Jennifer E. Hamer-Maansson

Pharmacokinetic profiles of extended release quetiapine fumarate compared with quetiapine immediate release

This 10-day, single-center, open-label, randomized, crossover study compared pharmacokinetic profiles and tolerability of extended release quetiapine fumarate (quetiapine XR) with quetiapine immediate release (quetiapine IR) in patients with schizophrenia, schizoaffective disorder or bipolar disorder. After a 2-day lead-in period during which patients received quetiapine XR 300 mg once daily, patients were randomized to quetiapine IR 150 mg twice daily followed by quetiapine XR 300 mg once daily, or quetiapine XR 300 mg once daily followed by quetiapine IR 150 mg twice daily. Pharmacokinetic parameters were evaluated at the end of each 4-day treatment period at steady state. Vital signs, laboratory values, and adverse events (AEs) were recorded throughout the study. The least squares means (90% confidence interval) of the ratio of the area under the plasma concentration-time curve over a 24 h dosing interval (AUC ([0-24 h])) for quetiapine XR/IR was 1.04 (0.92-1.19) and within the pre-defined range set for equivalence (0.80-1.25). Maximum plasma concentration at steady state (C(max)) was approximately 13% lower for quetiapine XR than for quetiapine IR (495.3 versus 568.1 ng/mL), time to reach C(max) (t(max)) was 5 h versus 2 h and mean concentration at the end of 24 h dosing interval (C(min)) was 95.3 versus 96.5 ng/mL, respectively. No patients withdrew from the study owing to AEs and there were no serious AEs or deaths related to study medication. No unexpected AEs, changes in vital signs or laboratory values were observed. These findings suggest that modifying the formulation does not change the overall absorption or elimination of quetiapine, and support emerging clinical evidence for the use of quetiapine XR as a once daily treatment in patients initiating therapy or those established on quetiapine IR.

Steady-State Pharmacokinetic, Safety, and Tolerability Profiles of Quetiapine, Norquetiapine, and Other Quetiapine Metabolites in Pediatric and Adult Patients with Psychotic Disorders

OBJECTIVE The aim of this study was to investigate the steady-state pharmacokinetic, safety, and tolerability profiles of immediate-release quetiapine administered by similar dose-escalation regimens in pediatric and adult populations with psychotic or mood disorders. METHODS Pediatric patients aged 10-17 years were titrated to a quetiapine dose of 200 mg twice daily (b.i.d. on days 5-7, 400 mg b.i.d. on days 11-12, with a final 400-mg dose on day 13. In a separate trial, adult patients aged 18-45 years were titrated to a quetiapine dose of 200 mg b.i.d. on days 4-6, 400 mg b.i.d. on days 10-11, with a final 400-mg dose on day 12. Concentrations of quetiapine and three metabolites (quetiapine sulfoxide, 7-hydroxy quetiapine, and norquetiapine) were quantified in plasma and urine. Adverse events, vital signs, 12-lead electrocardiogram (ECG), and clinical laboratory tests were evaluated throughout the studies. RESULTS In both pediatric and adult populations, plasma concentrations of quetiapine and norquetiapine increased proportionately as the dose was escalated from 200 mg b.i.d. to 400 mg b.i.d. There were no age-related differences in the dose-normalized quetiapine plasma concentration-time curve (AUC(SS)) and maximum plasma concentration (C(SS,max)). Quetiapine was rapidly absorbed after 200-mg and 400-mg doses in pediatric patients [median t(max) (time to maximum plasma concentration) 1.5 hours, both doses] and adult patients (median t(max) 1.0 hour and 1.2 hours, respectively). The mean quetiapine t(1/2) (terminal elimination half-life) was approximately 6 hours for pediatric and 5 hours for adult patients. Norquetiapine displayed a similar median t(max) and a longer t(1/2) compared with quetiapine. Quetiapine was well tolerated, with no serious adverse events and no unexpected events reported. CONCLUSION Pediatric and adult populations demonstrated similar pharmacokinetic, safety, and tolerability profiles for quetiapine administered by dose escalation. The predictability in quetiapine concentration profiles for children aged 10 years to adults suggests that no dosage adjustment may be required when treating patients of these ages.

Rapid dose escalation with quetiapine: a pilot study.

