Effect of Phosphate Binders and a Dietary Iron Supplement on the Pharmacokinetics of a Single Dose of Vadadustat in Healthy Adults.

Vadadustat is a hypoxia-inducible factor prolyl-hydroxylase inhibitor being developed for the treatment of anemia in patients with chronic kidney disease. Sequelae of chronic kidney disease include hyperphosphatemia and anemia, which are frequently treated with phosphate binders and iron supplements, respectively. Two studies evaluating the pharmacokinetics, safety, and tolerability of a single oral dose of vadadustat coadministered with a phosphate binder or iron supplement were conducted in healthy adult participants. In study 1, 54 healthy women and men were administered vadadustat (300 mg) alone and 1 hour before, concurrently with, or 2 hours after a phosphate binder (sevelamer carbonate 1600 mg, calcium acetate 1334 mg, or ferric citrate 2000 mg). In study 2, 10 healthy men were administered vadadustat (450 mg) alone and concomitantly with the oral iron supplement ferrous sulfate (325 mg [equivalent to 65 mg of elemental iron]). Vadadustat exposure was reduced by coadministration with sevelamer carbonate, calcium acetate, ferric citrate, or ferrous sulfate. Geometric least squares mean ratios for area under the concentration-time curve from time 0 to infinity were reduced 37% to 55% by phosphate binders and 46% by ferrous sulfate. However, when vadadustat was administered 1 hour before phosphate binders, 90% confidence intervals for vadadustat exposure were within the no-effect boundaries of +50% to -33%, indicating that drug-drug interactions can be reduced by administering vadadustat 1 hour before phosphate binders. Vadadustat was well tolerated when administered in conjunction with phosphate binders or an iron supplement.

Effect of Moderate Hepatic Impairment on the Pharmacokinetics of Vadadustat, an Oral Hypoxia-Inducible Factor Prolyl Hydroxylase Inhibitor.

Vadadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor in development for the treatment of anemia of chronic kidney disease. This phase 1, open-label, parallel-group, single-dose study evaluated the pharmacokinetics of 450-mg vadadustat in adults with moderate hepatic impairment (Child-Pugh class B) vs those with normal hepatic function. Primary end points were area under the plasma concentration-time curve (AUC) from dosing to last concentration and to infinity, as well as maximum concentration (Cmax ); additional pharmacokinetic parameters included time to Cmax (Tmax ) and half-life. Safety and tolerability were also assessed. All enrolled participants (n = 16) completed the study. Demographics were similar in both groups (overall, 100% White; 62.5% female; mean age, 59.2 years). Vadadustat plasma exposure was higher in the moderate hepatic impairment group, whereas maximum concentration was similar between groups. Point estimates of the hepatic impairment : normal geometric mean ratios (90% confidence interval) for AUC from dosing to last concentration, AUC from dosing to infinity, and Cmax were 1.05 (0.82-1.35), 1.06 (0.82-1.36), and 1.02 (0.79-1.32), respectively. Mean elimination half-life was 5.8 and 7.8 hours in the normal and hepatic impairment groups, respectively. Treatment-emergent adverse events were mostly mild in severity, and vadadustat was generally well tolerated. In conclusion, moderate hepatic impairment did not significantly impact vadadustat systemic exposure, and mild hepatic impairment is unlikely to alter vadadustat exposure.

Clinical Pharmacokinetics of Sulfobutylether-ß-Cyclodextrin in Patients With Varying Degrees of Renal Impairment.

Delafloxacin, a fluoroquinolone, has activity against Gram-positive organisms including methicillin-resistant S aureus and fluoroquinolone-susceptible and -resistant Gram-negative organisms. The intravenous formulation of delafloxacin contains the excipient sulfobutylether-ß-cyclodextrin (SBECD), which is eliminated by renal filtration. This study examined the pharmacokinetics and safety of SBECD after single intravenous (IV) infusions in subjects with renal impairment. The study was an open-label, parallel-group, crossover study in subjects with normal renal function or mild, moderate, or severe renal impairment, and those with end-stage renal disease undergoing hemodialysis. Subjects received 300 mg delafloxacin IV or placebo IV, containing 2400 mg SBECD, in 2 periods separated by ≥14-day washouts. SBECD total clearance decreased with decreasing renal function, with a corresponding increase in area under the concentration-time curve (AUC0-∞ ). After IV delafloxacin 300 mg administration, SBECD mean total clearance was 6.28 and 1.24 L/h, mean AUC0-∞ was 387 and 2130 h·µg/mL, and mean renal clearance was 5.36 and 1.14 L/h in normal and severe renal subjects, respectively. Similar values were obtained after IV placebo administration. In subjects with end-stage renal disease, delafloxacin 300 mg IV produced mean SBECD AUC0-48 values of 2715 and 7861 h·µg/mL when dosed before and after hemodialysis, respectively. Total SBECD clearance exhibited linear relationships to estimated glomerular filtration rate and creatinine clearance. Single doses of IV delafloxacin 300 mg and IV placebo were well tolerated in all groups. In conclusion, decreasing renal function causes reduced SBECD clearance and increased exposures, but SBECD continues to exhibit a good safety and tolerability profile in IV formulations.

