Virginia Parks

Absence of a pharmacokinetic interaction between etanercept and warfarin.

Etanercept, a soluble recombinant human tumor necrosis factor receptor (TNFr) fusion protein, is effective and well tolerated in the treatment of rheumatoid arthritis (RA), juvenile rheumatoid arthritis (JRA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). The primary objective of this study was to investigate the potential pharmacokinetic and pharmacodynamic interaction between a single dose of Rand S‐enantiomers of warfarin and multiple doses of etanercept after administration of warfarin and etanercept alone and together. In a nonrandomized, three‐period study, 12 healthy male subjects received a single oral 25‐mg dose of warfarin after an overnight fast, followed by twice‐weekly 25‐mg subcutaneous doses of etanercept for seven doses. The last dose of etanercept was administered concurrently with a second dose of warfarin. Serial blood samples for plasma warfarin concentration measurement and international normalized ratio (INR) assessment were collected before and up to 144 hours after dose administration. Serial blood samples for serum etanercept concentration measurement were collected before and up to 60 hours after the sixth dose and 264 hours after the seventh dose. Etanercept did not affect the pharmacokinetics and pharmacodynamics of warfarin. All ratios of maximum serum concentration (Cmax) and area under the serum concentration versus time curve (AUC) for pharmacokinetics (R‐ and S‐enantiomers of warfarin) and INR fell within the confidence interval of 0.8 to 1.25. Warfarin also did not cause a clinically significant alteration in the pharmacokinetics of etanercept. In conclusion, coadministration of etanercept and warfarin would not be expected to change the pharmacokinetics of either medication; therefore, no dosage adjustment is needed in cases in which warfarin and etanercept are coadministered.

Absence of a Clinically Relevant Interaction Between Etanercept and Digoxin

Etanercept, a soluble recombinant human tumor necrosis factor receptor (TNFr), is effective and well tolerated in the treatment of rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. The primary objective of this study was to investigate the potential pharmacokinetic and pharmacodynamic interaction between digoxin and etanercept at steady state. In a crossover, open‐label, nonrandomized, 3‐period study, 12 healthy male subjects received loading oral doses of digoxin 0.5 mg every 12 hours on day 1 and 0.25 mg every 12 hours on day 2, followed by a daily maintenance dose of 0.25 mg for a total of 27 days. Etanercept was administered as a twice‐weekly 25‐mg subcutaneous dose beginning on day 9 and continuing up to day 37 for a total of 9 doses. All ratios of maximum plasma concentration (Cmax) and area under the plasma concentration versus time curve (AUC) for pharmacokinetics of digoxin fell within the confidence interval of 0.8 to 1.25. Although not considered clinically relevant, the mean Cmax and AUC of etanercept were 4.2% and 12.5% lower, respectively, when etanercept was given with digoxin than when administered alone. There were no clinically relevant changes in the electrocardiogram (ECG) parameters, and adverse events did not increase when both drugs were combined. In conclusion, there is no clinically relevant interaction between etanercept and digoxin, and both drugs can be safely coadministered without the need for a dosage adjustment.

Safety, tolerability, pharmacokinetics and pharmacodynamics of ascending single and multiple doses of lecozotan in healthy young and elderly subjects.

AIMS To determine the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of oral immediate release (IR) lecozotan in healthy young and elderly subjects. METHODS Three randomized, double-blind, placebo-controlled, sequential, ascending dose Phase I studies of lecozotan were conducted. In a single-dose study, ascending doses of 2, 5 and 10 mg were administered to cohorts of eight young subjects. In the two ascending 14-day multiple-dose studies, 41 young subjects received 0.1, 0.25, 0.5, 1 and 5 mg q12h of lecozotan or placebo and 24 elderly received 0.5 mg and 5 mg q12h of lecozotan or placebo. Assessments included safety evaluations, a complete PK profile and PD. RESULTS Lecozotan was safe and well tolerated at steady state up to 5 mg q12. The maximum tolerated dose after multiple doses was >10 mg (5 mg q12). In the single-dose study, the maximum tolerated dose was 10 mg. Dose-limiting mild-to-moderate adverse events included paraesthesia, dizziness and visual disturbances peaking at t(max) and disappearing concomitantly with plasma concentrations. No clinically relevant changes in vital signs, ECG intervals or routine laboratory tests occurred. Lecozotan did not significantly change cognitive function, EEG or hormone levels. PK was characterized by rapid absorption, dose proportionality, extensive distribution and rapid elimination. The mean CL/F was approximately 35% lower in the elderly. CONCLUSIONS Lecozotan IR was safe and well tolerated after administration of multiple oral doses up to 5 mg q12h in young and elderly subjects. These results support the development of lecozotan in patients with Alzheimers disease.

