Helicobacter pylori treatment in children: defining a dose for rabeprazole as a part of a triple therapy regimen.

The proton pump inhibitor, rabeprazole, has been studied in children for the treatment of gastroesophageal reflux disease (GERD). In adults, rabeprazole is indicated for Helicobacter pylori eradication in combination with amoxicillin and clarithromycin. Nonlinear mixed effects modeling was conducted to estimate pharmacokinetic (PK) parameters for rabeprazole and its thioether metabolite from 336 subjects, 35% of whom were children 1-11 years with GERD from phase I and III studies. A 2-compartment disposition model with a transit absorption model provided the best fit for rabeprazole PK. The steady-state area under the concentration-time curves given several candidate doses were simulated to identify a dose per each body weight group that is comparable to a 20 mg twice-daily dose in adults, which is the recommended dose for treatment of H. pylori in adults. Simulations provided the following recommended twice-daily weight-based doses for children ≥1 year and <16 years: 10 mg for 6-10 kg, 15 mg for 10-30 kg, and 20 mg for ≥30 kg.

Population pharmacokinetics of rabeprazole and dosing recommendations for the treatment of gastroesophageal reflux disease in children aged 1-11 years.

BACKGROUND AND OBJECTIVE: Rabeprazole sodium is a proton pump inhibitor used for the treatment of gastroesophageal reflux disease (GERD). The objective of this study was to develop a population pharmacokinetic model for rabeprazole that describes concentration-time data arising from phase I and phase III studies in adult and pediatric subjects, including neonates and preterm infants, and propose dosing recommendations for pediatric subjects aged 1-11 years. METHODS: A total of 4,417 pharmacokinetic observations from 597 subjects aged 6 days to 55.7 years with body weights of 1.15-100 kg were used to develop the population pharmacokinetic model using non-linear mixed-effects modeling techniques. Weight and age were included in the structural model to describe clearance (CL) and central volume of distribution (V c). Other covariates considered during model development included sex, race, creatinine clearance, hepatic function, formulation, feeding status, and route of administration. The final model was used to determine doses for pediatric subjects aged 1-11 years to achieve a steady-state area under the plasma concentration-time curve across the dose interval of 24 h (AUC24) within the target adult AUC24 range obtained following a rabeprazole 10 mg dose. RESULTS: The best model was a two-compartment disposition model with a sequential zero-order duration of input (Dur), first-order absorption (k a) following a lag time (T lag), with weight and age effects on CL and V c. Formulation type and feeding status described some of the variability in bioavailability and the absorption parameters T lag, Dur, and k a. A dosage regimen of 5 mg once daily for children <15 kg, and 10 mg for children ≥15 kg is recommended for 1- to 11-year-old pediatric patients with GERD. CONCLUSIONS: The pharmacokinetics of rabeprazole were described with good precision following administration of rabeprazole across a range of doses and in a range of formulations.

Pharmacokinetics of rabeprazole granules versus tablets, and the effect of food on the pharmacokinetics of rabeprazole granules in healthy adults-cross-study comparison.

The primary objective was to compare the pharmacokinetics (PK) of rabeprazole granules versus rabeprazole tablets, and assess the effect of food on the PK of rabeprazole granules. Data from three phase 1, open-label, single-dose, randomized, crossover studies in healthy adult participants are presented separately and as a cross-study comparison; study 1: PK of phase 1 rabeprazole granules versus rabeprazole tablets under fasting conditions; study 2: PK of phase 3 rabeprazole granules versus phase 1 rabeprazole granules; study 3: bioequivalence of to-be-marketed rabeprazole granules (sprinkle capsules) versus phase 3 rabeprazole granules; and assessment of the food effect for the to-be-marketed rabeprazole granules. Overall, 123 of 130 participants enrolled completed the studies. The overall plasma exposure as measured by area under the plasma concentration-time curve (AUC) was comparable between rabeprazole granules and tablets; mean peak plasma concentration (Cmax ) was lower for the granules compared with tablets. The plasma elimination half-life was short and independent of formulation. Food intake prior to administration of the to-be-marketed granules delayed the absorption and reduced the estimated parameters for bioavailability by 55% (Cmax ) and 28% (AUCinf ). Rabeprazole was well-tolerated.

