Integration of modeling and simulation to support changes to ondansetron dosing following a randomized, double-blind, placebo-, and active-controlled thorough QT study.

Prolongation of the QT interval has been observed with ondansetron and other members of the 5-HT3 antagonist class. This is the first thorough QTc study of ondansetron conducted in accordance with ICH E14 guidelines, designed to investigate the effect of single intravenous (IV) doses of ondansetron on cardiac conduction compared to placebo and a positive control, moxifloxacin, in healthy subjects. Statistical analysis of dose-response showed the maximum mean difference in QTcF, compared to placebo and corrected for baseline (ddQTcF), was less than 10 milliseconds (ms) after an 8 mg IV dose and approximately 20 ms after the 32 mg dose, each infused over 15 minutes. The concentration-response (Cp-ddQTcF) model resulted in similar predictions for the 8 and 32 mg and was used to predict the maximum mean ddQTcF (upper 90% CI bound) of 9.2 (11.2) ms for 16 mg IV. As a result, single IV doses of ondansetron greater than 16 mg should no longer be used. Adult cancer patients, under 75 years, may receive up to a maximum initial 15-minute IV dose of 16 mg, prior to chemotherapy, followed by 2 additional IV or IM doses of 8 mg for the management of chemotherapy-induced nausea and vomiting (CINV).

Effects of vercirnon on the activity of CYP3A4, CYP2C19 and CYP2C8 enzymes and BCRP and OATP1B1 transporters using probe substrates.

PURPOSE: Vercirnon is a CCR9 chemokine receptor antagonist being developed for the treatment of Crohn's disease. As a variety of concomitant medications are often required for the treatment of Crohn's disease, it is important to characterise the drug interaction profile of vercirnon. To confirm the results of previous in vitro inhibition studies, this study assessed the in vivo effect of vercirnon on the activity of cytochrome P450 enzymes (CYP3A4, CYP2C19 and CYP2C8) and drug transport proteins (BCRP and OATP1B1) using probe substrates. METHODS: This was an open-label, single-sequence, repeat-dose study conducted in 24 healthy adult subjects. On days 1-4, subjects received probe substrates (midazolam, pioglitazone, omeprazole and rosuvastatin; in that order), followed by administration of vercirnon 500 mg twice daily (BID) on days 5-14. On days 11-14, in addition to vercirnon 500 mg BID, subjects also received probe substrates as on days 1-4. Blood samples were collected for pharmacokinetic analysis of probe substrates, vercirnon and two of its metabolites. RESULTS: Geometric least-squares mean ratios (90 % confidence interval) of area under the concentration-time curve from time zero to infinity for probe administered with vercirnon (test) compared with probe alone (reference) for midazolam, pioglitazone, omeprazole and rosuvastatin were 0.92 (0.85, 0.99), 1.01 (0.95, 1.07), 0.99 (0.76,1.31) and 0.98 (0.88, 1.09), respectively. CONCLUSIONS: Co-administration of probe substrates midazolam, pioglitazone, omeprazole, and rosuvastatin following repeat dosing of vercirnon 500 mg BID demonstrated vercirnon had no clinically significant effect on CYP3A4, CYP2C8, CYP2C19 enzyme activity or BCRP or OATP1B1 transporter activity.

Single-Dose Pharmacokinetics of the CCR9 Receptor Antagonist Vercirnon in Healthy US and Japanese Subjects.

Two randomized, single-dose, crossover studies were carried out to assess different formulations and doses of the CCR9 receptor antagonist vercirnon in healthy subjects. US study (n = 24): a five-period crossover study in healthy US subjects to assess the bioavailability of four new GlaxoSmithKline formulations compared with a "reference" formulation. Each subject received a single 500 mg dose of each of the five vercirnon formulations in a fed state. Primary pharmacokinetic (PK) endpoints were maximum plasma concentration, (Cmax ), and exposure as assessed by area under the curve (AUC). There was no significant difference in PK parameters and bioavailability between the formulations tested. Japanese study (n = 30): a four-period crossover study in healthy Japanese male subjects to assess PK and dose proportionality following single, ascending, oral doses of 250, 500, and 1,000 mg vercirnon under fasted and fed conditions. Vercirnon Cmax and AUC parameters in the fasted state increased in a less than dose proportional manner and were on average 20% higher in fed subjects compared with fasted subjects. Overall, these results support the premise that vercirnon has similar PK/safety profiles within US and Japanese populations. There was no evidence to preclude the use of the new vercirnon formulation in future studies.

Distinct pharmacokinetic profile and safety of a fixed-dose tablet of sumatriptan and naproxen sodium for the acute treatment of migraine.