Relative Bioavailability of Liquid and Tablet Formulations of the Antiparasitic Moxidectin.

The antiparasitic agent moxidectin is under development for the treatment of onchocerciasis. As the first‐in‐human study of moxidectin used a liquid formulation but other trials used tablets, a study was performed to determine the relative bioavailability of the 2 formulations and to gain more information about the pharmacokinetics of moxidectin. Fifty‐eight healthy male participants were randomized to receive open‐label moxidectin (10 mg) as a tablet (n = 29) or liquid (n = 29) formulation. The mean ± SD pharmacokinetic parameters observed following administration of the tablet were peak concentration (Cmax) 67.1 ± 27.4 ng/mL, time to peak concentration (tmax) 3.2 ± 1.4 hours, area under the concentration time curve (AUC) 4403 ± 2360 ng·h/mL, apparent volume of distribution 3635 ± 1720 L, oral clearance 2.83 ± 1.25 L/h, and elimination half‐life 1032 ± 502 hours. The Cmax and AUC observed following administration of the liquid formulation were 28.6% and 28.8% higher, respectively, and tmax 0.9 hours shorter compared with tablets. No serious adverse events (AEs) were observed. The most commonly reported AEs were headache, infection, diarrhea, asthenia, myalgia, and dizziness during the inpatient phase and flu syndrome, headache, and infection during the 6‐month outpatient phase. There was no difference in reporting of these AEs between formulations.

Excretion of Moxidectin into Breast Milk and Pharmacokinetics in Healthy Lactating Women

ABSTRACT Moxidectin, registered worldwide as a veterinary antiparasitic agent, is currently under development for humans for the treatment of onchocerciasis in collaboration with the World Health Organization. The objective of this study was to assess the pharmacokinetics of moxidectin in healthy lactating women, including the excretion into breast milk. Twelve women, ages 23 to 38 years, weighing 54 to 79 kg, all more than 5 months postpartum, were enrolled, following their plan to wean their infants and provision of informed consent. A single 8-mg, open-label dose was administered orally after consumption of a standard breakfast. Complete milk collection was done for approximately 28 days, and plasma samples were collected for 90 days. Moxidectin concentrations were measured by high-performance liquid chromatography (HPLC) with fluorescence detection, with a validated range of 0.08 to 120 ng/ml. Noncompartmental pharmacokinetic methods were used to find the following results: peak concentration in plasma (Cmax), 87 ± 25 ng/ml; time to Cmax (tmax), 4.18 ± 1.59 h; terminal-phase elimination half-life (t1/2), 832 ± 321 h; total area under the concentration-time curve (AUC), 4,046 ± 1,796 ng·h/ml; apparent oral dose clearance (CL/F), 2.35 ± 1.07 l/h; ratio of CL/F to the terminal-phase disposition rate constant, λz (Vλz/F), 2,526 ± 772 liters; percentage of maternal dose excreted in milk, 0.701 ± 0.299%; absolute amount excreted in milk, 0.056 ± 0.024 mg; relative infant dose, 8.73 ± 3.17% of maternal dose assuming complete absorption; clearance in milk (CLmilk), 0.016 ± 0.009 liter/h. Nine of 12 subjects reported adverse events, all of which were considered treatment emergent but not drug related and were mostly reported during the long outpatient period 8 to 90 days after dose administration. The most frequently reported adverse events were headache and nausea (n = 4), oropharyngeal pain (n = 2), rhinitis, viral pharyngitis, and viral upper respiratory tract infection (n = 2).