Pharmacokinetics of Intravenous Delafloxacin in Patients With End-Stage Renal Disease.

This was an open-label, parallel-group, crossover study that examined the pharmacokinetics and safety of delafloxacin, an anionic fluoroquinolone, after a single intravenous infusion in subjects with end-stage renal disease (ESRD; creatinine clearance <15 mL/min) undergoing hemodialysis compared with healthy subjects. Subjects received 300 mg delafloxacin containing sulfobutylether-ß-cyclodextrin in 2 periods separated by ≥14-day washouts. Blood and urine samples were collected, and pharmacokinetic parameters were calculated using noncompartmental methods. The mean total exposure (area under the curve) of delafloxacin was about 2.1 and 2.6 higher for subjects with ESRD compared to healthy subjects when dosed 1 hour before or 1 hour after hemodialysis, respectively. Compared to subjects with normal renal function, the maximum exposure to delafloxacin was 13% and 33% higher for ESRD subjects given delafloxacin 1 hour before and 1 hour after hemodialysis, respectively. The mean clearance was 13.7 L/h for healthy subjects and was lower for subjects with ESRD when given before (7.39 L/h) or after (5.69 L/h) hemodialysis. The clearance of delafloxacin in dialysate was 4.74 L/h with about 19.2% of the delafloxacin dose recovered after a 4-hour dialysis session. Delafloxacin was well tolerated in both healthy and ESRD subjects, with diarrhea being the most reported treatment-emergent adverse event.

Delafloxacin Pharmacokinetics in Subjects With Varying Degrees of Renal Function.

Delafloxacin, a fluoroquinolone, has activity against gram-positive organisms including methicillin-resistant Staphylococcus aureus and fluoroquinolone-susceptible and -resistant gram-negative organisms. This study was conducted to determine delafloxacin pharmacokinetics after a single intravenous infusion or oral dose administration in subjects with varying degrees of renal function. The study was an open-label, parallel-group crossover study in subjects with normal renal function or with mild, moderate, or severe renal impairment. Subjects received 300 mg delafloxacin intravenously, placebo intravenously, and 400 mg delafloxacin orally in 3 periods separated by ≥14-day washouts. Blood and urine pharmacokinetic parameters were calculated using noncompartmental methods. Delafloxacin total clearance decreased with decreasing renal function, with a corresponding increase in AUC0-∞ . After intravenous administration, mean total clearance was 13.7 and 7.07 L/h, and mean AUC0-∞ was 22.6 and 45.0 µg·h/mL in normal and severe renal subjects, respectively. Mean renal clearance as determined by urinary excretion was 6.03 and 0.44 L/h in normal and severe renal impairment subjects, respectively. Total clearance exhibited linear relationships to eGFR and CLCR . Similar observations were found after oral administration of delafloxacin. Single doses of delafloxacin 300 mg intravenously and 400 mg orally were well tolerated in all groups. In conclusion, renal insufficiency has an effect on delafloxacin clearance; a dosing adjustment for intravenous dosing is warranted for patients with severe renal impairment (eGFR < 30 mL/min).

The Pharmacokinetics of the CYP3A Substrate Midazolam After Steady-state Dosing of Delafloxacin.

