Prajakti A. Kothare

Effect of renal impairment on the pharmacokinetics of exenatide.

What is already known about this subject Nonclinical studies have shown that exenatide is primarily cleared by the renal system. It was not known to what degree the clinical pharmacokinetics and tolerability would be affected by increasing renal impairment (RI). What this study adds Patients with mild to moderate RI adequately tolerate current therapeutic doses of exenatide. However, exenatide is not recommended in patients with severe RI or end-stage renal disease. Aims To evaluate the pharmacokinetics (PK), safety and tolerability of a single exenatide dose in patients with renal impairment (RI). Methods Exenatide (5 or 10 µg) was injected subcutaneously in 31 subjects (one with Type 2 diabetes) stratified by renal function [Cockcroft–Gault creatinine clearance (CrCL), number of subjects]: normal (>80 ml min−1, n = 8), mild RI (51–80 ml min−1, n = 8), moderate RI (31–50 ml min−1, n = 7) or end-stage renal disease (ESRD) requiring haemodialysis (n = 8). PK data were combined with four previous single-dose studies in patients with Type 2 diabetes to explore the relationship of exenatide clearance (CLp/F) and CrCL. Results Mean half-life for healthy, mild RI, moderate RI and ESRD groups were 1.5, 2.1, 3.2 and 6.0 h, respectively. After combining data from multiple studies, least squares geometric means for CLp/F in subjects with normal renal function, mild RI, moderate RI and ESRD were 8.14, 5.19, 7.11 and 1.3 l h−1, respectively. Exenatide was generally well tolerated in the mild and moderate RI groups, but not in subjects with ESRD due to nausea and vomiting. Simulations of exenatide plasma concentrations also suggest patients with ESRD should have a propensity for poor tolerability at the lowest available therapeutic dosage (5 µg q.d.). Conclusions Since tolerability and PK changes were considered clinically acceptable in patients with mild to moderate RI, it would be appropriate to administer exenatide to these patients without dosage adjustment. However, poor tolerability and significant changes in PK make the currently available therapeutic doses (5 and 10 µg) unsuitable in severe RI or ESRD.

Effect of exenatide on gastric emptying and relationship to postprandial glycemia in type 2 diabetes

OBJECTIVES To evaluate the effect of exenatide on gastric emptying (GE) in type 2 diabetes using scintigraphy. METHODS Seventeen subjects with type 2 diabetes participated in a randomized, single-blind, 3-period, crossover study. In each 5-day period, 5 or 10 microg exenatide or placebo was administered subcutaneously BID. Oral antidiabetic treatments were continued. The presence of cardiac autonomic neuropathy was assessed during screening. On day 5, after the morning dose, subjects consumed a 450-kcal breakfast containing (99m)Tc-labeled eggs and (111)In-labeled water, and GE was measured by scintigraphy. Plasma glucose and insulin, perceptions of appetite, and plasma exenatide were also quantified. RESULTS Exenatide slowed GE of both solid and liquid meal components [solid (T(50)(90% confidence interval [CI]); placebo, 60(50-70) min; 5 microg exenatide, 111(94-132) min; 10 microg exenatide, 169(143-201) min; both P<0.01); liquid (T(50)(90% CI), placebo, 34(25-46) min; 5 microg exenatide, 87(65-117) min; 10 microg exenatide, 114(85-154) min; both P<0.01)]. GE was not different between subjects with cardiac autonomic neuropathy (n=7), compared with those without (n=10) (P>/=0.68). Exenatide reduced postprandial glucose (area under the curve [AUC((0-6 h))]) by 69-76% and peak insulin (C(max)) by 84-86% compared with placebo. There was an inverse relationship between the postprandial rise in glucose (AUC((0-3 h))) and GE (solid T(50), r=-0.49, P<0.001). CONCLUSIONS Exenatide slows GE substantially in type 2 diabetes, which could be an important mechanism contributing to the beneficial effect of exenatide on postprandial glycemia.

Pharmacokinetics and pharmacodynamics of exenatide extended-release after single and multiple dosing.

