R-praziquantel integrated population pharmacokinetics in preschool- and school-aged African children infected with Schistosoma mansoni and S. haematobium and Lao adults infected with Opisthorchis viverrini

Racemic praziquantel (PZQ) is the standard treatment for schistosomiasis and liver fluke infections (opisthorchiasis and clonorchiasis). The development of an optimal pediatric formulation and dose selection would benefit from a population pharmacokinetic (popPK) model. A popPK model was developed for R-PZQ, the active enantiomer of PZQ, in 664 subjects, 493 African children (2-15 years) infected with Schistosoma mansoni and S. haematobium, and 171 Lao adults (15-78 years) infected with Opisthorchis viverrini. Racemate tablets were administered as single doses of 20, 40 and 60 mg/kg in children and 30, 40 and 50 mg/kg in 129 adults, and as 3 × 25 mg/kg apart in 42 adults. Samples collected by the dried-blood-spot technique were assayed by LC-MS/MS. A two-compartment disposition model, with allometric scaling and dual first-order and transit absorption, was developed using Phoenix™ software. Inversely parallel functions of age described the apparent oral bioavailability (BA) and clearance maturation in children and ageing in adults. BA decreased slightly in children with dose increase, and by 35% in adults with multiple dosing. Crushing tablets for preschool-aged children increased the first-order absorption rate by 64%. The mean transit absorption time was 70% higher in children. A popPK model for R-PZQ integrated African children over 2 years of age with schistosomiasis and Lao adults with opisthorchiasis, and should be useful to support dose optimization in children. In vitro hepatic and intestinal metabolism data would help refining and validating the model in younger children as well as in target ethnic pediatric and adult groups.

Evaluation of sex differences in the pharmacokinetics of oral sumatriptan in healthy Korean subjects using population pharmacokinetic modeling

Sumatriptan was introduced in 1983, as the first of the triptans, selective 5‐hydroxytryptamine (5‐HT_1B/1D) receptor agonists, to treat moderate to severe migraine. Migraine predominates in females. Although there have been reports of sex differences in migraine‐associated features and pharmacokinetics (PKs) of some triptans, sex differences in the PKs of oral sumatriptan have never been evaluated in Korean. We conducted this study of oral sumatriptan to assess the sex differences in Korean population. Thirty‐eight healthy Korean subjects who participated in two separate clinical studies receiving a single oral dose of 50 mg sumatriptan with the same protocols were included in this analysis. A total of 532 sumatriptan concentration observations were used for a population PK modeling. Validation of final population PK model of sumatriptan was performed using bootstrap and visual predictive check. The PK profile of oral sumatriptan was adequately described by a one‐compartmental model with combined transit compartment model and a first‐order absorption. The covariate analysis showed that the clearance of oral sumatriptan was significantly higher in males than in females (male: 444 L/h, female: 281 L/h). Our results showed that there were sex differences in the clearance of oral sumatriptan. These results encourage further studies to establish the sumatriptan pharmacokinetic–pharmacodynamic model considering sex‐related PK differences, which may help to determine optimal dosing regimens for effective treatment of migraine in males and females. Clinical trial registration: CRIS Registration No. KCT0001784.

Pharmacological interventions for the treatment of insomnia: quantitative comparison of drug efficacy

PURPOSE

Although different forms of pharmacological intervention are often prescribed for insomnia disorder, the comparative efficacies among various drugs remain unclear. We therefore conducted this study to quantitatively compare the efficacy of various pharmacotherapies for insomnia by modeling.

METHODS

We searched PubMed, EMBASE and Cochrane Library databases for randomized placebo-controlled trials of insomnia medications that were conducted within a designated time period (from the inception dates to May 16, 2019). Pharmacodynamic models were established to describe the time course of changes from baseline in selected sleep parameters. Sleep quality and dropout rates were also compared by a single-arm meta-analysis.

RESULTS

In sum, 43 studies covering 44 trials (14,535 patients) were included in the analysis. The drugs evaluated included flurazepam, quazepam, temazepam, triazolam, eszopiclone, zaleplon, zolpidem, extended-release zolpidem, suvorexant, ramelteon and doxepin. The established models revealed eszopiclone had the highest efficacy in terms of sleep latency (SL), total sleep time (TST), and sleep quality, and was also associated with the lowest dropout rates. The effect of suvorexant on the parameter 'wake after sleep onset' (WASO) was significantly higher than that of the other drugs analyzed.

CONCLUSIONS

Each drug has its own characteristics in the treatment of insomnia, and this needs to be taken into consideration to meet individual clinical needs. These results serve as a quantitative supplement for clinical practice by reflecting the difference in efficacy of various drugs in the treatment of insomnia.

Population pharmacokinetics of orally administrated bromopride: Focus on the absorption process

Bromopride is a prokinetic and antiemetic drug used to treat nausea and vomiting. Although its prescription is common in Brazil, there is a lack of studies about bromopride pharmacokinetics. Therefore, the aims of this study were to investigate the population pharmacokinetics of bromopride and to evaluate the influence of covariates on its absorption. This study is a retrospective analysis of data collected from bioequivalence studies. The data was modeled using MONOLIX 2018R2. Assuming one-compartment and linear elimination, the absorption phase was evaluated with different structural models. The model of sequential first- and zero-order with combined error and exponential inter-individual variability in all parameters best described the atypical absorption profile of bromopride. Population estimates were first-order absorption rate (ka) of 0.08 h ^- 1, fraction of dose absorbed by first-order (Fr) of 32.60%, duration of the zero-order absorption (Tk0) of 0.88 h with latency time (Tlag) of 0.47 h, volume of distribution of 230 l and clearance of 46.80 l h ^- 1. Bodyweight affects Tk0, dosage form was found to correlate with Tk0 and Tlag, while gender affects Tlag. However, simulations evaluating the clinical importance of these covariates on steady-state indicated minimal changes on bromopride exposure. The mixed absorption model was reasonable to describe the absorption process of bromopride because it had the flexibility to fit multiple-peaks profile and shows good agreement with physicochemical properties of drug.

Determination of sumatriptan in human plasma using liquid chromatography-mass spectrometry for pharmacokinetic study in healthy Korean volunteers

This study describes the development of an analytical method to determine sumatriptan levels in human plasma using high performance liquid chromatography (HPLC) coupled with triple quadrupole tandem mass spectrometry (MS/MS) and its application to a pharmacokinetic study in healthy Korean volunteers. A single 50 mg dose of sumatriptan was orally administered to twelve healthy volunteers (nine women and three men). The HPLC-MS/MS analytical method was validated with respect to its specificity, linearity, sensitivity, accuracy, precision, recovery, and stability. The calibration curve was linear over a concentration range of 0.3–100 ng/mL (r > 0.999). The lower limit of quantitation for sumatriptan in plasma was 0.3 ng/mL. The accuracy and precision of the analytical method were acceptable within 15% at all quality control levels. We compared plasma concentration-time curves as well as pharmacokinetic parameters such as the area under the curve (AUC) and maximum plasma concentration (C_max). Both the mean AUC and C_max of sumatriptan were 1.56 times higher in women than in men. These differences could be largely explained by the difference in body weight (44%) between women and men. The outcomes may provide insights into developing appropriate individualized treatment strategies.