Pharmacokinetics, Pharmacodynamics, and Safety of Single-Dose Canagliflozin in Healthy Chinese Subjects.

PURPOSE: Canagliflozin, an orally active sodium-glucose cotransporter 2 inhibitor, is approved in many countries as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. The recommended dose of canagliflozin is 100 or 300 mg once daily. This Phase I study was conducted to evaluate the pharmacokinetics, pharmacodynamics, and safety profile of canagliflozin in healthy Chinese subjects. METHODS: In this double-blind, single-dose, 3-way crossover study, 15 healthy subjects were randomized (1:1:1) to receive single oral doses of canagliflozin 100 mg, canagliflozin 300 mg, or placebo. Pharmacokinetic, pharmacodynamic, and safety assessments were made at prespecified time points. FINDINGS: All participants are healthy Chinese adults. Mean AUC and Cmax of canagliflozin increased in a dose-dependent manner after single-dose administration (AUC0-∞, 10,521 ng · h/mL for 100 mg, 33,583 ng · h/mL for 300 mg; Cmax, 1178 ng/mL for 100 mg, 4113 ng/mL for 300 mg). The mean apparent t½ and the median Tmax of canagliflozin were independent of dose (t½, 16.0 hours for 100 mg, 16.2 hours for 300 mg; Tmax, ~1 hour). Mean CL/F and renal clearance of canagliflozin were comparable between the 2 doses. Mean plasma metabolite to parent molar ratios for Cmax and AUC0-∞ were similar with both doses. Canagliflozin decreased the 24-hour mean renal threshold for glucose, calculated by using measured creatinine clearance to estimate the glomerular filtration rate (67.9 and 60.7 mg/dL for canagliflozin 100 and 300 mg, respectively) and 24-hour increased urinary glucose excretion (33.8 and 42.9 g for canagliflozin 100 and 300 mg, respectively) in a dose-dependent manner; the 24-hour plasma glucose profile remained largely unchanged. No deaths, hypoglycemic events, or discontinuations due to adverse events were observed. IMPLICATIONS: Pharmacokinetics (AUC and Cmax) of canagliflozin increased in a dose-dependent manner after single oral doses of canagliflozin (100 and 300 mg) in these healthy Chinese subjects. Tmax and t½ of canagliflozin were independent of the dose. Canagliflozin decreased the 24-hour mean renal threshold for glucose and increased urinary glucose excretion in a dose-dependent manner; these results are consistent with those observed in other patient populations. Canagliflozin was generally safe and well tolerated in these healthy Chinese subjects. ClinicalTrials.gov identifier: NCT01707316.

Open-Label Study To Evaluate the Single-Dose Pharmacokinetics, Safety, and Tolerability of Doripenem in Infants Less than 12 Weeks in Chronological Age.

Doripenem, a parenteral carbapenem with broad-spectrum activity against aerobic Gram-negative and Gram-positive and anaerobic pathogens, is currently approved for use in adults in the United States and European Union. Single-dose doripenem pharmacokinetics in 52 infants <12 weeks in chronological age were investigated in this phase 1 study. Hospitalized, medically stable infants <12 weeks in chronological age were stratified into 6 groups based on chronological and gestational age designed to reflect increasing renal maturation and decreasing volume of distribution (Vz) for ß-lactam antimicrobials during the first 3 months of life. Subjects received single-dose doripenem (5 mg/kg of body weight for <8 weeks and 8 mg/kg for ≥8 weeks in chronological age) administered intravenously over 1 h. Plasma samples were obtained immediately before the end of the infusion and 1.5, 3, and 7 h after the start of the infusion. Urine was obtained by indwelling catheter during the 8 h following infusion. Doripenem showed linear pharmacokinetics across the 6 age groups. Neonates (<4 weeks in chronological age) had increased mean exposure (area under the plasma concentration-time curve from time zero to infinite time [AUC∞], 45.7 versus 32.4 µg · h/ml), longer elimination half-life (2.98 versus 1.79 h), and lower clearance (2.03 versus 3.03 ml/min/kg) compared with infants >4 weeks. Mean Vz was highest in subjects with the earliest gestational age (<32 weeks): 0.564 liter/kg for neonates and 0.548 liter/kg for infants. Single-dose pharmacokinetics of doripenem administered as a 1-hour infusion in term and preterm infants <12 weeks in chronological age were similar to what has been observed in neonates and very young infants with other carbapenems. Single-dose doripenem was generally safe and well tolerated. (This study has been registered with ClinicalTrials.gov under registration no. NCT01381848 and with EudraCT under registration no. 2009-014387-20.).