The effect of a high-fat breakfast on the pharmacokinetics of moxidectin in healthy male subjects: a randomized phase I trial.

The objective of this study was to assess the effect of a high-fat meal on the pharmacokinetics of moxidectin. Healthy male subjects were randomized to receive single oral 8 mg doses of moxidectin after an overnight fast or high-fat breakfast. In fasted subjects (N = 27), mean [SD] parameters were Cmax: 58.9 [12.5] ng/mL; tmax: 3.7 [1.5] h; area under concentration-time curve (AUC): 3,387 [1,328] ng/h/mL; Vλz/F: 2,829 [1,267] L; CL/F: 2.76 [1.28] L/h; and t½: 784 [347] h. Compared with fasted subjects, fed subjects (N = 27) exhibited a 34% increase in Cmax, delay in tmax to 5.3 [2.1] h, 44% increase in AUC, 40% decrease in Vλz/F, and a 35% decrease in CL/F. There was no significant change in t½. The changes are consistent with an increase in moxidectin bioavailability following administration with food. There were no clinically relevant changes in vital signs, laboratory tests, or electrocardiograms.

Pharmacokinetics of Sirolimus (Rapamycin) in Subjects With Severe Hepatic Impairment

Nine subjects with severe hepatic impairment (Child‐Pugh grade C) and 9 healthy matched control subjects were given a single 15‐mg dose of sirolimus by oral solution. Increases (P ≥ .002) in mean whole‐blood sirolimus t1/2 (168%), AUC0‐∞ (210%), and MRToral (261%), together with a decrease (P = .001) in CL/F (−67%), were observed in subjects with severe hepatic impairment compared with healthy matched controls. Sirolimus pharmacokinetic data in Child‐Pugh grade A (n = 13, mild) and B (n = 5, moderate) subjects from a previous identically designed study were available for an inter‐study comparison. Overall, mean t1/2, weight‐normalized AUC, and MRToral increased steadily, whereas mean CL/F decreased steadily, with increasing degrees of hepatic impairment. CL/F showed large intersubject variabilities within subject types and extensive overlap among the subject types. The results of this study suggest that an initial sirolimus dose reduction of approximately 60% is appropriate in patients with acute severe hepatic impairment; this should be followed by further dose adjustment, based on therapeutic drug monitoring, until the trough concentrations have stabilized at sirolimus levels existing prior to the onset of acute liver failure.

Effect of moxidectin on CYP3A4 activity as evaluated by oral midazolam pharmacokinetics in healthy subjects.

In order to evaluate the potential for CYP3A4 induction by moxidectin, midazolam pharmacokinetic (PK) parameters were compared before and after moxidectin administration. Healthy subjects received a single 8 mg dose of moxidectin and 3 single 7.5 mg doses of midazolam 3 days before, and 7 and 89 days after the moxidectin. Blood samples were taken for 24 hours to measure midazolam and metabolites in plasma, and for 89 days to measure moxidectin in plasma after dose administration. Noncompartmental PK analyses were performed for each analyte. Analysis of variance was performed on log‐transformed midazolam parameters with treatment day as a fixed effect. Adverse events were recorded and laboratory tests, physical examinations, pulse oximetry monitoring, vital sign measurement, and electrocardiograms performed. Thirty‐nine subjects were enrolled in the study; PK data were available for 37 subjects. Moxidectin PK parameters were similar to previous studies. There were no significant changes in PK for midazolam or its metabolites 7 or 89 days after moxidectin administration. Adverse events were generally mild and there were no relevant changes in safety assessments. Thus, 8 mg moxidectin does not induce CYP3A4 activity and other CYP3A4 substrates are unlikely to be affected by moxidectin co‐administration.