Investigation of metabolic profile of pimavanserin in rats by ultrahigh-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry

RATIONALE

Pimavanserin, a selective serotonin 2A receptor inverse agonist, is a promising candidate for treating Parkinson's disease psychosis. Our previous study revealed that there might be the presence of extensive metabolites of pimavanserin in rats. However, the metabolic fate of pimavanserin in vivo remains unknown. Thus, it is essential to develop an efficient method to investigate the metabolic profile of pimavanserin in rats. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to date has the highest mass measurement accuracy and resolution of any mass spectrometry platform.

METHODS

After a single intragastric administration of pimavanserin at a dose of 50 mg kg^-1 , plasma, bile, urine and feces were collected from rats. A novel and efficient strategy was developed to analyze the metabolic profile of pimavanserin in vivo based on ultrahigh-performance liquid chromatography (UHPLC) coupled with FT-ICR-MS.

RESULTS

A total of 23 metabolites were detected and tentatively identified through comparing their mass spectrometry profiles with those of pimavanserin. These metabolites were found in feces (22), bile (21), rat urine (16) and plasma (15). Results demonstrated that metabolic pathways of pimavanserin in rats included dehydrogenation, demethylation, deethylation, depropylation, debutylation, hydroxylation, dihydroxylation and trihydroxylation.

CONCLUSIONS

A total of 22 phase I metabolites of pimavanserin were detected and tentatively identified. This report presents the first study of screening and identification of the metabolites of pimavanserin. The UHPLC/FT-ICR-MS method is a powerful tool for exploring and identifying metabolites in complex biological samples.

A randomized, double-blind, placebo-controlled trial of camicinal in Parkinson's disease

Background: Delayed gastric emptying may impair l‐dopa absorption, contributing to motor fluctuations. We evaluated the effect of camicinal (GSK962040), a gastroprokinetic, on the absorption of l‐dopa and symptoms of PD.

Methods: Phase II, double‐blind, placebo‐controlled trial. Participants were randomized to receive camicinal 50 mg once‐daily (n = 38) or placebo (n = 20) for 7 to 9 days.

Results:l‐dopa exposure was similar with coadministration of camicinal compared to placebo. Median time to maximum l‐dopa concentration was reduced, indicating more rapid absorption of l‐dopa. Camicinal resulted in significant reduction in OFF time (–2.31 hours; 95% confidence interval: –3.71, –0.90), significant increase in ON time (+1.88 hours; 95% confidence interval: 0.28, 3.48) per day, and significant decrease in mean total MDS‐UPDRS score (–12.5; 95% confidence interval: –19.67, ‐5.29). Camicinal treatment was generally well tolerated.

Conclusions: PD symptom improvement with camicinal occurred in parallel with more rapid absorption of l‐dopa. This study provides evidence of an improvement of the motor response to l‐dopa in people with PD treated with camicinal 50 mg once‐daily compared with placebo, which will require further evaluation. © 2017 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Impact of novel N-aryl piperamide NO donors on NF-κB translocation in neuroinflammation: rational drug-designing synthesis and biological evaluation

NO donor drugs showed a significant therapeutic effect in the treatment of many diseases, such as arteriopathies, various acute and chronic inflammatory conditions, and several degenerative diseases. NO-releasing anti-inflammatory drugs are the prototypes of a novel class of compounds, combining the pharmacological activities of anti-inflammatory and anti-nociceptive of drugs with those of NO, thus possessing potential therapeutic applications in a great variety of diseases. In this study, we designed and predicted biological activity by targeting cyclooxygenase type 2 (COX-2) and NF-κB subunits and pharmacological profiling along with toxicity predictions of various N-aryl piperamides linked via an ester bond to a spacer that is bound to a NO-releasing moiety (-ONO2). The result of absorption, distribution, metabolism and excretion and Docking studies indicated that among 51 designed molecules PA-3′K showed the best binding potential in both the substrate and inhibitory binding pocket of the COX-2 enzyme with affinity values of –9.33 and –5.12 for PDB ID 1CVU and 3LN1, respectively, thereby having the potential to be developed as a therapeutic agent. The results of cell viabilities indicated that PA-3′k possesses the best cell viability property with respect to its dose (17.33 ng/ml), with 67.76% and 67.93% viable cells for CHME3 and SVG cell lines, respectively.

The killer of Socrates: Coniine and Related Alkaloids in the Plant Kingdom

Coniine, a polyketide-derived alkaloid, is poisonous to humans and animals. It is a nicotinic acetylcholine receptor antagonist, which leads to inhibition of the nervous system, eventually causing death by suffocation in mammals. Coniine’s most famous victim is Socrates who was sentenced to death by poison chalice containing poison hemlock in 399 BC. In chemistry, coniine holds two historical records: It is the first alkaloid the chemical structure of which was established (in 1881), and that was chemically synthesized (in 1886). In plants, coniine and twelve closely related alkaloids are known from poison hemlock (Conium maculatum L.), and several Sarracenia and Aloe species. Recent work confirmed its biosynthetic polyketide origin. Biosynthesis commences by carbon backbone formation from butyryl-CoA and two malonyl-CoA building blocks catalyzed by polyketide synthase. A transamination reaction incorporates nitrogen from l-alanine and non-enzymatic cyclization leads to γ-coniceine, the first hemlock alkaloid in the pathway. Ultimately, reduction of γ-coniceine to coniine is facilitated by NADPH-dependent γ-coniceine reductase. Although coniine is notorious for its toxicity, there is no consensus on its ecological roles, especially in the carnivorous pitcher plants where it occurs. Lately there has been renewed interest in coniine’s medical uses particularly for pain relief without an addictive side effect.

[Inhibition of the Janus kinase-signal transducer and activator of transcription is a new treatment modality of rheumatoid arthritis]

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease. The introduction of a new class of disease-modifying anti-rheumatic drugs, which work by inhibiting the Janus kinase-signal transducer and activator of transcription (JAK/STAT) pathway, has led to new possibilities for achieving remission of RA. Tofacitinib and baricitinib are both JAK/STAT inhibitors, which have shown efficacy in line with anti-tumour necrosis factor treatment. The side effects seem manageable, and up to now only increased risk of herpes zoster has raised consideration. JAK/STAT inhibitors create new possibilities for reaching low disease activity or remission for patients with RA.

Evaluation of Cytochrome P450 3A4-Mediated Drug-Drug Interaction Potential for Cobimetinib Using Physiologically Based Pharmacokinetic Modeling and Simulation

BACKGROUND AND OBJECTIVES

Cobimetinib is eliminated mainly through cytochrome P450 (CYP) 3A4-mediated hepatic metabolism in humans. A clinical drug-drug interaction (DDI) study with the potent CYP3A4 inhibitor itraconazole resulted in an approximately sevenfold increase in cobimetinib exposure. The DDI risk for cobimetinib with other CYP3A4 inhibitors and inducers needs to be assessed in order to provide dosing instructions.

METHODS

A physiologically based pharmacokinetic (PBPK) model was developed for cobimetinib using in vitro data. It was then optimized and verified using clinical pharmacokinetic data and itraconazole-cobimetinib DDI data. The contribution of CYP3A4 to the clearance of cobimetinib in humans was confirmed using sensitivity analysis in a retrospective simulation of itraconazole-cobimetinib DDI data. The verified PBPK model was then used to predict the effect of other CYP3A4 inhibitors and inducers on cobimetinib pharmacokinetics.

RESULTS

The PBPK model described cobimetinib pharmacokinetic profiles after both intravenous and oral administration of cobimetinib well and accurately simulated the itraconazole-cobimetinib DDI. Sensitivity analysis suggested that CYP3A4 contributes ~78 % of the total clearance of cobimetinib. The PBPK model predicted no change in cobimetinib exposure (area under the plasma concentration-time curve, AUC) with the weak CYP3A inhibitor fluvoxamine and a three to fourfold increase with the moderate CYP3A inhibitors, erythromycin and diltiazem. Similarly, cobimetinib exposure in the presence of strong (rifampicin) and moderate (efavirenz) CYP3A inducers was predicted to decrease by 83 and 72 %, respectively.

CONCLUSION

This study demonstrates the value of using PBPK simulation to assess the clinical DDI risk inorder to provide dosing instructions with other CYP3A4 perpetrators.

The use of 18F-Fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) as a non-invasive pharmacodynamic biomarker to determine the minimally pharmacologically active dose of AZD8835, a novel PI3Kα inhibitor

BACKGROUND

The phosphatidyl inositol 3 kinase (PI3K), AKT and mammalian target of rapamycin (mTOR) signal transduction pathway is frequently de-regulated and activated in human cancer and is an important therapeutic target. AZD8835 is a PI3K inhibitor, with selectivity against PI3K α and δ isoforms, which is currently in Phase 1 clinical trials. 18F-Fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) is a non-invasive pharmacodynamic imaging biomarker that has become an integral part of drug development. It has been used widely with PI3K inhibitors both clinically and pre-clinically because of the role of the PI3K pathway in glucose metabolism. In this study we investigated the potential of 18F-FDG PET as a non-invasive pharmacodynamic biomarker for AZD8835. We sought to understand if 18F-FDG PET could determine the minimally effective dose of AZD8835 and correlate with other pharmacodynamic biomarkers for validation of its use in clinical development. 18F-FDG PET scans were performed in nude mice in the BT474C breast xenograft model. Mice were fasted prior to imaging and static 18F-FDG PET was performed. Treatment groups received AZD8835 by oral gavage at a dose volume of 10ml/kg. Treatment groups received either 3, 6, 12.5, 25 or 50mg/kg AZD8835. Tumour growth was monitored throughout the study, and at the end of the imaging procedure, tumours were taken and a full pharmacodynamic analysis was performed.