PURPOSE: Delafloxacin is a novel anionic fluoroquinolone in Phase III development for the treatment of serious skin infections. The objective of this study was to evaluate the effects of delafloxacin on the pharmacokinetics of midazolam, a cytochrome P450 (CYP) 3A substrate. METHODS: CYP3A activity using midazolam as a probe was assessed before and after multiple doses of delafloxacin to reach steady state. In this nonrandomized, open-label, single-sequence, Phase I study, 22 healthy male and female subjects were administered a single 5-mg oral dose of midazolam on days 1 and 8, with oral delafloxacin 450 mg every 12 hours administered from days 3 to 8. Full pharmacokinetic profiles were obtained on days 1 and 8 (midazolam and 1-hydroxymidazolam) and days 3 and 7 (delafloxacin). FINDINGS: The geometric mean ratios (90% CIs) for AUC0-∞ and Cmax of midazolam coadministered with delafloxacin versus midazolam alone were 89.4 (83.2-96.0) and 93.6 (83.7-104.6). Similarly, the geometric ratio for the AUC0-∞ of 1-hydroxymidazolam, the primary metabolite of midazolam, was 105.7 (97.7-114.3); the ratio of Cmax was not equivalent at 116.1 (101.7-132.4), which was outside the CI of 80% to 125%. Multiple doses of oral delafloxacin for 6 days were generally well tolerated. IMPLICATIONS: Steady-state dosing of delafloxacin produced no significant changes in midazolam pharmacokinetics, except for a small but not clinically relevant change in the Cmax of 1-hydroxymidazolam. ClinicalTrials.gov identifier: NCT02505997.

Clinical Pharmacology of Delafloxacin in Patients With Hepatic Impairment.

Delafloxacin is a novel anionic fluoroquinolone with robust activity against Gram-positive, Gram-negative, atypical, and anaerobic bacteria, including methicillin-resistant S aureus. Delafloxacin is currently being studied for the treatment of acute bacterial skin and skin structure infections and community-acquired pneumonia. This was a phase 1, open-label pharmacokinetic and safety study of a single intravenous dose of 300 mg delafloxacin in subjects with mild, moderate, and severe hepatic impairment (Child-Pugh class A, B, and C, respectively) compared with matched healthy controls. The effects of hepatic impairment were assessed by ANOVA of log-transformed values for AUC0-∞ , Cmax , and systemic clearance, with hepatic group as a fixed effect. Mean AUC0-∞ and Cmax in each impairment group were not significantly different from those of the pooled healthy subjects (P > 0.05). The 90% confidence interval (CI) of the percentage ratios of least-squares means of AUC0-∞ did not indicate significant differences between the impairment groups and pooled healthy controls: Child-Pugh class A (mild) 114.4 (CI: 95.6, 137.0), Child-Pugh class B (moderate) 114.8 (CI: 95.9, 137.4), and Child-Pugh class C (severe) 115.1 (CI: 96.1, 137.8). A single IV infusion of delafloxacin was generally well tolerated in all treatment groups. The exposure and clearance of delafloxacin in subjects with mild, moderate, or severe hepatic impairment did not significantly differ from those of pooled, matched healthy subjects. Based on these pharmacokinetic data, dose adjustment of delafloxacin in the presence of hepatic impairment is not needed.

Safety, Tolerability, and Pharmacokinetic Properties of Intravenous Delafloxacin After Single and Multiple Doses in Healthy Volunteers.

PURPOSE: The objective of this report was to determine the pharmacokinetic properties, safety, and tolerability of single and multiple doses of intravenous delafloxacin. In addition, the absolute bioavailability (BA) of the 450-mg tablet formulation of delafloxacin was determined. METHODS: Three clinical trials are summarized. The first study was a randomized, double-blind, placebo-controlled, single- (300, 450, 600, 750, 900, and 1200 mg) ascending-dose study of IV delafloxacin in 62 (52 active, 10 placebo) healthy volunteers. The second study was a randomized, double-blind, placebo-controlled study of IV delafloxacin (300 mg) given as a single dose on day 1, followed by twice-daily dosing on days 2 through 14; 12 (8 active, 4 placebo) healthy volunteers were enrolled. The third study was an open-label, randomized, 2-period, 2-sequence crossover study in which 56 healthy volunteers were randomly assigned to 1 of 2 sequences of a single oral dose of delafloxacin (450-mg tablet) or IV delafloxacin (300 mg). Serial blood samples were collected, and plasma pharmacokinetic parameters of delafloxacin were calculated. FINDINGS: Delafloxacin Cmax values increased proportionally with increasing single IV dose for the dose range of 300 to 1200 mg, whereas the AUC values increased more than proportionally to dose for the same dose range. The mean terminal half-life of delafloxacin was approximately 12 hours (ranging from 8 to 17 hours). The volume of distribution (Vd) at steady state was approximately 35 L, which is similar to the volume of total body water. There was minimal accumulation of delafloxacin after twice-daily IV administration of 300 mg with an accumulation ratio of 1.09. The delafloxacin total exposure after a single 1-hour IV infusion of 300 mg and a single oral dose of a 450-mg tablet were equivalent with geometric least square mean ratio (90% CI) of 0.8768 (0.8356-0.9200) for AUC0-∞ and 0.8445 (0.8090-0.8815) for AUC0-t, respectively. The Cmax values of delafloxacin were not equivalent for the 2 formulations with a ratio (90% CI) of 0.5516 (0.5150-0.5908), respectively. The mean absolute bioavailability of delafloxacin was 58.8%. IMPLICATIONS: Delafloxacin was well tolerated in healthy volunteers after single and multiple IV doses. The total systemic exposure to IV (300 mg) and oral (450 mg) delafloxacin is comparable, supporting that a switch between the 2 formulations is appropriate.

