Christopher R. Curtin

Pharmacokinetics and Pharmacodynamics of Canagliflozin, a Sodium Glucose Co‐Transporter 2 Inhibitor, in Subjects With Type 2 Diabetes Mellitus

This study characterized single‐ and multiple‐dose pharmacokinetics of canagliflozin and its O‐glucuronide metabolites (M5 and M7) and pharmacodynamics (renal threshold for glucose [RTG], urinary glucose excretion [UGE0–24h], and 24‐hour mean plasma glucose [MPG0–24h]) of canagliflozin in subjects with type 2 diabetes. Thirty‐six randomized subjects received canagliflozin 50, 100, or 300 mg/day or placebo for 7 days. On Days 1 and 7, area under the plasma concentration‐time curve and maximum observed plasma concentration (Cmax) for canagliflozin and its metabolites increased dose‐dependently. Half‐life and time at which Cmax was observed were dose‐independent. Systemic molar M5 exposure was half that of canagliflozin; M7 exposure was similar to canagliflozin. Steady‐state plasma canagliflozin concentrations were reached by Day 4 in all active treatment groups. Pharmacodynamic effects were dose‐ and exposure‐dependent. All canagliflozin doses decreased RTG, increased UGE0–24h, and reduced MPG0–24h versus placebo on Days 1 and 7. On Day 7, placebo‐subtracted least‐squares mean decreases in MPG0–24h ranged from 42–57 mg/dL with canagliflozin treatment. Adverse events (AEs) were balanced between treatments; no treatment‐related serious AEs, AE‐related discontinuations, or clinically meaningful adverse changes in routine safety evaluations occurred. The observed pharmacokinetic/pharmacodynamic profile of canagliflozin in subjects with type 2 diabetes supports a once‐daily dosing regimen.

Single-Dose Pharmacokinetics of Intravenous Itraconazole and Hydroxypropyl-β-Cyclodextrin in Infants, Children, and Adolescents

ABSTRACT This investigation was designed to evaluate the single-dose pharmacokinetics of itraconazole, hydroxyitraconazole, and hydroxypropyl-β-cyclodextrin (HP-β-CD) after intravenous administration to children at risk for fungal infection. Thirty-three children aged 7 months to 17 years received a single dose of itraconazole (2.5 mg/kg in 0.1-g/kg HP-β-CD) administered over 1 h by intravenous infusion. Plasma samples for the determination of the analytes of interest were drawn over 120 h and analyzed by high-pressure liquid chromatography, and the pharmacokinetics were determined by traditional noncompartmental analysis. Consistent with the role of CYP3A4 in the biotransformation of itraconazole, a substantial degree of variability was observed in the pharmacokinetics of this drug after IV administration. The maximum plasma concentrations (Cmax) for itraconazole, hydroxyitraconazole, and HP-β-CD averaged 1,015 ± 692 ng/ml, 293 ± 133 ng/ml, and 329 ± 200 μg/ml, respectively. The total body exposures (area under the concentration-time curve from 0 to 24 h) for itraconazole, hydroxyitraconazole, and HP-β-CD averaged 4,922 ± 6,784 ng·h/ml, 3,811 ± 2,794 ng·h/ml, and 641.5 ± 265.0 μg·h/ml, respectively, with no significant age dependence observed among the children evaluated. Similarly, there was no relationship between age and total body clearance (702.8 ± 499.4 ml/h/kg); however, weak associations between age and the itraconazole distribution volume (r2 = 0.18, P = 0.02), Cmax (r2 = 0.14, P = 0.045), and terminal elimination rate (r2 = 0.26, P < 0.01) were noted. Itraconazole infusion appeared to be well tolerated in this population with a single adverse event (stinging at the site of infusion) deemed to be related to study drug administration. Based on the findings of this investigation, it appears that intravenous itraconazole can be administered to infants beyond 6 months, children, and adolescents using a weight-normalized approach to dosing.

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 pre-specified 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.

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). Canagliflozins 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 Canagliflozins 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.