Effect of hepatic or renal impairment on the pharmacokinetics of canagliflozin, a sodium glucose co-transporter 2 inhibitor.

PURPOSE: Canagliflozin is a sodium-glucose cotransporter 2 inhibitor approved for the treatment of type 2 diabetes mellitus (T2DM). Because T2DM is often associated with renal or hepatic impairment, understanding the effects of these comorbid conditions on the pharmacokinetics of canagliflozin, and further assessing its safety, in these special populations is essential. Two open-label studies evaluated the pharmacokinetics, pharmacodynamics (renal study only), and safety of canagliflozin in participants with hepatic or renal impairment. METHODS: Participants in the hepatic study (8 in each group) were categorized based on their Child-Pugh score (normal hepatic function, mild impairment [Child-Pugh score of 5 or 6], and moderate impairment [Child-Pugh score of 7-9]) and received a single oral dose of canagliflozin 300 mg. Participants in the renal study (8 in each group) were categorized based on their creatinine clearance (CLCR) (normal renal function [CLCR ≥80 mL/min]; mild [CLCR 50 to <80 mL/min], moderate [CLCR 30 to <50 mL/min], or severe [CLCR <30 mL/min] renal impairment; and end-stage renal disease [ESRD]) and received a single oral dose of canagliflozin 200 mg; the exception was those with ESRD, who received 1 dose postdialysis and 1 dose predialysis (10 days later). Canagliflozin's pharmacokinetics and pharmacodynamics (urinary glucose excretion [UGE] and renal threshold for glucose excretion [RTG]) were assessed at predetermined time points. FINDINGS: Mean maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from time zero to infinite (AUC)0-∞ values differed by <11% between the group with normal hepatic function and those with mild and moderate hepatic impairment. In the renal study, the mean Cmax values were 13%, 29%, and 29% higher and the mean AUC0-∞ values were 17%, 63%, and 50% higher in participants with mild, moderate, and severe renal impairment, respectively; values were similar in the ESRD group relative to the group with normal function, however. The amount of UGE declined as renal function decreased, whereas RTG was not suppressed to the same extent in the moderate to severe renal impairment groups (mean RTG, 93-97 mg/dL) compared with the mild impairment and normal function groups (mean RTG, 68-77 mg/dL). IMPLICATIONS: Canagliflozin's pharmacokinetics were not affected by mild or moderate hepatic impairment. Systemic exposure to canagliflozin increased in the renal impairment groups relative to participants with normal renal function. Pharmacodynamic response to canagliflozin, measured by using UGE and RTG, declined with increasing severity of renal impairment. A single oral dose of canagliflozin was well tolerated by participants in both studies. ClinicalTrials.gov identifiers: NCT01186588 and NCT01759576.

Pharmacokinetics of abiraterone in healthy Japanese men: dose-proportionality and effect of food timing.

PURPOSE: Abiraterone acetate (AA) was recently approved for castration-resistant prostate cancer in Japan. Two phase 1 studies were conducted to assess the pharmacokinetics of abiraterone after single-dose administration in Japanese healthy men and to evaluate the effects of food timing on abiraterone pharmacokinetics after single-dose administration of AA in Japanese and Caucasian healthy men. METHODS: In the dose-proportionality study, subjects (n = 30 Japanese) were randomly assigned to receive single doses of 250, 500, and 1,000 mg AA, and in the food-timing study, subjects (n = 22 Japanese and n = 23 Caucasian) randomly received single doses of 1,000 mg AA under fasted (overnight) and three different modified fasting conditions. RESULTS: Mean C(max) and AUC(∞) for abiraterone increased dose-dependently in Japanese healthy men; however, 90 % confidential interval (CI) was outside the predefined dose-proportionality criteria. Based on geometric mean ratios and 90 % CIs (versus overnight fasting condition), abiraterone exposure (AUC) increased significantly with dosing 1 h premeal, 2 h postmeal, or in between two meals 4 h apart by 57 %, 595 %, and 649 %, respectively. CONCLUSION: No clinically meaningful difference was observed in the pharmacokinetics of abiraterone between Caucasian and Japanese subjects.

Effect of canagliflozin, a sodium glucose co-transporter 2 inhibitor, on the pharmacokinetics of oral contraceptives, warfarin, and digoxin in healthy participants.

