Application of Parallel Reaction Monitoring to the Development and Validation of a Quantitative Assay for ST-246 in Human Plasma

In this work, we developed and validated a robust and sensitive method of liquid chromatography with high-resolution mass spectrometry in parallel reaction monitoring (PRM) mode for ST-246 (tecovirimat) quantification in human blood plasma. The method was compared with the multiple reaction monitoring (MRM) technique and showed better selectivity and similar sensitivity in a wider concentration range (10–5000 ng/mL). Within this range, intra- and interday variability of precision and accuracy were within acceptable ranges in accordance with the European Medicines Agency guidelines, and recovery was 87.9–100.6%. Samples were stable at 4 °C within 48 h and at −20 °C up to 3 months. The recovery and matrix effects in the proposed HRMS method were about 5% higher than those reported for the MRM method, but the PRM method showed better accuracy with comparable precision. It was found that the ST-246 concentration shown by the PRM method is approximately 24% higher than the output of the MRM one. Nonetheless, the high selectivity with similar sensitivity, as compared with traditional MRM methods, makes the proposed approach attractive for research and clinical use.

Safety and nonclinical and clinical pharmacokinetics of PC945, a novel inhaled triazole antifungal agent

PC945 is a novel antifungal triazole formulated for nebulized delivery to treat lung Aspergillus infections. Pharmacokinetic and safety profiles from nonclinical studies and clinical trials in healthy subjects, and subjects with mild asthma were characterized. Toxicokinetics were assessed following daily 2-hour inhalation for 14 days. Potential for drug-drug interactions was evaluated using pooled human liver microsomes. Clinical safety and pharmacokinetics were assessed following (a) single inhaled doses (0.5-10 mg), (b) 7-day repeat doses (5 mg daily) in healthy subjects; (c) a single dose (5 mg) in subjects with mild asthma. Cmax occurred 4 hours (rats) or immediately (dogs) after a single dose. PC945 lung concentrations were substantially higher (>2000-fold) than those in plasma. PC945 only inhibited CYP3A4/5 substrate metabolism (IC50 : 1.33 µM [testosterone] and 0.085 µM [midazolam]). Geometric mean Cmax was 322 pg/mL (healthy subjects) and 335 pg/mL (subjects with mild asthma) 4-5 hours (median tmax ) after a single inhalation (5 mg). Following repeat, once daily inhalation (5 mg), Day 7 Cmax was 951 pg/mL (0.0016 µM) 45 minutes after dosing. Increases in Cmax and AUC0-24h were approximately dose-proportional (0.5-10 mg). PC945 administration was well tolerated in both healthy subjects and subjects with mild asthma. Treatment-emergent adverse events were mild/moderate and resolved before the study ended. No clinically significant lung function changes were observed. PC945 pharmacokinetics translated from nonclinical species to humans showed slow absorption from lungs and low systemic exposure, thereby limiting the potential for adverse side effects and drug interactions commonly seen with systemically delivered azoles.

Characterization of the pharmacokinetics of entrectinib and its active M5 metabolite in healthy volunteers and patients with solid tumors

BACKGROUND

Entrectinib is an oral, CNS-active, potent inhibitor of tyrosine receptor kinases A/B/C, tyrosine kinase ROS proto-oncogene 1, and anaplastic lymphoma kinase approved for use in patients with solid tumors. We describe 3 clinical studies, including one investigating the single/multiple dose pharmacokinetics of entrectinib in patients and two studies in healthy volunteers investigating the absorption/distribution/metabolism/excretion (ADME) of entrectinib, its relative bioavailability, and effect of food on pharmacokinetics.

METHODS

The patient study is open-label with dose-escalation and expansion phases. Volunteers received entrectinib (100-400 mg/m², and 600-800 mg) once daily with food in continuous 28-day cycles. In the ADME study, volunteers received a single oral dose of [¹⁴C]entrectinib 600 mg. In the third study, volunteers received single doses of entrectinib 600 mg as the research and marketed formulations in the fasted state (Part 1), and the marketed formulation in the fed and fasted states (Part 2). Entrectinib and its major active metabolite M5 were assessed in all studies.

RESULTS

Entrectinib was absorbed in a dose-dependent manner with maximum concentrations at ~4 h postdose and an elimination half-life of ~20 h. Entrectinib was cleared mainly through metabolism and both entrectinib and metabolites were eliminated mainly in feces (minimal renal excretion). At steady-state, the M5-to-entrectinib AUC ratio was 0.5 (with 600 mg entrectinib research formulation in patients). The research and marketed formulations were bioequivalent and food had no relevant effect on pharmacokinetics.

CONCLUSIONS

Entrectinib is well absorbed, with linear PK that is suitable for once-daily dosing, and can be taken with or without food.

Pharmacodynamics and pharmacokinetics of the novel synthetic opioid, U-47700, in male rats

Novel synthetic opioids are appearing in recreational drug markets worldwide as adulterants in heroin or ingredients in counterfeit analgesic medications. Trans-3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methyl-benzamide (U-47700) is an example of a non-fentanyl synthetic opioid linked to overdose deaths. Here, we examined the pharmacodynamics and pharmacokinetics of U-47700 in rats. Male Sprague-Dawley rats were fitted with intravenous (i.v.) catheters and subcutaneous (s.c.) temperature transponders under ketamine/xylazine anesthesia. One week later, rats received s.c. injections of U-47700 HCl (0.3, 1.0 or 3.0 mg/kg) or saline, and blood samples (0.3 mL) were withdrawn via i.v. catheters at 15, 30, 60, 120, 240, 480 min post-injection. Pharmacodynamic effects were assessed at each blood withdrawal, and plasma was assayed for U-47700 and its metabolites by liquid chromatography tandem mass spectrometry. U-47700 induced dose-related increases in hot plate latency (ED₅₀ = 0.5 mg/kg) and catalepsy (ED₅₀ = 1.7 mg/kg), while the 3.0 mg/kg dose also caused hypothermia. Plasma levels of U-47700 rose linearly as dose increased, with maximal concentration (C_max) achieved by 15-38 min. C_max values for N-desmethyl-U-47700 and N,N-didesmethyl-U-47700 were delayed but reached levels in the same range as the parent compound. Pharmacodynamic effects were correlated with plasma U-47700 and its N-desmethyl metabolite. Using radioligand binding assays, U-47700 displayed high affinity for μ-opioid receptors (Ki = 11.1 nM) whereas metabolites were more than 18-fold weaker. Our data reveal that U-47700 induces typical μ-opioid effects which are related to plasma concentrations of the parent compound. Given its high potency, U-47700 poses substantial risk to humans who are inadvertently exposed to the drug.

Novel Bruton tyrosine kinase inhibitor acalabrutinib quantification by validated LC-MS/MS method: An application to pharmacokinetic study in Sprague Dawley rats

USFDA has approved a novel Bruton tyrosine kinase (BTK) inhibitor acalabrutinib (ACA) for the treatment of mantle cell lymphoma in adults. ACA is more potent and selective with fewer side effects compared to other Bruton tyrosine kinase inhibitors. In the current work a highly sensitive, selective and specific LC-MS/MS method for the estimation of acalabrutinib (ACA) in rat plasma was developed. Agilent Eclipse Plus C 8 column (50 mm × 4.6 mm, μm), with gradient elution using 10 mM ammonium formate and acetonitrile as mobile phase at a flow rate of 0.6 mL/min was used for the chromatographic separation. The ion transitions were quantified in positive mode with MRM transition of 466.1→372.3 for ACA and 236.8→194.0 for internal standard (IS). Solid phase extraction process was used as sample preparation approach. The method was validated according to USFDA bioanalytical guidelines. The method provided good linearity over the range of 0.2-199.14 ng/mL for ACA with short run time of 4 min. The method offers very high sensitivity (0.2 ng/mL) and was free from matrix interferences. The validated LC-MS/MS method was successfully applied for in vivo pharmacokinetic study in Sprague Dawley rats. The C_max of ACA was found to be 25.56 ng/mL reaching at time of 0.5 h. The developed analytical method can also be utilized for bioequivalence studies and/or for pharmacokinetic studies in clinics.

