Therapeutic drug monitoring and pharmacokinetic compartmental analysis of sulpiride double-peak absorption profile after oral administration to human volunteers

Dopamine D2 Receptor Modulates Exercise Related Effect on Cortical Excitation/Inhibition and Motor Skill Acquisition

Exercise is known to benefit motor skill learning in health and neurological disease. Evidence from brain stimulation, genotyping, and Parkinson's disease studies converge to suggest that the dopamine D2 receptor, and shifts in the cortical excitation and inhibition (E:I) balance, are prime candidates for the drivers of exercise-enhanced motor learning. However, causal evidence using experimental pharmacological challenge is lacking. We hypothesized that the modulatory effect of the dopamine D2 receptor on exercise-induced changes in the E:I balance would determine the magnitude of motor skill acquisition. To test this, we measured exercise-induced changes in excitation and inhibition using paired-pulse transcranial magnetic stimulation (TMS) in 22 healthy female and male humans, and then had participants learn a novel motor skill-the sequential visual isometric pinch task (SVIPT). We examined the effect of D2 receptor blockade (800 mg sulpiride) on these measures within a randomized, double-blind, placebo-controlled design. Our key result was that motor skill acquisition was driven by an interaction between the D2 receptor and E:I balance. Specifically, poorer skill learning was related to an attenuated shift in the E:I balance in the sulpiride condition, whereas this interaction was not evident in placebo. Our results demonstrate that exercise-primed motor skill acquisition is causally influenced by D2 receptor activity on motor cortical circuits.

Evaluation of Pharmacokinetic Feasibility of Febuxostat/L-pyroglutamic Acid Cocrystals in Rats and Mice

Febuxostat (FBX), a selective xanthine oxidase inhibitor, belongs to BCS class II, showing low solubility and high permeability with a moderate F value (<49%). Recently, FBX/L-pyroglutamic acid cocrystal (FBX-PG) was developed with an improving 4-fold increase of FBX solubility. Nevertheless, the in vivo pharmacokinetic properties of FBX-PG have not been evaluated yet. Therefore, the pharmacokinetic feasibility of FBX in FBX- and FBX-PG-treated rats and mice was compared in this study. The results showed that the bioavailability (F) values of FBX were 210% and 159% in FBX-PG-treated rats and mice, respectively. The 2.10-fold greater total area under the plasma concentration-time curve from time zero to infinity (AUC0-inf) of FBX was due to the increased absorption [i.e., 2.60-fold higher the first peak plasma concentration (Cmax,1) at 15 min] and entero-hepatic circulation of FBX [i.e., 1.68-fold higher the second peak plasma concentration (Cmax,2) at 600 min] in FBX-PG-treated rats compared to the FBX-treated rats. The 1.59-fold greater AUC0-inf of FBX was due to a 1.65-fold higher Cmax,1 at 5 min, and a 1.15-fold higher Cmax,2 at 720 min of FBX in FBX-PG-treated mice compared to those in FBX-treated mice. FBX was highly distributed in the liver, stomach, small intestine, and lungs in both groups of mice, and the FBX distributions to the liver and lungs were increased in FBX-PG-treated mice compared to FBX-treated mice. The results suggest the FBX-PG has a suitable pharmacokinetic profile of FBX for improving its oral F value.

D2 receptor blockade eliminates exercise-induced changes in cortical inhibition and excitation

BACKGROUND

Although cardiorespiratory exercise is known to affect cortical excitatory and inhibitory activity, the neurochemical mechanisms driving this effect are poorly understood. Animal models of Parkinson's disease identify dopamine D2 receptor expression as a candidate mechanism, but the link between the D2 receptor and exercise-induced changes in cortical activity in humans is unknown.

OBJECTIVE

Here, we examined the effect of a selective dopamine D2 receptor antagonist, sulpiride, on exercise-induced changes in cortical activity.

METHODS

We acquired measures of excitatory and inhibitory activity of the primary motor cortex using transcranial magnetic stimulation (TMS) from 23 healthy adults, both before and after a 20-min bout of high-intensity interval cycling exercise. We examined the effect of D2 receptor blockade (800 mg sulpiride) on these measures within a randomised, double-blind, placebo-controlled crossover design.