OBJECTIVE: Drug-drug interactions between canagliflozin, a sodium glucose co-transporter 2 inhibitor approved for the management of type-2 diabetes mellitus, and an oral contraceptive (OC), warfarin, and digoxin were evaluated in three phase 1 studies in healthy participants. METHODS: All studies were open-label; study 1 included a fixed-sequence design, and studies 2 and 3 used a crossover design. Regimens were: study 1: OC (levonorgestrel (150 µg) + ethinyl estradiol (30 µg))/day (day 1), canagliflozin 200 mg/day (days 4 - 8), and canagliflozin with OC (day 9); study 2: canagliflozin 300 mg/day (days 1 - 12) with warfarin 30 mg/day (day 6) in period 1, and only warfarin 30 mg/day (day 1) in period 2, or vice versa; study 3: digoxin alone (0.5 mg/day (day 1) + 0.25 mg/day (days 2 - 7)) in period 1, and with canagliflozin 300 mg/day (days 1 - 7) in period 2, or vice versa. Pharmacokinetics (PK) were assessed at prespecified intervals; OC: days 1 and 9, canagliflozin: days 8 - 9 (study 1); warfarin: days 6 (period 1) and 1 (period 2) (study 2); and digoxin: days 5 - 7 (periods 1 and 2) (study 3). Warfarin's pharmacodynamics (PD; International Normalized Ratio (INR)) was assessed on days 6 (period 1) and 1 (period 2). RESULTS: Canagliflozin increased the plasma exposure of OC (maximum plasma concentration (Cmax): 22%, area under the curve (AUC): 6%) and digoxin (Cmax: 36%, AUC: 20%); but did not alter warfarin'€™s PK and PD. No clinically relevant safety findings (including hypoglycemia) were noted. CONCLUSION: Canagliflozin can be coadministered with OC, warfarin, or digoxin without dose adjustments. All treatments were well-tolerated.

Effects of rifampin, cyclosporine A, and probenecid on the pharmacokinetic profile of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in healthy participants.

OBJECTIVE: Canagliflozin, a sodium-glucose co-transporter 2 inhibitor, approved for the treatment of type-2 diabetes mellitus (T2DM), is metabolized by uridine diphosphate-glucuronosyltransferases (UGT) 1A9 and UGT2B4, and is a substrate of P-glycoprotein (P-gp). Canagliflozin exposures may be affected by coadministration of drugs that induce (e.g., rifampin for UGT) or inhibit (e.g. probenecid for UGT; cyclosporine A for P-gp) these pathways. The primary objective of these three independent studies (single-center, open-label, fixed-sequence) was to evaluate the effects of rifampin (study 1), probenecid (study 2), and cyclosporine A (study 3) on the pharmacokinetics of canagliflozin in healthy participants. METHODS: Participants received; in study 1: canagliflozin 300 mg (days 1 and 10), rifampin 600 mg (days 4-12); study 2: canagliflozin 300 mg (days 1-17), probenecid 500 mg twice daily (days 15-17); and study 3: canagliflozin 300 mg (days 1-8), cyclosporine A 400 mg (day 8). Pharmacokinetics were assessed at prespecified intervals on days 1 and 10 (study 1); on days 14 and 17 (study 2), and on days 2-8 (study 3). RESULTS: Rifampin decreased the maximum plasma canagliflozin concentration (Cmax) by 28% and its area under the curve (AUC) by 51%. Probenecid increased the Cmax by 13% and the AUC by 21%. Cyclosporine A increased the AUC by 23% but did not affect the Cmax. CONCLUSION: Coadministration of canagliflozin with rifampin, probenecid, and cyclosporine A was well-tolerated. No clinically meaningful interactions were observed for probenecid or cyclosporine A, while rifampin coadministration modestly reduced canagliflozin plasma concentrations and could necessitate an appropriate monitoring of glycemic control.

Single- and multiple-dose pharmacokinetics and pharmacodynamics of canagliflozin, a selective inhibitor of sodium glucose co-transporter 2, in healthy participants.