Phosphodiesterase 4 inhibition reduces lung fibrosis following targeted type II alveolar epithelial cell injury

Fibrosis of the lung constitutes a major clinical challenge and novel therapies are required to alleviate the associated morbidity and mortality. Investigating the antifibrotic efficacy of drugs that are already in clinical practice offers an efficient strategy to identify new therapies. The phosphodiesterase 4 (PDE4) inhibitors, approved for the treatment of chronic obstructive pulmonary disease, harbor therapeutic potential for pulmonary fibrosis by augmenting the activity of endogenous antifibrotic mediators that signal through cyclic AMP. In this study, we tested the efficacy of several PDE4 inhibitors including a novel compound (Compound 1) in a murine model of lung fibrosis that results from a targeted type II alveolar epithelial cell injury. We also compared the antifibrotic activity of PDE4 inhibition to the two therapies that are FDA-approved for idiopathic pulmonary fibrosis (pirfenidone and nintedanib). We found that both preventative (day 0-21) and therapeutic (day 11-21) dosing regimens of the PDE4 inhibitors significantly ameliorated the weight loss and lung collagen accumulation that are the sequelae of targeted epithelial cell damage. In a therapeutic protocol, the reduction in lung fibrosis with PDE4 inhibitor administration was equivalent to pirfenidone and nintedanib. Treatment with this class of drugs also resulted in a decrease in plasma surfactant protein D concentration, a reduction in the plasma levels of several chemokines implicated in lung fibrosis, and an in vitro inhibition of fibroblast profibrotic gene expression. These results motivate further investigation of PDE4 inhibition as a treatment for patients with fibrotic lung disease.

Novel highly selective peroxisome proliferator-activated receptor δ (PPARδ) modulators with pharmacokinetic properties suitable for once-daily oral dosing

Optimization of benzamide PPARδ modulator 1 led to (E)-6-(2-((4-(furan-2-yl)-N-methylbenzamido)methyl)phenoxy)-4-methylhex-4-enoic acid (18), a potent selective PPARδ modulator with significantly improved exposure in multiple species following oral administration.

Safety, tolerability and pharmacokinetics of the fibroblast growth factor receptor inhibitor AZD4547 in Japanese patients with advanced solid tumours: a Phase I study

Background AZD4547 is a potent, oral, highly selective fibroblast growth factor receptor (FGFR) inhibitor in clinical development for treating tumours with a range of FGFR aberrations, including FGFR mutations, amplifications and fusions. Methods This open-label, Phase I, multicentre study (NCT01213160) evaluated the safety, pharmacokinetics, and preliminary antitumour efficacy (RECIST v1.1) of AZD4547 monotherapy in Japanese patients with advanced solid tumours. Part A was a dose-escalation part; Part B was a dose-expansion part in patients with FGFR-amplified tumours, confirmed by fluorescence in situ hybridization. Results Thirty patients enrolled in Part A (dose range: 40 mg twice daily [bid] to 120 mg bid; 160 mg once daily [qd]), four in Part B (80 mg bid). No dose-limiting toxicities were observed and maximum tolerated dose was not determined. Most common adverse events (AEs; any grade) were: dysgeusia (50% of patients); stomatitis (41%); diarrhoea (38%); hyperphosphataemia (38%); dry mouth (35%). Common grade ≥3 AEs were nausea (12% of patients) and neutropenia (9%). No complete or partial responses were observed: 21/30 patients had stable disease ≥4 weeks in Part A, and 1/4 patients had stable disease ≥10 weeks in Part B. Following single and multiple dosing, absorption rate appeared moderate; peak plasma concentrations generally occurred 3-4 h post-dose, then declined biphasically with terminal half-life ~30 h. Steady state was reached by day 8. Compared with single dosing, plasma concentrations were, on average, 2.4- and 3.3- to 5.4-fold higher after qd and bid dosing, respectively. Conclusions AZD4547 was well tolerated in Japanese patients, with best response of stable disease ≥4 weeks.

Determining pharmacological selectivity of the kappa opioid receptor antagonist LY2456302 using pupillometry as a translational biomarker in rat and human

BACKGROUND

Selective kappa opioid receptor antagonism is a promising experimental strategy for the treatment of depression. The kappa opioid receptor antagonist, LY2456302, exhibits ~30-fold higher affinity for kappa opioid receptors over mu opioid receptors, which is the next closest identified pharmacology.

METHODS

Here, we determined kappa opioid receptor pharmacological selectivity of LY2456302 by assessing mu opioid receptor antagonism using translational pupillometry in rats and humans.

RESULTS

In rats, morphine-induced mydriasis was completely blocked by the nonselective opioid receptor antagonist naloxone (3mg/kg, which produced 90% mu opioid receptor occupancy), while 100 and 300 mg/kg LY2456302 (which produced 56% and 87% mu opioid receptor occupancy, respectively) only partially blocked morphine-induced mydriasis. In humans, fentanyl-induced miosis was completely blocked by 50mg naltrexone, and LY2456302 dose-dependently blocked miosis at 25 and 60 mg (minimal-to-no blockade at 4-10mg).

CONCLUSIONS

We demonstrate, for the first time, the use of translational pupillometry in the context of receptor occupancy to identify a clinical dose of LY2456302 achieving maximal kappa opioid receptor occupancy without evidence of significant mu receptor antagonism.

[Potential clinical benefit of therapeutic drug monitoring of imatinib in oncology]

Imatinib mesylate is a competitive inhibitor of BCR/ ABL tyrosine kinase and inhibits also several receptor tyrosin kinases. Since its launch to the market, imatinib has proven to be very valuable in the treatment of Philadelphia chromosome (BCR/ ABL) -  positive (Ph+) chronic myeloid leukemia and Kit (CD117) positive gastrointestinal stromal tumors. The drug is metabolized by cytochrome P450, and there are many clinically important pharmacokinetic drug-drug interactions described in the literature. Frequent polypharmacy in oncological patients increases probability of such interactions, and also adherence may play its role during longterm treatment. Fixed dosing therapeutic regimens fail to respect known interindividual variability in pharmacokinetics of the drug and thus, some patients may not achieve sufficient plasma concentrations. Based on current evidence, there seems to be a relationship between plasma concentration and clinical response to imatinib. Therefore, imatinib appears to be suitable candidate for therapeutic drug monitoring. Here, we present an overview of pharmacokinetics, drug-drug interactions and current knowledge and suggestions on therapeutic drug monitor-ing of imatinib, its potential benefits and limitations.

Imatinib plasma levels during successful long-term treatment of metastatic-gastrointestinal stromal tumors

BACKGROUND/AIMS

To investigate whether imatinib dosage correlated with effective plasma levels and clinical characteristics for Japanese patients undergoing long-term (≥2 years) imatinib therapy for GISTs.

METHODOLOGY

Twenty-five patients who received imatinib for a metastatic pathologically diagnosed GISTs at our hospital were enrolled. Imatinib response was assessed according to Choi’s criteria. Blood samples were collected 22–26 h after the previous imatinib dose before the next scheduled dose. Results: Fourteen patients were male and the median age was 65 years. The median duration of imatinib therapy was 3.8 years (range, 2.0–11.5 years). The median plasma level of imatinib was 1098 ng/ml and the minimal plasma level after ≥5 years of therapy was 789 ng/ml. Imatinib dosage was significantly correlated with history of gastrectomy. The minimum body surface area of patients who received 400-mg/day imatinib dosage was 1.560 m2.

CONCLUSIONS

The minimum level in all patients showing response for ≥5 years of treatment was 789 ng/ml, suggesting an effective plasma imatinib level of ≥800 ng/ml. Our results suggest that imatinib dosage of 400 mg/day is recommended for a patient with a large BSA (≥1.56 m2) and that of 300 mg/day might be sufficient for patients who have undergone a gastrectomy.

Bioequivalence study of 400 and 100 mg imatinib film-coated tablets in healthy volunteers

The aim of the study was to investigate the bioavailability of a generic product of 100 mg and 400 mg imatinib film-coated tablets (test) as compared to that of a branded product (reference) at the same strength to determine bioequivalence. The secondary objective of the study was to evaluate tolerability of both products. An open-label, randomized, crossover, two-period, single-dose, comparative study was conducted in 43 (Imatynib-Biofarm 100 mg film-coated tablet) and in 42 (Imatynib-Biofarm 400 mg film-coated tablet), brand name Imatenil, Caucasian healthy volunteers in fed conditions. A single oral dose administration of the test or reference product was separated by 14-day washout period. The imatinib and its metabolite N-desmethyl imatinib concentrations were determined using a validated LC MS/MS method. The results of the single-dose study in healthy volunteers indicated that the film-coated tablets of Imatynib-Biofarm 100 mg and 400 mg film-coated tablets manufactured by Biofarm Sp. z o.o. (test products) are bioequivalent to those of Glivec 100 mg and 400 mg film-coated tablets manufactured by Novartis Pharma GmbH (reference products). Both products in the two doses of imatinib were well tolerated.

CD117 (c-kit) expression on CD34+ cells participates in the cytogenetic response to imatinib in patients with chronic myeloid leukemia in the first chronic phase

BACKGROUND

Chronic myeloid leukemia (CML) biology seemed to be perfectly explored especially at the beginning of the tyrosine kinase inhibitors era. Later years with imatinib and second-generation tyrosine kinase inhibitors showed a variety of resistance mechanisms and it became obvious that the bcr-abl chimeric gene is not the only enemy to fight. Some studies assumed the decreased rate of programmed cell death (apoptotic) to be the primary mechanism by which BCR-ABL affects expansion of the leukemic clone in CML. Therefore, the aim of this study was to investigate the role of c-kit inhibition in treatment response.