Absence of a Pharmacokinetic Interaction Between Intravenous Theophylline and Orally Administered Levofloxacin

A randomized, placebo‐controlled, two‐way crossover study in 16 healthy men was performed to determine the effect of orally administered levofloxacin at steady‐state conditions, given at 500 mg every 12 hours, on the pharmacokinetics of theophylline given as a single 4.5‐mg/kg intravenous infusion. Participants were assigned randomly to receive theophylline with levofloxacin in one study period and theophylline with placebo in the other period. Fourteen individuals completed the study. Mean (± SD) values for theophylline pharmacokinetic parameters for the levofloxacin and placebo treatments, respectively, were peak plasma concentrations (Cmax) of 11.4 (1.8) μg/mL and 10.7 (1.3) μg/mL; areas under the concentration time curve from time 0 extrapolated to infinity (AUC0‐∞) of 124 (32) μg · hr/mL and 126 (30) μg · hr/mL; volumes of distribution at steady state (Vdss) 31.7 (3.5) L and 32.0 (3.9) L; clearances (Cl) of 48.6 (11.6) mL/min and 47.4 (10.3) mL/min; and half‐lives (t1/2) of 8.1 (1.9) hours and 8.2 (1.8) hours. There were no statistically significant differences between treatments for any of these parameters. There was no pharmacokinetic interaction between levofloxacin administered orally at steady‐state conditions and intravenously administered theophylline.

Pharmacokinetics of topiramate in patients with renal impairment, end-stage renal disease undergoing hemodialysis, or hepatic impairment

PURPOSE Topiramate is primarily renally excreted. Chronic renal and hepatic impairment can affect the clearance of topiramate. Therefore, the objective was to establish dosage guidelines for topiramate in chronic renal impairment, end-stage renal disease (ESRD) undergoing hemodialysis, or chronic hepatic impairment patients. METHODS In 3 separate open-label, parallel group studies (n=5-7/group), in patients with mild-moderate and severe renal impairment (based on creatinine clearance), ESRD requiring hemodialysis, or moderate-severe hepatic impairment (based on Child-Pugh classification) and matching healthy participants, pharmacokinetics of a single oral 100mg topiramate was determined. RESULTS Compared with healthy controls, overall exposure (AUC0-∞) for topiramate was higher in mild-moderate (85%) and severe renal impairment (117%), consistent with significantly (p<0.05) lower apparent total body clearance (CL/F) and renal clearance (CLR), leading to longer elimination half-life. Both CLR and CL/F of topiramate correlated well with renal function. CL/F was comparable in ESRD and severe renal impairment. Half of usual starting and maintenance dose is recommended in moderate-severe renal impairment patients, and those with ESRD. Hemodialysis effectively removed plasma topiramate with mean dialysis clearance approximately 12-fold greater than CL/F (123.5 mL/min versus 10.8 mL/min). Compared with healthy matched, patients with moderate-severe hepatic impairment exhibited small increase (29%) in topiramate peak plasma concentrations and AUC0-∞ values, consistent with lower CL/F (26%). Topiramate was generally well tolerated. CONCLUSION Half of usual dose is recommended for moderate-severe renal impairment and ESRD. Supplemental dose may be required during hemodialysis. Dose adjustments might not be required in moderate-severe hepatic impairments; however, the small sample size limits generalization.