Randomized, open-label, single-dose, crossover, relative bioavailability study in healthy adults, comparing the pharmacokinetics of rabeprazole granules administered using soft food or infant formula as dosing vehicle versus suspension.

BACKGROUND: A sprinkle capsule formulation containing enteric-coated, delayed-release rabeprazole granules is being developed for the treatment of children with gastrointestinal reflux disease. The granules are designed to be mixed with vehicles that facilitate delivery to children, who may be unable to swallow solid formulations. OBJECTIVE: The primary objective of this study-conducted on the sponsor's initiative-was to compare the bioavailability of rabeprazole granules when mixed with various dosing vehicles (small amount of soft food or infant formula) with that of a rabeprazole suspension with inactive vehicle granules (reference), to determine which dosing vehicle can be used to deliver rabeprazole in children. Tolerability was also assessed. METHODS: This single-center, single-dose, randomized, open-label, 5-period crossover study was conducted in 35 healthy adult subjects. In a randomized sequence, fasting subjects received a single dose of 10-mg rabeprazole granules per treatment period, mixed with small amounts of 1 of 5 dosing vehicles (a strawberry-flavored suspension of rabeprazole granules with inactive vehicle granules reconstituted with water, yogurt [1 tablespoon], applesauce [1 tablespoon], or infant formula [5 mL], or a suspension of rabeprazole granules with inactive vehicle tablet reconstituted with water). Full plasma pharmacokinetic (PK) profiles of rabeprazole and its thioether metabolite were collected; concentrations were estimated via LC-MS/MS. PK properties were estimated using noncompartmental methods; 90% CIs around least squares mean test-to-reference ratios were calculated for C(max) and AUC values. All treatment-emergent adverse events (TEAEs) were recorded and assessed for severity (mild, moderate, or severe) and relationship to study drug. RESULTS: A total of 35 subjects were enrolled (mean age, 38 years; 54.3% female; 100% white; mean weight, 71.4 kg). Thirty-four subjects completed the study. Rabeprazole and rabeprazole thioether plasma PK properties were comparable between all of the dosing vehicles tested. Median T(max) was 2.5 to 3.0 hours, and mean elimination half-life was 1.27 to 1.43 hours. The 90%CIs for the least squares mean ratios for rabeprazole and rabeprazole thioether exposure were within the 80% to 125% bioequivalence limits for all relevant comparisons. All TEAEs were of mild or moderate intensity, with headache being the most commonly reported; 21 subjects (60%) experienced TEAEs during the study. No deaths or serious AEs were reported during the study; 1 subject experienced a TEAE (urinary tract infection) that led to the discontinuation of treatment. CONCLUSION: In these healthy adult subjects, the bioavailability of rabeprazole granules was comparable between all of the dosing vehicles tested, and rabeprazole was well tolerated. Soft food suitable for young children or infant formula may be appropriate for use as dosing vehicles for rabeprazole granules.

Effect of multiple doses of omeprazole on the pharmacokinetics, pharmacodynamics, and safety of a single dose of rivaroxaban.

Many patients with acute coronary syndrome receive chronic dual antiplatelet therapy (acetylsalicylic acid and clopidogrel) for secondary event prophylaxis, and new oral anticoagulants are being investigated as adjunctive therapy in this indication. Gastrointestinal side effects such as bleeding are commonly associated with antiplatelet use; accordingly, many patients receive proton pump inhibitors (PPIs) to mitigate this. PPIs can reduce the antiplatelet activity of clopidogrel through cytochrome P450 2C19 inhibition, and pantoprazole reduces the bioavailability of dabigatran, a direct thrombin inhibitor that acts via cytochrome P450 2C19-independent mechanisms. These observations support the investigation of potential pharmacokinetic and pharmacodynamic interactions between PPIs and anticoagulants. We evaluated the influence of administering once-daily omeprazole 40 mg for 5 days on the pharmacokinetics and pharmacodynamics of a single 20-mg dose of the oral direct factor Xa inhibitor, rivaroxaban, in a randomized, open-label, 2-way, crossover, drug-drug interaction study in healthy subjects. No clinically meaningful interactions were observed; geometric mean ratios were 101%, 101%, and 93.5% for rivaroxaban area under the plasma concentration-time curve from time 0 to the time of the last quantifiable concentration (AUClast), or until infinity (AUC∞), and maximum plasma concentration (Cmax), respectively. Prothrombin time increased similarly in both treatment groups, with maximal values observed approximately 4 hours post rivaroxaban administration. A single 20-mg rivaroxaban dose appears well tolerated when administered alone or after 5 days of once-daily omeprazole 40 mg administration.