METHODS

Cytogenetic analysis, real-time quantitative reverse-transcriptase polymerase chain reaction, flow-cytometric analysis and imatinib serum level quantification were applied.

RESULTS

The percentage of CD34+ cells expressing c-kit (CD117) isolated from bone marrow samples of 54 CML patients treated with standard-dose imatinib was significantly lower among imatinib responders. The fraction of apoptotic CD34+CD117+ cells in this patient group was significantly higher than in nonresponders.

CONCLUSION

To achieve optimal treatment response in CML patients, the elimination of CD34+CD117+ may be necessary through an apoptotic pathway.

Nanostructured lipid carriers containing a high percentage of a Pluronic copolymer increase the biodistribution of novel PDE4 inhibitors for the treatment of traumatic hemorrhage

Although the application of nanotechnology to drug therapy has been widely investigated, very few nanomedicine-based treatments for traumatic hemorrhage have been reported so far. The aim of this work was to develop nanostructured lipid carriers (NLCs) loaded with phosphodiesterase 4 (PDE4) inhibitors to treat acute inflammation in peripheral organs. The pharmacokinetics and biodistribution of DSM-RX78 and EFB-1, two novel PDE4 inhibitors, were examined using rats as an animal model. Entrapment by NLCs resulted in sustained drug release. The plasma concentrations of DSM-RX78 and EFB-1 in NLCs were lower, and their half-lives were much shorter in the NLC condition than in the control condition. PDE4 inhibitors delivered in NLCs accumulated with high abundance in many organs, especially the brain and lungs. Polyethylene glycol (PEG) coating on the particulate surface (P-NLCs) significantly reduced brain delivery of the drugs. P-NLCs enhanced drug distribution to the lungs by 5-fold compared to free control. In vivo real-time imaging confirmed rapid escape of nanoparticles from the blood circulation. Histological examination and aminotransferase measurement revealed that P-NLCs containing EFB-1 improved hemorrhagic shock-induced injuries in the lungs, intestines, and liver. P-NLCs even reversed acute lung inflammation to the level observed in an uninjured condition. Our results indicate that NLC-based delivery of PDE4 inhibitors is a candidate treatment for traumatic hemorrhage.

Novel Roflumilast analogs as soft PDE4 inhibitors

PDE4 inhibitors are of high interest for treatment of a wide range of inflammatory or autoimmune diseases. Their potential however has not yet been realized due to target-associated side effects, resulting in a low therapeutic window. We herein report the design, synthesis and evaluation of novel PDE4 inhibitors containing a γ-lactone structure. Such molecules are designed to undergo metabolic inactivation when entering circulation, thereby limiting systemic exposure and reducing the risk for side effects. The resulting inhibitors were highly active on both PDE4B1 and PDE4D2 and underwent rapid degradation in human plasma by paraoxonase 1. In contrast, their metabolites displayed markedly reduced permeability and/or on-target activity.

P-glycoprotein (MDR1/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) restrict brain accumulation of the JAK1/2 inhibitor, CYT387

CYT387 is an orally bioavailable, small molecule inhibitor of Janus family of tyrosine kinases (JAK) 1 and 2. It is currently undergoing Phase I/II clinical trials for the treatment of myelofibrosis and myeloproliferative neoplasms. We aimed to establish whether the multidrug efflux transporters P-glycoprotein (P-gp; MDR1; ABCB1) and breast cancer resistance protein (BCRP;ABCG2) restrict oral availability and brain penetration of CYT387. In vitro, CYT387 was efficiently transported by both human MDR1 and BCRP, and very efficiently by mouse Bcrp1 and its transport could be inhibited by specific MDR1 inhibitor, zosuquidar and/or specific BCRP inhibitor, Ko143. CYT387 (10 mg/kg) was orally administered to wild-type (WT), Bcrp1(-/-), Mdr1a/1b(-/-) and Bcrp1;Mdr1a/1b(-/-) mice and plasma and brain concentrations were analyzed. Over 8h, systemic exposure of CYT387 was similar between all the strains, indicating that these transporters do not substantially limit oral availability of CYT387. Despite the similar systemic exposure, brain accumulation of CYT387 was increased 10.5- and 56-fold in the Bcrp1;Mdr1a/1b(-/-) mice compared to the WT strain at 2 and 8h after CYT387 administration, respectively. In single Bcrp1(-/-) mice, brain accumulation of CYT387 was more substantially increased than in Mdr1a/1b(-/-) mice, suggesting that CYT387 is a slightly better substrate of Bcrp1 than of Mdr1a at the blood-brain barrier. These results indicate a marked and additive role of Bcrp1 and Mdr1a/1b in restricting brain penetration of CYT387, potentially limiting efficacy of this compound against brain (micro) metastases positioned behind a functional blood-brain barrier.

[Effects of imatinib mesylate on the levels of endocrine hormones]

OBJECTIVE

To measure the levels of hormones in chronic myelogenous leukemia (CML) patients receiving imatinib mesylate (IM) and evaluate the effects of IM on endocrine system.

METHODS

69 patients with CML while taking IM were enrolled and a total of 86 peripheral blood samples were detected. The levels of total triiodothyronine (TT3), total tetraiodothyronine (TT4), thyroid stimulating hormone (TSH), testosterone, progesterone, estradiol (E2), plasma total cortisol (PTC) at 8:00-10:00 am measured. Concentration of hormones in different groups were measured to evaluate the effects of IM on endocrine system and relationships with its administration duration, plasma concentration and clinical symptoms.

RESULTS

(1) Of the 7 types of hormones, an elevation of TSH level was found in 14 patients (20.3%), a decrease of TT3 and testosterone in 8 patients (11.6%) and 8 males (18.6%), respectively. (2) A significant decline of TT3 and testosterone was observed in all patients divided by different administration duration. Negative correlation was seen between TT3 level and duration of administration (r=-0.273, P=0.010), which was also found for testosterone (r=-0.302, P=0.025). (3) There was no correlation between serum levels of the seven hormones and concentration of IM.

CONCLUSION

IM affect the levels of thyroid and sex hormones in some patients with clinical manifestations: a decrease of TT3, testosterone and testosterone, an increase of TSH, which have relationship with the duration of administration.

A multicenter clinical study evaluating the confirmed complete molecular response rate in imatinib-treated patients with chronic phase chronic myeloid leukemia by using the international scale of real-time quantitative polymerase chain reaction

Achievement of complete molecular response in patients with chronic phase chronic myeloid leukemia has been recognized as an important milestone in therapy cessation and treatment-free remission; the identification of predictors of complete molecular response in these patients is, therefore, important. This study evaluated complete molecular response rates in imatinib-treated chronic phase chronic myeloid leukemia patients with major molecular response by using the international standardization for quantitative polymerase chain reaction analysis of the breakpoint cluster region-Abelson1 gene. The correlation of complete molecular response with various clinical, pharmacokinetic, and immunological parameters was determined. Complete molecular response was observed in 75/152 patients (49.3%). In the univariate analysis, Sokal score, median time to major molecular response, ABCG2 421C>A, and regulatory T cells were significantly lower in chronic phase chronic myeloid leukemia patients with complete molecular response than in those without complete molecular response. In the multivariate analysis, duration of imatinib treatment (odds ratio: 1.0287, P=0.0003), time to major molecular response from imatinib therapy (odds ratio: 0.9652, P=0.0020), and ABCG2 421C/C genotype (odds ratio: 0.3953, P=0.0284) were independent predictors of complete molecular response. In contrast, number of natural killer cells, BIM deletion polymorphisms, and plasma trough imatinib concentration were not significantly associated with achieving a complete molecular response. Several predictive markers for achieving complete molecular response were identified in this study. According to our findings, some chronic myeloid leukemia patients treated with imatinib may benefit from a switch to second-generation tyrosine kinase inhibitors (ClinicalTrials.gov, UMIN000004935).

Imatinib plasma monitoring-guided dose modification for managing imatinib-related toxicities in gastrointestinal stromal tumor patients

Imatinib, the first-line treatment in patients with advanced gastrointestinal stromal tumors (GIST), is generally well tolerated, although some patients have difficulty tolerating the standard dose of 400 mg/day. Adjusting imatinib dosage by plasma level monitoring may facilitate management of patients who experience intolerable toxicities due to overexposure to the drug. We present two cases of advanced GIST patients in whom we managed imatinib-related toxicities through dose modifications guided by imatinib plasma level monitoring. Imatinib blood level testing may be a promising approach for fine-tuning imatinib dosage for better tolerability and optimal clinical outcomes in patients with advanced GIST.