OBJECTIVE: To evaluate the pharmacokinetics of oral canagliflozin and its O-glucuronide metabolites (M7 and M5) after single and multiple doses in healthy adult participants. The pharmacodynamics, safety, and tolerability of canagliflozin were also evaluated. METHODS: In this open-label, single- (day 1) and multiple-dose (days 4-9), parallel-group, phase 1 study, 27 healthy participants were randomized into three groups (1:1:1) to receive 50, 100, or 300 mg canagliflozin. Pharmacokinetics and pharmacodynamics were assessed at pre-pecified timepoints on days 1, 9, and 10. RESULTS: Mean area under the plasma concentration-time curve, and the maximum observed plasma concentration of canagliflozin, M7, and M5 increased in a dose-dependent manner, across all the 3 doses, following single- and multiple-dose administration. The mean apparent elimination half-lives of canagliflozin, M7, and M5 were independent of the dose. Canagliflozin decreased the renal threshold for glucose (RTG) and increased the urinary glucose excretion (UGE) in a concentration- and dose-dependent manner. The relationship between drug concentrations and RTG was described by a sigmoidal relationship with RTGmin (minimum value of RTG) of 37.5 ng/mL (95% confidence interval (CI): 34.3, 40.8) and half-maximal effective concentration (EC50) of 21 ng/mL (95% CI: 18.3, 23.8). No deaths, serious adverse events, hypoglycemic events, or discontinuations due to adverse events were observed. CONCLUSION: Pharmacokinetics of canagliflozin and its metabolites (M7 and M5) were linear, and no time-dependent changes were observed after single- and multiple-dose administration. Similarly, pharmacodynamic effects of canagliflozin on RTG and UGE were found to be dose- and concentration-dependent. Overall, canagliflozin was well-tolerated in healthy participants.

Impact on abiraterone pharmacokinetics and safety: Open-label drug-drug interaction studies with ketoconazole and rifampicin.

We evaluated the impact of a strong CYP3A4 inhibitor, ketoconazole, and a strong inducer, rifampicin, on the pharmacokinetic (PK) exposure of abiraterone in two studies in healthy men. All subjects received 1,000 mg of abiraterone acetate on Days 1 and 14. Study A subjects (n = 20) received 400 mg ketoconazole on Days 11-16. Study B subjects (n = 19) received 600 mg rifampicin on Days 8-13. Serial PK sampling was done on Days 1 and 14. Study A: When given with ketoconazole, abiraterone exposure increased by 9% for maximum plasma concentration (Cmax ) and 15% for area under the plasma concentration-time curve from 0 to time of the last quantifiable concentration (AUClast ) and AUC from time 0 to infinity (AUC∞ ) compared to abiraterone acetate alone. Study B: When given with rifampicin, abiraterone exposure was reduced to 45% for Cmax and AUC∞ and to 42% for AUClast compared to abiraterone acetate alone. Ketoconazole had no clinically meaningful impact on abiraterone exposure. Rifampicin decreased abiraterone exposure by half. Hence, strong CYP3A4 inducers should be avoided or used with careful evaluation of clinical efficacy when administered with abiraterone acetate.

Effect of canagliflozin, a sodium glucose co-transporter 2 inhibitor, on C-peptide kinetics.

Canagliflozin, a sodium glucose co-transporter 2 inhibitor, improves indices of ß-cell function estimated based on circulating C-peptide and glucose concentrations (e.g., Homeostasis Model Assessment [HOMA2-%B], meal tolerance test-based indices). However, use of these ß-cell function indices assumes C-peptide kinetics are not altered by canagliflozin. This 2-period crossover study assessed the effect of a single canagliflozin 300-mg dose on C-peptide kinetics in 10 healthy participants. Two hours after receiving canagliflozin or placebo, participants received intravenous somatostatin infusion to suppress endogenous C-peptide secretion and 1 hour later received a bolus injection of synthetic human C-peptide 150 µg. Serum C-peptide was measured over 3 hours and urinary glucose and C-peptide excretion were measured. C-peptide kinetic parameters, including total clearance (CLtotal ) and renal clearance (CLrenal ), were calculated. Serum C-peptide profiles were similar following canagliflozin or placebo treatment. C-peptide CLtotal was slightly lower with canagliflozin versus placebo (mean (SD) of 190 (37) vs. 197 (30) mL/min; canagliflozin/placebo ratio [90% CI] = 96.1% [93.0%; 99.3%]). Other kinetic parameters, including CLrenal , were generally similar between treatments. Results indicate canagliflozin 300 mg does not meaningfully alter C-peptide clearance or other kinetic parameters; therefore, C-peptide-based measurements of insulin secretion are appropriate for assessing ß-cell function in canagliflozin-treated participants.

Canagliflozin, a sodium glucose co-transporter 2 inhibitor, reduces post-meal glucose excursion in patients with type 2 diabetes by a non-renal mechanism: results of a randomized trial.

