day or matching placebo with a meal for 10 days in each crossover period, in a randomised sequence, with at least a 14-day washout between the treatment periods. Continuous 24-h ambulatory blood pressure monitoring was done on day -1 and day 10 of each treatment period in this study. The primary or secondary endpoints of safety and tolerability were assessed in both studies by monitoring clinical adverse experiences, physical examinations, vital signs, 12-lead electrocardiogram, and laboratory safety. Analysis was per protocol. These trials are registered with ClinicalTrials.gov, number NCT00565292 and NCT00565006. FINDINGS: In the dyslipidaemia study, one patient withdrew consent and one was excluded from the data analysis for HDL-C and LDL-C because complete pre-dose measurements were not available. Anacetrapib produced dose-dependent lipid-altering effects with peak lipid-altering effects of 129% (mean 51.1 [SD 3.8]-114.9 [7.9] mg/dL) increase in HDL-C and a 38% (138.2 [11.4]-77.6 [7.9] mg/dL) decrease in LDL-C in patients with dyslipidaemia. In the 24-h ambulatory blood pressure study in healthy individuals, least squares difference between anacetrapib and placebo groups on day 10 were 0.60 (90% CI -1.54 to 2.74; p=0.634) mm Hg for systolic blood pressure and 0.47 (90% CI -0.90 to 1.84; p=0.561) mm Hg for diastolic blood pressure. INTERPRETATION: Anacetrapib seems to exhibit HDL-C increases greater than those seen with other investigational drugs in this class and LDL-C lowering effects similar to statins. Despite greater lipid-altering effects relative to other members of this class, anacetrapib seems not to increase blood pressure, suggesting that potent CETP inhibition by itself might not lead to increased blood pressure.

Sitagliptin, an dipeptidyl peptidase-4 inhibitor, does not alter the pharmacokinetics of the sulphonylurea, glyburide, in healthy subjects.

AIMS: Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is an incretin enhancer that is approved for the treatment of Type 2 diabetes. Sitagliptin is mainly renally eliminated and not an inhibitor of CYP450 enzymes in vitro. Glyburide, a sulphonylurea, is an insulin sensitizer and mainly metabolized by CYP2C9. Since both agents may potentially be co-administered, the purpose of this study was to examine the effects of sitagliptin on glyburide pharmacokinetics. METHODS: In this open-label, randomized, two-period crossover study, eight healthy normoglycaemic subjects, 22-44 years old, received single 1.25-mg doses of glyburide alone in one period and co-administered with sitagliptin on day 5 following a multiple-dose regimen for sitagliptin (200-mg q.d. x 6 days) in the other period. RESULTS: The geometric mean ratios and 90% confidence intervals [(glyburide + sitagliptin)/glyburide] for AUC(0-infinity) and C(max) were 1.09 (0.96, 1.24) and 1.01 (0.84, 1.23), respectively. CONCLUSION: Sitagliptin does not alter the pharmacokinetics of glyburide in healthy subjects.

Multiple-dose administration of sitagliptin, a dipeptidyl peptidase-4 inhibitor, does not alter the single-dose pharmacokinetics of rosiglitazone in healthy subjects.

Sitagliptin, a dipeptidyl peptidase-4 inhibitor, is an incretin enhancer that is approved for the treatment of type 2 diabetes. Sitagliptin is mainly renally eliminated and not a potent inhibitor of CYP450 enzymes in vitro. Rosiglitazone, a thiazolidenedione, is an insulin sensitizer and mainly metabolized by CYP2C8. Since both agents may potentially be coadministered, the purpose of this study was to examine the effects of sitagliptin on rosiglitazone pharmacokinetics. In this open-label, randomized, 2-period, crossover study, 12 healthy normoglycemic subjects, 21 to 44 years, received single 4-mg doses of rosiglitazone alone in one period and coadministered with sitagliptin on day 5 following a multiple-dose regimen for sitagliptin (200 mg once daily x 5 days) in the other period. The geometric mean ratios and 90% confidence intervals ([rosiglitazone + sitagliptin]/rosiglitazone) for rosiglitazone AUC(0-infinity) and Cmax were 0.98 (0.93, 1.02) and 0.99 (0.88, 1.12), respectively. In conclusion, sitagliptin did not alter the pharmacokinetics of rosiglitazone in healthy subjects.

Effects of ezetimibe on cyclosporine pharmacokinetics in healthy subjects.