RESULTS

Results showed that AZD8835 reduced 18F-FDG uptake at a dose of 12.5, 25 and 50mg/kg with no significant reduction at doses of 3 and 6mg/kg. These results were consistent with other pharmacodynamics biomarkers measured and show 18F-FDG PET as a sensitive biomarker with the ability to determine the minimal effective dose of AZD8835.

CONCLUSIONS

Our pre-clinical studies support the use of 18F-FDG PET imaging as a sensitive and non- invasive pharmacodynamic biomarker (understanding the role of PI3K signalling in glucose uptake) for AZD8835 with a decrease in 18F-FDG uptake observed at only two hours post treatment. The decrease in 18F-FDG uptake was dose dependent and data showed excellent PK/PD correlation. This data supports and parallels observations obtained with this class of compounds in patients.

Effects of P-Glycoprotein on the Transport of DL0410, a Potential Multifunctional Anti-Alzheimer Agent

In our study, we attempted to investigate the influences of P-glycoprotein (P-gp) on DL0410, a novel synthetic molecule for Alzheimer's disease (AD) treatment, for intestinal absorption and blood-brain barrier permeability in vitro and related binding mechanisms in silico. Caco-2, MDCK, and MDCK-MDR1 cells were utilized for transport studies, and homology modelling of human P-gp was built for further docking study to uncover the binding mode of DL0410. The results showed that the apparent permeability (Papp) value of DL0410 was approximately 1 × 10-6 cm/s, indicating the low permeability of DL0410. With the presence of verapamil, the directional transport of DL0410 disappeared in Caco-2 and MDCK-MDR1 cells, suggesting that DL0410 should be a substrate of P-gp, which was also confirmed by P-gp ATPase assay. In addition, DL0410 could competitively inhibit the transport of Rho123, a P-gp known substrate. According to molecular docking, we also found that DL0410 could bind to the drug binding pocket (DBP), but not the nucleotide binding domain (NBD). In conclusion, DL0410 was a substrate as well as a competitive inhibitor of P-gp, and P-gp had a remarkable impact on the intestine and brain permeability of DL0410, which is of significance for drug research and development.

Application of Physiologically-Based Pharmacokinetic Modeling for the Prediction of Tofacitinib Exposure in Japanese

Tofacitinib (3-[(3R,4R)-4-methyl-3-[methyl(7H-pyrrolo[2,3-d]pyrimidin-4-yl)amino]piperidin-1-yl]-3 -oxopropanenitrile) is an oral Janus kinase inhibitor that is approved in countries including Japan and the United States for the treatment of rheumatoid arthritis, and is being developed across the globe for the treatment of inflammatory diseases. In the present study, a physiologically-based pharmacokinetic model was applied to compare the pharmacokinetics of tofacitinib in Japanese and Caucasians to assess the potential impact of ethnicity on the dosing regimen in the two populations. Simulated plasma concentration profiles and pharmacokinetic parameters, i.e. maximum concentration and area under plasma concentration-time curve, in Japanese and Caucasian populations after single or multiple doses of 1 to 30 mg tofacitinib were in agreement with clinically observed data. The similarity in simulated exposure between Japanese and Caucasian populations supports the currently approved dosing regimen in Japan and the United States, where there is no recommendation for dose adjustment according to race. Simulated results for single (1 to 100 mg) or multiple doses (5 mg twice daily) of tofacitinib in extensive and poor metabolizers of CYP2C19, an enzyme which has been shown to contribute in part to tofacitinib elimination and is known to exhibit higher frequency in Japanese compared to Caucasians, were also in support of no recommendation for dose adjustment in CYP2C19 poor metabolizers. This study demonstrated a successful application of physiologically-based pharmacokinetic modeling in evaluating ethnic sensitivity in pharmacokinetics at early stages of development, presenting its potential value as an efficient and scientific method for optimal dose setting in the Japanese population.

Tofacitinib as Induction and Maintenance Therapy for Ulcerative Colitis

BACKGROUND

Tofacitinib, an oral, small-molecule Janus kinase inhibitor, was shown to have potential efficacy as induction therapy for ulcerative colitis in a phase 2 trial. We further evaluated the efficacy of tofacitinib as induction and maintenance therapy.

METHODS

We conducted three phase 3, randomized, double-blind, placebo-controlled trials of tofacitinib therapy in adults with ulcerative colitis. In the OCTAVE Induction 1 and 2 trials, 598 and 541 patients, respectively, who had moderately to severely active ulcerative colitis despite previous conventional therapy or therapy with a tumor necrosis factor antagonist were randomly assigned to receive induction therapy with tofacitinib (10 mg twice daily) or placebo for 8 weeks. The primary end point was remission at 8 weeks. In the OCTAVE Sustain trial, 593 patients who had a clinical response to induction therapy were randomly assigned to receive maintenance therapy with tofacitinib (either 5 mg or 10 mg twice daily) or placebo for 52 weeks. The primary end point was remission at 52 weeks.

RESULTS

In the OCTAVE Induction 1 trial, remission at 8 weeks occurred in 18.5% of the patients in the tofacitinib group versus 8.2% in the placebo group (P=0.007); in the OCTAVE Induction 2 trial, remission occurred in 16.6% versus 3.6% (P<0.001). In the OCTAVE Sustain trial, remission at 52 weeks occurred in 34.3% of the patients in the 5-mg tofacitinib group and 40.6% in the 10-mg tofacitinib group versus 11.1% in the placebo group (P<0.001 for both comparisons with placebo). In the OCTAVE Induction 1 and 2 trials, the rates of overall infection and serious infection were higher with tofacitinib than with placebo. In the OCTAVE Sustain trial, the rate of serious infection was similar across the three treatment groups, and the rates of overall infection and herpes zoster infection were higher with tofacitinib than with placebo. Across all three trials, adjudicated nonmelanoma skin cancer occurred in five patients who received tofacitinib and in one who received placebo, and adjudicated cardiovascular events occurred in five who received tofacitinib and in none who received placebo; as compared with placebo, tofacitinib was associated with increased lipid levels.

CONCLUSIONS

In patients with moderately to severely active ulcerative colitis, tofacitinib was more effective as induction and maintenance therapy than placebo. (Funded by Pfizer; OCTAVE Induction 1, OCTAVE Induction 2, and OCTAVE Sustain ClinicalTrials.gov numbers, NCT01465763 , NCT01458951 , and NCT01458574 , respectively.).

Pisa syndrome due to donepezil: pharmacokinetic interactions to blame?

We report a case of Pisa syndrome (PS) due to the acetylcholinesterase inhibitor donepezil which may have been precipitated by pharmacokinetic interactions with commonly used medications. PS is defined as a reversible lateral bending of the trunk with a tendency to lean to one side. This is a rare but very distressing complication with this commonly used medication which was not initially recognised, leading to increasing disability for the patient and significant carer stress. Cessation of donepezil and modulation of potential interacting medications resulted in complete resolution.

A previously published propofol-remifentanil response surface model does not predict patient response well in video-assisted thoracic surgery

Modern anesthesia usually employs a hypnotic and an analgesic to produce synergistic sedation and analgesia. Two remifentanil-propofol interaction response surface models were used to predict sedation using Observer's Assessment of Alertness/Sedation (OAA/S) scores; one predicts an OAA/S <2 and the other <4. We hypothesized that both models would predict regained responsiveness (RR) after video-assisted thoracic surgery (VATS) to reduce total anesthesia time and make early extubation clinically relevant. We included 30 patients undergoing VATS received total intravenous anesthesia (TIVA) combined with thoracic epidural anesthesia (TEA). Pharmacokinetic profiles were calculated using Tivatrainer. Model predictions were compared with observations to evaluate the accuracy and precision of emergence model predictions. The mean (standard deviation) differences between when a patient responded to their name and the time when the model predicted a 50% probability of patient response were 30.80 ± 17.77 and 13.71 ± 11.35 minutes for the OAA/S <2 model and <4 model, respectively. Both models had a limited ability to predict patient response in our patients. Both models identified target concentration pairs predicting time of RR in volunteers and some elective surgeries, but another model of epidural and intravenous anesthetic combinations may be needed to predict time of RR after VATS under TIVA with TEA.

Pharmacokinetic based study on "lagged stimulation" of Curcumae Longae Rhizoma - Piper nigrum couplet in their main active components' metabolism using UPLC-MS-MS

BACKGROUND

Curcumae Longae Rhizoma is one of the commonly used traditional Chinese medicines, which has multiple biological activities such as relieving stagnation and stasis, pain alleviation, curing amenorrhea and wounds. However, its main active component-curcumin has poor absorption and very fast metabolism in body. To solve this problem, Piper nigrum was introduced for its ability to strengthen bioavailability of other compounds.

PURPOSE

In most cases of TCM couplets, all ingredients were prepared and taken simultaneously, which in our opinion did not take full advantage of their interactions. Therefore, order of administration should be adjusted according to pharmacokinetic parameters of the ingredients, which the ones act as supplement can first be taken, and main therapeutic components followed when the former reached its peak.