OBJECTIVE: To describe the pharmacokinetic and safety profiles of sumatriptan 85 mg formulated with RT Technology (RT) and naproxen sodium 500 mg in a fixed-dose combination tablet (sumatriptan/naproxen sodium) that targets both serotonergic dysmodulation and inflammation in migraine. METHODS: Six open-label, crossover studies were conducted in healthy volunteers (Studies 1, 2, 3, 4, 5) or patients with migraine (Study 6). RESULTS: Consistently across studies, naproxen administered as a component of sumatriptan/naproxen sodium demonstrated a delayed-release profile similar to that of an enteric-coated product. Naproxen from the combination tablet showed a delayed time to peak plasma concentration and lower peak plasma concentration while exposures (area under the plasma concentration-time curve) were similar. The peak plasma concentration for naproxen was approximately 36% lower and the time to peak plasma concentration approximately 4 hours later when naproxen was administered as sumatriptan/naproxen sodium compared with a single naproxen sodium 550 mg tablet. Sumatriptan peak plasma concentration and area under the plasma concentration-time curve after administration of sumatriptan/naproxen sodium (containing sumatriptan 85 mg) were comparable to those after administration of a commercially available sumatriptan 100 mg (RT) tablet. Sumatriptan time to peak plasma concentration occurred, on average, 30 minutes earlier with sumatriptan/naproxen sodium compared with sumatriptan 100 mg (RT). No clinically significant differences between sumatriptan/naproxen sodium and sumatriptan tablets 100 mg (RT) were identified with respect to electrocardiograms, blood pressure, or heart rate. In addition, food had no significant effect on the bioavailability of naproxen or sumatriptan after administration of sumatriptan/naproxen sodium but slightly delayed the time to peak plasma concentration of sumatriptan by approximately 40 minutes. The pharmacokinetics of sumatriptan and naproxen did not differ according to whether sumatriptan/naproxen sodium was administered during a migraine attack or a migraine-free period. The pharmacokinetics of 2 sumatriptan/naproxen sodium tablets administered 2 hours apart were consistent with the pharmacokinetic predictions from a single dose of the combination tablet. The adverse-event profile of the sumatriptan/naproxen sodium combination tablet did not appear to differ from that of the individual components of the same or similar dosage strengths administered alone or in combination. In addition, the incidence of adverse events with 2 sumatriptan/naproxen sodium tablets administered 2 hours apart was lower than that with the single dose. CONCLUSION: The combination tablet of sumatriptan/naproxen sodium has unique pharmacokinetic properties. The rapid absorption of sumatriptan with the delayed-release properties of naproxen sodium from sumatriptan/naproxen sodium might contribute to its therapeutic advantage over monotherapy with either component. No clinically meaningful effects of food, administration during a migraine attack, or administration of a second tablet (2 hours after initial dose) on the pharmacokinetics or safety of sumatriptan/naproxen sodium were observed.

Population pharmacokinetics of intravenous ondansetron in oncology and surgical patients aged 1-48 months.

PURPOSE: Until recently, ondansetron was approved for the prevention of nausea and vomiting only in patients older than 2 years. However, as the use of ondansetron in patients younger than 2 years had been documented, characterization of ondansetron pharmacokinetics in this younger pediatric age group was warranted. METHODS: The pharmacokinetics of intravenously administered ondansetron were evaluated in oncology and surgical patients aged 1-48 months. Pooled data from 124 patients, including 745 pharmacokinetic samples, were analyzed using nonlinear mixed-effects modeling. RESULTS: Ondansetron pharmacokinetics were described by a two-compartment model. Body-size effects on ondansetron disposition were accounted for via standard allometric relationships, normalized to 10.4 kg. A maturation process with a half-life of approximately 4 months was incorporated to describe a decrease in clearance (CL) in infants. Clearance [95% confidence interval (CI)] for a typical patient was 1.53 (1.34-1.78) L/h/kg(0.75) with an interindividual variability of 56.8%. Ondansetron CL was reduced by 31%, 53%, and 76% for the typical 6-month-, 3-month-, and 1-month-old patient, respectively. Simulations showed that an ondansetron dose of 0.1 mg/kg in children younger than 6 months produced exposure similar to a 0.15-mg/kg dose in older children. CONCLUSIONS: The population pharmacokinetic analysis of ondansetron allows for characterization of individual patients based on body weight and age. It is recommended that patients younger than 4 months receiving ondansetron be closely monitored.

The effect of 5alpha-reductase inhibition with dutasteride and finasteride on semen parameters and serum hormones in healthy men.

CONTEXT: Dutasteride and finasteride are 5alpha-reductase inhibitors (5ARIs) that dramatically reduce serum levels of dihydrotestosterone (DHT). OBJECTIVE: Because androgens are essential for fertility, we sought to determine the impact of 5ARI administration on serum testosterone (T), DHT, and spermatogenesis. DESIGN, SETTING, SUBJECTS, AND INTERVENTION: We conducted a randomized, double-blinded, placebo-controlled trial in 99 healthy men randomly assigned to receive dutasteride (D; 0.5 mg) (n = 33), finasteride (F; 5 mg) (n = 34), or placebo (n = 32) once daily for 1 yr. MAIN OUTCOME MEASURES: Blood and semen samples were collected at baseline and 26 and 52 wk of treatment and 24 wk after treatment and were assessed for T, DHT, and semen parameters. RESULTS: D and F significantly (P < 0.001) suppressed serum DHT, compared with placebo (D, 94%; F, 73%) and transiently increased serum T. In both treatment groups, total sperm count, compared with baseline, was significantly decreased at 26 wk (D, -28.6%; F, -34.3%) but not at 52 wk (D, -24.9%; F, -16.2%) or the 24-wk follow-up (D, -23.3%; F, -6.2%). At 52 wk, semen volume was decreased (D, -29.7%; F, -14.5%, significantly for D) as was sperm concentration (D, -3.2%; [corrected] F, -7.4%, neither significant). There was a significant reduction of -6 to 12% in sperm motility during treatment with both D and F and at follow-up. Neither treatment had any effect on sperm morphology. CONCLUSIONS: This study demonstrates that the decrease in DHT induced by 5ARIs is associated with mild decreases in semen parameters that appear reversible after discontinuation.