RESULTS

Sulpiride abolished exercise-induced modulation of the cortical excitation:inhibition balance relative to placebo (P < 0.001, Cohen's d = 1.76). Sulpiride blocked both the increase in glutamatergic excitation and reduction in gamma-aminobutyric acid (GABA) inhibition that was observed following exercise in the placebo condition.

CONCLUSION

Our results provide causal evidence that D2 receptor blockade eliminates exercise-induced changes in excitatory and inhibitory cortical networks, and have implications for how exercise should be prescribed in diseases of dopaminergic dysfunction.

Precisely Fabricated Sulpiride-Loaded Nanolipospheres with Ameliorated Oral Bioavailability and Antidepressant Activity

BACKGROUND

Sulpiride (SUL), is a selective antidopaminergic drug that had extensive biological activities. However, its sparingly aqueous solubility and limited gastrointestinal permeability lead to scanty oral bioavailability which hinders its clinical efficacy.

OBJECTIVE

SUL-loaded lipospheres (SUL-LPS) were designed to serve as an oral biocompatible nanovector for improving SUL permeability as well as conquering its low oral absorption and then in turn enhancing its antidepressant action.

METHODS

SUL-LPS were fabricated via two processing techniques namely, melt emulsification and solvent evaporation. The impact of different lipid cores, phospholipid shells together with various surfactant concentrations and types on the lipospheres properties were screened. Detailed physicochemical elucidations were performed followed by ex vivo permeation appraisal using the non-everted intestine model. The pharmacokinetic parameters of SUL-LPS, free SUL and marketed product were assessed following oral administration to healthy rats. Reserpine-induced depression rat model was used to assess the antidepressant action of SUL-LPS on which full behavioural and biochemical analysis was conducted. Safety attributes of nanoencapsulated SUL on the brain and other internal organs were evaluated.

RESULTS

The optimum LPS revealed an excellent nanosize with a narrow PdI, negative zeta potential and acceptable entrapment efficiency of 68.62 nm, 0.242, -30.4 mV and 84.12%, respectively. SUL-LPS showed a sustained release pattern and 2.1-fold enhancement in the intestinal permeation parameters with low mucin interaction. Oral pharmacokinetic appraisal exhibited that LPS provided 3.4-fold improvement in SUL oral bioavailability together with long-circulating properties, relative to the free drug. Pharmacodynamic study confirmed the superior antidepressant action of SUL-LPS as evident by 1.6 and 1.25-fold elevation in the serotonin and dopamine expressions, respectively. Meanwhile, nanotoxicological appraisal proved the biocompatibility of SUL-LPS upon repetitive oral administration.

CONCLUSION

Rationally designed lipospheres hold promising in vitro and in vivo characteristics for efficient delivery of SUL with high oral bioavailability, antidepressant activity together with a good safety profile.

Effect of Micronization on Panax notoginseng: In Vitro Dissolution and In Vivo Bioavailability Evaluations

Panax notoginseng (PN) has become the most widely used dietary supplement and herbal in Asian countries. The effect of micronization on PN is not entirely clear. The aim of this study was to investigate the effects of particle size of Panax notoginseng powder (PNP) and the potential to improve the bioavailability. The results showed that particle size reduction significantly changed the Panax notoginseng saponins (PNS) in vitro dissolution and in vivo pharmacokinetics. The size of the Panax notoginseng powder (PNP) ranges from 60 to 214 μm. The surface morphology and thermal properties of PNP were extensively characterized, and these changes in physicochemical properties of PNP provide a better understanding of the in vitro and in vivo release behaviors of PNS. The in vitro studies demonstrated that the dissolution of PNS and particle size were nonlinear (dose- and size-dependent). The pharmacokinetics parameters of PNP in rats were determined by UHPLC-MS/MS. Powder 4 (90.38 ± 8.28 μm) showed significantly higher AUC_0-T values in plasma (P < 0.05). In addition, we also investigated the influence of the hydrothermal treatment of PNP. The results showed that the PNS in vitro release and in vivo bioavailability of PNP pretreatment at 40°C were the highest. This suggests that PNP with a particle size of around 90 μm and heat pretreatment at 40°C would be beneficial. These results provided an experimental basis, and it was beneficial to choose an appropriate particle size and hydrothermal temperature when PNP was used in clinical treatment.