Deltoid injections of risperidone long-acting injectable in patients with schizophrenia.

BACKGROUND: Risperidone long-acting injectable was previously approved for treatment of schizophrenia as biweekly injections in the gluteal muscle only. We present data on local injection-site tolerability and safety of risperidone long-acting injectable and comparability of systemic exposure of deltoid versus gluteal injections. METHODS: Risperidone long-acting injectable was administered in an open-label, single-dose, two-way crossover study, with patients randomized to receive either 25mg gluteal/37.5mg deltoid crossover in two treatment periods or 50mg gluteal/50mg deltoid injections crossover; each treatment period was separated by an 85-day observation period (Study 1) and an open-label, multiple-dose study (4 sequential 37.5mg or 50mg deltoid injections every 2 weeks) (Study 2). The pharmacokinetic results from both the studies have already been published. RESULTS: In Study 1 (n=170), the majority of patients had no local injection-site findings, based on investigator and patient-rated evaluations. In Study 2 (n=53), seven of the 51 patients who received at least two deltoid injections discontinued (primary endpoint). However, none of the discontinuations were due to injection-site related reasons. The 90-percent upper confidence limit of the true proportion of injection-site issue withdrawals was 5.7 percent. No moderate or severe injection-site reactions were reported. CONCLUSION: Intramuscular injections via the deltoid and gluteal sites are equivalent routes of administration of risperidone long-acting injectable with respect to local injection-site tolerability. The overall safety and tolerability profile of risperidone long-acting injectable was comparable when administered as an intramuscular injection in the deltoid (37.5mg and 50mg) and gluteal (25mg and 50mg) sites.

Pharmacokinetics and pharmacodynamics of rivaroxaban and its effect on biomarkers of hypercoagulability in patients with chronic heart failure.

BACKGROUND: Heart failure (HF) is associated with a hypercoagulable state that predisposes to thromboembolism and anti-coagulation may improve clinical outcomes. The oral, direct Factor Xa inhibitor, rivaroxaban, has not been studied in patients with HF. We hypothesized that rivaroxaban would also reduce biomarkers of hypercoagulability in patients with HF. METHODS: This study consisted of two cohorts: Cohort 1, open-label, actively controlled with enoxaparin 40 mg once daily, included 8 patients with acute decompensated HF; Cohort 2, double-blind and placebo-controlled, included 18 patients with stable, severe New York Heart Association Class III/IV HF. RESULTS: The pharmacokinetics (PK) and pharmacodynamics (PD) of rivaroxaban were similar across both cohorts. Biomarker assessments were performed in Cohort 2; prothrombin fragment 1.2 (F1.2) mean concentration decreased by 2.7 ng/ml over 7 days with rivaroxaban, and increased by 11.6 ng/ml with placebo, an absolute difference of 14.3 ng/ml (p = 0.0009). A non-significant reduction in rate of increase of D-dimer (DD) and thrombin-anti-thrombin complex (TAT) levels with rivaroxaban was observed over 7 days (p = 0.31 and p = 0.77, respectively). CONCLUSION: Rivaroxaban has similar PK/PD in patients with either acute or chronic HF. In vivo, hypercoagulability biomarkers appear to increase over time. Rivaroxaban reversed this trend for F1.2, and may reduce the rate of increase of DD and TAT in patients with stable, severe HF.

Population pharmacokinetics of oral risperidone in children, adolescents and adults with psychiatric disorders.