Background and ObjectivesExenatide is a glucagon-like peptide-1 receptor agonist, available in an immediate-release (IR), twice-daily formulation, which improves glycaemic control through enhancement of glucose-dependent insulin secretion, suppression of inappropriately elevated postprandial glucagon secretion, slowing of gastric emptying and reduction of food intake. The objectives of these studies were to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of an extended-release (ER) exenatide formulation in patients with type 2 diabetes mellitus.Patients and MethodsPatients with type 2 diabetes participated in either a single-dose trial (n=62) or a repeated-administration trial (n = 45). The pharmacokinetic and safety effects of single-dose subcutaneous administration of exenatide ER (2.5 mg, 5 mg, 7 mg or 10 mg) versus placebo were studied over a period of 12 weeks in patients with type 2 diabetes. These results were used to predict the dose regimen of exenatide ER required to achieve steady-state therapeutic plasma exenatide concentrations. A second clinical study investigated the pharmacokinetics, pharmacodynamics and safety of weekly exenatide ER subcutaneous injections (0.8 mg or 2 mg) versus placebo in patients with type 2 diabetes over a period of 15 weeks. Furthermore, population-based analyses of these studies were performed to further define the exposure-response relationships associated with exenatide ER.ResultsExenatide exposure increased with dose (2.5 mg, 5 mg, 7 mg or 10 mg) and exhibited a multiple-peak profile over approximately 10 weeks. Multiple-dosing pharmacokinetics were predicted from superpositioning of single-dose data; weekly administration of exenatide ER 0.8 mg and 2 mg for 15 weeks confirmed the predictions. Weekly dosing resulted in steady-state plasma exenatide concentrations after 6–7 weeks. Fasting plasma glucose levels were reduced similarly with both doses after 15 weeks (−42.7 ±15.7 mg/dL with the 0.8mg dose and −39.0±9.3mg/dL with the 2mg dose; both p<0.001 vs placebo), and the integrated exposure-response analysis demonstrated that the drug concentration producing 50% of the maximum effect (EC50) on fasting plasma glucose was 56.8 pg/mL (a concentration achieved with both the 0.8 mg and 2mg doses of exenatide ER). The 2 mg dose reduced bodyweight (−3.8 ± 1.4kg; p<0.05 vs placebo) and postprandial glucose excursions. Glycosylated haemoglobin (HbAlc) levels were reduced with the 0.8 mg dose (−1.4±0.3%; baseline 8.6%) and with the 2mg dose (−1.7 ± 0.3%; baseline 8.3%) [both p<0.001 vs placebo]. Adverse events were generally transient and mild to moderate in intensity.ConclusionThese studies demonstrated that (i) a single subcutaneous dose of exenatide ER resulted in dose-related increases in plasma exenatide concentrations; (ii) single-dose exposure successfully predicted the weekly-dosing exposure, with 0.8 mg and 2 mg weekly subcutaneous doses of exenatide ER eliciting therapeutic concentrations of exenatide; and (iii) weekly dosing with either 0.8 or 2 mg of exenatide ER improved fasting plasma glucose control, whereas only the 2 mg dose was associated with improved postprandial glucose control and weight loss.[Clinicaltrials.gov Identifier: NCT00103935]

Exenatide: effect of injection time on postprandial glucose in patients with Type 2 diabetes

Aims  Exenatide is an incretin mimetic whose effect on glycaemic control in patients with Type 2 diabetes is currently under investigation. This study assessed the effect of injection time relative to a standardized meal on postprandial pharmacodynamics of exenatide in patients with Type 2 diabetes.

Effect of exenatide on the steady-state pharmacokinetics of digoxin.