Single and Multiple Ascending-dose Studies of Oral Delafloxacin: Effects of Food, Sex, and Age.

PURPOSE: The objective of this report is describe the results of 2 studies that examined the pharmacokinetic parameters, safety profile, and tolerability of single and multiple ascending doses of oral delafloxacin and the effects of food, sex, and age on oral delafloxacin pharmacokinetic parameters, safety profile, and tolerability. METHODS: The first study contained 3 parts and used unformulated delafloxacin in a capsule. Part 1 was a randomized, double-blind, placebo-controlled, single (50, 100, 200, 400, 800, 1200, and 1600 mg) ascending-dose study of oral delafloxacin in healthy men. Part 2 was a single-dose crossover study in which 20 men received 250 mg delafloxacin with or without food. Part 2 also included a parallel group, double-blind, placebo-controlled study in 16 women and 16 elderly men and women who were randomized (3:1) to receive 250 mg delafloxacin or placebo. Part 3 was a randomized, double-blind, placebo-controlled, multiple (100, 200, 400, 800, 1200 mg once daily for 5 days) ascending-dose study of oral delafloxacin in healthy men. The second study was a single-dose, randomized, 3-period crossover study in which participants received 900 mg delafloxacin (2 × 450-mg tablets) under fasted conditions, with a high-fat meal, or fasted with a high-fat meal 2 hours after dosing. Serial blood samples were collected, and plasma pharmacokinetic parameters of delafloxacin were determined. FINDINGS: Delafloxacin Cmax and AUC0-∞ increased with increasing oral dose over the dose range of 50 to 1600 mg. The increases in delafloxacin AUC0-∞ were dose proportional at doses of ≥200 mg. Steady state was reached by day 3 of dosing with minimal accumulation of delafloxacin. The Cmax of delafloxacin was decreased slightly in the presence of food. No sex difference in delafloxacin pharmacokinetic parameters was observed. In the elderly men and women, mean delafloxacin Cmax and AUC0-∞ were 35% higher than observed for young adults, which could be partially explained by a decrease in the creatinine clearance in the elderly men and women. Delafloxacin was well tolerated at the tested doses, with gastrointestinal adverse effects observed more commonly at doses ≥1200 mg. IMPLICATIONS: Delafloxacin exhibits linear pharmacokinetic parameters that reached steady state after 3 days of daily oral dosing with minimal accumulation. Delafloxacin was well tolerated throughout both studies, with gastrointestinal effects observed at the higher doses (≥1200 mg).

Serum adalimumab concentration and clinical remission in patients with Crohn's disease.

BACKGROUND: Drug concentration monitoring may be useful to guide therapeutic adjustments for anti-tumor necrosis factor agents in Crohn's disease. The relationship between serum adalimumab concentrations and clinical outcomes was assessed using data from CLinical Assessment of Adalimumab Safety and Efficacy Studied as Induction Therapy in Crohn's Disease (CLASSIC) I/II. METHODS: Serum adalimumab concentrations at week 4 of CLASSIC I and weeks 4, 24, and 56 of CLASSIC II were compared by clinical remission status (yes/no). Logistic regression and Classification and Regression Tree analyses explored factors associated with remission at weeks 4, 24, and 56. Threshold analyses and receiver operating characteristic curves evaluated the relationship between serum concentrations and clinical remission/response. RESULTS: Serum adalimumab concentrations for 275 patients were available. Median adalimumab concentrations were significantly higher in patients who achieved clinical remission than those who did not at week 4 of CLASSIC I (8.10 versus 5.05 µg/mL, P < 0.05). At all time points, adalimumab concentrations demonstrated considerable variability and overlap between patients with and without remission. With Classification and Regression Tree analyses, baseline Crohn's Disease Activity Index, baseline C-reactive protein, and adalimumab concentrations were associated with early remission at week 4 of CLASSIC I and week 4 of CLASSIC II, but not at weeks 24 and 56. Receiver operating characteristic curves demonstrated low utility of cutoff thresholds to discriminate by clinical response/remission status. CONCLUSIONS: A positive association between serum adalimumab concentration and remission was identified at several time points. A threshold concentration reliably associated with remission was not identified. Further prospective evaluations are needed before recommendations for adalimumab concentration monitoring can be made.