OBJECTIVE: Canagliflozin is a sodium glucose co-transporter 2 inhibitor approved for treating patients with type 2 diabetes. This study evaluated renal and non-renal effects of canagliflozin on postprandial plasma glucose (PG) excursion in patients with type 2 diabetes inadequately controlled with metformin. MATERIALS/METHODS: Patients (N=37) were randomized to a four-period crossover study with 3-day inpatient stays in each period and 2-week wash-outs between periods. Patients received Treatments (A) placebo/placebo, (B) canagliflozin 300 mg/placebo, (C) canagliflozin 300 mg/canagliflozin 300 mg, or (D) canagliflozin 300 mg/canagliflozin 150 mg on Day 2/Day 3 in one of four treatment sequences (similar urinary glucose excretion [UGE] expected for Treatments B-D). A mixed-meal tolerance test (MMTT) was given 20 minutes post-dose on Day 3 of each period. RESULTS: A single dose of canagliflozin 300 mg reduced both fasting and postprandial PG compared with placebo, with generally similar effects on fasting PG and UGE observed for Treatments B-D. An additional dose of canagliflozin 300 mg (Treatment C), but not 150 mg (Treatment D), prior to the MMTT on Day 3 provided greater postprandial PG reduction versus placebo (difference in incremental glucose AUC0-2h, -7.5% for B vs A; -18.5% for C vs A; -12.0% [P = 0.012] for C vs B), leading to modestly greater reductions in total glucose AUC0-2h with Treatment C versus Treatment B or D. Canagliflozin was generally well tolerated. CONCLUSIONS: These findings suggest that a non-renal mechanism (ie, beyond UGE) contributes to glucose lowering for canagliflozin 300 mg, but not 150 mg.

Effects of hydrochlorothiazide on the pharmacokinetics, pharmacodynamics, and tolerability of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in healthy participants.

BACKGROUND: Many patients with type 2 diabetes mellitus (T2DM) also have hypertension, which is commonly treated with thiazide diuretics, including hydrochlorothiazide (HCTZ). Canagliflozin, a sodium glucose cotransporter 2 inhibitor developed for the treatment of T2DM, lowers plasma glucose by inhibiting renal glucose reabsorption, thereby increasing urinary glucose excretion and mild osmotic diuresis. Because patients with T2DM are likely to receive concurrent canagliflozin and HCTZ, potential interactions were evaluated. OBJECTIVE: This study evaluated the effects of HCTZ on the pharmacokinetic and pharmacodynamic properties and tolerability of canagliflozin in healthy participants. METHODS: This Phase I, single-center, open-label, fixed-sequence, 2-period study was conducted in healthy participants. During period 1, participants received canagliflozin 300 mg once daily for 7 days, followed by a 14-day washout period. During period 2, participants received HCTZ 25 mg once daily for 28 days, followed by canagliflozin 300 mg + HCTZ 25 mg once daily for 7 days. Blood samples were taken before and several times after administration on day 7 of period 1 and on days 28 and 35 of period 2 for canagliflozin and HCTZ pharmacokinetic analyses using LC-MS/MS. Blood and urine samples were collected for up to 24 hours after canagliflozin administration on day 1 of period 1 and day 35 of period 2 for pharmacodynamic glucose assessment. Tolerability was also evaluated. RESULTS: Thirty participants were enrolled (16 men, 14 women; all white; mean age, 43.7 years). Canagliflozin AUC during a dosing interval (T) at steady state (AUCτ,ss) and Cmax at steady state (Cmax,ss) were increased when canagliflozin was coadministered with HCTZ, with geometric mean ratios (90% CI) of 1.12 (1.08-1.17) and 1.15 (1.06-1.25), respectively. AUCτ,ss and Cmax,ss for HCTZ were similar with and without canagliflozin coadministration. The 24-hour mean renal threshold for glucose and mean plasma glucose were comparable for canagliflozin alone and coadministered with HCTZ. The change in 24-hour urine volume from baseline was -0.1 L with canagliflozin alone and 0.4 L with HCTZ alone and with canagliflozin + HCTZ. The overall incidence of adverse events (AEs) was higher with canagliflozin + HCTZ (69%) than with canagliflozin (47%) or HCTZ (50%) alone; most AEs were of mild severity. Overall, minimal changes in serum electrolytes (eg, sodium, potassium) were observed after coadministration of canagliflozin + HCTZ compared with individual treatments. CONCLUSIONS: Adding canagliflozin treatment to healthy participants on HCTZ treatment had no notable pharmacokinetic or pharmacodynamic effects; canagliflozin coadministered with HCTZ was generally well tolerated, with no unexpected tolerability concerns. ClinicalTrials.gov identifier: NCT01294631.

Canagliflozin lowers postprandial glucose and insulin by delaying intestinal glucose absorption in addition to increasing urinary glucose excretion: results of a randomized, placebo-controlled study.