Pharmacokinetics and interspecies allometric scaling of ST-246, an oral antiviral therapeutic for treatment of orthopoxvirus infection

Plasma pharmacokinetics of ST-246, smallpox therapeutic, was evaluated in mice, rabbits, monkeys and dogs following repeat oral administrations by gavage. The dog showed the lowest T_max of 0.83 h and the monkey, the highest value of 3.25 h. A 2- to 4-fold greater dose-normalized C_max was observed for the dog compared to the other species. The mouse showed the highest dose-normalized AUC, which was 2-fold greater than that for the rabbit and monkey both of which by approximation, recorded the lowest value. The Cl/F increased across species from 0.05 L/h for mouse to 42.52 L/h for dog. The mouse showed the lowest V_D/F of 0.41 L and the monkey, the highest V_D/F of 392.95 L. The calculated extraction ratios were 0.104, 0.363, 0.231 and 0.591 for mouse, rabbit, monkey and dog, respectively. The dog showed the lowest terminal half-life of 3.10 h and the monkey, the highest value of 9.94 h. The simple allometric human V_D/F and MLP-corrected Cl/F were 2311.51 L and 51.35 L/h, respectively, with calculated human extraction ratio of 0.153 and terminal half-life of 31.20 h. Overall, a species-specific difference was observed for Cl/F with this parameter increasing across species from mouse to dog. The human MLP-corrected Cl/F, terminal half-life, extraction ratios were in close proximity to the observed estimates. In addition, the first-in-humans (FIH) dose of 485 mg, determined from the MLP-corrected allometry Cl/F, was well within the dose range of 400 mg and 600 mg administered in healthy adult human volunteers.

[The test of benzamide derivative neuroleptics using the technique of thin-layer chromatography]

The article presents the data concerning the application of technique of thin-layer chromatography in the conditions of laboratory diagnostics to identify benzamide derivative neuroleptics (amisupride, sulpiride, tiapride) in derivate from human biologic fluids and tissues with the possibility to separate the analyzed tissues from soextractive tissues.

Simultaneous quantitation of IC87114, roflumilast and its active metabolite roflumilast N-oxide in plasma by LC-MS/MS: application for a pharmacokinetic study

A sensitive and reliable high-performance liquid chromatography-mass spectrometry (LC-MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N-oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid-liquid extraction and separated on a reverse phase C(18) column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1-60 ng.mL(-1) for RFM and RFN and 6 to 2980 ng.mL(-1) for IC87114. Intra- and inter-day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r(2) ) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug-drug interaction study in Wistar rats.

Simple methodology for the therapeutic drug monitoring of the tyrosine kinase inhibitors dasatinib and imatinib

A simple HPLC method has been developed to measure imatinib and N-desmethylimatinib (norimatinib) in plasma or serum at concentrations attained during therapy. Adaptation of this method to LC-MS/MS also allows dasatinib assay. A small sample volume (100 μL HPLC-UV, 50 μL LC-MS/MS) is required and analysis time is <5 min in each case. Detection was by UV (270 nm) or selective reaction monitoring (two transitions per analyte) tandem mass spectrometry. Assay calibration was linear (0.05-10 mg/L imatinib, 0.01-2.0 mg/L norimatinib and 1-200 µg/L dasatinib), with acceptable accuracy (86-114%) and precision (<14% RSD) for both methods. A comparison between whole blood and plasma confirmed that plasma is the preferred sample for imatinib and norimatinib assay. For dasatinib, although whole blood concentrations were slightly higher, plasma is still the preferred sample. Despite considerable variation in the (median, range) plasma imatinib and norimatinib concentrations in patient samples [1.66 (0.02-4.96) and 0.32 (0.01-0.99) mg/L, respectively, N = 104], plasma imatinib was >1 mg/L (suggested target for response) in all but one sample from patients achieving complete molecular response. As to dasatinib, the median (range) plasma dasatinib concentration was 13 (2-143) µg/L (N = 33). More observations are needed to properly assess the potential role of therapeutic drug monitoring in guiding treatment with dasatinib.

Liquid chromatography-tandem mass spectrometric assay for the JAK2 inhibitor CYT387 in plasma

A quantitative bioanalytical liquid chromatography-tandem mass spectrometric (LC-MS/MS) assay for the JAK2 inhibitor CYT387 was developed and validated. Plasma samples were pre-treated using protein precipitation with acetonitrile containing cediranib as internal standard. The extract was directly injected into the chromatographic system after dilution with water. This system consisted of a sub-2 μm particle, trifunctional bonded octadecyl silica column with a gradient using 0.005% (v/v) of formic acid in a mixture of water and methanol. The eluate was transferred into the electrospray interface with positive ionization and the analyte was detected in the selected reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was validated in a 0.25-1000 ng/ml calibration range. Within day precisions were 3.0-13.5%, between day precisions 5.7% and 14.5%. Accuracies were between 96% and 113% for the whole calibration range. The drug was stable under all relevant analytical conditions. Finally, the assay was successfully used to assess drug levels in mice.

[Study on imatinib trough concentration, efficacy and their relation in chronic myelocytic leukemia]

OBJECTIVE

To determine plasma imatinib concentration, intracellular imatinib concentration, and hOCT1 and ABCB1 mRNA expression in bone marrow cells of CML patients to further evaluate the potential usefulness of these measures as markers of imatinib efficacy and their clinical relationships.

METHODS

Eighty CML patients in chronic phase receiving imatinib were enrolled in this study, including 56 males and 24 females with a median age of 39.5 (6 - 76) years. Imatinib was administered at a median dose of 400 (200 - 800) mg/d orally per day with a median course of 24 (3 - 90) months. The intracellular imatinib concentrations in bone marrow cells of 28 patients were simultaneously determined. Real-time quantitative PCR with a taqman probe was used to assess hOCT1 and ABCB1 mRNA expression on bone marrow cells of 36 patients. Imatinib trough concentration was determined by high-performance liquid chromatography-tandem mass spectrometry with a detectability of 2 - 10 000 µg/L. Serum α1-acid glycoprotein (AGP) was measured by immune turbidimetry on a BNProspec protein analyzer (Dade Behring, USA). All patients were divided into MMR, CCyR, PCyR or drug-resistant groups according to response.

RESULTS

Plasma imatinib trough concentration of 80 patients was (1274.1 ± 559.1) (109.0 - 3400.0) µg/L. The plasma imatinib trough concentration of 59 (73.8%) patients with a dose of 400 mg/d was (1252.0 ± 569.5) (109 - 3400) µg/L, including 37 (62.7%) patients with concentrations of more than 1000 µg/L and 9 (15.2%) patients more than 800 µg/L. Plasma imatinib trough concentration in the MMR group \[(1531.9 ± 634.1) µg/L\] was significant higher than in the PCyR \[(812.8 ± 480.3) µg/L\] or drug-resistant group \[(875.2 ± 243.1) µg/L\] (P < 0.05). Plasma imatinib trough concentration in the CCyR group \[(1288.4 ± 498.2) µg/L\] was significant higher than in the PCyR group (P = 0.027). There was no significant difference between CCyR and MMR groups with regard to plasma imatinib trough concentration (P = 0.136). The intracellular imatinib concentration in bone marrow cells in the CCyR group \[12.6 (2.4 - 90.4) µg/L\] was significantly higher than drug-resistant \[6.6 (2.6 - 111.0) µg/L\] or PCyR \[2.7 (2.4 - 4.7) µg/L\] groups (P = 0.013). The hOCT1 mRNA expression on bone marrow cells in the CCyR group \[25.9(0.7 - 123.9) × 10(-5)\] was significantly higher than in drug-resistant \[7.8 (2.5 - 33.5) × 10(-5)\] or PCyR \[4.2 (1.4 - 11.9) × 10(-5)\] groups (P = 0.036). The ABCB1 mRNA expression on bone marrow cells in drug-resistant group \[136.7 (15.0 - 1604.9) × 10(-5)\] was significantly higher than in CCyR \[129.1 (12.9 - 783.3) × 10(-5)\] or PCyR \[34.4 (2.2 -108.2) × 10(-5)\] groups (P = 0.013). Plasma imatinib trough concentration was positively correlated with AGP (r = 0.446, P = 0.000) or dose (r = 0.346, P = 0.002). There were no significant correlations between plasma imatinib trough concentration and height, weight or body surface area (P > 0.05). There were no significant differences among different courses with regard to plasma imatinib trough concentration (P > 0.05).

CONCLUSION

Clinical responses in CML patients were correlated with plasma and intracellular imatinib trough concentrations. Imatinib concentration was regulated by AGP and the activities of hOCT1 and ABCB1.

[Analysis of plasma trough level of imatinib in Chinese CML patients]

OBJECTIVE

To evaluate the relationship between plasma trough level of imatinib and clinical outcomes in Chinese CML patients.

METHODS

Plasma trough levels in 416 CML patients who received imatinib orally in six general hospitals were assessed. The correlations of imatinib plasma trough level with baseline characteristics including age, weight and BSA, and clinical response were evaluated.