BACKGROUND AND OBJECTIVES: Oral risperidone is licensed globally for the treatment of several psychiatric disorders in children, adolescents and adults. The pharmacokinetic profile of risperidone is well documented in adults. In this study, the pharmacokinetics of oral risperidone in children and adolescents were investigated along with population pharmacokinetics in paediatric and adult subjects. METHODS: The pharmacokinetics of oral risperidone in children and adolescents were investigated through non-compartmental analysis (paediatric phase I study; n = 24) and population pharmacokinetic analysis using nonlinear mixed-effects modelling software (NONMEM) on a pooled database including both paediatric (n = 304) and adult (n = 476) data. Monte Carlo simulations were performed to evaluate the relevance of the effects of covariates on the plasma exposure of the active antipsychotic fraction. RESULTS: Non-compartmental pharmacokinetic analysis showed that, after correcting doses for bodyweight, plasma exposure was comparable between children and adolescents and in line with historical adult data. Pooled population pharmacokinetic analysis, using a priori allometric scaling of the clearance and volume of distribution, showed that apparent renal clearance of the active antipsychotic fraction was 0.96 L/h and apparent metabolic clearance was 4.26 L/h for a typical patient weighing 62 kg, aged 18.1 years, with a median creatinine clearance of 117.6 mL/min. For a typical child (11 years, 39 kg), adolescent (15 years, 60 kg) and adult (33 years, 70 kg), the apparent total oral clearance values were 4.35, 5.30 and 5.04 L/h, respectively. None of the tested demographic or biochemical characteristics were found to have a relevant effect on any of the pharmacokinetic parameters of risperidone and the active antipsychotic fraction. CONCLUSION: Population pharmacokinetics and Monte Carlo simulations demonstrated similar pharmacokinetics of risperidone in children, adolescents and adults.

Risperidone long-acting injection: pharmacokinetics following administration in deltoid versus gluteal muscle in schizophrenic patients.

Long-acting injectable (LAI) risperidone for intramuscular injection into the gluteal muscle every 2 weeks is approved for schizophrenia. The deltoid muscle provides a more accessible injection site and could therefore facilitate patient acceptance of an injectable medication. Two studies in chronic schizophrenic subjects evaluated the pharmacokinetics and tolerability of LAI risperidone administered into the deltoid muscle. The pharmacokinetics following deltoid injection and bioequivalence between deltoid and gluteal administration were assessed in an open-label, single-dose, crossover, fully powered bioavailability study. Tolerability and safety of deltoid LAI risperidone were investigated in an open-label multiple-dose study in subjects who were previously being treated with gluteal injections of LAI risperidone. Patients received 4 sequential intramuscular injections of LAI risperidone, administered every 2 weeks into the deltoid muscle. Deltoid and gluteal injections of LAI risperidone were shown to be bioequivalent at equal doses with respect to peak and total plasma exposure and exhibited dose-proportional pharmacokinetics, independent of injection site. In addition, deltoid injection was safe and well tolerated. Injection of LAI risperidone into the deltoid muscle can be considered an alternative route of administration, because deltoid and gluteal injections are interchangeable in terms of drug exposure, with no additional safety or tolerability issues.

Pharmacokinetics of dapoxetine hydrochloride in healthy Chinese, Japanese, and Caucasian men.

Dapoxetine is a short-acting selective serotonin reuptake inhibitor developed for the on-demand treatment of premature ejaculation and is approved in some European Union countries, as well as Mexico and Korea, for this indication. The pharmacokinetics of dapoxetine 30 mg and 60 mg in healthy Chinese (single dose), Japanese, and Caucasian men (single and multiple dose) were assessed in 2 studies. In the 3 ethnic groups, dapoxetine was rapidly absorbed following oral administration, with peak plasma concentrations evident approximately 1 hour after dosing, independent of dose, dosing frequency (single or multiple dosing), or ethnicity. Dapoxetine was eliminated in a biphasic manner with an apparent mean terminal half-life of 14 to 17 hours. There was a dose-proportional increase in dapoxetine maximum plasma concentration (C(max)) and area under concentration-time curves (AUCs). The single-dose pharmacokinetic parameters of dapoxetine metabolites were also similar for the 3 ethnic groups, as were the pharmacokinetics of dapoxetine and its metabolites following single and multiple dosing in Caucasian and Japanese men. Dapoxetine was well tolerated by all 3 ethnic groups.

No pharmacokinetic interaction between paliperidone extended-release tablets and trimethoprim in healthy subjects.