METHOD

the extract of Piper nigrum (containing at least 95% piperine) was taken by rats 6h before taking Curcumae Longae Rhizoma extract (containing at least 95% curcumin). Then, a UPLC-MS-MS method was developed to determine their content in plasma simultaneously. Determination was carried out by on a C18 column within 5min by isocratic elution using 0.2% formic acid and acetonitrile (50:50, v/v). Tandem mass detection was conducted by selective reaction monitoring (SRM) via electrospray ionization (ESI) source in positive mode. Samples were pre-treated by liquid-liquid extraction (LLE), and verapamil was used as internal standard (IS).

RESULTS

For both curcumin and piperine, the proposed method had good linearity (r²=0.999) within the concentration range of 1-1000ng/ml, with good recovery, precision and stability. The lower limit of quantification (LLOQ) was 1ng/ml. As pharmacokinetic data indicated, Maximum concentration (C_max) of curcumin increased significantly to 394.06; the time reach maximum concentration (T_max) and elimination half-life (T_1/2) were 0.5 and 0.67h, respectively; CONCLUSION: The results provide a good strategy for the investigation of TCM formula especially the couplets, as well as a fast, selective and sensitive UPLC-MS-MS method determining active components in-vivo. Furthermore, the finding of "lagged stimulation" suggested that the use of complex formula should take pharmacokinetics into much more careful consideration.

Donepezil Plus Solifenacin (CPC-201) Treatment for Alzheimer's Disease

Available cholinergic drugs for treating Alzheimer's disease (AD) provide modest symptomatic benefit. We hypothesized that co-administration of a peripheral anticholinergic to reduce dose-limiting adverse effects (AEs) would enable the safe/tolerable use of higher cholinesterase inhibitor doses and thus improve their antidementia efficacy. A modified single-blind, ascending-dose, phase IIa study of donepezil plus solifenacin (CPC-201) lasting 26 weeks was conducted in 41 patients with probable AD of moderate severity. Entry criteria included the use of donepezil at a dose of 10 mg/day during the preceding 3 months. The primary outcome measure was the maximum tolerated dose (MTD) of donepezil achieved (to protocol limit of 40 mg/day) when administered with the anticholinergic solifenacin 15 mg/day. Secondary measures included assessments of cognitive and global function, as well as of AEs. The mean ± SD donepezil MTD increased to 38 ± 0.74 mg/day (median 40 mg/day; p < 0.001); 88% of the study population safely attained this dose at the end of titration. Markedly reduced donepezil AE frequency, especially gastrointestinal, allowed this dose increase. There were no drug-related serious AEs or clinically significant laboratory abnormalities. At 26 weeks, Alzheimer's Disease Assessment Scale Cognitive Component scores in the efficacy evaluable population improved by 0.35 ± 0.85 points over baseline (p < 0.05), an estimated 2.5 ± 0.84 points above 10 mg/day donepezil and 5.4 ± 0.84 points above historic placebo (both p < 0.05). Clinical Global Impression of Improvement scores improved by 0.94 ± 0.20 to 3.1 ± 0.20 points (p < 0.001). The findings suggest that limiting donepezil AEs by co-administration of solifenacin allows the safe administration of substantially higher cholinesterase inhibitors doses that may augment cognitive and global benefits in patients with AD.

Pharmacokinetics of LBPT and its primary metabolites, as well as tolerability in the first-in-human study

BACKGROUND

LBPT is a novel platelet-activating factor (PAF) receptor antagonist that is developed for the treatment of rheumatoid arthritis. The purpose of this first-in-human study was to evaluate the tolerability and safety of LBPT, to investigate the pharmacokinetics of LBPT and its primary metabolites, as well as to assess the food effect on the pharmacokinetics in healthy Chinese subjects.

MATERIALS AND METHODS

LBPT was evaluated in 2 clinical studies. The first study was a double blind, placebo-controlled and ascending dose study. Eighty-five healthy Chinese subjects received oral dose of 2, 4, 6, 8, 15, 25, 50, 75, 100, 125, 150, 225, 300, 400 or 500mg of LBPT or placebo. The pharmacokinetics of LBPT and its primary metabolites were investigated in the last 4 dose cohorts. The tolerability was evaluated by monitoring adverse events (AEs), physical examinations, 12-lead electrocardiograms (ECG) and laboratory tests. The second study was an open-label, 2-period cross-over study with a washout interval of 3days. Twelve subjects received 300mg of LBPT after an overnight fasting or a high-fat breakfast. The pharmacokinetics of LBPT in subjects under fasted and fed conditions were compared.

RESULTS

LBPT was well tolerated up to 500mg-dose and there were no serious AEs in the study. The incidence and severity of AEs were closely related to dose. Following single oral administration of 225, 300, 400 and 500mg of LBPT, plasma C_max was reached at 0.5h and the mean t_1/2 was 0.6-1.6h. Plasma exposure increased with dose escalation but proportionality was not observed. LBPT was eliminated in forms of metabolites and 20-40% of the given dose was recovered in urine. Compared with the subjects under fasting conditions, AUC and C_max were lower and t_max was delayed in the fed subjects.

CONCLUSION

LBPT was well tolerated in healthy subjects with a pattern of dose-related AEs. The pharmacokinetics was non-linear and was impacted by food intake.

Development of New Benzenesulfonamides As Potent and Selective Nav1.7 Inhibitors for the Treatment of Pain

By taking advantage of certain features in piperidine 4, we developed a novel series of cyclohexylamine- and piperidine-based benzenesulfonamides as potent and selective Nav1.7 inhibitors. However, compound 24, one of the early analogs, failed to reduce phase 2 flinching in the mouse formalin test even at a dose of 100 mpk PO due to insufficient dorsal root ganglion (DRG) exposure attributed to poor membrane permeability. Two analogs with improved membrane permeability showed much increased DRG concentrations at doses of 30 mpk PO, but, confoundingly, only one of these was effective in the formalin test. More data are needed to understand the disconnect between efficacy and exposure relationships.

Androgen Dependent Mammary Gland Virilism in Rats Given the Selective Estrogen Receptor Modulator LY2066948 Hydrochloride

A selective estrogen receptor modulator (SERM) is a nonsteroidal compound with tissue specific estrogen receptor (ER) agonist or antagonist activities. In animals, SERMs may produce morphologic changes in hormonally-sensitive tissues like the mammary gland. Mammary glands from female rats given the SERM LY2066948 hydrochloride (LY2066948) for 1 month at ≥ 175 mg/kg had intralobular ducts and alveoli lined by multiple layers of vacuolated, hypertrophied epithelial cells, resembling in part the morphology of the normal male rat mammary gland. We hypothesized that these SERM-mediated changes represented an androgen-dependent virilism of the female rat mammary gland. To test this hypothesis, the androgen receptor antagonist flutamide was co-administered with LY2066948 (175 mg/kg) to female rats for 1 month. Female rats given SERM alone had hyperandrogenemia and the duct and alveolar changes described here. Flutamide cotreatment did not affect serum androgen levels but completely blocked the SERM-mediated mammary gland change. In the mouse, a species that does not have the sex-specific differences in the mammary gland observed in the rat, SERM treatment resulted in hyperandrogenemia but did not alter mammary gland morphology. These studies demonstrate that LY2066948 produces species-specific, androgen-dependent mammary gland virilism in the female rat.

Pharmacokinetics, Pharmacodynamics and Population Pharmacokinetic/Pharmacodynamic Modelling of Bilastine, a Second-Generation Antihistamine, in Healthy Japanese Subjects

BACKGROUND AND OBJECTIVES

Bilastine is a novel second-generation antihistamine for the symptomatic treatment of allergic rhinitis and urticaria. The objective of this study was to evaluate the pharmacokinetics, pharmacodynamics, and tolerability of bilastine following single and multiple oral doses in healthy Japanese subjects. The pharmacokinetic and pharmacodynamic profiles were compared with those reported in Caucasian subjects.

METHODS

In a single-blind, randomized, placebo-controlled, parallel-group, single- and multiple-ascending dose study, bilastine tablets were administered at single doses of 10, 20, and 50 mg (Part I), and once daily for 14 days at 20 and 50 mg (Part II).

RESULTS

After single oral doses, maximum plasma concentrations (C _max) were reached at 1.0-1.5 h postdose. Plasma exposure [C _max and area under the plasma concentration-time curve (AUC)] increased dose-proportionally at single doses of 10-50 mg. In repeated-dose administration, no remarkable differences were observed between Day 1 and Day 14 for C _max or AUC. For inhibitory effects on wheal and flare response, bilastine 20 and 50 mg showed significant inhibition from 1.5 h after administration as compared with placebo, and the significant effect persisted for 24 h after administration. The rates of adverse events (AEs) were comparable between bilastine and placebo in both Part I and Part II. In addition, no dose- or administration period-dependent tendency of increase in rate of AEs or worsening of severity was observed.

CONCLUSION

Bilastine exhibits similar single- and multiple-dose pharmacokinetic and pharmacodynamic characteristics in healthy Japanese subjects compared with those observed in Caucasian subjects in previous studies.

