A course in constructing effective displays of data for pharmaceutical research personnel.

Interpreting data and communicating effectively through graphs and tables are requisite skills for statisticians and non-statisticians in the pharmaceutical industry. However, the quality of visual displays of data in the medical and pharmaceutical literature and at scientific conferences is severely lacking. We describe an interactive, workshop-driven, 2-day short course that we constructed for pharmaceutical research personnel to learn these skills. The examples in the course and the workshop datasets source from our professional experiences, the scientific literature, and the mass media. During the course, the participants are exposed to and gain hands-on experience with the principles of visual and graphical perception, design, and construction of both graphic and tabular displays of quantitative and qualitative information. After completing the course, with a critical eye, the participants are able to construct, revise, critique, and interpret graphic and tabular displays according to an extensive set of guidelines.

Repeatability of edited lactate and other metabolites in astrocytoma at 3T.

PURPOSE: To assess the repeatability of measurement of lactate and other metabolites in tumors using magnetic resonance spectroscopy (MRS). MATERIALS AND METHODS: MRS with spectral editing for lactate was performed on 10 patients with astrocytoma (two Grade III, eight Grade IV) using an 8-channel receive coil at 3T. Lactate, lipid, choline, creatine, and N-acetyl aspartate (NAA) signals were measured in regions of tumor and contralateral white matter. Metabolites were quantified relative to unsuppressed water using LCModel fitting software. RESULTS: The within-patient coefficients of variation were ≈16% (tumor lactate), 6%-8% (tumor choline and contralateral choline, creatine, and NAA), and 22% (tumor lipid). As expected due to their low concentration in normal tissue, lactate and lipid were not reliably detected in white matter but were found at high levels in most tumors. NAA and creatine were lower in tumors than in normal white matter, and choline varied between above- and below-normal values. No consistent short-term variation in metabolite levels was observed, despite differences in the time elapsed since administration of contrast agent. CONCLUSION: MRS appears repeatable enough to provide longitudinal measures of metabolite content in tumors and contralateral tissue in the brain in vivo.

A course for clinical trial personnel in clinical study designs, randomization, allocation schedules, and interactive response systems.

This continuing education course for professionals involved in all areas of clinical trials integrates concepts related to the role of randomization in the scientific process. The course includes two interactive lecture and discussion sections and a workshop practicum. The first interactive lecture introduces basic clinical trial issues and statistical principles such as bias, blinding, randomization, control groups, and the importance of formulating clear and discriminating clinical and statistical hypotheses. It then focuses on the most commonly used clinical study designs and the corresponding patient randomization schemes. The second interactive lecture focuses on the implementation of randomization of patients and drug supply through allocation and component ID schedules. The workshop practicum, conducted in small groups, enables students to apply the lecture concepts to real clinical studies. Flexibility was built into the workshop practicum materials to allow the course content to be customized to specific audiences, and the interactive lecture sessions can be stretched to cover more advanced topics according to class interest and time availability.

Pharmacokinetics of aprepitant after single and multiple oral doses in healthy volunteers.

Aprepitant is the first NK1 receptor antagonist approved for use with corticosteroids and 5HT3 receptor antagonists to prevent chemotherapy-induced nausea and vomiting (CINV). The effective dose to prevent CINV is a 125-mg capsule on day 1 followed by an 80-mg capsule on days 2 and 3. Study 1 evaluated the bioavailability of the capsules and estimated the effect of food. The mean (95% confidence interval [CI]) bioavailabilities of 125-mg and 80-mg final market composition (FMC) capsules, as assessed by simultaneous administration of stable isotope-labeled intravenous (i.v.) aprepitant (2 mg) and FMC capsules, were 0.59 (0.53, 0.65) and 0.67 (0.62, 0.73), respectively. The geometric mean (90% CI) area under the plasma concentration time curve (AUC) ratios (fed/fasted) were 1.2 (1.10, 1.30) and 1.09 (1.00, 1.18) for the 125-mg and 80-mg capsule, respectively, demonstrating that aprepitant can be administered independently of food. Study 2 defined the pharmacokinetics of aprepitant administered following the 3-day regimen recommended to prevent CINV (125 mg/80 mg/80 mg). Consistent daily plasma exposures of aprepitant were obtained following this regimen, which was generally well tolerated.

