The Importance of Assessing Drug Pharmacokinetics and Pharmacodynamics in the Obese Population During Drug Development.

Obesity remains a US national health crisis and a growing concern worldwide. Concerningly, individuals who are obese are at an increased risk for comorbid diseases that include, but are not limited to, hypertension, diabetes, cardiovascular disease, and cancer. Beyond the risk for developing these conditions, obesity may also impact the pharmacological activity of the therapies being used to treat them and other disease states. The pharmacokinetics (PK), pharmacodynamics (PD), safety, and efficacy of therapies, both currently marketed and under clinical development, may be directly impacted by the physiological alterations that occur secondary to the occurrence of chronic excess body weight. The increased prevalence of this disease should not be ignored. Both private and federal institutions involved in drug research and development should consider, as appropriate, a greater inclusion of individuals who are obese in clinical trials throughout the entirety of drug development, and leverage the available PK, PD, safety, and efficacy data to make more informed dosing recommendations.

Pharmacokinetics and tolerability of rabeprazole in children 1 to 11 years old with gastroesophageal reflux disease.

BACKGROUND: The pharmacokinetics of rabeprazole after a single oral dose and once-daily administration for 5 consecutive days was characterized in children 1 to 11 years old with gastroesophageal reflux disease (GERD). PATIENTS AND METHODS: The initial 8 patients received rabeprazole sodium (hereafter referred to as rabeprazole) 0.14 mg/kg (part 1); the next 20 patients were randomized to receive 0.5 or 1 mg/kg (part 2) to target concentrations in plasma expected to be safe and effective. Pharmacokinetic parameters of rabeprazole and the thioether metabolite were calculated using noncompartmental methods. Subjective evaluations of GERD severity, rabeprazole short-term effectiveness, palatability, and safety were also characterized. RESULTS: Rabeprazole concentrations increased in a dose-dependent manner. Little or no accumulation was observed after repeated administration. The results suggest that formation of the thioether is an important metabolic pathway in young patients, which is consistent with adults. Plasma area under the concentration-time curve values of rabeprazole and the metabolite were poorly correlated with individual age and body weight. Furthermore, oral rabeprazole clearance values (not adjusted for weight) were similar to historical adult data. However, weight-adjusted values were higher for the pediatric patients, and approximately 2 to 3 times the milligram per kilogram dose of rabeprazole in these children was necessary to achieve comparable concentrations in adults. Subjective evaluations demonstrated an improvement of GERD symptoms in most patients after rabeprazole treatment. CONCLUSIONS: Palatability of the formulation was reported to be good or excellent. Rabeprazole was well tolerated, with no notable differences in safety among the dose groups.

Pharmacokinetic evaluation of tapentadol extended-release tablets in healthy subjects.

OBJECTIVE: To evaluate serum pharmacokinetics of tapentadol administered to healthy subjects as extended-release (ER) tablets. DESIGN: Seven single-dose studies (five randomized, crossover, bioequivalence studies; a study in Japanese men; and a randomized, crossover, effects-of-food study) and one repeated-dose study. SETTING: Clinical research settings in the United States and The Netherlands. PATIENTS OR PARTICIPANTS: Healthy males and females were enrolled into seven studies; one study enrolled only Japanese males. INTERVENTIONS: In the bioequivalence studies, subjects first received one polyethylene oxide- or hypromellose-based tapentadol ER tablet (50, 100, 150, 200, or 250 mg; one dose per study), then (after washout) the other formulation (matching dose). In all other studies, subjects received polyethylene oxide-based tapentadol ER tablets. In the repeated-dose study, subjects received one 250 mg tablet, then (after washout) one 250 mg tablet every 12 hours (five doses). In the food-effect study, subjects received one 250 mg tablet within 30 minutes after a high-fat meal or after 10 hours of fasting. In the study in Japanese men, subjects received one 100 mg tablet. MAIN OUTCOME MEASURES: Maximum tapentadol concentrations (Cmax) were typically observed 5 hours after dosing. Mean terminal half-life values ranged from 4.4 to 5.9 hours. Tapentadol Cmax and AUC values increased proportionally following single ER (polyethylene oxide-based tablets) doses of 50 to 250 mg. Trough tapentadol concentrations increased during repeat dosing until reaching steady-state by the third dose. Serum Cmax and area under the concentration-time curve (AUC) values at steady state were 1.6 and 1.9 times higher relative to single-dose administration. Coadministration of the 250 mg dose with a high-fat meal increased Cmax and AUC values by an average of < 17 percent. CONCLUSIONS: The pharmacokinetics of tapentadol ER are consistent after repeated and single-dose administration. Tapentadol ER may be administered without regard to food intake. No clinically significant differences were observed in the pharmacokinetics of tapentadol between Japanese and Caucasian subjects.