This single-center, open-label, 2-period crossover study investigated the effects of multiple-dose ezetimibe (EZE) on a single dose of cyclosporine (CyA). Healthy subjects received 2 treatments in random order with a 14-day washout: (1) CyA 100 mg alone and (2) EZE 20 mg for 7 days with CyA 100 mg coadministered on day 7; EZE 20 mg alone was administered on day 8. AUC(0-last) and Cmax geometric mean ratios (90% confidence interval) for ([CyA + EZE]/CyA alone) were 1.15 (1.07, 1.25) and 1.10 (0.97, 1.26), respectively. Tmax (approximately 1.3 hours) was similar with and without EZE (P >.200). Mean CyA exposure slightly increased (approximately 15%) with multiple-dose EZE 20 mg; however, this value was contained within (0.80, 1.25). The implications for chronic EZE dosing within the usual clinical paradigm of chronic CyA dosing have not been established; caution is recommended when using these agents concomitantly. CyA concentrations should be monitored in patients receiving EZE and CyA.

Interaction of single-dose ezetimibe and steady-state cyclosporine in renal transplant patients.

This open-label, single-period study evaluated the single-dose pharmacokinetics of ezetimibe (EZE) 10 mg in the setting of steady-state cyclosporine (CyA) dosing in renal transplant patients. A single 10-mg dose of EZE was coadministered with the morning dose of CyA (75-150 mg twice a day). Total EZE (sum of unconjugated, parent EZE and EZE-glucuronide; EZE-total) AUC(0-last) and Cmax were compared to values derived from a prespecified database of healthy volunteers. Geometric mean ratios (90% CIs) for (EZE + CyA)/EZE alone for EZE-total AUC((0-last)) and Cmax were 3.41 (2.55, 4.56) and 3.91 (3.13, 4.89), respectively. Compared to healthy controls, EZE-total AUC((0-last)) was 3.4-fold higher in transplant patients receiving CyA; similar exposure levels were seen in a prior multiple-dose study in which EZE 50 mg was administered to healthy volunteers without dose-related toxicity. Because the long-term safety implications of both higher EZE exposures and undetermined effect on CyA are not yet understood, the clinical significance of this interaction is unknown.

Pharmacokinetics of aprepitant after single and multiple oral doses in healthy volunteers.

Aprepitant is the first NK1 receptor antagonist approved for use with corticosteroids and 5HT3 receptor antagonists to prevent chemotherapy-induced nausea and vomiting (CINV). The effective dose to prevent CINV is a 125-mg capsule on day 1 followed by an 80-mg capsule on days 2 and 3. Study 1 evaluated the bioavailability of the capsules and estimated the effect of food. The mean (95% confidence interval [CI]) bioavailabilities of 125-mg and 80-mg final market composition (FMC) capsules, as assessed by simultaneous administration of stable isotope-labeled intravenous (i.v.) aprepitant (2 mg) and FMC capsules, were 0.59 (0.53, 0.65) and 0.67 (0.62, 0.73), respectively. The geometric mean (90% CI) area under the plasma concentration time curve (AUC) ratios (fed/fasted) were 1.2 (1.10, 1.30) and 1.09 (1.00, 1.18) for the 125-mg and 80-mg capsule, respectively, demonstrating that aprepitant can be administered independently of food. Study 2 defined the pharmacokinetics of aprepitant administered following the 3-day regimen recommended to prevent CINV (125 mg/80 mg/80 mg). Consistent daily plasma exposures of aprepitant were obtained following this regimen, which was generally well tolerated.

Pharmacokinetic and pharmacodynamic properties of multiple oral doses of sitagliptin, a dipeptidyl peptidase-IV inhibitor: a double-blind, randomized, placebo-controlled study in healthy male volunteers.