Effect of chongmyungtang, a traditional Korean polyherbal formula, on the Pharmacokinetic profiles of donepezil in rats

Chongmyungtang (CMT) is a famous Korean herbal medicine for improving learning and memory, which has been reported to have anti-cholinergic and neuroprotective effects. Therefore, drug-drug interactions were examined between CMT and donepezil as a first screening of combination therapy for cognitive deficits. Rats received oral co-administration of donepezil with distilled water as a control or donepezil with CMT as a combination. The distilled water or CMT was co-administered at intervals within 5min after donepezil or 1.5h intervals. The plasma samples were analyzed for donepezil concentration and its pharmacokinetic parameters of T_max, C_max, AUC, t_1/2 and MRT_inf. In the single co-administration at intervals within 5min, donepezil was detected lower in the combination than control at 0.5h and 2h post-treatment (P<0.05). In addition, the combination showed significant increases in MRT_inf compared to the control (P<0.05). This suggests drug-drug interactions between donepezil and CMT in the co-administration within 5 min. However, no meaningful differences were found in the pharmacokinetic profiles of donepezil by single dosing with CMT at 1.5h intervals and even by the repeated dosing for a week at 1.5h intervals potential combination therapy of donepezil with CMT.

The pharmacokinetics and pharmacodynamics of alogliptin in children, adolescents, and adults with type 2 diabetes mellitus

Purpose

The aim of this study is to determine the pharmacokinetics (PK) and pharmacodynamics (PD) of a single 12.5- or 25-mg dose of alogliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, in pediatric (children and adolescents) and adult subjects with type 2 diabetes mellitus (T2DM).

Methods

A randomized, open-label, multicenter study was conducted in pediatric and adult subjects. Subjects in two pediatric groups (children and adolescents) were randomized 1:1 to receive a single oral dose of alogliptin 12.5 or 25 mg, respectively; all gender- and race-matched adult subjects received alogliptin 25 mg. Blood and urine samples were collected at prespecified time points for PK/PD analyses. A PK/PD model was developed using data from the study for steady-state simulations. Safety was also assessed.

Results

In pediatric subjects receiving the 25-mg dose, the mean alogliptin peak plasma concentrations (C_max) and AUC_0-inf values were 26 and 23% lower, respectively, than in adults receiving the 25-mg dose, but maximum observed DPP-4 inhibition effect (E_max) and AUEC_0–24 values were similar to those in adults. In pediatric subjects receiving the 12.5-mg dose, the mean alogliptin C_max and AUC_0-inf values were 58 and 54% lower, respectively, than those in adults, hence E_max and AUEC_0–24 values were also lower by 11 and 17%, respectively. The PK/PD model simulated data were consistent with study results. No safety concern was found.

Conclusions

A 25-mg dose of alogliptin in pediatric subjects achieved alogliptin exposures and DPP-4 inhibition similar to those in adult T2DM patients without safety concerns; therefore, this dose is recommended for a pediatric phase 3 trial.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-016-2175-1) contains supplementary material, which is available to authorized users.

Influence of the selective antagonist of the NR2B subunit of the NMDA receptor, traxoprodil, on the antidepressant-like activity of desipramine, paroxetine, milnacipran, and bupropion in mice

Pre-clinical and clinical studies indicated that a blockade of the NMDA receptor complex creates new opportunities for the treatment of affective disorders, including depression. The aim of the present study was to assess the influence of traxoprodil (10 mg/kg) on the activity of desipramine (10 mg/kg), paroxetine (0.5 mg/kg), milnacipran (1.25 mg/kg), and bupropion (10 mg/kg), each at sub-therapeutic doses. Moreover, brain levels of traxoprodil and tested agents were determined using HPLC. The obtained results were used to ascertain the nature of occurring interaction between traxoprodil and studied antidepressants. The experiment was carried out on naïve adult male Albino Swiss mice. Traxoprodil and other tested drugs were administered intraperitoneally. The influence of traxoprodil on the activity of selected antidepressants was evaluated in forced swim test (FST). Locomotor activity was estimated to exclude false positive/negative data. To assess the influence of traxoprodil on the concentration of used antidepressants, their levels were determined in murine brains using HPLC. Results indicated that traxoprodil potentiated activity of all antidepressants examined in FST and the observed effects were not due to the increase in locomotor activity. Only in the case of co-administration of traxoprodil and bupropion, increased bupropion concentrations in brain tissue were observed. All tested agents increased the traxoprodil levels in the brain. Administration of a sub-active dose of traxoprodil with antidepressants from different chemical groups, which act via enhancing monoaminergic transduction, caused the antidepressant-like effect in FST in mice. The interactions of traxoprodil with desipramine, paroxetine, milnacipran, and bupropion occur, at least partially, in the pharmacokinetic phase.

Evaluation of the Enantiomer Specific Biokinetics and Radiation Doses of [(18)F]Fluspidine-A New Tracer in Clinical Translation for Imaging of σ₁ Receptors

The enantiomers of [(18)F]fluspidine, recently developed for imaging of σ₁ receptors, possess distinct pharmacokinetics facilitating their use in different clinical settings. To support their translational potential, we estimated the human radiation dose of (S)-(-)-[(18)F]fluspidine and (R)-(+)-[(18)F]fluspidine from ex vivo biodistribution and PET/MRI data in mice after extrapolation to the human scale. In addition, we validated the preclinical results by performing a first-in-human PET/CT study using (S)-(-)-[(18)F]fluspidine. Based on the respective time-activity curves, we calculated using OLINDA the particular organ doses (ODs) and effective doses (EDs). The ED values of (S)-(-)-[(18)F]fluspidine and (R)-(+)-[(18)F]fluspidine differed significantly with image-derived values obtained in mice with 12.9 μSv/MBq and 14.0 μSv/MBq (p < 0.025), respectively. A comparable ratio was estimated from the biodistribution data. In the human study, the ED of (S)-(-)-[(18)F]fluspidine was calculated as 21.0 μSv/MBq. Altogether, the ED values for both [(18)F]fluspidine enantiomers determined from the preclinical studies are comparable with other (18)F-labeled PET imaging agents. In addition, the first-in-human study confirmed that the radiation risk of (S)-(-)-[(18)F]fluspidine imaging is within acceptable limits. However, as already shown for other PET tracers, the actual ED of (S)-(-)-[(18)F]fluspidine in humans was underestimated by preclinical imaging which needs to be considered in other first-in-human studies.

[Pitolisant for the treatment of narcolepsy with or without cataplexy]

Since March 2016, a new treatment option for adult patients with narcolepsy – with or without cataplexy – has been granted marketing authorization in Europe. Pitolisant (Wakix®) is an inverse agonst at the histamine-3 (H3) receptor. In clinical studies, tests for measurement of wakefulness and attention, pitolisant showed significantly better results in comparison with placebo and similar results in comparison with modafinil. Pitolisant is well tolerated. Postmarketing analyses have to collect data about the long-term safety of pitolisant when used in a real-life setting.

Altered pharmacokinetics and pharmacodynamics of repaglinide by ritonavir in rats with healthy, diabetic and impaired hepatic function

BACKGROUND

Ritonavir is an antiretroviral drug to treat HIV AIDS and inhibits cytochrome P450 3A4. To treat diabetes mellitus in HIV, repaglinide is coadministered with ritonavir in the clinic. Multiple cytochrome P450 (CYP) isoforms are involved in the metabolism of repaglinide like CYP2C8 and CYP 3A4. In order to predict and understand drug-drug interactions of these two drugs, the pharmacokinetics and pharmacodynamics (PK/PD) of repaglinide and ritonavir were studied in normal, diabetic and hepatic impaired rats. The purpose of the study was to assess the influence of ritonavir on the PK/PD of repaglinide in rats with normal, diabetic and impaired hepatic function.

METHODS

Human oral therapeutic doses of ritonavir and repaglinide were extrapolated to rats based on the body surface area. Ritonavir (20 mg/kg, p.o.), alone and along with repaglinide (0.5 mg/kg, p.o.), was given to normal, diabetic and hepatic impaired rats, and the PK/PD were studied.

RESULTS

The pharmacokinetic parameters like peak plasma concentration (Cmax), area under the plasma concentration time profile (AUC) and elimination half life of repaglinide were significantly (p<0.0001) increased when compared to repaglinide control rats. The repaglinide clearance (CL) was significantly (p<0.0001) decreased in the presence of ritonavir treatment. In the presence of ritonavir, repaglinide hypoglycemic activity was increased significantly (p<0.0005) when compared with repaglinide control group.

CONCLUSIONS

The significant difference in the PK/PD changes have been due to the increased plasma exposure and decreased total body clearance of repaglinide, which may be due to the inhibition of the CYP P450 metabolic system and organic anion-transporting polypeptide transporter by ritonavir.

The discovery of 2-substituted phenol quinazolines as potent RET kinase inhibitors with improved KDR selectivity

Deregulation of the receptor tyrosine kinase RET has been implicated in medullary thyroid cancer, a small percentage of lung adenocarcinomas, endocrine-resistant breast cancer and pancreatic cancer. There are several clinically approved multi-kinase inhibitors that target RET as a secondary pharmacology but additional activities, most notably inhibition of KDR, lead to dose-limiting toxicities. There is, therefore, a clinical need for more specific RET kinase inhibitors. Herein we report our efforts towards identifying a potent and selective RET inhibitor using vandetanib 1 as the starting point for structure-based drug design. Phenolic anilinoquinazolines exemplified by 6 showed improved affinities towards RET but, unsurprisingly, suffered from high metabolic clearance. Efforts to mitigate the metabolic liability of the phenol led to the discovery that a flanking substituent not only improved the hepatocyte stability, but could also impart a significant gain in selectivity. This culminated in the identification of 36; a potent RET inhibitor with much improved selectivity against KDR.