This open‐label study investigated the effect of exenatide coadministration on the steady‐state plasma pharmacokinetics of digoxin. A total of 21 healthy male subjects received digoxin (day 1, 0.5 mg twice daily; days 2–12, 0.25 mg once daily) and exenatide (days 8–12, 10 μg twice daily). Digoxin plasma and urine concentrations were measured on days 7 and 12. Exenatide coadministration did not change the overall 24‐hour steady‐state digoxin exposure (AUCτ,ss) and Cmin,ss but caused a 17% decrease in mean plasma digoxin Cmax,ss (1.40 to 1.16 ng/mL) and an increase in digoxin tmax,ss (median increase, 2.5 hours). Although the decrease in digoxin Cmax,ss was statistically significant, peak concentrations were within the therapeutic concentration range in all subjects. Digoxin urinary pharmacokinetic parameters were not altered. Gastrointestinal symptoms, the most common adverse effects of exenatide, decreased over time. Exenatide administration does not cause any changes in digoxin steady‐state pharmacokinetics that would be expected to have clinical sequelae; thus, dosage adjustment does not appear warranted, based on pharmacokinetic considerations.

Pharmacokinetics, Pharmacodynamics, Tolerability, and Safety of Exenatide in Japanese Patients With Type 2 Diabetes Mellitus

In this single‐blind, parallel, placebo‐controlled study, the pharmacokinetics, pharmacodynamics, tolerability, and safety of subcutaneous exenatide were evaluated in 40 Japanese patients with type 2 diabetes. Patients were allocated to 4 groups and randomized to receive exenatide (n = 8/group) or placebo (n = 2/group), with all receiving placebo on day 1. On day 2, patients received single‐dose exenatide (2.5 μg [group A] or 5 μg [groups B, C, and D]) or placebo and then bid on days 3 to 5. On days 6 to 10, groups A and B continued on 2.5 and 5 μg bid; groups C and D received 10 and 15 μg bid, respectively. The last dose was given on the morning of day 10. All adverse events were mild or moderate in severity. Exenatide was generally well tolerated up to 10 μg. Exenatide was well absorbed with a median tmax of 1.5 hours and mean t1/2 of 1.6 hours; exposure increased with dose. Up to 10 μg, exenatide reduced postprandial glucose concentrations in a dose‐dependent fashion compared with placebo; decreases were similar for 10 and 15 μg. An Emax model demonstrated that doses higher than 2.5 μg were necessary for adequate glycemic response. Based on tolerability and pharmacokinetic/pharmacodynamic relationships, 5 and 10 μg exenatide may be considered for further clinical development in Japanese patients with type 2 diabetes.

Effect of exenatide on the pharmacokinetics and pharmacodynamics of warfarin in healthy Asian men

Exenatide, a treatment for type 2 diabetes, slows gastric emptying as part of its pharmacologic action and may alter the absorption of concomitant oral drugs. This open‐label, 2‐period, fixed‐sequence study evaluated the influence of exenatide coadministration on the pharmacokinetics and pharmacodynamics of warfarin, a narrow therapeutic index drug, in healthy men (N = 16). A single, 25‐mg oral dose of warfarin, with a standardized breakfast, was administered alone in period 1 and concomitantly with 10 μg exenatide subcutaneous twice daily in period 2. Exenatide did not produce significant changes in R‐ or S‐warfarin pharmacokinetics. Although there were minor reductions in warfarin anticoagulant effect, the ratios of geometric means for the area under the international normalized ratio (INR)–time curve from dosing until the time of the last measurable INR value or maximum‐observed INR response being 0.94 (0.93‐0.96) and 0.88 (0.84‐0.92), respectively, the magnitude and direction of these changes do not suggest a safety concern from this interaction.

Pharmacodynamics and pharmacokinetics of single doses of prasugrel 30 mg and clopidogrel 300 mg in healthy chinese and white volunteers: An open-label trial