BACKGROUND: Dipeptidyl peptidase-IV (DPP-IV) inhibitors represent a new class of oral antihyperglycemic agents. Sitagliptin is an orally active and selective DPP-IV inhibitor currently in Phase III development for the treatment of type 2 diabetes mellitus. OBJECTIVE: The aim of this study was to assess the pharmacokinetic and pharmacodynamic (PK/PD) properties and tolerability of multiple oral once-daily or twice-daily doses of sitagliptin. METHODS: This double-blind, randomized, placebo-controlled,incremental oral-dose study was conducted at SGS Biopharma, Antwerp, Belgium. Healthy, nonsmoking male volunteers aged 18 to 45 years with a creatinine clearance rate of >80 mL/min and normoglycemia and weighing within 15% of their ideal height/weight range were randomly assigned to 1 of 8 treatment groups: sitagliptin 25, 50, 100, 200, or 400 mg or placebo, QD for 10 days; a single dose of sitagliptin 800 mg administered on day 1 followed by 600 mg QD on days 3 to 10; or sitagliptin 300 mg BID for 10 days. For analysis of PK properties, plasma and urine samples were obtained before study drug administration on day 1 and at 0.5, 1, 2, 4, 6, 8, 10, 12, and 16 hours after study drug administration on day 1; before study drug administration on days 2 to 9; and every 24 hours for 96 hours after the last dose on day 10, and analyzed for sitagliptin concentrations. Assays were used to measure inhibition of plasma DPP-IV activity and plasma concentrations of active and total glucagon-like peptide-1 (GLP-1), glucose, and glucagon, and serum concentrations of insulin, C-peptide, insulin-like growth factor-1, and insulin like growth factor binding protein-3. Tolerability was assessed throughout the study using physical examination, including vital sign measurements; 12-lead electrocardiography; and laboratory analysis, including hematology, biochemistry (hepatic aminotransferase and creatine phosphokinase), and urinalysis. RESULTS: Seventy subjects were enrolled (mean age, 32.9 years [range, 18-45 years]; mean weight, 79.7 kg [range, 63.4-97.7 kg]; 8 patients per sitagliptin study group and 14 patients in the control group). In the sitagliptin groups, the plasma concentration-time profiles and principal PK parameters (T(max), C(max), and t((1/2))) were statistically similar at days 1 (single dose) and 10 (steady state). In the groups receiving sitagliptin QD doses, accumulation of sitagliptin was modest (AUC accumulation ratio [day 10/day 1] range, 1.05-1.29), and the apparent terminal elimination t((1/2)) was 11.8 to 14.4 hours. At steady state in the sitagliptin QD groups, the mean proportion of drug excreted unchanged in the urine was approximately 70.6%. Dose-dependent inhibition of plasma DPP-IV activity was apparent, and the pattern of inhibition at steady state (day 10) was statistically similar to that observed on day 1. Day-10 weighted mean inhibition of plasma DPP-IV activity over 24 hours was > or = 80% for doses of > or = 50 mg QD. After a standard meal, active GLP-1 concentrations were significantly increased in the sitagliptin groups by approximately 2-fold compared with that in the control group, a finding consistent with near-maximal acute glucose lowering in preclinical studies. Across doses, no apparent adverse effects, including hypoglycemia, were found or reported. CONCLUSIONS: The results from this study in a select population of healthy male volunteers suggest that multiple oral doses of sitagliptin inhibited plasma DPP-IV activity and affected active GLP-1 concentrations in a dose-dependent manner, without producing hypoglycemia. Multiple dosing of sitagliptin exhibited a PK/PD profile consistent with that of a QD regimen and was well tolerated.

Ezetimibe: a review of its metabolism, pharmacokinetics and drug interactions.

Ezetimibe is the first lipid-lowering drug that inhibits intestinal uptake of dietary and biliary cholesterol without affecting the absorption of fat-soluble nutrients. Following oral administration, ezetimibe is rapidly absorbed and extensively metabolised (>80%) to the pharmacologically active ezetimibe-glucuronide. Total ezetimibe (sum of 'parent' ezetimibe plus ezetimibe-glucuronide) concentrations reach a maximum 1-2 hours post-administration, followed by enterohepatic recycling and slow elimination. The estimated terminal half-life of ezetimibe and ezetimibe-glucuronide is approximately 22 hours. Consistent with the elimination half-life of ezetimibe, an approximate 2-fold accumulation is observed upon repeated once-daily administration. The recommended dose of ezetimibe 10 mg/day can be administered in the morning or evening without regard to food. There are no clinically significant effects of age, sex or race on ezetimibe pharmacokinetics and no dosage adjustment is necessary in patients with mild hepatic impairment or mild-to-severe renal insufficiency. The major metabolic pathway for ezetimibe consists of glucuronidation of the 4-hydroxyphenyl group by uridine 5'-diphosphate-glucuronosyltransferase isoenzymes to form ezetimibe-glucuronide in the intestine and liver. Approximately 78% of the dose is excreted in the faeces predominantly as ezetimibe, with the balance found in the urine mainly as ezetimibe-glucuronide. Overall, ezetimibe has a favourable drug-drug interaction profile, as evidenced by the lack of clinically relevant interactions between ezetimibe and a variety of drugs commonly used in patients with hypercholesterolaemia. Ezetimibe does not have significant effects on plasma levels of HMG-CoA reductase inhibitors commonly known as statins (atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, simvastatin), fibric acid derivatives (gemfibrozil, fenofibrate), digoxin, glipizide, warfarin and triphasic oral contraceptives (ethinylestradiol and levonorgestrel). Concomitant administration of food, antacids, cimetidine or statins had no significant effect on ezetimibe bioavailability. Although coadministration with gemfibrozil and fenofibrate increased the bioavailability of ezetimibe, the clinical significance is thought to be minor considering the relatively flat dose-response curve of ezetimibe and the lack of dose-related increase in adverse events. In contrast, coadministration with the bile acid binding agent colestyramine significantly decreased ezetimibe oral bioavailability (based on area under the plasma concentration-time curve of total ezetimibe). Hence, ezetimibe and colestyramine should be administered several hours apart to avoid attenuating the efficacy of ezetimibe. Finally, higher ezetimibe exposures were observed in patients receiving concomitant ciclosporin, and ezetimibe caused a small but statistically significant effect on plasma levels of ciclosporin. Because treatment experience in patients receiving ciclosporin is limited, physicians are advised to exercise caution when initiating ezetimibe in the setting of ciclosporin coadministration, and to carefully monitor ciclosporin levels.