Pharmacokinetic interactions between topiramate and pioglitazone and metformin

OBJECTIVE To investigate potential drug-drug interactions between topiramate and metformin and pioglitazone at steady state. METHODS Two open-label studies were performed in healthy adult men and women. In Study 1, eligible participants were given metformin alone for 3 days (500 mg twice daily [BID]) followed by concomitant metformin and topiramate (titrated to 100mg BID) from days 4 to 10. In Study 2, eligible participants were randomly assigned to treatment with pioglitazone 30 mg once daily (QD) alone for 8 days followed by concomitant pioglitazone and topiramate (titrated to 96 mg BID) from days 9 to 22 (Group 1) or to topiramate (titrated to 96 mg BID) alone for 11 days followed by concomitant pioglitazone 30 mg QD and topiramate 96 mg BID from days 12 to 22 (Group 2). An analysis of variance was used to evaluate differences in pharmacokinetics with and without concomitant treatment; 90% confidence intervals (CI) for the ratio of the geometric least squares mean (LSM) estimates for maximum plasma concentration (Cmax), area under concentration-time curve for dosing interval (AUC12 or AUC24), and oral clearance (CL/F) with and without concomitant treatment were used to assess a drug interaction. RESULTS A comparison to historical data suggested a modest increase in topiramate oral clearance when given concomitantly with metformin. Coadministration with topiramate reduced metformin oral clearance at steady state, resulting in a modest increase in systemic metformin exposure. Geometric LSM ratios and 90% CI for metformin CL/F and AUC12 were 80% (75%, 85%) and 125% (117%, 134%), respectively. Pioglitazone had no effect on topiramate pharmacokinetics at steady state. Concomitant topiramate resulted in decreased systemic exposure to pioglitazone and its active metabolites, with geometric LSM ratios and 90% CI for AUC24 of 85.0% (75.7%, 95.6%) for pioglitazone, 40.5% (36.8%, 44.6%) for M-III, and 83.8% (76.1%, 91.2%) for M-IV, respectively. This effect appeared more pronounced in women than in men. Coadministration of topiramate with metformin or pioglitazone was generally well tolerated by healthy participants in these studies. CONCLUSIONS A modest increase in metformin exposure and decrease in topiramate exposure was observed at steady state following coadministration of metformin 500 mg BID and topiramate 100mg BID. The clinical significance of the observed interaction is unclear but is not likely to require a dose adjustment of either agent. Pioglitazone 30 mg QD did not affect the pharmacokinetics of topiramate at steady state, while coadministration of topiramate 96 mg BID with pioglitazone decreased steady-state systemic exposure to pioglitazone, M-III, and M-IV. While the clinical consequence of this interaction is unknown, careful attention should be given to the routine monitoring for adequate glycemic control of patients receiving this concomitant therapy. Concomitant administration of topiramate with metformin or pioglitazone was generally well tolerated and no new safety concerns were observed.

Pharmacokinetics and pharmacodynamics of once- and twice-daily multiple-doses of canagliflozin, a selective inhibitor of sodium glucose co-transporter 2, in healthy participants.

AIMS Assess the steady-state pharmacokinetics, pharmacodynamics and safety of once-daily (q.d.) versus twice-daily (b.i.d.) dosing with canagliflozin at the same total daily doses of 100 and 300 mg in healthy participants. METHODS 34 participants (17 in each cohort) were enrolled in this single-center, open-label, multiple-dose, 2-cohort, 2-way crossover study. Participants in each cohort received a total daily dose of either 100 or 300 mg canagliflozin for 5 days with q.d. then b.i.d. dosing or vice versa. Pharmacokinetics and pharmacodynamics were assessed on day 5 of each period. RESULTS The canagliflozin Cmax,ss of 100 and 300 mg q.d. dosing were higher by 66% and 72% than corresponding morning Cmax,ss of the 50 mg and 150 mg b.i.d. regimen, respectively. The geometric mean ratios (90% CI) of b.i.d./q.d. for AUC0-24h,ss at total doses of 100 and 300 mg were 97.08 (94.08; 99.62) and 99.32 (94.71; 104.16) respectively. Median tmax and mean t1/2 were independent of dose and regimen. Mean (SE) 24-h mean renal glucose threshold values for b.i.d. and q.d. regimens were 59.2 (1.03) and 60.2 (1.03) mg/dL for the 100 mg daily doses and 51.0 (1.04) and 52.5 (1.04) mg/dL for the 300 mg daily doses. Mean (SE) values of 24-h urinary glucose excretion for b.i.d. and q.d. regimens were 52.8 (1.94) and 48.6 (1.94) g for the 100 mg daily doses and 58.6 (3.81) and 57.8 (3.81) g for the 300 mg daily doses. Both doses were safe and well tolerated. CONCLUSION Pharmacokinetics and pharmacodynamics of canagliflozin administered q.d. relative to b.i.d. at the same 100 and 300 mg total daily doses were comparable. Overall, canagliflozin was well tolerated.