OBJECTIVE: Canagliflozin, a sodium glucose cotransporter (SGLT) 2 inhibitor, is also a low-potency SGLT1 inhibitor. This study tested the hypothesis that intestinal canagliflozin levels postdose are sufficiently high to transiently inhibit intestinal SGLT1, thereby delaying intestinal glucose absorption. RESEARCH DESIGN AND METHODS: This two-period, crossover study evaluated effects of canagliflozin on intestinal glucose absorption in 20 healthy subjects using a dual-tracer method. Placebo or canagliflozin 300 mg was given 20 min before a 600-kcal mixed-meal tolerance test. Plasma glucose, (3)H-glucose, (14)C-glucose, and insulin were measured frequently for 6 h to calculate rates of appearance of oral glucose (RaO) in plasma, endogenous glucose production, and glucose disposal. RESULTS: Compared with placebo, canagliflozin treatment reduced postprandial plasma glucose and insulin excursions (incremental 0- to 2-h area under the curve [AUC0-2h] reductions of 35% and 43%, respectively; P < 0.001 for both), increased 0- to 6-h urinary glucose excretion (UGE0-6h, 18.2 ± 5.6 vs. <0.2 g; P < 0.001), and delayed RaO. Canagliflozin reduced AUC RaO by 31% over 0 to 1 h (geometric means, 264 vs. 381 mg/kg; P < 0.001) and by 20% over 0 to 2 h (576 vs. 723 mg/kg; P = 0.002). Over 2 to 6 h, canagliflozin increased RaO such that total AUC RaO over 0 to 6 h was <6% lower versus placebo (960 vs. 1,018 mg/kg; P = 0.003). A modest (∼10%) reduction in acetaminophen absorption was observed over the first 2 h, but this difference was not sufficient to explain the reduction in RaO. Total glucose disposal over 0 to 6 h was similar across groups. CONCLUSIONS: Canagliflozin reduces postprandial plasma glucose and insulin by increasing UGE (via renal SGLT2 inhibition) and delaying RaO, likely due to intestinal SGLT1 inhibition.

Doripenem dosing recommendations for critically ill patients receiving continuous renal replacement therapy.

Doripenem dosing regimens for patients receiving continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodiafiltration (CVVHDF) were devised based on an established efficacy criterion (free plasma doripenem concentrations above the minimum inhibitory concentration [fT > MIC] of 1 mg/L for ≥35% of the dosing interval) while maintaining exposure below that with the highest studied dose of 1000 mg infused over 1 hour every 8 hours in healthy subjects. Simulations were utilized to assure ≥90% probability of achieving the efficacy criterion with the recommended doripenem regimens. Inflated intersubject variability of 40% (coefficient of variation) was used for pharmacokinetic parameters (representative of clinical variation) and nonrenal clearance was doubled to account for potential changes with acute renal insufficiency. Results indicate that a reduction in doripenem dose will be needed for critically ill patients receiving CVVH or CVVHDF. This work was conducted to fulfill a health authority request and resulted in the addition of dosing recommendations to the Doribax Summary of Product Characteristics.

Pharmacokinetics of single-dose doripenem in adults with cystic fibrosis.

The pharmacokinetics of doripenem and doripenem-M-1 (inactive metabolite) were evaluated in an open-label, 2-period, single-sequence study in which single 1-g and 2-g doses of doripenem were administered intravenously over 4 hours to adult patients with cystic fibrosis (CF). The systemic exposure to doripenem and doripenem-M-1, as measured by observed apparent maximum plasma concentration (C(max)) and area under the plasma concentration-time curve (AUC), increased approximately proportionally to the increase in dose. Other pharmacokinetic parameters of doripenem and doripenem-M-1, including clearance, volume of distribution, and elimination half-life, were similar for the 1-g and 2-g doses. The results from this study were also compared with those from a previous study in adult healthy volunteers (HVs) without CF, from a previously conducted pharmacokinetic study, who received single doses of 500 mg and 1 g doripenem administered over 4 hours. The pharmacokinetics of doripenem in adult patients with CF are similar to those from adult HVs, noting some differences in the disposition when comparing body mass index-adjusted pharmacokinetic parameters.

Effect of multiple doses of omeprazole on the pharmacokinetics, pharmacodynamics, and safety of a single dose of rivaroxaban.