RESULTS

(1) Effects of age, body weight and BSA on imatinib plasma trough levels were not to be clinically significant. (2) Median imatinib plasma trough levels was 1271 (109-4329). Imatinib plasma trough level was related to dose of imatinib administration. Plasma trough levels at imatinib of dose < 400, 400 and > 400 mg were (969 ± 585), (1341 ± 595) and (1740 ± 748) µg/L (P < 0.01), respectively. (3) There was no statistic difference in imatinib plasma trough level with complete cytogenetic response [CCyR (1337 ± 571) µg/L vs no CCyR (1354 ± 689) µg/L, P = 0.255]. (4) Imatinib plasma trough level might be important for a good clinical response in some CML patients.

CONCLUSION

There was a large interpatient variability in imatinib plasma concentration in Chinese CML patients. No correlation of imatinib plasma trough level with CCyR was observed. However, higher doses of imatinib were shown to attain greater trough plasma concentration, suggesting that imatinib plasma trough level might be important for a good clinical response in some CML patients.

A nonclinical safety and pharmacokinetic evaluation of N6022: a first-in-class S-nitrosoglutathione reductase inhibitor for the treatment of asthma

S-nitrosoglutathione reductase is the primary enzyme responsible for the metabolism of S-nitrosoglutathione (GSNO), the body's main source of bioavailable nitric oxide. Through its catabolic activity, GSNO reductase (GSNOR) plays a central role in regulating endogenous S-nitrosothiol levels and protein S-nitrosation-based signaling. By inhibiting GSNOR, we aim to increase pulmonary GSNO and induce bronchodilation while reducing inflammation in lung diseases such as asthma. To support the clinical development of N6022, a first-in-class GSNOR inhibitor, a 14-day toxicology study was conducted. Sprague-Dawley rats were given 2, 10 or 50 mg/kg/day N6022 via IV administration. N6022 was well tolerated at all doses and no biologically significant adverse findings were noted in the study up to 10 mg/kg/day. N6022-related study findings were limited to the high dose group. One male rat had mild hepatocellular necrosis with accompanying increases in ALT and AST and several male animals had histological lung assessments with a slight increase in foreign body granulomas. Systemic exposure was greater in males than females and saturation of plasma clearance was observed in both sexes in the high dose group. Liver was identified as the major organ of elimination. Mechanistic studies showed dose-dependent effects on the integrity of a rat hepatoma cell line.

Relative bioavailability of a 5 mg mosapride/10 mg rabeprazole fixed dose combination tablet versus separate single tablets in healthy volunteers: a single-dose randomized open-label crossover study

OBJECTIVE

To evaluate the relative bioavailability of a new formulation containing 5 mg mosapride and 10 mg rabeprazole (T) and compare it with the branded formulations of both drugs co-administered in separate tablets (R) to meet the regulatory requirements of bioequivalence in Argentina.

METHODS

A randomized-sequence, open-label, two-period crossover study was conducted on 24 healthy Caucasian volunteers in a fasting state. A single oral dose of either T or R formulations was followed by a 7-day washout period. Blood samples for mosapride were collected before administration (baseline) and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 18, and 24 h after administration. Samples for rabeprazole were taken baseline and at 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8 and 10 h after dosing. Mosapride and rabeprazole concentrations were determined using a validated LC-MS/MS method. Adverse events were monitored based on clinical parameters and volunteer reports.

RESULTS

The geometric means (90% CI) C(max) for mosapride in T and R were 23.13 (20.05-39.45) and 23.09 (21.69-32.37) ng/mL, the AUC(0-)(t) were 70.80 (66.23-102.37) and 70.81 (66.35-93.26) ng h/mL and the AUC(0-∞) were 74.05 (69.29-106.11) and 74.98 (70.43-97.77) ng h/mL. For rabeprazole T and R the C(max) were 197.42 (186.12-239.91) and 195.50 (186.08-250.07) ng/mL, the AUC(0-)(t) were 294.90 (275.13-374.15) and 296.96 (280.11-387.89) ng h/mL and the AUC(0-∞) were 301.12 (280.78-380.82) and 304.07 (286.60-394.21), respectively. No differences were detected between the formulations. The T/R ratios (90% CI) for C(max), AUC(0-)(t) and AUC(0-∞) were 100.17% (82.35-121.84), 99.99% (87.58-114.16) and 98.77% (87.02-112.11) for mosapride, and 100.99% (85.14-119.77), 99.31% (84.74-116.38) and 99.03% (85.07-115.28) for rabeprazole. No subject complained of adverse events.

CONCLUSIONS

In this single-dose study, the mosapride/rabeprazole tablets (test formulation) met the criterion for bioequivalence with the reference formulations. Study limitations include single-dose, open-label design, and a small sample of healthy volunteers.

A phase I study of tasisulam sodium (LY573636 sodium), a novel anticancer compound in patients with refractory solid tumors

PURPOSE

This phase I study was carried out to determine the phase II recommended dose of tasisulam sodium (hereafter, tasisulam), a novel anticancer agent with a unique mechanism of action.

METHODS

Tasisulam was administered intravenously, every 21 days, in patients with refractory solid tumors using a three-plus-three dose-escalation schema.

RESULTS

Fifty-three patients were enrolled; the first 34 were treated with a flat dose of tasisulam of up to 2,400 mg, the dose level at which all three patients had dose-limiting toxicity (DLT). Controlling for C(max) proved important to reduce the risk of toxicity; therefore, we initially focused on identifying which parameters explained C(max) (end-of-infusion concentration) variability. Pharmacokinetic analysis indicated that C(max) negatively correlates with lean body weight (LBW). Thus, the dosing regimen was revised using a LBW-based algorithm targeting a specific C(max). A loading/chronic dose paradigm was then implemented as pharmacokinetic results revealed a long terminal half-life of tasisulam, likely because of its high-affinity albumin binding. C(max)-based dose escalation was stopped at the 420-μg/mL cohort, in which one of the 16 patients had DLT (transient hepatic transaminase elevation); grade 3/4 hematologic toxicity was noted in later cycles in three patients. Although response was not a primary objective, 33% of heavily pretreated patients with post-dose radiological assessments had stable disease.

CONCLUSION

Implementation of a novel targeted C(max)-based dosing regimen allowed for the recommendation of a phase II tasisulam dose (loading dose of 420 μg/mL targeted C(max) with all subsequent doses administered at 65% of chronic dose given every 21 days) despite pharmacological challenges posed by high albumin binding.

Targeted inhibition of the serotonin 5HT2A receptor improves coronary patency in an in vivo model of recurrent thrombosis

BACKGROUND

Release of serotonin and activation of serotonin 5HT2A receptors on platelet surfaces is a potent augmentative stimulus for platelet aggregation. However, earlier-generation serotonin receptor antagonists were not successfully exploited as antiplatelet agents, possibly owing to their lack of specificity for the 5HT2A receptor subtype.

OBJECTIVE

To assess whether targeted inhibition of the serotonin 5HT2A receptor attenuates recurrent thrombosis and improves coronary patency in an in vivo canine model mimicking unstable angina.

METHODS

In protocol 1, anesthetized dogs were pretreated with a novel, selective inverse agonist of the 5HT2A receptor (APD791) or saline. Recurrent coronary thrombosis was then initiated by coronary artery injury+stenosis, and coronary patency was monitored for 3 h. Protocol 2 was similar, except that: (i) treatment with APD791 or saline was begun 1 h after the onset of recurrent thrombosis; (ii) template bleeding time was measured; and (iii) blood samples were obtained for in vitro flow cytometric assessment of platelet responsiveness to serotonin.

RESULTS

APD791 attenuated recurrent thrombosis, irrespective of the time of treatment: in both protocols, flow-time area (index of coronary patency; normalized to baseline coronary flow) averaged 58-59% (P<0.01) following administration of APD791 vs. 21-28% in saline controls. Moreover, the in vivo antithrombotic effect of APD791 was not accompanied by increased bleeding, but was associated with significant and selective inhibition of serotonin-mediated platelet activation.

CONCLUSION

5HT2A receptor inhibition with APD791, even when initiated after the onset of recurrent thrombosis, improves coronary patency in the in vivo canine model.

The protective effects of selenoorganic compounds against peroxynitrite-induced changes in plasma proteins and lipids

Many selenoorganic compounds play an important role in biochemical processes and act as antioxidants, enzyme inhibitors or drugs. The effects of a new selenocompound — bis(2-aminophenyl)-diselenide on oxidative/nitrative changes in human plasma proteins induced by peroxynitrite (ONOO⁻) were studied in vitro and compared with the those of ebselen, a well-known antioxidant. We also studied the role of the tested selenocompounds in peroxynitrite-induced plasma lipid peroxidation. Exposure of the plasma to peroxynitrite (0.1 mM) resulted in an increase in the level of carbonyl groups and nitrotyrosine residues in plasma proteins (estimated using the ELISA method and Western blot analysis). In the presence of different concentrations (0.025–0.1 mM) of the tested selenocompounds, 0.1 mM peroxynitrite caused a distinct decrease in the level of carbonyl group formation and tyrosine nitration in plasma proteins. Moreover, these selenocompounds also inhibited plasma lipid peroxidation induced by ONOO⁻¹ (0.1 mM). The obtained results indicate that in vitro bis(2-aminophenyl)-diselenide and ebselen have very similar protective effects against peroxynitrite-induced oxidative/nitrative damage to human plasma proteins and lipids.