OBJECTIVE: The effect of trimethoprim, a potent organic cation transport inhibitor, on the pharmacokinetics (PK) of paliperidone extended-release tablets (paliperidone ER), an organic cation mainly eliminated via renal excretion, was assessed. METHODS: Open-label, two-period, randomized, crossover study in 30 healthy males. Single dose of paliperidone ER 6 mg was administered either alone on day 1 or day 5 during an 8-day treatment period of trimethoprim 200 mg twice daily. Serial blood and urine samples were collected for PK and plasma protein binding of paliperidone and its enantiomers. The 90% confidence interval (CI) of ratios with/without trimethoprim for PK parameters of paliperidone and its enantiomers calculated. RESULTS: Creatinine clearance decreased from 119 to 102 mL min(-1) with trimethoprim. Addition of trimethoprim increased unbound fraction of paliperidone by 16%, renal clearance by 13%, AUC(infinity) by 9%, and t((1/2)) by 19%. The 90% CIs for ratios with/without trimethoprim were within the 80-125% range for C(max), AUC(last), and renal clearance. For AUC(infinity), 90% CI was 79.37-101.51, marginally below the lower bound of the acceptance range. Paliperidone did not affect steady-state plasma concentrations of trimethoprim. CONCLUSIONS: No clinically important drug interactions are expected when paliperidone ER is administered with organic cation transport inhibitors.

Rapidly disintegrating risperidone in subjects with schizophrenia or schizoaffective disorder: a summary of ten phase I clinical trials assessing taste, tablet disintegration time, bioequivalence, and tolerability.

BACKGROUND: Schizophrenia and schizoaffective disorder are severe and chronic psychiatric illnesses for which treatment compliance is important in the prevention of relapse. Atypical antipsychotic drugs, such as risperidone, have been found to be effective in the treatment of a range of psychiatric disorders. Although the oral route of administration is generally preferable to injection, some patients (eg, elderly patients or children) find swallowing physically difficult and thus refuse oral treatments. Rapidly disintegrating (RD) oral formulations of these drugs have been developed to improve their acceptability to patients and thus improve compliance. OBJECTIVE: The aim of this report was to describe the results from clinical studies that have assessed the taste, time to disintegration, and tolerability of RD risperidone tablets, and bioequivalence of RD risperidone tablets (2 x 0.5 mg, 2 mg, and reduced-size 4 mg) versus conventional (CV) risperidone tablets. METHODS: This study used data from 10 clinical trials conducted between 1996 and 2003. Eight trials were open-label, crossover trials; 2 were pilot trials, and all of the trials were short-term. The results from 2 trials were published previously; the remainder are unpublished trials. Taste, time to dissolution, and tolerability of RD risperidone tablets were assessed, and bioequivalence (based on the guidelines from the European and US health care evaluation agencies) of RD versus CV risperidone tablets were determined for risperidone, the active metabolite (9-hydroxy-risperidone), and the total antipsychotic fraction (sum of risperidone and the active moiety, 9-hydroxy-risperidone). RESULTS: In total, these trials included 264 subjects(160 patients with schizophrenia or schizoaffective disorder, 104 healthy volunteers; 173 men, 91 women; age range, 20-61 years). The taste of the RD risperidone tablets was rated as "nice" in 54.2% of subjects compared with 18.3% of subjects who rated CV risperidone as "nice." Totals of 28.8% and 49.2% of subjects described the RD risperidone tablets as "sweet" or "other taste" (commonly mint), respectively. A total of 66.7% of subjects rated the 4-mg RD risperidone tablets as "acceptable, but could be improved," while 85.7% rated the lower-dose RD risperidone tablets as "good." The median time to complete disintegration of the RD risperidone tablet was 38.0 seconds. The mean plasma concentration-time profiles of risperidone and the active moiety of RD or CV risperidone tablets were similar, and these 2 risperidone formulations were found to be bioequivalent. The RD and CV risperidone tablets were well tolerated; there were no serious adverse events reported. CONCLUSIONS: In the 10 studies analyzed, the taste of RD risperidone tablets was found to be acceptable in the majority of healthy subjects and patients with schizophrenia or schizoaffective disorder. In addition, RD risperidone tablets were found to be bioequivalent to CV risperidone tablets.