What dominates the changeable pharmacokinetics of natural sesquiterpene lactones and diterpene lactones: a review focusing on absorption and metabolism

Sesquiterpene lactones (STLs) and diterpene lactones (DTLs) are two groups of common phytochemicals with similar structures. It's frequently reported that both exhibit changeable pharmacokinetics (PK) in vivo, especially the unstable absorption and extensive metabolism. However, the recognition of their PK characteristics is still scattered. In this review, representative STLs (atractylenolides, alantolactone, costunolide, artemisinin, etc.) and DTLs (ginkgolides, andrographolide, diosbulbins, triptolide, etc.) as typical cases are discussed in detail. We show how the differences of treatment regimens and subjects alter the PK of STLs and DTLs, with emphasis on the effects from absorption and metabolism. These compounds tend to be quite permeable in intestinal epithelium, but gastrointestinal pH and efflux transporters (represented by P-glycoprotein) have great impact and result in the unstable absorption. As the only characteristic functional moiety, the metabolic behavior of lactone ring is not dominant. The α, β-unsaturated lactone moiety has the strongest metabolic activity. While with the increase of low-activity saturated lactone moieties, the metabolism is led by other groups more easily. The phase I (oxidation, reduction and hydrolysis reaction) and II metabolism (conjugation reaction) are both extensive. CYP450s, mainly CYP3A4, are largely involved in biotransformation. However, only UGTs (UGT1A3, UGT1A4, UGT2B4 and UGT2B7) has been mentioned in studies about phase II metabolic enzymes. Our work offers a beneficial reference for promoting the safety evaluation and maximizing the utilization of STLs and DTLs.

Enhancing the Low Oral Bioavailability of Sulpiride via Fast Orally Disintegrating Tablets: Formulation, Optimization and In Vivo Characterization

Sulpiride (SUL) is a dopamine D₂-receptor antagonist used for management of GIT disturbance and it has anti-psychotic activities based on the administered dose. SUL undergoes P-glycoprotein efflux, which lead to poor bioavailability and erratic absorption. Therefore, the objective of this research was an attempt to enhance the oral bioavailability of SUL via formulation of fast disintegrating tablets (SUL-FDTs) with a rapid onset of action. A 3² full-factorial design was performed for optimization of SUL-FDTs using desirability function. The concentration of superdisintegrant (X₁) and Prosolv^® (X₂) were selected as independent formulation variables for the preparation and optimization of SUL-FDTs using direct compression technique. The prepared SUL-FDTs were investigated regarding their mechanical strength, disintegration time, drug release and in vivo pharmacokinetic analysis in rabbits. The optimized formulation has hardness of 4.58 ± 0.52 KP, friability of 0.73 ± 0.158%, disintegration time of 37.5 ± 1.87 s and drug release of 100.51 ± 1.34% after 30 min. In addition, the optimized SUL-FDTs showed a significant (p < 0.01) increase in C_max and AUC(_0-∞) and a relative bioavailability of about 9.3 fold compared to the commercial product. It could be concluded that SUL-FDTs are a promising formulation for enhancing the oral bioavailability of SUL concomitant with a fast action.

Methylphenidate boosts choices of mental labor over leisure depending on striatal dopamine synthesis capacity

The cognitive enhancing effects of methylphenidate are well established, but the mechanisms remain unclear. We recently demonstrated that methylphenidate boosts cognitive motivation by enhancing the weight on the benefits of a cognitive task in a manner that depended on striatal dopamine. Here, we considered the complementary hypothesis that methylphenidate might also act by changing the weight on the opportunity cost of a cognitive task, that is, the cost of foregoing alternative opportunity. To this end, 50 healthy participants (25 women) completed a novel cognitive effort-discounting task that required choices between task and leisure. They were tested on methylphenidate, placebo, as well as the selective D2-receptor agent sulpiride, the latter to strengthen inference about dopamine receptor selectivity of methylphenidate's effects. Furthermore, they also underwent an [18F]DOPA PET scan to quantify striatal dopamine synthesis capacity. Methylphenidate boosted choices of cognitive effort over leisure across the group, and this effect was greatest in participants with more striatal dopamine synthesis capacity. The effects of sulpiride did not reach significance. This study strengthens the motivational account of methylphenidate's effects on cognition, and suggests that methylphenidate reduces the cost of mental labor by increasing striatal dopamine.