The oral, once-daily phosphodiesterase 4 inhibitor roflumilast lacks relevant pharmacokinetic interactions with inhaled budesonide

This open-label, randomized, 3-period crossover study evaluated the pharmacokinetic interaction potential of roflumilast and budesonide following repeated coadministration to healthy male subjects (N = 12). Treatments consisted of oral roflumilast 500 mug, once daily, orally inhaled budesonide 800 mug, twice daily, and concomitant administration of both treatments for 7 days each. Roflumilast and roflumilast N-oxide in plasma and budesonide serum levels were measured by specific assays. Geometric mean test/reference ratios of steady-state pharmacokinetic parameters were evaluated by analysis of variance. Safety and tolerability were monitored. Pharmacokinetic parameters of roflumilast, roflumilast N-oxide, and budesonide after coadministration of roflumilast and budesonide were similar to those after mono-treatment. Compared with budesonide and roflumilast mono-treatments, slightly lower maximum serum/plasma concentration (C(max)) and area under the curve (AUC) values of roflumilast N-oxide and budesonide (ranging from -8% to -16%) were observed with combined treatment. All test/reference ratios were within predefined equivalence acceptance ranges for roflumilast AUC (0.80, 1.25) and C(max) (0.70, 1.43) and for roflumilast N-oxide and budesonide AUC and C(max) (all 0.67, 1.50). Coadministration of roflumilast and budesonide did not alter the steady-state disposition of each other and did not affect safety and tolerability of either drug.

Effect of fluvoxamine on the pharmacokinetics of roflumilast and roflumilast N-oxide

OBJECTIVE

To investigate the effects of steady-state dosing of fluvoxamine, an inhibitor of cytochrome P450 (CYP) 1A2 and CYP2C19, on the pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 (PDE4) inhibitor and its pharmacodynamically active metabolite roflumilast N-oxide.

METHODS

In an open-label, non-randomised, one-sequence, two-period, two-treatment crossover study, 14 healthy subjects received a single oral dose of roflumilast 500 microg on study day 1. After a 6-day washout period, repeated doses of fluvoxamine 50 mg once daily were given from days 8 to 21. On day 15, roflumilast 500 microg and fluvoxamine 50 mg were taken concomitantly. Percentage ratios of test/reference (reference: roflumilast alone; test: roflumilast plus steady-state fluvoxamine) of geometric means and their 90% confidence intervals for area under the plasma concentration-time curve, maximum plasma concentration (roflumilast and roflumilast N-oxide) and plasma clearance of roflumilast were calculated.

RESULTS

Upon co-administration with steady-state fluvoxamine, the exposure to roflumilast as well as roflumilast N-oxide increased by a factor of 2.6 and 1.5, respectively. Roflumilast plasma clearance decreased by a factor of 2.6, from 9.06 L/h (reference) to 3.53 L/h (test). The combined effect of fluvoxamine co-administration on roflumilast and roflumilast N-oxide exposures resulted in a moderate (i.e. 59%) increase in total PDE4 inhibitory activity.

CONCLUSION

Co-administration of roflumilast and fluvoxamine affects the disposition of roflumilast and its active metabolite roflumilast N-oxide most likely via a potent dual pathway inhibition of CYP1A2 and CYP2C19 by fluvoxamine. The exposure increases observed for roflumilast N-oxide are suggested to be attributable to CYP2C19 co-inhibition by fluvoxamine and thus, are not to be expected to occur when roflumilast is co-administered with more selective CYP1A2 inhibitors.

[Determination of mosapride in human plasma by high performance liquid chromatography tandem mass spectrometry]

To develop a sensitive and specific high performance liquid chromatography-tandem mass spectrometric (HPLC-MS/MS) method for the determination of mosapride in human plasma, mosapride and internal standard tamsulosin were extracted from plasma with liquid-liquid extraction, then separated on a Waters ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 microm ID) with gradient elution at flow-rate of 0.25 mL x min(-1). The mobile phase was water (containing 0.3% formic acid) and acetonitrile under gradient conditions. Electrospray ionization (ESI) source was applied and operated in the positive ion mode. Multiple reaction monitoring (MRM) mode with the transitions of m/z 422 --> m/z 198 and m/z 409 --> m/z 228 were used to quantify mosapride and the internal standard, respectively. The linear calibration curve was obtained in the concentration range of 0.17 - 68.00 ng x mL(-1). The lower limit of quantification was 0.17 ng x mL(-1). The inter- and intra-day precision (RSD) was less than 13%, and the accuracy (RE) was within +/- 6.3% calculated from QC samples. The method was used to determine the concentration of mosapride in plasma after a single oral dose of 5 mg mosapride citrate to 20 healthy male Chinese volunteers. The method has been proved to be selective, sensitive, rapid and suitable for pharmacokinetic study of mosapride.

Steady-state pharmacokinetics of roflumilast and roflumilast N-oxide in patients with mild and moderate liver cirrhosis

BACKGROUND

Roflumilast and its primary N-oxide metabolite are targeted phosphodiesterase 4 (PDE4) inhibitors with similar in vivo potency. Roflumilast is being developed for the treatment of inflammatory airway diseases such as chronic obstructive pulmonary disease and asthma.

OBJECTIVE

To investigate the effects of mild and moderate liver cirrhosis on the steady-state pharmacokinetics of roflumilast and roflumilast N-oxide.

METHODS

Patients with mild (n = 8, Child-Pugh A) and moderate (n = 8, Child-Pugh B) liver cirrhosis and healthy subjects (n = 8) matched with patients with cirrhosis with regard to sex, age and bodyweight received oral roflumilast 250 microg once daily for 14 days. Blood samples were collected for 24 hours after the last dose on day 14. Steady-state plasma concentrations of roflumilast and roflumilast N-oxide were determined using a validated high-performance liquid chromatography with tandem mass spectrometry assay. The pharmacokinetics were compared between groups using ANOVA.

RESULTS

In patients with liver cirrhosis, the average total exposure (area under the plasma concentration-time curve from 0 to 24 hours [AUC(24)]) of roflumilast was approximately 51% (Child-Pugh A) and 92% (Child-Pugh B) higher than in healthy subjects. In contrast, roflumilast maximum plasma concentration (C(max)) was unaltered in Child-Pugh A patients and was increased by 27% in Child-Pugh B patients. Changes in the AUC(24) of roflumilast N-oxide were less distinct, with 24% and 41% increases and corresponding C(max) increases of 26% and 40% in Child-Pugh A and B patients, respectively, compared with healthy subjects. Overall, changes in average potency-corrected exposure to the sum of the free fractions of both compounds were estimated to result in approximately 26% and 46% increases in total PDE4 inhibitory capacity (tPDE4i) in Child-Pugh A and B patients, respectively, relative to healthy subjects. Roflumilast was well tolerated.

CONCLUSIONS

Mild and moderate liver cirrhosis resulted in distinct alterations of exposure to roflumilast but only in modest alterations of exposure to roflumilast N-oxide. The integrated exposure-weighted assessment of the observed pharmacokinetic changes of roflumilast and roflumilast N-oxide (tPDE4i) indicates modest average exposure increases to the sum of both compounds. These findings and the favourable tolerability profile suggest that roflumilast can be safely used in patients with mild and moderate liver cirrhosis without special precautions or dose adjustment.

New perspectives in bio-analytical techniques for preclinical characterization of a drug candidate: UPLC-MS/MS in in vitro metabolism and pharmacokinetic studies

Lead optimization requires rapid bio-analytical turnover for the generation of early absorption, distribution, metabolism, excretion (ADME) and pharmacokinetics (PK) data maintaining a high quality level. Therefore, one of the major challenges in the bio-analytical field is to achieve faster and more sensitive quantification protocols. In the present communication, a comparison between HPLC and ultra performance liquid chromatography (UPLC) performances in terms of sensitivity and resolution is shown using a pharmakokinetic study and a metabolism study as models. The studies highlight the features of the new technology and the resulting impact in the PK throughput and in the characterization of isomeric metabolites using UPLC/MS/MS technique.