Development of easy-to-use reverse-phase liquid chromatographic methods for determining PRE-084, RC-33 and RC-34 in biological matrices. The first step for in vivo analysis of sigma1 receptor agonists

Over the years there has been a growing interest in the therapeutic potential for central nervous system pathologies of sigma receptor modulators. The widely studied PRE-084 and our compounds RC-33 and RC-34 are very potent and selective sigma 1 receptor agonists that could represent promising drug candidates for Amyotrophic Lateral Sclerosis (ALS). Herein, we develop and validate robust and easy-to-use reverse-phase chromatographic methods suitable for detecting and quantifying PRE-084, RC-33 and RC-34 in mouse blood, brain and spinal cord. An HPLC/UV/ESI-MS system was employed for analyzing PRE-084 and an HPLC/UV-PDA system for determining RC-33 and RC-34. Chromatographic separations were achieved on Waters Symmetry RP18 column (150 × 3.9 mm, 5 µm), eluting with water and acetonitrile (both containing 0.1% formic acid) in gradient conditions. The recovery of PRE-084, RC-33 and RC-34 was >95% in all the considered matrices. Their limits of quantitation and detection were also determined. Validation proved the methods be suitable for separating tested compounds from endogenous interferences, being characterized by good sensitivity, linearity, precision and accuracy. A preliminary central nervous system distribution study showed a high distribution of RC-33 in brain and spinal cord, with concentration values well above the determined limit of quantitation. The proposed methods will be used in future preclinical investigations.

Toward the identification of neuroprotective agents: g-scale synthesis, pharmacokinetic evaluation and CNS distribution of (R)-RC-33, a promising SIGMA1 receptor agonist

AIM

Nowadays, there is a great interest in the therapeutic potential of sigma1 receptor ligands for treating different CNS pathologies. Our previous investigations led to identify (R)-RC-33 as a potent and selective S1R agonist.

RESULTS

Herein, we report the gram-scale synthesis, pharmacokinetic profile and CNS distribution of (R)-RC-33 in the mouse to determine the most suitable dosage schedule for in vivo administration. For comparative purposes, the same experiments were also performed with PRE-084, the most widely used S1R agonist commonly in pharmacological experiments.

DISCUSSION

(R)-RC-33 shows a similar pharmacokinetic profile and a better CNS distribution when compared with PRE-084.

CONCLUSION

(R)-RC-33 may be a promising candidate for in vivo studies in animal models of neurodegenerative diseases.

Propofol Pharmacokinetics and Estimation of Fetal Propofol Exposure during Mid-Gestational Fetal Surgery: A Maternal-Fetal Sheep Model

BACKGROUND

Measuring fetal drug concentrations is extremely difficult in humans. We conducted a study in pregnant sheep to simultaneously describe maternal and fetal concentrations of propofol, a common intravenous anesthetic agent used in humans. Compared to inhalational anesthesia, propofol supplemented anesthesia lowered the dose of desflurane required to provide adequate uterine relaxation during open fetal surgery. This resulted in better intraoperative fetal cardiac outcome. This study describes maternal and fetal propofol pharmacokinetics (PK) using a chronically instrumented maternal-fetal sheep model.

METHODS

Fetal and maternal blood samples were simultaneously collected from eight mid-gestational pregnant ewes during general anesthesia with propofol, remifentanil and desflurane. Nonlinear mixed-effects modeling was performed by using NONMEM software. Total body weight, gestational age and hemodynamic parameters were tested in the covariate analysis. The final model was validated by bootstrapping and visual predictive check.

RESULTS

A total of 160 propofol samples were collected. A 2-compartment maternal PK model with a third fetal compartment appropriately described the data. Mean population parameter estimates for maternal propofol clearance and central volume of distribution were 4.17 L/min and 37.7 L, respectively, in a typical ewe with a median heart rate of 135 beats/min. Increase in maternal heart rate significantly correlated with increase in propofol clearance. The estimated population maternal-fetal inter-compartment clearance was 0.0138 L/min and the volume of distribution of propofol in the fetus was 0.144 L. Fetal propofol clearance was found to be almost negligible compared to maternal clearance and could not be robustly estimated.

CONCLUSIONS

For the first time, a maternal-fetal PK model of propofol in pregnant ewes was successfully developed. This study narrows the gap in our knowledge in maternal-fetal PK model in human. Our study confirms that maternal heart rate has an important influence on the pharmacokinetics of propofol during pregnancy. Much lower propofol concentration in the fetus compared to maternal concentrations explain limited placental transfer in in-vivo paired model, and less direct fetal cardiac depression we observed earlier with propofol supplemented inhalational anesthesia compared to higher dose inhalational anesthesia in humans and sheep.

Elucidating the Mechanism of Tofacitinib Oxidative Decyanation

BACKGROUND

Tofacitinib is known to generate two metabolites M2 (alcohol) and M4 (acid), which are formed as the result of oxidation and loss of the nitrile [1].

METHOD

Systematic in vitro investigation into generation of M2 and M4 from tofacitinib.

RESULTS

In vitro using human liver microsomes, we found a new geminal diol metabolite of tofacitinib (MX) that lost the nitrile. MX was further reduced or oxidized to M2 (alcohol) and M4 (acid), respectively by enzymes such as aldo-keto reductase 1C1, aldehyde oxidase and possibly CYP3A4. Stable label studies using H2 18O and D2O suggested the source of oxygen was from water in the media. This was due to rapid water exchange with MX in the media prior to reduction to M2. In case of deuterium, one was incorporated in M2 and this was mainly as a result of tofacitinib rapid exchange of two deuterium atoms from D2O onto methylene position. After formation of MX, there was one deuterium that no longer exchanged with water and therefore retained in M2 for further reduction.

CONCLUSION

The proposed mechanism involved the initial oxidation by P450 at the α-carbon to the nitrile group generating an unstable cyanohydrin intermediate; followed by the loss of the nitrile group to form a new geminal diol metabolite (MX).

Comparative Pharmacokinetics Study of Icariin and Icariside II in Rats

To explore the pharmacokinetic properties of icariin (ICA) and icariside II (ICA II) following intragastric and intravenous administration in rats, a rapid and sensitive method by using ultra-performance liquid chromatography–tandem mass spectroscopy (UPLC-MS/MS) was developed and validated for the simultaneous quantification of ICA and ICA II in rat plasma. The quantification was performed by using multiple reaction monitoring of the transitions m/z 677.1/531.1 for ICA, 515.1/369.1 for ICA II and 463.1/301.1 for diosmetin-7-O-β-d-glucopyranoside (IS). The assay showed linearity over the concentration range of 1.03–1032 ng/mL, with correlation coefficients of 0.9983 and 0.9977. Intra- and inter-day precision and accuracy were within 15%. The lower limit of quantification for both ICA and ICA II was 1.03 ng/mL, respectively. The recovery of ICA and ICA II was more than 86.2%. The LC-MS/MS method has been successfully used in the pharmacokinetic studies of ICA and ICA II in rats. The results indicated that 91.2% of ICA was transformed into ICA II after oral administration by rats, whereas only 0.4% of ICA was transformed into ICA II after intravenous administration. A comparison of the pharmacokinetics of ICA and ICA II after oral administration revealed that the C_max and AUC_0–t of ICA II were 3.8 and 13.0 times higher, respectively, than those of ICA. However, after intravenous administration, the C_max and AUC_0–t of ICA II were about only 12.1% and 4.2% of those of ICA. These results suggest that ICA and ICA II have distinct pharmacokinetic properties, and the insights obtained facilitate future pharmacological action studies.

Synthesis and evaluation of a new vesamicol analog o-[(11)C]methyl-trans-decalinvesamicol as a PET ligand for the vesicular acetylcholine transporter

INTRODUCTION

We focused on the vesicle acetyl choline transporter (VAChT) as target for early diagnosis of Alzheimer's diseases because the dysfunction of the cholinergic nervous system is closely associated with the symptoms of AD, such as problem in recognition, memory, and learning. Due to its low binding affinity for the sigma receptors (σ-1 and σ-2), o-methyl-trans-decalinvesamicol (OMDV) demonstrated a high binding affinity and selectivity for vesicular acetyl choline transporter (VAChT). [(11)C]OMDV was prepared and investigated the potential as a new PET ligand for VAChT imaging through in vivo evaluation.

METHOD

[(11)C]OMDV was prepared by a palladium-promoted cross-coupling reaction using [(11)C]methyl iodide, with a radiochemical yield of 60-75%, a radiochemical purity of greater than 98%, and a specific activity of 5-10 TBq/mmol 30 min after EOB. In vivo biodistribution study of [(11)C]OMDV in blood, brain regions and major organs of rats was performed at 2, 10, 30 and 60 min post-injection. In vivo blocking study and PET-CT imaging study were performed to check the binding selectivity of [(11)C]OMDV for VAChT.

RESULTS

In vivo studies demonstrated [(11)C]OMDV passage through the blood-brain barrier (BBB) and accumulation in the rat brain. The regional brain accumulation of [(11)C]OMDV was significantly inhibited by co-administration of vesamicol. In contrast, brain accumulation of [(11)C]OMDV was not significantly altered by co-administration of (+)-pentazocine, a selective σ-1 receptor ligand, or (+)-3-(3-hydroxyphenyl)-N-propylpiperidine [(+)-3-PPP], a σ-1 and σ-2 receptor ligand. PET-CT imaging revealed inhibition of [(11)C]OMDV accumulation in the brain by co-administration of vesamicol.