Many patients with acute coronary syndrome receive chronic dual antiplatelet therapy (acetylsalicylic acid and clopidogrel) for secondary event prophylaxis, and new oral anticoagulants are being investigated as adjunctive therapy in this indication. Gastrointestinal side effects such as bleeding are commonly associated with antiplatelet use; accordingly, many patients receive proton pump inhibitors (PPIs) to mitigate this. PPIs can reduce the antiplatelet activity of clopidogrel through cytochrome P450 2C19 inhibition, and pantoprazole reduces the bioavailability of dabigatran, a direct thrombin inhibitor that acts via cytochrome P450 2C19-independent mechanisms. These observations support the investigation of potential pharmacokinetic and pharmacodynamic interactions between PPIs and anticoagulants. We evaluated the influence of administering once-daily omeprazole 40 mg for 5 days on the pharmacokinetics and pharmacodynamics of a single 20-mg dose of the oral direct factor Xa inhibitor, rivaroxaban, in a randomized, open-label, 2-way, crossover, drug-drug interaction study in healthy subjects. No clinically meaningful interactions were observed; geometric mean ratios were 101%, 101%, and 93.5% for rivaroxaban area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUClast), or until infinity (AUC∞), and maximum plasma concentration (Cmax), respectively. Prothrombin time increased similarly in both treatment groups, with maximal values observed approximately 4 hours post rivaroxaban administration. A single 20-mg rivaroxaban dose appears well tolerated when administered alone or after 5 days of once-daily omeprazole 40 mg administration.

Influence of continuous venovenous hemofiltration and continuous venovenous hemodiafiltration on the disposition of doripenem.

The pharmacokinetics, safety, and tolerability of a single 1-hour, 500-mg intravenous infusion of doripenem were assessed in dialysis-dependent subjects with stage 5 chronic kidney disease undergoing continuous renal replacement therapy (CRRT) via 12-hour continuous venovenous hemofiltration (CVVH) (n = 6) or continuous venovenous hemodiafiltration (CVVHDF) (n = 5). Healthy volunteers were also assessed (n = 12). Concentrations of doripenem and the primary metabolite doripenem-M-1 were measured in plasma and ultrafiltrate or ultrafiltrate/dialysate by a validated liquid chromatography-tandem mass spectrometry method. In dialysis-dependent subjects, levels of systemic exposure to doripenem and doripenem-M-1 were approximately 3- and 5-fold greater, respectively, than those in healthy subjects: for doripenem, 98 µg·h/ml for CVVH and 77 µg·h/ml for CVVHDF versus 32 µg·h/ml for healthy subjects, and for doripenem-M-1, 24 µg·h/ml for CVVH and 22 µg·h/ml for CVVHDF versus 4.7 µg·h/ml for healthy subjects. The mean sieving coefficients and saturation coefficients were >0.67 for both doripenem and doripenem-M-1. During CVVH and CVVHDF, respectively, the percentages of administered doripenem dose removed were 38% and 29%, and clearances of doripenem were 22 and 25 ml/min. Both CVVH and CVVHDF efficiently removed doripenem and doripenem-M-1. Despite significant removal of drug by CVVH and CVVHDF, a single 1-hour, 500-mg doripenem infusion produced significantly higher plasma concentrations of doripenem, higher systemic exposure (area under the plasma concentration-time curve from time zero to 12 h after the start of infusion [AUC(0-12)]), and longer half-life (t(1/2)) in subjects receiving CVVH or CVVHDF than in healthy volunteers. The recovery of drug in ultrafiltrate and ultrafiltrate/dialysate and the enhanced rate of reduction of plasma concentrations indicate that CVVH and CVVHDF significantly augmented residual total body clearance of doripenem in subjects receiving CRRT. Doripenem dosage regimens for patients receiving CRRT thus need to be adjusted.

Pharmacokinetics, safety, and tolerability of doripenem after 0.5-, 1-, and 4-hour infusions in healthy volunteers.

The pharmacokinetics, safety, and tolerability of doripenem in healthy subjects were evaluated in 2 studies. Study 1 was a double-blind, randomized, placebo-controlled dose-escalation study in which doripenem was administered for 7 days by infusion over 30 minutes (500 mg) or 1 hour (1000 mg). Study 2 was an open-label, randomized, 3-way crossover study in which each subject received a single dose of each of the following doripenem treatments on separate occasions: 500 mg infused over 1 hour, 500 mg infused over 4 hours, and 1000 mg infused over 4 hours. Doripenem exhibited linear pharmacokinetics with concordance between the studies for pharmacokinetic parameters. Doripenem did not accumulate with repeated dosing over 7 days. The area under the plasma concentration-time curve (AUC) for doripenem 500 mg infused over 1 hour versus 4 hours was bioequivalent, and the AUC and Cmax increased proportionally with dose for the 500- and 1000-mg doses administered over 4 hours. These results, along with the stability profile of doripenem, support its use as a prolonged infusion. All regimens of doripenem were safe and well tolerated.