Effect of impaired renal function and haemodialysis on the pharmacokinetics of aprepitant.

BACKGROUND: The neurokinin NK(1)-receptor antagonist aprepitant has demonstrated efficacy in preventing highly emetogenic chemotherapy-induced nausea and vomiting. OBJECTIVE: The objective of the present study was to investigate the effects of impaired renal function on the pharmacokinetics and safety of aprepitant. SUBJECTS AND METHODS: A total of 32 patients and healthy subjects were evaluated in this open-label, two-part study. Pharmacokinetic parameters after a single oral dose of aprepitant 240 mg were measured in eight patients with end-stage renal disease (ESRD) requiring haemodialysis, eight patients with severe renal insufficiency (SRI [24-hour creatinine clearance <30 mL/min/1.73 m(2)]) and 16 healthy and age-, sex- and weight-matched subjects (controls). RESULTS: In ESRD patients, the area under the plasma concentration-time curve (AUC) from 0 to 48 hours (AUC(48)) for aprepitant was on average approximately 36% lower than that observed in control subjects (ratio [ESRD patients/healthy controls] of geometric means = 0.64), but the 90% confidence interval 0.52, 0.78 for the ratio of true mean AUC(48) fell within the predefined target interval of 0.5, 2.0. Also in ESRD patients, there was no statistically or clinically significant difference in unbound aprepitant AUC (which may be more clinically relevant than total aprepitant AUC) when compared with healthy control subjects. Aprepitant pharmacokinetic parameters in ESRD patients were clinically similar when haemodialysis was initiated at 4 hours or 48 hours after aprepitant administration. In SRI patients, the ratio (SRI patients/healthy controls) of aprepitant AUC from zero to infinity (AUC(infinity)) geometric mean value was 0.79 with a 90% confidence interval of 0.56, 1.10. On average, in SRI patients the principal aprepitant pharmacokinetic parameters (AUC(infinity), initial maximum plasma concentration [C(max)], time to initial C(max), and apparent elimination half-life) were not statistically different from those obtained in healthy control subjects. Aprepitant was generally well tolerated in both ESRD and SRI patients. CONCLUSION: The results of this study demonstrate that ESRD, haemodialysis and SRI have no clinically meaningful effect on aprepitant pharmacokinetics. Therefore, no dosage adjustment of aprepitant is warranted in SRI or ESRD patients.

Human positron emission tomography studies of brain neurokinin 1 receptor occupancy by aprepitant.

BACKGROUND: Aprepitant is a highly selective substance P (neurokinin 1 [NK(1)] receptor) antagonist that significantly improves the pharmacotherapy of acute and delayed highly emetogenic chemotherapy-induced nausea and vomiting, probably through an action in the brain stem region of the central nervous system. Here, we report the use of positron emission tomography imaging with the NK(1) receptor binding-selective tracer [(18)F]SPA-RQC to determine the levels of central NK(1) receptor occupancy achieved by therapeutically relevant doses of aprepitant in healthy humans. METHODS: Two single-blind, randomized, placebo-controlled studies in healthy subjects were performed. The first study evaluated the plasma concentration-occupancy relationships for aprepitant dosed orally at 10, 30, 100, or 300 mg, or placebo (n = 12). The second study similarly evaluated oral aprepitant 30 mg and placebo (n = 4). In each study, dosing was once daily for 14 consecutive days. Data from both studies were combined for analyses. The ratio of striatal/cerebellar [(18)F]SPA-RQ (high receptor density region/reference region lacking receptors) was used to calculate trough receptor occupancy 24 hours after the last dose of aprepitant. RESULTS: Brain NK(1) receptor occupancy increased after oral aprepitant dosing in both a plasma concentration-related (r =.97; 95% confidence interval [CI] =.94-1.00, p <.001) and a dose-related (r =.94; 95% CI =.86-1.00, p <.001) fashion. High (> or =90%) receptor occupancy was achieved at doses of 100 mg/day or greater. The plasma concentrations of aprepitant that achieved 50% and 90% occupancy were estimated as approximately 10 ng/mL and approximately 100 ng/mL, respectively. CONCLUSIONS: Positron emission tomography imaging with [(18)F]SPA-RQ allows brain NK(1) receptor occupancy by aprepitant to be predicted from plasma drug concentrations and can be used to guide dose selection for clinical trials of NK(1) receptor antagonists in central therapeutic indications.