Effect of impaired renal function and haemodialysis on the pharmacokinetics of aprepitant.

BACKGROUND: The neurokinin NK(1)-receptor antagonist aprepitant has demonstrated efficacy in preventing highly emetogenic chemotherapy-induced nausea and vomiting. OBJECTIVE: The objective of the present study was to investigate the effects of impaired renal function on the pharmacokinetics and safety of aprepitant. SUBJECTS AND METHODS: A total of 32 patients and healthy subjects were evaluated in this open-label, two-part study. Pharmacokinetic parameters after a single oral dose of aprepitant 240 mg were measured in eight patients with end-stage renal disease (ESRD) requiring haemodialysis, eight patients with severe renal insufficiency (SRI [24-hour creatinine clearance <30 mL/min/1.73 m(2)]) and 16 healthy and age-, sex- and weight-matched subjects (controls). RESULTS: In ESRD patients, the area under the plasma concentration-time curve (AUC) from 0 to 48 hours (AUC(48)) for aprepitant was on average approximately 36% lower than that observed in control subjects (ratio [ESRD patients/healthy controls] of geometric means = 0.64), but the 90% confidence interval 0.52, 0.78 for the ratio of true mean AUC(48) fell within the predefined target interval of 0.5, 2.0. Also in ESRD patients, there was no statistically or clinically significant difference in unbound aprepitant AUC (which may be more clinically relevant than total aprepitant AUC) when compared with healthy control subjects. Aprepitant pharmacokinetic parameters in ESRD patients were clinically similar when haemodialysis was initiated at 4 hours or 48 hours after aprepitant administration. In SRI patients, the ratio (SRI patients/healthy controls) of aprepitant AUC from zero to infinity (AUC(infinity)) geometric mean value was 0.79 with a 90% confidence interval of 0.56, 1.10. On average, in SRI patients the principal aprepitant pharmacokinetic parameters (AUC(infinity), initial maximum plasma concentration [C(max)], time to initial C(max), and apparent elimination half-life) were not statistically different from those obtained in healthy control subjects. Aprepitant was generally well tolerated in both ESRD and SRI patients. CONCLUSION: The results of this study demonstrate that ESRD, haemodialysis and SRI have no clinically meaningful effect on aprepitant pharmacokinetics. Therefore, no dosage adjustment of aprepitant is warranted in SRI or ESRD patients.

Simvastatin does not have a clinically significant pharmacokinetic interaction with fenofibrate in humans.

Simvastatin and fenofibrate are both commonly used lipid-regulating agents with distinct mechanisms of action, and their coadministration may be an attractive treatment for some patients with dyslipidemia. A 2-period, randomized, open-label, crossover study was conducted in 12 subjects to determine if fenofibrate and simvastatin are subject to a clinically relevant pharmacokinetic interaction at steady state. In treatment A, subjects received an 80-mg simvastatin tablet in the morning for 7 days. In treatment B, subjects received a 160-mg micronized fenofibrate capsule in the morning for 7 days, followed by a 160-mg micronized fenofibrate capsule dosed together with an 80-mg simvastatin tablet on days 8 to 14. Because food increases the bioavailability of fenofibrate, each dose was administered with food to maximize the exposure of fenofibric acid. The steady-state pharmacokinetics (AUC(0-24h), C(max), and t(max)) of active and total HMG-CoA reductase inhibitors, simvastatin acid, and simvastatin were determined following simvastatin administration with and without fenofibrate. Also, fenofibric acid steady-state pharmacokinetics were evaluated with and without simvastatin. The geometric mean ratios (GMRs) for AUC(0-24h) (80 mg simvastatin [SV] + 160 mg fenofibrate)/(80 mg simvastatin alone) and 90% confidence intervals (CIs) were 0.88 (0.80, 0.95) and 0.92 (0.82, 1.03) for active and total HMG-CoA reductase inhibitors. The GMRs and 90% CIs for fenofibric acid (80 mg SV + 160 mg fenofibrate/160 mg fenofibrate alone) AUC(0-24h) and C(max) were 0.95 (0.88, 1.04) and 0.89 (0.77, 1.02), respectively. Because both the active inhibitor and fenofibric acid AUC GMR 90% confidence intervals fell within the prespecified bounds of (0.70, 1.43), no clinically significant pharmacokinetic drug interaction between fenofibrate and simvastatin was concluded in humans. The coadministration of simvastatin and fenofibrate in this study was well tolerated.