Disposition, metabolism, and excretion of [14C]doripenem after a single 500-milligram intravenous infusion in healthy men.

In this open-label, single-center study, eight healthy men each received a single 500-mg dose of [(14)C]doripenem, containing 50 microCi of [(14)C]doripenem, administered as a 1-h intravenous infusion. The concentrations of unchanged doripenem and its primary metabolite (doripenem-M-1) resulting from beta-lactam ring opening were measured in plasma and urine by a validated liquid chromatography method coupled to a tandem mass spectrometry assay. Total radioactivity was measured in blood, plasma, urine, and feces by liquid scintillation counting. Further metabolite profiling was conducted on urine samples using liquid chromatography coupled to radiochemical detection and high-resolution mass spectrometry. Unchanged doripenem and doripenem-M-1 accounted for means of 80.7% and 12.7% of the area under the plasma total-radioactivity-versus-time curve (area under the concentration-time curve extrapolated to infinity) and exhibited elimination half-lives of 1.1 and 2.5 h, respectively. Total clearance of doripenem was 16 liters/h, and renal clearance was 12.5 liters/h. At 7 days after the single dose, 95.3% of total doripenem-related radioactivity was recovered in urine and 0.72% in feces. A total mean of 97.2% of the administered dose was excreted in the urine as unchanged doripenem (78.7% +/- 5.7%) and doripenem-M-1 (18.5% +/- 2.6%). Most of the urinary recovery occurred within 4 h of dosing. Three additional minor metabolites were identified in urine: the glycine and taurine conjugates of doripenem-M-1 and oxidized doripenem-M-1. These results show that doripenem is predominantly eliminated in urine as unchanged drug, with only a fraction metabolized to doripenem-M-1 and other minor metabolites.

Pharmacokinetic and pharmacodynamic profiles of extended dosing of epoetin alfa in anemic patients who have chronic kidney disease and are not on dialysis.

BACKGROUND AND OBJECTIVES: Emerging evidence suggests that epoetin alfa can be administered at extended intervals of up to 4 wk. This open-label, randomized study was performed to characterize the pharmacokinetic and pharmacodynamic profiles of four dosing regimens of epoetin alfa administered subcutaneously in anemic patients who had chronic kidney disease and were not on dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Thirty-eight patients, enrolled from nine centers in the United States, were > or =18 yr of age and had hemoglobin <11.0 g/dl and GFR 12 to 60 ml/min per 1.73 m(2). Patients received one of four epoetin alfa dosing regimens: 50 IU/kg three times per week, 10,000 IU once weekly, or 20,000 IU every 2 wk for 36 d or 40,000 IU every 4 wk for 64 d. Each regimen provided a similar dosage of epoetin alfa over 4 wk. Dosage adjustments were not permitted. RESULTS: Drug exposure to epoetin alfa over 4 wk, based on area under the curve, was somewhat higher with the extended interval regimens compared with the three-times-weekly regimen. Mean change in hemoglobin during the study period was similar for all regimens. No patients were transfused. Three patients experienced five serious adverse events, none of which was considered treatment related. CONCLUSIONS: Extended dosing interval regimens of epoetin alfa yielded modest pharmacokinetic differences but a similar pharmacodynamic response, suggesting that less frequent, higher dosages of epoetin alfa may be as effective as the current three-times-weekly regimen in anemic patients who have chronic kidney disease and are not on dialysis.

Pharmacokinetics and pharmacodynamics of a transdermal contraceptive patch and an oral contraceptive.

This open-label, randomized, 2-way crossover study characterized the pharmacokinetics and pharmacodynamics of a transdermal contraceptive patch and a norgestimate-containing oral contraceptive. Healthy women (n = 34) applied a patch once weekly for 3 consecutive weeks during each of 2 cycles and received an oral contraceptive for 21 consecutive days during each of 2 cycles. Plasma concentrations of norelgestromin and ethinyl estradiol peaked and waned after daily oral contraceptive administration, whereas they rose and reached steady-state levels after first patch application. Norelgestromin exposure was similar; ethinyl estradiol exposure was higher for the patch than oral contraceptive. Hepatic estrogenic activity, assessed by hepatic globulin synthesis, was similar for corticosteroid-binding globulin and corticosteroid-binding globulin-binding capacity and higher for sex hormone-binding globulin for the patch versus oral contraceptive. The clinical significance of the differences in pharmacokinetic and pharmacodynamic profiles between the patch and oral contraceptive is not fully known. No serious adverse events or discontinuations due to adverse events were recorded.