First-in-patient study of hetrombopag in patients with chronic idiopathic thrombocytopenic purpura

BACKGROUND

Idiopathic thrombocytopenic purpura (ITP) especially refractory and (or) relapsed ITP, is a serious and global health burden and its clinical treatment is far from being satisfied. Hetrombopag is a novel, small-molecule thrombopoietin receptor agonist for the treatment of chronic idiopathic thrombocytopenic purpura (CITP).

OBJECTIVES

This first-in-patient study aimed to investigate the safety, pharmacokinetics, and anticipated therapeutic dose of hetrombopag in CITP patients.

METHODS

In this multicenter, first-in-patient study, CITP patients received hetrombopag in a dose escalation (2.5 mg/day, 5 mg/day, or 7.5 mg/day) cohort. All patients received hetrombopag in fasting condition once daily for 2 weeks.

RESULTS

Of 44 patients screened, 32 were enrolled and treated. Most adverse events were graded 1 to 2 (ie, mild to moderate), and the incidence and severity were similar for three study cohorts. The pharmacokinetics of hetrombopag were found to be nonlinear with greater than dose-proportional: 12.5% of patients (1/8) in the 2.5 mg/d cohort, 58.3% of patients (7/12) in the 5 mg/d cohort, 66.7% of patients (8/12) in the 7.5 mg/d cohort reached the primary study endpoint of a platelet count exceeding 50 × 109 /L on day 28.

CONCLUSION

Hetrombopag was well tolerated and preliminarily efficacious. Efficacy, safety, and pharmacokinetic data suggest that 7.5 mg hetrombopag once daily was the anticipated therapeutic dose of hetrombopag in CITP patients and has been recommended for investigation in a later confirmatory clinical study of hetrombopag.

Review of Chromatographic Methods Coupled with Modern Detection Techniques Applied in the Therapeutic Drugs Monitoring (TDM)

Therapeutic drug monitoring (TDM) is a tool used to integrate pharmacokinetic and pharmacodynamics knowledge to optimize and personalize various drug therapies. The optimization of drug dosing may improve treatment outcomes, reduce toxicity, and reduce the risk of developing drug resistance. To adequately implement TDM, accurate and precise analytical procedures are required. In clinical practice, blood is the most commonly used matrix for TDM; however, less invasive samples, such as dried blood spots or non-invasive saliva samples, are increasingly being used. The choice of sample preparation method, type of column packing, mobile phase composition, and detection method is important to ensure accurate drug measurement and to avoid interference from matrix effects and drug metabolites. Most of the reported procedures used liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) techniques due to its high selectivity and sensitivity. High-performance chromatography with ultraviolet detection (HPLC-UV) methods are also used when a simpler and more cost-effective methodology is desired for clinical monitoring. The application of high-performance chromatography with fluorescence detection (HPLC-FLD) with and without derivatization processes and high-performance chromatography with electrochemical detection (HPLC-ED) techniques for the analysis of various drugs in biological samples for TDM have been described less often. Before chromatographic analysis, samples were pretreated by various procedures-most often by protein precipitation, liquid-liquid extraction, and solid-phase extraction, rarely by microextraction by packed sorbent, dispersive liquid-liquid microextraction. The aim of this article is to review the recent literature (2010-2020) regarding the use of liquid chromatography with various detection techniques for TDM.

Preclinical PK/PD model for the combinatorial use of dexamethasone and sulpiride in the treatment of breast cancer

Previous studies show that dopamine D₂-like receptor (D2DR) antagonist sulpiride (SUL) enhances the antitumor efficacy of dexamethasone (DEX) in drug-resistant breast cancer involving cancer stem-like cells (CSCs). In this study, we investigated the pharmacokinetic (PK) properties of SUL in nude mice and developed a semi-mechanism PK/PD model to quantitatively characterize the synergistic effect of DEX and SUL in preclinical breast cancer xenografts. After nude mice received oral administration of a single dose of SUL (50 mg/kg, ig), plasma concentrations were assessed using LC-MS/MS. A two-compartment model with double first-order absorption rate was developed to describe the PK profiles of SUL. The pharmacodynamic (PD) study was conducted in nude mice bearing human breast cancer MCF-7/Adr xenografts, which received oral administration of DEX (1, 8 mg·kg⁻¹·d⁻¹) or SUL (25, 50 mg·kg⁻¹·d⁻¹) alone or in various combination. Tumor volumes were measured every other day. The PK model of SUL as well as that of DEX with a time-dependent clearance were integrated into the final PK/PD model both using Hill’s function, where DEX exerted its antitumor efficacy by inhibiting the proliferation of tumor cells, and SUL enhanced DEX responses by decreasing the sensitivity parameter EC₅₀. The PK/PD model was evaluated and subjected external validation. Finally, simulations were performed to predict the antitumor efficacy of DEX combined with SUL under various dose regimens, where changing dosing frequency of SUL had little effect, while the antitumor efficacy was predicted to be improved when DEX was given more frequently. The established PK/PD model in this study quantitatively characterizes the antitumor efficacy of the DEX combined with SUL as well as their synergism, and the simulations could provide reference for dose optimization of the combination in future studies.