Single-dose Pharmacokinetics and Pharmacodynamics of Canagliflozin, a Selective Inhibitor of Sodium Glucose Cotransporter 2, in Healthy Indian Participants.

PURPOSE Canagliflozin, an orally active selective inhibitor of sodium glucose cotransporter 2, has been approved in several countries for the treatment of type 2 diabetes mellitus. This study assessed the pharmacokinetic (PK) and pharmacodynamic (PD) properties and tolerability of single-dose canagliflozin 200 or 300 mg in healthy Indian participants. METHODS In this Phase 1, single-center, open-label, 2-period crossover study, healthy adult participants were randomly assigned to receive a single dose of canagliflozin 200 mg in period 1, followed by canagliflozin 300 mg in period 2, or vice versa. The 2 periods were separated by a washout interval of 14 days. The PK and PD properties and tolerability of canagliflozin were assessed at prespecified time points. FINDINGS Of 15 randomized participants, 14 completed the study. After the administration of single doses of 200 and 300 mg, the mean (SD) Cmax values were 1792 (430) ng/mL and 2789 (941) ng/mL, respectively; AUC0-∞, values were 18,706 (3818) ng·h/mL and 28,207 (5901) ng·h/mL, respectively. The Tmax and t½ of canagliflozin were independent of dose (Tmax, 1.5 hours at both doses; t½, 13.0 and 12.6 hours with 200 and 300 mg). Over the first 4 hours, mean (SD) renal threshold for glucose (RTG) values were 60.8 (8.90) and 61.2 (7.04) mg/dL with the 200- and 300-mg doses, respectively. No effect on plasma glucose concentrations over 0 to 4 hours relative to baseline was observed with either dose. The only treatment-emergent adverse event (TEAE) reported in >1 participant was dizziness (2 participants with the 200-mg dose). None of the participants in the 300-mg group reported any TEAEs. No deaths, discontinuations due to TEAEs, or hypoglycemic episodes were reported. IMPLICATIONS The mean plasma exposure (Cmax and AUC) to canagliflozin increased in a dose-dependent manner after the administration of single-dose oral canagliflozin 200 and 300 mg in these healthy Indian participants. The Tmax and t½ of canagliflozin appeared to be independent of dose. Overall, PK characteristics were consistent with previous findings in other ethnic populations. The reductions in RTG with canagliflozin were similar to those reported in Western participants, whereas the amount of urinary glucose excretion was somewhat less than those previously observed in studies in Western participants. Canagliflozin was generally well tolerated in these healthy Indian participants. ClinicalTrials.gov identifier: NCT01748526.

Pharmacokinetic interactions between topiramate and diltiazem, hydrochlorothiazide, or propranolol

Drug–drug interactions between topiramate and diltiazem, hydrochlorothiazide, or propranolol were evaluated along with safety/tolerability in three open‐label studies. Healthy participants (aged 18–45 years) received topiramate 75 mg every 12 hours (q12h) and diltiazem 240 mg/day (study 1); topiramate 96 mg q12h and hydrochlorothiazide 25 mg/day (study 2); topiramate 100 mg q12h and propranolol 40–80 mg q12h (study 3). The pharmacokinetic parameters for topiramate, diltiazem (and active metabolites, desacetyldiltiazem [DEA], N‐demethyl diltiazem [DEM]), hydrochlorothiazide, and propranolol (and its active metabolite) were assessed at steady state. Results showed no effect of diltiazem on topiramate pharmacokinetics. However, a modest reduction in systemic exposures of diltiazem and DEA (10–27%) occurred during coadministration with topiramate. Systemic exposure of DEM was unaffected. Furthermore, oral and renal clearance of topiramate decreased (22–30%) significantly (P < 0.05) during coadministration with hydrochlorothiazide, while systemic exposure increased by 27–29%. Topiramate had no effect on hydrochlorothiazide pharmacokinetics. The results demonstrated lack of pharmacokinetic interaction between topiramate and propranolol. Overall, no new safety concerns emerged when topiramate was coadministered with diltiazem, hydrochlorothiazide, or propranolol.