Evaluation of potential inductive effects of aprepitant on cytochrome P450 3A4 and 2C9 activity.

The NK(1) receptor antagonist aprepitant (EMEND(R)), developed for use in combination with a 5HT(3) receptor antagonist and a corticosteroid to prevent highly emetogenic chemotherapy-induced nausea and vomiting (CINV), has been shown to have a moderate inhibitory effect as well as a possible inductive effect on cytochrome P450 (CYP) 3A4. Aprepitant has been noted to produce modest decreases in plasma S(-)-warfarin concentrations, suggesting potential induction of CYP2C9. Because metabolism of some chemotherapeutic agents may involve CYP3A4, the potential inductive effect of the CINV dosing regimen of aprepitant on this metabolic pathway was evaluated using intravenous midazolam, a sensitive probe substrate of CYP3A4. The time course of induction of CYP2C9 by aprepitant was also evaluated using oral tolbutamide, a probe substrate of CYP2C9. In this double-blind, randomized, placebo-controlled, single-center study, 24 healthy subjects were randomized (12 subjects per group) to receive either an aprepitant 3-day regimen (aprepitant 125 mg p.o. on day 1 and aprepitant 80 mg p.o. on days 2 and 3) or matching placebo. All subjects also received probe drugs (midazolam 2 mg i.v. and tolbutamide 500 mg p.o.) once prior to aprepitant dosing (baseline) and again on days 4, 8, and 15. The ratio (aprepitant/placebo) of the geometric mean area under the plasma concentration curve (AUC) fold-change from baseline for midazolam was 1.25 on day 4 (p < 0.01), 0.81 on day 8 (p < 0.01), and 0.96 on day 15 (p = 0.646). The ratio (aprepitant/placebo) of the geometric mean AUC fold-change from baseline for tolbutamide was 0.77 on day 4 (p < 0.01), 0.72 on day 8 (p < 0.001), and 0.85 on day 15 (p = 0.05). Assessed using intravenous midazolam as a probe, aprepitant 125/80 mg p.o. administered over days 1 to 3 produced clinically insignificant weak inhibition (day 4) and induction (day 8) of CYP3A4 activity and no effect on CYP3A4 activity on day 15. Assessed using oral tolbutamide as a probe, the aprepitant regimen also produced modest induction of CYP2C9 activity on days 4 and 8, which resolved nearly to baseline by day 15. Thus, the aprepitant regimen for CINV results in modest, transient induction of CYPs 3A4 and 2C9 in the 2 weeks following administration.

Quantitative magnetic resonance fat measurements in humans correlate with established methods but are biased.

Precision and accuracy of the quantitative magnetic resonance (QMR) system for measuring fat in phantoms and total body fat (TBF) in humans were investigated. Measurements were made using phantoms: oil, beef with water, beef with oil, and humans with oil and water. TBF(QMR) in humans was compared with TBF by a four-compartment model (TBF(4C)). The coefficient of variation (CV) for replicate TBF(QMR) was 0.437%. QMR fat was lower at 23 °C vs. 37 °C. The fat increase in QMR phantom studies was consistent with the oil increase. When oil was added with humans, the increase in TBF(QMR) was >250 g for the initial 250 g of oil. With additional oil increments, the increase in TBF(QMR) was consistent with the amount of oil added. When water was added with humans, the TBF(QMR) increased independent of the amount of water added. TBF(QMR) was significantly less (mean ± s.e.) than TBF(4C) (females: -0.68 ± 0.27 kg, males: -4.66 ± 0.62 kg; P = 0.0001), TBF(BV) (females: -1.90 ± 0.40 kg; males: -5.68 ± 0.75 kg; P = 0.0001), and TBF(D2O) for males, but greater for females (1.19 ± 0.43 kg vs. -3.69 ± 0.81 kg for males; P = 0.0003). TBF(QMR) was lower than TBF(iDXA) with the difference greater in males (P = 0.001) and decreased with age (P = 0.011). The strong linear relationships between TBF(QMR) and TBF(4C), TBF(BV), and TBF(D2O) with slopes consistent with unity suggest that modifications are required to improve the accuracy. Should the latter be accomplished, QMR holds promise as a highly precise, rapid, and safe, noninvasive method for estimating the amount of and changes in TBF in overweight and severely obese persons.