L-454,560, a potent and selective PDE4 inhibitor with in vivo efficacy in animal models of asthma and cognition

Type 4 phosphodiesterases (PDE4) inhibitors are emerging therapeutics in the treatment of a number of chronic disorders including asthma, chronic obstructive pulmonary disease (COPD) and cognitive disorders. This study delineates the preclinical profile of L-454,560, which is a potent, competitive and preferential inhibitor of PDE4A, 4B, and 4D with IC50 values of 1.6, 0.5 and 1.2 nM, respectively. In contrast to the exclusive binding of cilomilast and the preferential binding of roflumilast to the PDE4 holoenzyme state (Mg2+-bound form), L-454,560 binds to both the apo-(Mg2+-free) and holoenzyme states of PDE4. The intrinsic enzyme potency for PDE4 inhibition by L-454,560 also results in an effective blockade of LPS-induced TNFalpha formation in whole blood (IC50 = 161 nM) and is comparable to the human whole blood potency of roflumilast. The cytokine profile of inhibition of L-454,560 is mainly a Th1 profile with significant inhibition of IFNgamma and no detectable inhibition of IL-13 formation up to 1 microM. L-454,560 was also found to be efficacious in two models of airway hyper-reactivity, the ovalbumin (OVA) sensitized and challenged guinea pig and the ascaris sensitized sheep model. Furthermore, L-454560 was also effective in improving performance in the delayed matching to position (DMTP) version of the Morris watermaze, at a dose removed from that associated with potential emesis. Therefore, L-454,560 is a novel PDE4 inhibitor with an overall in vivo efficacy profile at least comparable to roflumilast and clearly superior to cilomilast.

Roflumilast, a once-daily oral phosphodiesterase 4 inhibitor, lacks relevant pharmacokinetic interactions with inhaled salbutamol when co-administered in healthy subjects

OBJECTIVE

Roflumilast is an oral, once-daily phosphodiesterase 4 inhibitor under investigation for the treatment of chronic obstructive pulmonary disease and asthma. In clinical practice, the drug is likely to be co-administered with inhaled bronchodilating beta2-adrenoceptor agonists. Therefore, this study investigated the pharmacokinetic characteristics of roflumilast and its pharmacodynamically active metabolite roflumilast N-oxide when co-administered with orally inhaled salbutamol in healthy subjects.

METHODS

In this open, randomized clinical study, 12 healthy male subjects received repeated doses of oral roflumilast 500 microg once daily, orally inhaled salbutamol 200 microg 3 times daily, and a combination of both drugs over 7 days according to a 3-period, changeover design with 14 days washout between treatments.

RESULTS

Co-administration of roflumilast and salbutamol did not markedly change roflumilast or roflumilast N-oxide disposition. Point estimates (90% confidence intervals) of area under the curve from 0-24 h (AUC 0-24) and maximum plasma concentration in steady state (Cmax,ss) for roflumilast with salbutamol versus roflumilast alone were 1.05 (0.94, 1.17) and 0.97 (0.84, 1.10); the respective point estimates (90% confidence intervals) for AUC 0-24 and Cmax,ss of roflumilast N-oxide were 0.98 (0.91, 1.06) and 0.98 (0.92, 1.03). Roflumilast co-administration did not alter the pharmacokinetics of steady state salbutamol. The respective point estimates (90% confidence intervals) for AUC 0-6 and Cmax,ss of salbutamol with roflumilast versus salbutamol alone were 1.10 (0.99, 1.21), 1.08 (0.91, 1.28). The combination of both drugs was well tolerated.

CONCLUSION

There were no relevant pharmacokinetic interactions between roflumilast and salbutamol at therapeutically effective doses.

Investigation of a potential food effect on the pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor, in healthy subjects

This open, randomized, single-dose crossover study investigated effects of a high-fat meal on the pharmacokinetics of roflumilast and its major active N-oxide metabolite. Twelve healthy subjects received oral roflumilast 500 microg (2 x 250 microg) after overnight fasting and after breakfast. Blood was sampled up to 54 hours for pharmacokinetic profiling of roflumilast and N-oxide. Geometric mean ratios (fed/fasted) for point estimates (PE) and 90% confidence intervals (CI) were calculated for AUC(0-last), AUC(0-infinity), and C(max) of both compounds. After the meal, roflumilast C(max) (PE, 0.59; 90% CI, 0.49-0.70) was modestly reduced; N-oxide C(max) (PE, 0.95; 90% CI, 0.90-1.01) was unchanged. Roflumilast t(max) was delayed in fed state (2.0 +/- 0.4 hours) versus fasted state (1.0 +/- 0.2 hours); N-oxide t(max) was unaltered. No significant food effect on roflumilast AUC(0-last) (PE, 1.04; 90% CI, 0.90-1.21), AUC(0-infinity) (PE, 1.12; 90% CI, 1.00-1.25), and respective N-oxide AUCs (PE, 0.91; 90% CI, 0.79-1.04; PE, 0.99; 90% CI, 0.92-1.06) occurred. Because roflumilast N-oxide is the major contributor to roflumilast's overall pharmacologic effects, these findings suggest that roflumilast can be taken with or without food.

Dose-proportional intraindividual single- and repeated-dose pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor

The dose-proportional, intraindividual, single- and repeated-dose pharmacokinetics of roflumilast, an oral, once-daily phosphodiesterase 4 inhibitor under investigation for chronic obstructive pulmonary disease and asthma, was investigated in healthy subjects. In an open, randomized, 2-period, 2-sequence crossover study, 15 subjects received immediate-release tablets of roflumilast 250 or 500 microg as single (day 1) and as repeated, once-daily doses for 8 days (days 5-12). Dose-adjusted point estimates and 90% confidence intervals of test (500 microg)/reference (250 microg) ratios for AUC and Cmax of roflumilast and its pharmacologically active N-oxide metabolite after single and repeated dosing were all within the standard equivalence acceptance range (0.80, 1.25) indicating dose proportionality. The pharmacokinetic properties of both roflumilast dosage forms provide clinically relevant evidence of predictable, intraindividual total (AUC) and maximum (Cmax) exposure of roflumilast and roflumilast N-oxide. Repeated oral dosing with roflumilast 250 and 500 microg once daily was well tolerated.

Lack of a pharmacokinetic interaction between steady-state roflumilast and single-dose midazolam in healthy subjects

AIMS

The aim of this study was to investigate the effects of roflumilast, an investigational PDE4 inhibitor for the treatment of COPD and asthma, on the pharmacokinetics of the CYP3A probe drug midazolam and its major metabolites.

METHODS

In an open, randomized (for midazolam treatment sequence) study, 18 healthy male subjects received single doses of midazolam (2 mg oral and 1 mg i.v., 1 day apart) alone, repeated doses of roflumilast (500 microg once daily for 14 days) alone, and repeated doses of roflumilast together with single doses of midazolam (2 mg oral and 1 mg i.v., 1 day apart).

RESULTS

A comparison of clearance and peak and systemic exposure to midazolam following administration of roflumilast indicated no effect of roflumilast dosed to steady state on the pharmacokinetics of midazolam. Point estimates (90% CI) were 0.97 (0.84, 1.13) for the AUC of i.v. midazolam and 0.98 (0.82, 1.17) for that of oral midazolam with and without roflumilast.

CONCLUSIONS

Therapeutic steady state concentrations of roflumilast and its N-oxide do not alter the disposition of the CYP3A substrate midazolam in healthy subjects. This finding suggests that roflumilast is unlikely to alter the clearance of drugs that are metabolized by CYP3A4.

Determination of itopride in human plasma by liquid chromatography coupled to tandem mass spectrometric detection: Application to a bioequivalence study

A simple method using a one-step liquid-liquid extraction (LLE) with butyl acetate followed by high-performance liquid chromatography (HPLC) with positive ion electrospray ionization tandem mass spectrometric (ESI-MS/MS) detection was developed for the determination of itopride in human plasma, using sulpiride as an internal standard (IS). Acquisition was performed in multiple reaction monitoring (MRM) mode, by monitoring the transitions: m/z 359.5>166.1 for itopride and m/z 342.3>111.6 for IS, respectively. Analytes were chromatographed on an YMC C18 reverse-phase chromatographic column by isocratic elution with 1 mM ammonium acetate buffer-methanol (20: 80, v/v; pH 4.0 adjusted with acetic acid). Results were linear (r2=0.9999) over the studied range (0.5-1000 ng mL(-1)) with a total analysis time per run of 2 min for LC-MS/MS. The developed method was validated and successfully applied to bioequivalence studies of itopride hydrochloride in healthy male volunteers.