Adalimumab for the induction and maintenance of clinical remission in Japanese patients with Crohn's disease.

BACKGROUND AND AIMS: Adalimumab has been shown to be efficacious and well-tolerated in Western patients with Crohn's disease. These 2 randomized, double-blind clinical trials evaluated adalimumab efficacy and safety in Japanese patients with moderate to severe Crohn's disease. METHODS: 90 patients enrolled in the induction trial and were randomized to receive adalimumab 160/80 mg, adalimumab 80/40 mg or placebo at Weeks 0/2. At Week 4, patients who achieved a decrease in CDAI ≥ 70 points versus Baseline entered the maintenance trial and were randomized to adalimumab 40 mg every other week or placebo for 52 weeks. All other patients received 4 more weeks of blinded adalimumab before entering the open-label portion of the maintenance trial. At/after Week 4 of the maintenance trial, blinded patients who flared/failed to respond entered the open-label portion. Open-label maintenance patients received adalimumab 40 mg every other week with the option of 80 mg every other week for flare/non-response. RESULTS: Clinical remission rates at Week 4 in the induction trial were 33.3%, 17.6% and 13.0% in the adalimumab 160/80 mg, adalimumab 80/40 mg and placebo groups, respectively. Maintenance remission rates were 38.1% for adalimumab and 9.1% for placebo at Week 52. Anti-TNF naïve patients achieved greater efficacy than anti-TNF exposed patients. Patients randomized to adalimumab achieved greater quality of life improvement versus placebo. There were no clinically relevant differences in safety between adalimumab and placebo. CONCLUSIONS: Adalimumab is effective and well-tolerated for inducing and maintaining clinical remission in Japanese patients with moderate to severe Crohn's disease.

Disposition and pharmacokinetics of L-N6-(1-iminoethyl)lysine-5-tetrazole-amide, a selective iNOS inhibitor, in rats.

The metabolism, pharmacokinetics, tissue distribution, and excretion of L-N6-(1-iminoethyl)lysine-5-tetrazole-amide (L-NIL-TA), a selective inducible NO synthase (iNOS) inhibitor, were investigated in rats. [(14)C]L-NIL-TA is extensively metabolized after either oral or IV administration with a minor amount (<1%) excreted as the prodrug. L-NIL-TA is metabolized via a single hydrolysis pathway to form the active drug, L-N6-(1-iminoethyl)lysine (L-NIL). The oxidative deamination of 2-amino group of L-NIL forms a 2-keto metabolite (M5), which further loses carbon dioxide to yield a carboxylic acid metabolite (M6). Acetylation of L-NIL and M5 resulted in the formations of metabolites M7 and M4, respectively. Complete recovery of the radioactive dose was achieved after either oral (91.2% in urine and 4.66% in feces) and IV (99.3% in urine and 5.11% in feces) administration. L-NIL-TA-related material was extensively distributed to the tissues, with the highest concentration of radioactivity being found in muscle. Maximal concentration of radioactivity was reached between 0.5 and 1 h post-dose in the majority of tissues, with the exception of muscle and skin where the maximal concentrations were achieved at 8 h post-dose.

Pharmacology of cyclooxygenase-2 inhibition in the kidney.

Cyclooxygenase (COX) exists as two unique isoforms (that is, COX-1 and COX-2) which are poorly understood with regard to their roles in renal function. The renal effects of conventional non-steroidal anti-inflammatory drugs (NSAIDs) are believed to result from the inhibition of one or both isoforms. Drugs that selectively inhibit COX-2 provide useful pharmacological tools for discerning the effects associated with the inhibition of the individual isoforms, and may help clarify the renal roles of COX-1 and COX-2. This review summarizes the current data on the renal expression of COX isoforms and their potential roles in renal function, and reviews the studies that have attempted to correlate renal functional changes with selective isoform inhibition. Since there are significant differences in the expression of COX isoforms in the kidneys of laboratory animals and humans, this review also examines the correlation of the results of COX inhibition in experimental studies in laboratory animals with clinical data. Because of potential interspecies differences in the roles of COX isoforms in renal function, animal models may have limited predictive value for patients, particularly those with renal risk factors. Accordingly, any uncertainty concerning the safety or therapeutic benefit of COX-2-specific drugs in these patient populations will need to be resolved with clinical investigations.