CONCLUSION

[(11)C]OMDV selectively binds to VAChT with high affinity in the rat brain in vivo, and that [(11)C]OMDV may be utilized in the future as a specific VAChT ligand for PET imaging.

Vibrational spectra, HOMO, LUMO, NBO, MEP analysis and molecular docking study of 2,2-diphenyl-4-(piperidin-1-yl)butanamide

The Fourier-Transform Infrared and Fourier-Transform Raman spectra of 2,2-diphenyl-4-(piperidin-1-yl)butanamide were recorded in the region 4000-400 cm(-1) and 4000-0 cm(-1). The vibrational wavenumbers are computed using HF and DFT methods. The complete vibrational assignments were performed on the basis of potential energy distribution using GAR2PED program. The geometrical parameters of the title compound are in agreement with the XRD data. From the MEP study, the negative electrostatic potential regions are mainly localized of carbonyl group and are possible sites for electrophilic attack and the positive regions are localized all the rings, indicating possible sites for nucleophilic attack. Stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using natural bond orbital analysis. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. PASS analysis of the title compound predicts among other activities, antidyskinetic activity. Molecular docking results draw us to the conclusion that the compound might exhibit inhibitory activity against adenosine A2A and may act as antidyskinetic agent.

Navigator® and SmartPilot® View are helpful in guiding anesthesia and reducing anesthetic drug dosing

BACKGROUND

The recently introduced Navigator® (GE Healthcare, Helsinki, Finland) and SmartPilot® View (Dräger Medical, Lübeck, Germany) show the concentrations and predicted effects of combined anesthetic drugs, and should facilitate more precisely their titration. Our aim was to evaluate if Navigator® or SmartPilot® View guided anesthesia was associated with a good quality of analgesia, depth of hypnosis and may reduce anesthetic requirements.

METHODS

We performed a prospective non-randomized study. Sixty ASA I-II patients undergoing balanced general anesthesia for abdominal and plastic surgery were enrolled. Patients were divided in 4 groups. Group 1 (N. 15) and group 3 (N. 15) were cases in whom anesthesia was performed with standard monitoring plus the aid of Navigator® (Nav) or SmartPilot® View (SPV) display. Group 2 (N. 15) and group 4 (N. 15) were controls in whom anesthesia was performed with standard monitoring (heart rate, NIBP, SpO2, end-tidal CO2, end-expired sevoflurane concentration, train of four, Bispectral Index [Aspect Medical Systems, Natick, MA, USA] or Entropy [GE Healthcare]). Patients' vital parameters and end-expired sevoflurane concentration were recorded during anesthesia.

RESULTS

All patients recovered uneventfully and showed hemodynamic stability. End-tidal sevoflurane concentrations values [median (min-max)], during maintenance of anesthesia, were significantly (P<0.05) lower in SPV [1.1% (0.8-1.5)] and Nav [1%(0.8-1.8)] groups compared to SPV-control group [1.5%(1-2.5)] and Nav-control group [1.5%(0.8-2)]. BIS and entropy values were respectively higher in the SPV group [53 (46-57)] compared to the control group [43 (37-51)] (P<0.05) and Nav group [53 (43-60)] compared to the control group [41 (35-51)] (P<0.05). No significant differences in Remifentanil dosing were observed in the four groups.

CONCLUSION

Navigator® and SmartPilot® View may be of clinical use in monitoring adequacy of anesthesia. Both displays can optimize the administration and monitoring of anesthetic drugs during general anesthesia and may reduce the consumption of volatile anesthetic agents.

Design, synthesis, and pharmacological evaluation of JDTic analogs to examine the significance of the 3- and 4-methyl substituents

The design and discovery of JDTic as a potent and selective kappa opioid receptor antagonist used the N-substituted trans-3,4-dimethyl-4-(3-hydroxyphenyl)piperidine pharmacophore as the lead structure. In order to determine if the 3-methyl or 4-methyl groups were necessary in JDTic and JDTic analogs for antagonistic activity, compounds 4a-c, and 4d-f which have either the 3-methyl or both the 3- and 4-methyl groups removed, respectively, from JDTic and analogs were synthesized and evaluated for their in vitro opioid receptor antagonist activities using a [(35)S]GTPγS binding assay. Other ADME properties were also assessed for selected compounds. These studies demonstrated that neither the 3-methyl or 3,4-dimethyl groups present in JDTic and analogs are required to produce potent and selective κ opioid receptor antagonists.

Oral prenylation inhibition with lonafarnib in chronic hepatitis D infection: a proof-of-concept randomised, double-blind, placebo-controlled phase 2A trial

BACKGROUND

Therapies for chronic hepatitis delta virus (HDV) infection are unsatisfactory. Prenylation is essential for HDV and inhibition abrogates HDV production in experimental models. In a proof-of-concept study, we aimed to assess the effect on HDV RNA levels, safety, and tolerability of the prenylation inhibitor lonafarnib in patients with chronic delta hepatitis.

METHODS

In this phase 2A double-blind, randomised, placebo-controlled study, patients aged 18 years or older with chronic HDV infection were randomly assigned (3:1 in group 1 and 2:1 in group 2) to receive lonafarnib 100 mg (group 1) or lonafarnib 200 mg (group 2) twice daily for 28 days with 6 months' follow-up. Participants were randomised by random-number tables blocked in groups of four without stratification. Both groups enrolled six treatment participants and two placebo participants. Group 1 placebo patients received open-label lonafarnib as group 2 participants. The primary therapeutic endpoint was a decrease in HDV RNA viral titre in serum and the primary safety endpoint was the ability to tolerate the drug at the prescribed dose for the full 4-week duration, defined as drug discontinuation due to intolerance or grade 3/4 adverse events. This trial is registered with ClinicalTrials.gov, number NCT01495585.

FINDINGS

Between Jan 19, 2012, and April 28, 2014, 14 patients were enrolled, of whom eight were assigned to group 1 and six were assigned to group 2. At day 28, compared with placebo, mean log HDV RNA declines from baseline were -0·73 log IU/mL in group 1 (95% CI 0·17-1·31; p=0·03) and -1·54 log IU/mL in group 2 (1·21-1·93; p<0·0001). Lonafarnib serum concentrations correlated with HDV RNA change (r(2)=0·78, p<0·0001). Model fits show that hepatitis B surface antigen (HBsAg) remained stable after a short pharmacological delay (0·75 days [SE 0·24]), lonafarnib effectiveness in blocking HDV production was greater in group 2 than in group 1 (0·952 [SE 0·06] vs 0·739 [0·05], p<0·001), and the HDV half-life was 1·62 days (0·07). There was no evidence of virological resistance. Adverse events were mainly mild to moderate with group 1 patients experiencing diarrhoea in three patients (50%) and nausea in two patients (33%) and in group 2 with all patients (100%) experiencing nausea, diarrhoea, abdominal bloating, and weight loss greater than 2 kg (mean of 4 kg). No treatment discontinuations occurred in any treatment groups.

INTERPRETATION

Treatment of chronic HDV with lonafarnib significantly reduces virus levels. The decline in virus levels significantly correlated with serum drug levels, providing further evidence for the efficacy of prenylation inhibition in chronic HDV.

FUNDING

National Institute of Diabetes and Digestive and Kidney Diseases and National Cancer Institute, National Institutes of Health, and Eiger Biopharmaceuticals Inc.

A novel once-daily fixed-dose combination of memantine extended release and donepezil for the treatment of moderate to severe Alzheimer's disease: two phase I studies in healthy volunteers

BACKGROUND

Combining two standard-of-care medications for Alzheimer's disease (AD) into a single once-daily dosage unit may improve treatment adherence, facilitate drug administration, and reduce caregiver burden. A new fixed-dose combination (FDC) capsule containing 28 mg memantine extended release (ER) and 10 mg donepezil was evaluated for bioequivalence with co-administered commercially available memantine ER and donepezil, and for bioavailability with regard to food intake.

METHODS

Two phase I, single-dose, randomized, open-label, crossover studies were conducted in 18- to 45-year-old healthy individuals. In MDX-PK-104 study, fasting participants (N = 38) received co-administered memantine ER and donepezil or the FDC. In MDX-PK-105 study, participants (N = 36) received three treatments: intact FDC taken while fasting or after a high-fat meal, or FDC contents sprinkled on applesauce while fasting. Standard pharmacokinetic parameters for memantine and donepezil were calculated from the plasma concentration time-curve using non-compartmental analyses. Linear mixed-effects models were used to compare: (a) FDC versus co-administered individual drugs; (b) FDC fasted versus with food; and (c) FDC sprinkled on applesauce versus FDC intact, both fasted. Safety parameters were also evaluated.

RESULTS

The FDC capsule was bioequivalent to co-administered memantine ER and donepezil. There was no significant food effect on the bioavailability of the FDC components. There were no clinically relevant differences in time to maximum plasma concentration or safety profiles across treatments.

CONCLUSIONS

An FDC capsule containing 28 mg memantine ER and 10 mg donepezil is bioequivalent to commercially available memantine ER and donepezil, and bioavailability is not affected by food intake or sprinkling of capsule contents on applesauce.

[The Hemodynamics and Bispectral Index Score during Lower Abdominal Surgery under Balanced Anesthesia with the Two Different Combination Doses of Desflurane and Remifentanil]

BACKGROUND

The purpose of this study was to examine the hemodynamics and bispectral index score during lower abdominal surgery under balanced anesthesia with the two different combination doses of desflurane and remifentanil.

