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Purpose This study aimed to investigate the influence of diagnosis, body weight, sex, age, smoking, formulations, and concomitant drugs on steady‐state dose‐corrected serum concentrations (C/D) of venlafaxine (VEN) and O‐desmethylvenlafaxine (ODV). Methods: A retrospective analysis of therapeutic drug monitoring (TDM) was carried out. Patients' demographic data, therapeutic regimens, and concentrations were collected. Results: We included 91 verified samples from 80 patients. Females had by average 13% smaller body weight, 50% higher C/D of VEN, and VEN + ODV and 25% smaller ODV/VEN than males. Patients >60 years had by average 33–59% higher C/D levels of ODV and VEN + ODV than younger patients. The concomitant use of valproic acid caused an average 51% higher C/D of ODV and a 2.2‐fold larger ODV/VEN, while clozapine was related with 40% smaller ratio of ODV/VEN and 38% lower C/D levels of ODV. Positive correlations were detected between valproic acid concentrations and the C/D of VEN and VEN + ODV. In a multiple linear regression analysis, variance in the C/D of VEN + ODV was partly attributed to the daily dose of VEN, sex, age and valproic acid concentration. Conclusion: Our results suggested daily dose of VEN, sex, age, and valproic acid as indicators for the C/D of VEN + ODV in Chinese patients. TDM as a valuable tool was suggested in elderly female patients and patients receiving polypharmacy. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to investigate the potential effects of a meal and grapefruit juice on the pharmacokinetics of blonanserin and its metabolite N-desethyl blonanserin in healthy Chinese volunteers. Methods: This was a single-centre, open-label, fixed-sequence study, where 12 healthy Chinese volunteers received a single dose of 8 mg blonanserin after an overnight fast in period 1 (reference), a high-fat meal during period 2 and with co-administration of 250 mL of grapefruit juice in period 3. The washout period was 7 days. Series of plasma samples were collected after each dose to determine concentrations of blonanserin and its metabolite N-desethyl blonanserin using liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were estimated by non-compartmental analysis and compared between periods by standard average bioequivalence ANOVA. Adverse events were monitored throughout the study. Results: All subjects completed the study. High-fat meals significantly increased blonanserin exposure (AUC) 2.58-fold (90% CI 2.21, 3.02), relative to the reference period. Co-administration of blonanserin with grapefruit juice remarkably prolonged elimination half-life of blonanserin (from 9.7 to 21.4 h) and significantly increased exposures to blonanserin and N-desethyl blonanserin by 5.82-fold (90% CI 4.57, 7.42) and 1.81-fold (90% CI 1.65, 1.98), respectively. Conclusions: These results suggested that blonanserin was largely metabolised in the intestinal tract before becoming systemically available, and both food and grapefruit juice enhanced exposure to blonanserin and N-desethyl blonanserin. Grapefruit juice increased bioavailability and may have reduced systemic clearance of blonanserin. Further intestinal CYP3A4 and hepatic CYP3A4 might be postulated to explain the delayed elimination of blonanserin. Dose adjustment of blonanserin is needed on the basis of co-intake of known strong CYP3A4 inhibitor. Patients taking high-dose blonanserin also need to be cautious about the ingestion of grapefruit juice. [ABSTRACT FROM AUTHOR]

To prepare rivastigmine liposome, rivastigmine was loaded into liposome via ammonium sulfate gradient method. Its pharmacokinetic profile in rats was evaluated after intranasal administration. The size, zeta potential, entrapped efficiency and release of rivastigmine from the liposome in vitro were determined. Plasma concentration of rivastigmine was determined by high performance liquid chromatography-tandem mass spectrometry (HPLC/MS) using antipyrine as internal standard. The pharmacokinetic parameters were calculated by DAS 2.0. The entrapped efficiency of rivastigmine liposome was (33.41 +/- 6.58) %, with the mean diameter of 154-236 nm and zeta potential of (-10.47 +/- 2.41) mV. The release behavior of rivastigmine was fitting the first order equation in vitro. The pharmacokinetic studies indicated that the C(max), T(max) and AUC(0-infinity), of rivastigmine liposome were (1.50 +/- 0.15) mg x L(-1), 15 min and (89.06 +/- 8.30) mg x L(-') x min, respectively. Rivastimine liposome was absorbed rapidly, and could reach a certain concentration in rat plasma after intranasal delivery.