Abstract: The original dosing recommendations for quetiapine in the treatment of schizophrenia suggested escalation to 400 mg/d using the following schedule, administered twice daily in divided doses: Day 1, 50 mg; Day 2, 100 mg; Day 3, 200 mg; Day 4, 300 mg; Day 5, 400 mg. In practice, however, clinicians often exceed these recommendations because of the need to obtain a therapeutic response in patients with psychosis as quickly as possible. This study was designed to determine a faster tolerable dosage-escalation schedule for quetiapine in acutely ill, hospitalized patients with schizophrenia. In this multicenter, placebo-controlled, double-blind pilot study, adult patients were randomly assigned to escalation schedules that would achieve a target dosage of 400 mg/d in either 5, 3, or 2 days. Safety and tolerability were assessed by interviews, physical examinations and vital signs, laboratory tests, and electrocardiograms. The enrolled population consisted of 69 patients who were randomized to 1 of the 3 dose-escalation schedules. Treatment-related adverse events were few among the 67 evaluable patients, with most rated as mild in intensity. Among 69 enrolled patients, only 3 withdrew because of an adverse event (agitation). Objective assessments and adverse events were similar between the 3 groups. In this study of patients with acute schizophrenia, quetiapine dosage was increased to 400 mg/d in 5, 3, and 2 days with similar safety and tolerability, suggesting that escalation to therapeutically effective dosages can be accomplished in less than 5 days.

Twice‐daily dapagliflozin co‐administered with metformin in type 2 diabetes: a 16‐week randomized, placebo‐controlled clinical trial

To evaluate the efficacy and safety of twice‐daily dosing of dapagliflozin and metformin, exploring the feasibility of a fixed‐dose combination.

Dapagliflozin twice daily or once daily: effect on pharmacokinetics and urinary glucose excretion in healthy subjects.

The primary objective of this single‐centre, open‐label crossover study (NCT01072578) was to assess the effect of dapagliflozin on the amount of glucose in the blood and urine in healthy volunteers when dapagliflozin was administered once a day (10 mg) versus twice a day (5 mg every 12 h) after 5 days of dosing. At steady state, the AUCss (0‐24) (area under the dapagliflozin curve (0‐24 hours) at steady state), Css, av (average concentration at steady state) between dapagliflozin 5 mg twice daily and 10 mg once daily were similar AUCss(0‐24) [5 mg bid, (458.0 (28.7)) and 10 mg qd, (470.0 (28.5))] and Css, av [5 mg bid 18.8 (28.9)) and 10 mg qd, (19.6(28.5))], but minimum and maximum plasma levels of dapagliflozin differed significantly. Percent inhibition of renal glucose reabsorption (%IRGRA) and total urinary glucose excretion over 24 h were similar for both doses. The relationship between the mean dapagliflozin concentration and %IRGRA and the total urinary glucose excreted was well described by a maximum effect model. The results indicate that dapagliflozin may be used for either once daily or twice daily administration.

Bioequivalence of fixed‐dose combinations of dapagliflozin and metformin with single‐component tablets in healthy subjects and the effect of food on bioavailability

The pharmacokinetics (PK) of dapagliflozin and metformin administered as fixed‐dose combination (FDC) tablets (2.5 mg dapagliflozin/850 mg metformin or 5 mg dapagliflozin/1000 mg metformin) or as separate tablets in healthy subjects were evaluated in 2 separate studies. Study 1 evaluated PK by measuring mean ratios of area under the plasma concentration–time curve (time zero to infinity [AUCinf]), AUC from zero to time of last measurable concentration (AUC0–t), and maximum observed plasma concentration (Cmax) for single‐component or FDC tablets following a non‐high‐fat meal. Mean ratios of AUCinf, AUC0–t, and Cmax for FDC or single‐component dapagliflozin and metformin tablets were close to unity. In study 2, AUCinf, AUC0–t, and Cmax for the FDC tablet were obtained fasting and after a high‐fat meal. Dapagliflozin 5 mg and metformin 1000 mg geometric mean Cmax was increased in the fasted versus fed state (61.9 vs 43.9 and 1600 vs 1330 ng/mL, respectively), but AUC0–t was similar (267 and 265 and 11 000 and 10 600 ng · h/mL, respectively). In summary, FDC tablets were bioequivalent to single‐component tablets, and total absorption (AUC) was similar for non‐high‐fat and high‐fat meals.