BACKGROUND Prasugrel is an oral antiplatelet agent approved for the reduction of atherothrombotic cardiovascular events in patients presenting with acute coronary syndrome and undergoing percutaneous coronary intervention. Although the approved loading dose is 60 mg, earlier studies of prasugrel suggested that active-metabolite exposure and pharmacodynamic response may be higher in Asian subjects than in white subjects. OBJECTIVES This study compared the pharmacodynamic response to a single 30-mg dose of prasugrel in healthy Chinese and white subjects and the response to a single 30-mg dose of prasugrel and a single 300-mg dose of clopidogrel in healthy Chinese subjects. The pharmacokinetics and tolerability of both drugs were also assessed. METHODS This was an open-label, single-dose study conducted in Singapore. Chinese subjects were randomly allocated to receive prasugrel 30 mg or clopidogrel 300 mg; after a 14-day washout period, they received the alternative drug. White subjects received only prasugrel 30 mg. Blood samples for pharmaco-dynamic assessments were collected before dosing and at 0.5, 1, 2, 4, and 24 hours after dosing. Three methods were used to measure inhibition of platelet aggregation (IPA)-traditional light transmission aggregometry (LTA), the Verify Now P2Y12 (VN-P2Y12) assay, and a vasodilator-stimulated phosphoprotein (VASP) phosphorylation flow cytometry assay-and their results were compared. Blood samples for pharmacokinetic assessments were collected at 0.25, 0.5, 1, 1.5, 2, 4, 8, 12, and 24 hours after dosing. Concentrations of the active metabolite of prasugrel were measured using a validated LC-MS/MS method. RESULTS The study enrolled 18 Chinese subjects and 14 white subjects. Chinese subjects had a mean (SD) age of 31 (10) years and a mean body weight of 65.2 (8.9) kg; 83% were male. The corresponding values for white subjects were 30 (10) years, 77.2 (12.4) kg, and 86%. Thirty of the 32 enrolled subjects completed the study. Two Chinese men were withdrawn from the study, one due to a low platelet-rich plasma count after receipt of prasugrel 30 mg and the other due to mild, intermittent rectal bleeding after bowel movements that began approximately 2 days after receipt of clopidogrel 300 mg. The mean IPA with prasugrel was significantly higher in Chinese than in white subjects at 0.5, 1, and 2 hours after dosing (P < 0.05), but not at 4 or 24 hours. In Chinese subjects, mean maximal IPA (87%) occurred 1 hour after prasugrel dosing; in white subjects, mean maximal IPA (78%) occurred 2 hours after prasugrel dosing. In Chinese subjects, the mean IPA was significantly higher at all time points after administration of prasugrel 30 mg than after administration of clopidogrel 300 mg (P <0.001). After administration of Clopidogrel 300 mg in Chinese subjects, mean maximal IPA (58%) occurred at 4 hours. The VN-P2Y12 and VASP phosphorylation assays yielded results comparable to those obtained by LTA. Mean exposure to prasugrels active metabolite was higher in Chinese than in white subjects (geometric least squares mean ratio for AUC(0-t) = 1.47 (90% CI, 1.24-1.73). Both drugs were well tolerated. CONCLUSIONS In this study, platelet inhibition was significantly higher in Chinese than in white subjects up to 2 hours after a single 30-mg dose of prasugrel. Platelet inhibition was significantly higher in Chinese subjects at all time points after a 30-mg dose of prasugrel than after a 300-mg dose of clopidogrel. Both treatments were generally well tolerated.

Pharmacology and Tolerability of a Single Dose of Exenatide in Adolescent Patients With Type 2 Diabetes Mellitus Being Treated With Metformin: A Randomized, Placebo-Controlled, Single-Blind, Dose-Escalation, Crossover Study