METHODS

Twenty patients undergoing total hysterectomy were allocated into two groups; 1) 10 patients received 4.5% end-tidal concentration of desflurane combined with remifentanil 0.125 μg x kg(-1) x min(-1) (H group) and 2) 10 patients received 3.0% end-tidal concentration of desflurane combined with remifentanil 0.2 μg x kg(-1) X min(-1) (L group). Mean arterial pressure (MAP), heart rate (HR) and BIS were recorded 5 times (on admission to operating room, immediately before surgery, 5 minutes after the skin incision, at the moment of uterine extraction and during retroperitoneal closure).

RESULTS

MAP and HR during surgery did not increase compared with those on admission to operating room, and BIS was unchanged throughout the study in both two groups.

CONCLUSIONS

The patients could be anesthetized adequately during lower abdominal surgery under balanced anesthesia with the two different combination doses of desflurane and remifentanil.

Imaging MALDI MS of Dosed Brain Tissues Utilizing an Alternative Analyte Pre-extraction Approach

Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry has been adopted in the pharmaceutical industry as a useful tool to detect xenobiotic distribution within tissues. A unique sample preparation approach for MALDI imaging has been described here for the extraction and detection of cobimetinib and clozapine, which were previously undetectable in mouse and rat brain using a single matrix application step. Employing a combination of a buffer wash and a cyclohexane pre-extraction step prior to standard matrix application, the xenobiotics were successfully extracted and detected with an 8 to 20-fold gain in sensitivity. This alternative approach for sample preparation could serve as an advantageous option when encountering difficult to detect analytes.

No correlation between remifentanil blood, cerebrospinal fluid and cerebral extracellular fluid levels and TCI prediction: a pharmacokinetic study

BACKGROUND

The aims of this paper were to elucidate the difference in concentration among remifentanil blood, cerebrospinal fluid and cerebral extracellular fluid levels, and to verify the presumable existence of a correlation between arterial and cerebral remifentanil. We used brain microdialysis to shed light on this aspect of the pharmacokinetic and to correlate these findings with Minto's model.

METHODS

The study population was formed by 9 patients scheduled for elective intracranial surgery for cerebral supratentorial neoplasia. All patients received general anaesthetic; 100 microliters of dialysate were collected. Furthermore, arterial blood samples of 3 mL each were collected, respectively one at the beginning and one at the end of the sampling period. We determined the concentration of remifentanil and its main metabolite, remifentanil acid, in the blood and in the brain. The predictive performance of the Minto pharmacokinetic parameter set was evaluated by examining the performance error.

RESULTS

The mean Performance Error was -45.13% (min -21.80, max -88.75) for the first series of arterial samples, -38.29% (min -6.57, max -79.17) for the second one and 67.73% (min 7, max -93.12) for the extra cellular fluid sample. The concentration of remifentanil set pumps was correlated with blood concentration for both series of samples. Neither the set concentration, nor the arterial samples were correlated with extra cellular fluid values.

CONCLUSION

There was a wide interindividual variability with regard both to blood and cerebral remifentanil concentration. Moreover, the ratio between arterial blood and cerebral remifentanil was not consistent among our patients in spite of a stable infusion rate of remifentanil; at the end we found a trend of over prediction in the ratio between the various compartments examined.

Patient controlled analgesia with remifentanil versus epidural analgesia in labour: randomised multicentre equivalence trial

OBJECTIVE

To determine women's satisfaction with pain relief using patient controlled analgesia with remifentanil compared with epidural analgesia during labour.

DESIGN

Multicentre randomised controlled equivalence trial.

SETTING

15 hospitals in the Netherlands.

PARTICIPANTS

Women with an intermediate to high obstetric risk with an intention to deliver vaginally. To exclude a clinically relevant difference in satisfaction with pain relief of more than 10%, we needed to include 1136 women. Because of missing values for satisfaction this number was increased to 1400 before any analysis. We used multiple imputation to correct for missing data.

INTERVENTION

Before the onset of active labour consenting women were randomised to a pain relief strategy with patient controlled remifentanil or epidural analgesia if they requested pain relief during labour.

MAIN OUTCOME MEASURES

Primary outcome was satisfaction with pain relief, measured hourly on a visual analogue scale and expressed as area under the curve (AUC), thus providing a time weighted measure of total satisfaction with pain relief. A higher AUC represents higher satisfaction with pain relief. Secondary outcomes were pain intensity scores, mode of delivery, and maternal and neonatal outcomes. Analysis was done by intention to treat. The study was defined as an equivalence study for the primary outcome.

RESULTS

1414 women were randomised, of whom 709 were allocated to patient controlled remifentanil and 705 to epidural analgesia. Baseline characteristics were comparable. Pain relief was ultimately used in 65% (447/687) in the remifentanil group and 52% (347/671) in the epidural analgesia group (relative risk 1.32, 95% confidence interval 1.18 to 1.48). Cross over occurred in 7% (45/687) and 8% (51/671) of women, respectively. Of women primarily treated with remifentanil, 13% (53/402) converted to epidural analgesia, while in women primarily treated with epidural analgesia 1% (3/296) converted to remifentanil. The area under the curve for total satisfaction with pain relief was 30.9 in the remifentanil group versus 33.7 in the epidural analgesia group (mean difference -2.8, 95% confidence interval -6.9 to 1.3). For who actually received pain relief the area under the curve for satisfaction with pain relief after the start of pain relief was 25.6 in the remifentanil group versus 36.1 in the epidural analgesia group (mean difference -10.4, -13.9 to -7.0). The rate of caesarean section was 15% in both groups. Oxygen saturation was significantly lower (SpO2 <92%) in women who used remifentanil (relative risk 1.5, 1.4 to 1.7). Maternal and neonatal outcomes were comparable between both groups.

CONCLUSION

In women in labour, patient controlled analgesia with remifentanil is not equivalent to epidural analgesia with respect to scores on satisfaction with pain relief. Satisfaction with pain relief was significantly higher in women who were allocated to and received epidural analgesia.

TRIAL REGISTRATION

Netherlands Trial Register NTR2551.

Small-animal single-photon emission computed tomographic imaging of the brain serotoninergic systems in wild-type and mdr1a knockout rats

The pharmacokinetic properties of radiotracers are crucial for successful in vivo single-photon emission computed tomographic (SPECT) imaging. Our goal was to determine if MDR1A-deficient animals could allow better SPECT imaging outcomes than wild-type (WT) animals for a selection of serotoninergic radioligands. Thus, we compared the performances of 123I-p-MPPI, 123I-R91150, 123I-SB207710, and 123I-ADAM radioligands, for imaging of their respective targets (5-hydroxytryptamine [5-HT]1A, 5-HT2A, 5-HT4, and serotonin transporter [SERT]), in WT and Mdr1a knockout (KO) rats. With 123I-SB207710, virtually no SPECT signal was recorded in the brain of WT or KO animals. For 123I-p-MPPI, low nondisplaceable binding potentials (BPND, mean ± SD) were observed in WT (0.49 ± 0.25) and KO (0.89 ± 0.52) animals. For 123I-ADAM, modest imaging contrast was observed in WT (1.27 ± 0.02) and KO (1.31 ± 0.09) animals. For 123I-R91150, the BPND were significantly higher in Mdr1a KO (3.98 ± 0.65) animals compared to WT animals (1.22 ± 0.26). The pharmacokinetics of 123I-SB207710 and 123I-p-MPPI do not make them ideal tracers for preclinical SPECT neuroimaging. 123I-ADAM showed adequate brain uptake regardless of Mdr1a expression and appeared suitable for preclinical SPECT neuroimaging in both animal strains. The use of Mdr1a KO animals significantly improved the brain penetration of 123I-R91150, making this animal strain an interesting option when considering SPECT neuroimaging of 5-HT2A receptors in rat.

Role of P-glycoprotein on the brain penetration and brain pharmacodynamic activity of the MEK inhibitor cobimetinib

Cobimetinib is a MEK inhibitor currently in clinical trials as an anticancer agent. The objectives of this study were to determine in vitro and in vivo if cobimetinib is a substrate of P-glycoprotein (P-gp) and/or breast cancer resistance protein (Bcrp1) and to assess the implications of efflux on cobimetinib pharmacokinetics (PK), brain penetration, and target modulation. Cell lines transfected with P-gp or Bcrp1 established that cobimetinib was a substrate of P-gp but not a substrate of Bcrp1. In vivo, after intravenous and oral administration of cobimetinib to FVB (wild-type; WT), Mdr1a/b(-/-), Bcrp1 (-/-), and Mdr1a/b(-/-)/Bcrp(-/-) knockout (KO) mice, clearance was similar in WT (35.5 ± 16.7 mL/min/kg) and KO animals (22.0 ± 3.6 to 27.6 ± 5.2 mL/min/kg); oral exposure was also similar between WT and KO animals. After an oral 10 mg/kg dose of cobimetinib, the mean total brain to plasma ratio (Kp) at 6 h postdose was 0.3 and 0.2 in WT and Bcrp1(-/-) mice, respectively. In Mdr1a/b(-/-) and Mdr1a/1b/Bcrp1(-/-) KO mice and WT mice treated with elacridar (a P-gp and BCRP inhibitor), Kp increased to 11, 6, and 7, respectively. Increased brain exposure in Mdr1a/b(-/-) and Mdr1a/1b/Bcrp1(-/-) KO and elacridar treated mice was accompanied by up to ∼65% suppression of the target (pErk) in brain tissue, compared to WT mice. By MALDI imaging, the cobimetinib signal intensity was relatively high and was dispersed throughout the brain of Mdr1a/1b/Bcrp1(-/-) KO mice compared to low/undetectable signal intensity in WT mice. The efflux of cobimetinib by P-gp may have implications for the treatment of patients with brain tumors/metastases.