Neuropsychopharmacological aesthetics: A theoretical consideration of pharmacological approaches to causative brain study in aesthetics and art

Recent developments in neuroaesthetics have heightened the need for causative approaches to more deeply understand the mechanism underlying perception, emotion, and aesthetic experiences. This has recently been the topic for empirical work, employing several causative methods for changing brain activity, as well as comparative assessments of individuals with brain damage or disease. However, one area of study with high potential, and indeed a long history of often nonscientific use in the area of aesthetics and art, employing psychopharmacological chemicals as means of changing brain function, has not been systematically utilized. This chapter reviews the literature on this topic, analyzing neuroendocrinological (neurochemical) approaches and mechanisms that might be used to causatively study the aesthetic brain. We focus on four relevant neuromodulatory systems potentially related to aesthetic experience: the dopaminergic, serotonergic, cannabinoid, and the opioidergic system. We build a bridge to psychopharmacological methods and review drug-induced behavioral and neurobiological consequences. We conclude with a discussion of hypotheses and suggestions for future research.

Comparison of solvent-wetted and kneaded l-sulpiride-loaded solid dispersions: Powder characterization and in vivo evaluation

The purpose of this study was to compare the powder properties, solubility, dissolution and oral absorption of solvent-wetted (SWSD) and kneaded (KNSD) l-sulpiride-loaded solid dispersions. The SWSD and KNSD were prepared with silicon dioxide, sodium laurylsulfate and D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) using a spray dryer and high shear mixer, respectively. Their powder properties, solubility, dissolution and oral absorption were assessed compared to l-sulpiride powder. The drug in SWSD was in the amorphous state; however, in KNSD, it existed in the crystalline state. The SWSD with a drug/sodium laurylsulphate/TPGS/silicon dioxide ratio of 5/1/2/12 gave the higher drug solubility and dissolution compared to the KNSD with the same composition. The oral absorption of drug in the SWSD was 1.4 fold higher than the KNSD and 3.0 fold higher than the l-sulpiride powder (p<0.05) owing to better solubility and reduced crystallinity. Furthermore, the SWSD at the half dose was bioequivalent of commercial l-sulpiride-loaded product in rats. Thus, the SWSD with more improved oral absorption would be recommended as an alternative for the l-sulpiride-loaded oral administration.

Pediatric suppositories of sulpiride solid dispersion for treatment of Tourette syndrome: in vitro and in vivo investigations

Pharmaceutical development was adopted in the current study to propose a pediatric rectal formulation of sulpiride as a substitute to the available oral or parenteral formulations in the management of Tourette syndrome (TS). The goal was to formulate a product that is easy to use, stable, and highly bioavailable and to achieve a rapid clinical efficacy. Towards this aim, sulpiride solid dispersion (SD) with tartaric acid at a weight ratio of 1:0.25 was incorporated into different suppository bases, namely witepsol W25, witepsol H15, witepsol E75, suppocire NA, suppocire A, glycerogelatin, and polyethylene glycols. The formulae were evaluated in vitro using different pharmacotechnical methods such as visual, melting, weight and content uniformities, drug release, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) analyses. In vivo bioavailability was also assessed in rabbits to compare the bioavailability of either raw sulpiride-incorporated or its SD-incorporated witepsol H15-based suppositories to its oral suspension (reference). Sulpiride SD-incorporated witepsol H15 formulation showed acceptable in vitro characteristics with a bioavailability of 117% relative to oral dosing, which excel that in humans (27% after dosing of oral product). In addition, the proposed formula not only passed the 6-month stability study but also proposed a promising scale-up approach. Hence, it showed a great potential for pediatric product development to manage TS in rural areas.