OBJECTIVE This study assessed the pharmacokinetics, pharmacodynamics, and tolerability of single doses of exenatide in adolescent patients with type 2 diabetes mellitus (T2DM). METHODS This was a randomized, single-blind, dose-escalation, crossover study in adolescent (age 10-16 years) patients with T2DM who were being treated with diet and exercise or a stable dose of metformin, a sulfonylurea, or a combination of metformin and a sulfonylurea for at least 3 months before screening. Eligible patients were allocated to receive single subcutaneous doses of exenatide 2.5 microg, exenatide 5 microg, and placebo, each followed by a standardized meal, on 3 separate days (maximum interval between first and third doses, 5 weeks). Exenatide 2.5 microg always preceded exenatide 5 microg in each treatment sequence. The primary end points were the pharmacokinetics and safety profile of exenatide; secondary end points included postprandial plasma glucose, serum insulin, and plasma glucagon concentrations. RESULTS The study enrolled 13 adolescent patients with T2DM (7 females, 6 males; mean [SD] age, 15 [1] years; body mass index, 32.5 [5.0] kg/m(2); glycosylated hemoglobin, 8.2% [1.5%]). After administration of exenatide 5 microg, the geometric mean (SE) exenatide AUC(0-infinity) and C(max) were 339.5 (39.6) pg * h/mL and 85.1 (11.5) pg/mL, respectively (n = 12). The exenatide AUC appeared to be dose dependent, although exenatide was not quantifiable in all patients at the 2.5-microg dose; after administration of exenatide 2.5-microg, the geometric mean AUC(0-infinity)) was 159.2 (23.1) pg * h/mL (n = 6) and the geometric mean C(max) was 56.3 (10.1) pg/mL (n = 9). Both exenatide doses were associated with significant reductions in postprandial plasma glucose excursions compared with placebo (P < 0.01); the incremental mean (SE) AUC(15-360min) was -3465.6 (1587.3) mg * min/dL for exenatide 2.5 pg, -4422.2 (2434.4) mg * min/dL for exenatide 5 microg, and 3457.4 (1615.5) mg * min/dL for placebo. The 2 exenatide doses were also associated with significant reductions in postprandial plasma glucagon concentrations compared with placebo (P < 0.01); the respective incremental mean values for AUC(15-180min) were 125.5 (658.4), -1403.8 (632.1), and 1843.1 (540.6) pg * min/mL. There were no significant differences in serum insulin concentrations between exenatide and placebo. Exenatide was generally well tolerated, with no hypoglycemic events recorded during the study. CONCLUSIONS In these adolescent patients with T2DM, administration of single 2.5- and 5-microg doses of exenatide were associated with dose-dependent increases in plasma exenatide concentrations and improved postprandial glucose concentrations compared with placebo. Both doses appeared to be well tolerated. ClinicalTrials.gov Identifier: NCT00254254.

Effect of exenatide on the pharmacokinetics of a combination oral contraceptive in healthy women: an open-label, randomised, crossover trial

BackgroundConsistent with its effect on gastric emptying, exenatide, an injectable treatment for type 2 diabetes, may slow the absorption rate of concomitantly administered oral drugs resulting in a decrease in maximum concentration (Cmax). This study evaluated the drug interaction potential of exenatide when administered adjunctively with oral contraceptives, given their potential concomitant use.MethodsThis trial evaluated the effect of exenatide co-administration on single- and multiple-dose pharmacokinetics of a combination oral contraceptive (ethinyl estradiol [EE] 30 μg, levonorgestrel [LV] 150 μg [Microgynon 30®]). Thirty-two healthy female subjects participated in an open-label, randomised, crossover trial with 3 treatment periods (oral contraceptive alone, 1 hour before exenatide, 30 minutes after exenatide). Subjects received a single dose of oral contraceptive on Day 8 of each period and QD doses on Days 10 through 28. During treatment periods of concomitant usage, exenatide was administered subcutaneously prior to morning and evening meals at 5 μg BID from Days 1 through 4 and at 10 μg BID from Days 5 through 22. Single- (Day 8) and multiple-dose (Day 22) pharmacokinetic profiles were assessed for each treatment period.ResultsExenatide did not alter the bioavailability nor decrease daily trough concentrations for either oral contraceptive component. No substantive changes in oral contraceptive pharmacokinetics occurred when oral contraceptive was administered 1 hour before exenatide. Single-dose oral contraceptive administration 30 minutes after exenatide resulted in mean (90% CI) Cmax reductions of 46% (42-51%) and 41% (35-47%) for EE and LV, respectively. Repeated daily oral contraceptive administration 30 minutes after exenatide resulted in Cmax reductions of 45% (40-50%) and 27% (21-33%) for EE and LV, respectively. Peak oral contraceptive concentrations were delayed approximately 3 to 4 hours. Mild-to-moderate nausea and vomiting were the most common adverse events observed during the trial.ConclusionsThe observed reduction in Cmax is likely of limited importance given the unaltered oral contraceptive bioavailability and trough concentrations; however, for oral medications that are dependent on threshold concentrations for efficacy, such as contraceptives and antibiotics, patients should be advised to take those drugs at least 1 hour before exenatide injection.Trial registrationClinicalTrials.gov: NCT00254800.