Acute toxicity associated with the recreational use of the novel dissociative psychoactive substance methoxphenidine

INTRODUCTION

Methoxphenidine is a novel dissociative designer drug of the diarylethylamine class which shares structural features with phencyclidine (PCP), and is not at present subject to restrictive regulations. There is very limited information about the acute toxicity profile of methoxphenidine and the only sources are anonymous internet sites and a 1989 patent of the Searle Company. We report a case of analytically confirmed oral methoxphenidine toxicity.

CASE DETAILS

A 53-year-old man was found on the street in a somnolent and confusional state. Observed signs and symptoms such as tachycardia (112 bpm), hypertension (220/125 mmHg), echolalia, confusion, agitation, opisthotonus, nystagmus and amnesia were consistent with phencyclidine-induced adverse effects. Temperature (99.1°F (37.3°C)) and peripheral oxygen saturation while breathing room air (99%) were normal. Laboratory analysis revealed an increase of creatine kinase (max 865 U/L), alanine aminotransferase (72 U/L) and gamma-glutamyl transpeptidase (123 U/L). Methoxphenidine was identified by a liquid chromatography tandem mass spectrometry toxicological screening method using turbulent flow online extraction in plasma and urine samples collected on admission. The clinical course was favourable and signs and symptoms resolved with symptomatic treatment.

CONCLUSION

Based on this case report and users' web reports, and compatible with the chemical structure, methoxphenidine produces effects similar to those of the arylcyclohexylamines, as PCP.

Dose-dependent sigma-1 receptor occupancy by donepezil in rat brain can be assessed with (11)C-SA4503 and microPET

RATIONALE

Sigma-1 receptor agonists are under investigation as potential disease-modifying agents for several CNS disorders. Donepezil, an acetylcholinesterase inhibitor used for the symptomatic treatment of Alzheimer's disease, is also a high-affinity sigma-1 agonist.

OBJECTIVES

The objectives of the present study were to investigate if the sigma-1 agonist tracer (11)C-SA4503 and microPET can be used to determine sigma-1 receptor occupancy (RO) of donepezil in the rat brain; to establish RO of donepezil at doses commonly used in rodent behavioural studies; and to determine the effective plasma concentration of donepezil required for 50 % of max-min occupancy (EC50).

METHODS

Male Wistar rats were pre-treated with donepezil (0.1 to 10 mg/kg) for about 1 h before microPET scans using (11)C-SA4503. The total distribution volume (V T) of the tracer was determined by Logan graphical analysis using time activity curves from arterial plasma and regions of interest drawn around the entire brain and individual brain regions. RO by donepezil was calculated from a modified Lassen plot, and ED50 was estimated from the sigmoidal dose-response curves obtained when the RO was plotted against log donepezil dose.

RESULTS

A dose-dependent reduction was observed for V T in the whole brain as well as individual brain regions. RO increased dose-dependently and was 93 % at 10 mg/kg. ED50 was 1.29 mg/kg.

CONCLUSIONS

Donepezil, in the common dose range, was found to dose-dependently occupy a significant fraction of the sigma-1 receptor population. The data indicate that it is possible to determine sigma-1 RO by an agonist drug in rat brain, using (11)C-SA4503 and microPET.

Dipeptidyl peptidase-4 inhibitors: pharmacokinetics, efficacy, tolerability and safety in renal impairment

The dipeptidyl peptidase-4 (DPP-4) inhibitors are a new class of blood glucose-lowering therapy with proven efficacy, tolerability and safety. Four of the five commercially available DPP-4 inhibitors are subject to significant renal clearance, and pharmacokinetic studies in people with renal impairment have led to lower recommended doses based on creatinine clearance in order to prevent drug accumulation. Data from these pharmacokinetic studies and from supratherapeutic doses in healthy individuals and people with uncomplicated diabetes during development suggest, however, that there is a wide therapeutic margin. This should protect against toxicity if people with renal impairment are inadvertently prescribed higher doses than recommended. Doses appropriate to renal function are associated with reductions in HbA1c that are equivalent to those observed in people with type 2 diabetes who do not have renal impairment. Recent large-scale cardiovascular safety trials of saxagliptin and alogliptin have identified heart failure as a potential concern and renal impairment may increase the risk of this complication. Although the incidence of pancreatitis does not appear to be significantly increased by DPP-4 inhibitor therapy, renal impairment is also an independent risk factor. Additional data from other ongoing DPP-4 inhibitor cardiovascular safety trials should provide a more precise assessment of the risks of these uncommon complications, including in people with renal impairment.

Reciprocal alterations in cortical cannabinoid receptor 1 binding relative to protein immunoreactivity and transcript levels in schizophrenia

The deleterious effects of cannabis use in schizophrenia have been linked, in part, to underlying disturbances in endogenous cannabinoid signaling in the prefrontal cortex. However, while receptor autoradiography studies of the primary cannabinoid receptor (CB1R) have consistently found higher CB1R binding in the prefrontal cortex in schizophrenia, deficits in CB1R mRNA levels and protein immunoreactivity have also been reported in the illness. To investigate this apparent discrepancy, we quantified CB1R binding using receptor autoradiography with the selective CB1R ligand [(3)H]-OMAR in the prefrontal cortex of 21 subjects with schizophrenia who were previously found to have lower levels of both CB1R mRNA using in situ hybridization and CB1R protein using radioimmunocytochemistry relative to matched healthy comparison subjects. We observed higher levels of [(3)H]-OMAR binding in the prefrontal cortex of schizophrenia subjects that did not appear to be attributable to psychotropic medications or substance abuse. The combination of lower levels of CB1R mRNA and immunoreactivity with higher CB1R receptor binding may reflect 1) altered trafficking of the receptor resulting in higher levels of membrane-bound CB1R or 2) higher CB1R affinity. In either case, greater CB1R receptor availability may contribute to the increased susceptibility of schizophrenia subjects to the deleterious effects of cannabis use.

Distribution of intravenously administered acetylcholinesterase inhibitor and acetylcholinesterase activity in the adrenal gland: 11C-donepezil PET study in the normal rat

Purpose

Acetylcholinesterase (AChE) inhibitors have been used for patients with Alzheimer's disease. However, its pharmacokinetics in non-target organs other than the brain has not been clarified yet. The purpose of this study was to evaluate the relationship between the whole-body distribution of intravenously administered ¹¹C-Donepezil (DNP) and the AChE activity in the normal rat, with special focus on the adrenal glands.

Methods

The distribution of ¹¹C-DNP was investigated by PET/CT in 6 normal male Wistar rats (8 weeks old, body weight  = 220±8.9 g). A 30-min dynamic scan was started simultaneously with an intravenous bolus injection of ¹¹C-DNP (45.0±10.7 MBq). The whole-body distribution of the ¹¹C-DNP PET was evaluated based on the Vt (total distribution volume) by Logan-plot analysis. A fluorometric assay was performed to quantify the AChE activity in homogenized tissue solutions of the major organs.

Results

The PET analysis using Vt showed that the adrenal glands had the 2nd highest level of ¹¹C-DNP in the body (following the liver) (13.33±1.08 and 19.43±1.29 ml/cm³, respectively), indicating that the distribution of ¹¹C-DNP was the highest in the adrenal glands, except for that in the excretory organs. The AChE activity was the third highest in the adrenal glands (following the small intestine and the stomach) (24.9±1.6, 83.1±3.0, and 38.5±8.1 mU/mg, respectively), indicating high activity of AChE in the adrenal glands.

Conclusions

We demonstrated the whole-body distribution of ¹¹C-DNP by PET and the AChE activity in the major organs by fluorometric assay in the normal rat. High accumulation of ¹¹C-DNP was observed in the adrenal glands, which suggested the risk of enhanced cholinergic synaptic transmission by the use of AChE inhibitors.

A population pharmacokinetic model of remifentanil in pediatric patients using body-weight-dependent allometric exponents

BACKGROUND

Allometric exponents in population pharmacokinetic analysis are regularly used but the issue of fixing or estimating an allometric exponent remains controversial. The objective of the current analysis is to evaluate the performance of a body-weight-dependent allometric exponent (BDE) model of remifentanil.

METHODS

The study was conducted in 34 patients (neonates to 17 years and 2.5 to 97 kg body weight) following a single intravenous (IV) infusion of remifentanil (5 μg/kg). A population pharmacokinetic approach was taken to describe drug clearance by the following BDE equation: CL=CLpop(BW/14.6 kg)L×BW(-M). Three allometric models were used to explore the impact of allometric exponents on the total clearance of remifentanil.

RESULTS

All model-fitted structural, covariate, and statistical parameters were estimated with good to excellent precision (%RSE). However, on the basis of calculated Akaike weights (0.000 for model 1, 0.004 for model 2, and 0.996 for model 3), model 3 is the most robust model to describe individual clearance estimates.

CONCLUSIONS

The BDE model performed best for the estimation of remifentanil clearance and is realistic and of practical value. Further investigation should be conducted for such models.