Preparation and in vitro/in vivo evaluation of nano-sized crystals for dissolution rate enhancement of ucb-35440-3, a highly dosed poorly water-soluble weak base

Ucb-35440-3 is a new drug entity under investigation at UCB S.A. Due to its physicochemical characteristics, the drug, a poorly water-soluble weak base, shows poor solubility and dissolution characteristics. In rat, the low oral bioavailability (F < 10%) is largely due to poor absorption. In order to enhance the solubility and dissolution characteristics, formulation of ucb-35440-3 as nanocrystals has been achieved in this study. Nanoparticles were prepared using high pressure homogenization and were characterized in terms of size and morphology. In vitro dissolution characteristics were investigated and compared to the un-milled drug in order to verify the theoretical hypothesis on the benefit of increased surface area. In vivo pharmacokinetic evaluation of ucb-35440-3 nanoparticles was also carried out on rats. Crystalline state evaluation before and following particle size reduction was conducted through polarized light microscopy and PXRD to denote any possible transformation to an amorphous state during the homogenization process. Drug chemical stability was also assessed following homogenization. The dissolution rate increased significantly at pH 3.0, 5.0 and 6.5 for ucb-35440-3 nanoparticles. However, the pharmacokinetic profile obtained yielded lower systemic exposure than the un-milled compound (in fed state), this although being thought to be the consequence of the drug and formulation characteristics.

A liquid chromatography/tandem mass spectrometry assay to quantitate MS-275 in human plasma

A rapid, sensitive and selective method was developed and validated using LC/MS/MS for determination of MS-275 in human plasma. Sample preparation involved a single step liquid-liquid extraction by the addition of 0.2 ml of plasma with 5 ml acetonitrile/n-butyl-chloride. Separation of the compounds of interest, including the internal standard paclitaxel, was achieved on a Waters X-Terra C(18) (50 mm x 2.1mm i.d., 3.5 microm) analytical column using a mobile phase consisting of acetonitrile/ammonium acetate (pH 2.9; 2mM)(60:40, v/v) containing 0.1% formic acid and isocratic flow at 0.15 ml/min for 3 min. The analytes were monitored by tandem-mass spectrometry with electrospray positive ionization. Linear calibration curves were generated over the range of 0.5-100 ng/ml with values for the coefficient of determination of >0.99. The values for both within day and between day precision and accuracy were well within the generally accepted criteria for analytical methods (<15%). This method was subsequently used to measure concentrations of MS-275 in cancer patients receiving an oral weekly dose of 4 mg/m(2).

Factors affecting the pharmacokinetic profile of MS-275, a novel histone deacetylase inhibitor, in patients with cancer

AIMS

To evaluate elimination pathways of the histone deacetylase inhibitor MS-275 in vitro and screen for relationships between demographic factors that may affect its pharmacokinetics in vivo.

PATIENTS AND METHODS

Substrate specificity of MS-275 for the liver-specific organic anion transporting polypeptides (OATPs) was assessed using Xenopus laevis oocytes, and in vitro metabolism was evaluated using human liver microsomes. In vivo pharmacokinetic data were obtained from 64 adult patients (36 male/28 female; median age, 57 years) receiving MS-275 orally (dose range, 2 to 12 mg/m2).

RESULTS

Accumulation of [G-3H]MS-275 by oocytes expressing OATP1B1 or OATP1B3 was not significantly different from water-injected controls (p = 0.82). Furthermore, no metabolites could be detected after incubation of MS-275 in human liver microsomes, suggesting that hepatic metabolism is a minor pathway of elimination. The mean (+/- SD) apparent oral clearance of MS-275 was 38.5 +/- 18.7 L/h, with a coefficient of variation (%CV) of 48.7%. When clearance was adjusted for body-surface area (BSA), the inter-individual variability was similar (%CV = 50.1%). In addition, in a linear-regression analysis, except for adjusted ideal body weight (p = 0.02, |r| = 0.29), none of the studied measures (BSA, lean-body mass, ideal body weight, body-mass index, height, weight, age, and sex) was a significant covariate (p > 0.13; |r| < 0.11) for oral clearance.

CONCLUSIONS

The current analysis has eliminated a number of candidate covariates from further consideration as important determinants of MS-275 absorption and disposition. Furthermore, MS-275 can be added to the list of cancer drugs where BSA-based dosing is not more accurate than fixed dosing.

Effects of itopride hydrochloride on plasma gut-regulatory peptide and stress-related hormone levels in healthy human subjects

Itopride hydrochloride (itopride), a gastrokinetic drug, has recently been evaluated for its clinical usefulness in functional dyspepsia. We investigated effects of itopride on human plasma gastrin-, somatostatin-, motilin-, and cholecystokinin (CCK)-like immunoreactive substances (IS); adrenocorticotropic hormone (ACTH)-immunoreactive substances (IS), and cortisol under stress conditions in healthy subjects. A single administration of itopride caused significant increases in plasma somatostatin- and motilin-IS levels compared to placebo. Itopride significantly decreased plasma CCK-IS, and suppressed the ACTH-IS level compared to placebo. We hypothesize that itopride may have an accelerating gastric emptying effect, and a modulatory effect on the hypothalamo-pituitary-adrenal axis and autonomic nervous functions. These effects might be beneficial in stress-related diseases, suggesting that itopride has clinicopharmacological activities.

In vitro efficacy of lufenuron against filamentous fungi and blood concentrations after PO administration in horses

Lufenuron is a benzoylphenyl urea-derived insecticide that has been recently introduced as a novel treatment for fungal infections in horses. The purposes of this study were to determine (1) the in vitro efficacy of lufenuron against Aspergillus and Fusarium spp. and (2) the ability of lufenuron to reach efficacious blood concentrations after PO administration in horses. Fungal colonies isolated from diseased equine corneas were tested against lufenuron solutions up to 700 microg/mL. Twenty-one adult horses received 1 of 3 PO lufenuron treatment regimens: 5 mg/kg body weight (BW) q24h for 3 days, 20 mg/kg BW q24h for 3 days, or 60 mg/ kg BW q24h for 1 day. Blood samples were collected up to 96 hours after drug administration and analyzed by high-performance liquid chromatography. Statistical analyses of lufenuron blood concentrations were performed by analysis of variance and Fischer's Least Significant Difference test, with statistical significance set at P < .05. Lufenuron showed no effect on the in vitro growth of Aspergillus or Fusarium spp. Lufenuron was detected in the blood of all but 1 horse and showed no adverse effects. The maximum blood lufenuron concentration (83.5 +/- 58.7 microg/L) was lower than the concentrations proven to be ineffective in vitro in this study. Further therapeutic use of lufenuron as an antifungal agent in horses should be based on proven efficacy against specific strains of clinically relevant fungi with pharmacokinetic data demonstrating sufficient lufenuron concentrations in target tissues.

Pharmacological characterization of 2NTX-99 [4-methoxy-N1-(4-trans-nitrooxycyclohexyl)-N3-(3-pyridinylmethyl)-1,3-benzenedicarboxamide], a potential antiatherothrombotic agent with antithromboxane and nitric oxide donor activity in platelet and vascular preparations

Thromboxane (TX) A(2), prostacyclin (PGI(2)), and nitric oxide (NO) regulate platelet function and interaction with the vessel wall. Inhibition of TXA(2), implemented synthesis of PGI(2), and supply of exogenous NO may afford therapeutic benefit. 2NTX-99 [4-methoxy-N(1)-(4-trans-nitrooxycyclohexyl)-N(3)-(3-pyridinylmethyl)-1,3-benzenedicarboxamide], a new chemical entity related to picotamide, showed antithromboxane activity and NO donor properties. 2NTX-99 relaxed rabbit aortic rings precontracted with norepinephrine or U46619 (9,11-dideoxy-9alpha,11alpha-methanoepoxy-prosta-5Z,13E-dien-1-oic acid; EC(50), 7.9 and 17.1 microM, respectively), an effect abolished by 10 microM 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ). 2NTX-99 inhibited arachidonic acid (AA)-induced washed platelet aggregation (EC(50), 9.8 microM) and TXB(2) formation (-71% at 10 microM), and its potency increased in the presence of aortic rings (EC(50), 1.4 microM). In whole rabbit aorta incubated with homologous platelets, AA caused contraction and TXA(2) formation, reduced by 2NTX-99 (10-40 microM): contraction, -28 and -47%, TXA(2) formation, -37 and -75.4%, respectively, with concomitant increase in PGI(2). 2NTX-99 (20-40 microM) inhibited U46619-induced aggregation in rabbit platelet-rich plasma (PRP) (-74 +/- 6.7 and -96 +/- 2.4%, respectively) and inhibited collagen-induced aggregation in human PRP (-48.2 +/- 10 and -79.2 +/- 6%), whereas ozagrel was ineffective. In human embryonic kidney 293 cells transfected with the TXA(2) receptor isophorm alpha receptor, 2NTX-99 did not compete with the ligand, [(3)H]SQ29,548 ([(3)H][1S-[1alpha,2beta(5Z),3beta,4alpha]]-7-[3-[[2-(phenylamino)-carbonyl]hydrazino]methyl]-7-oxabicyclo[2,2,1]-hept-2-yl]-5-heptanoic acid), or prevent inositol phosphate accumulation. After oral administration (50-250 mg/kg), 2NTX-99 inhibited TXA(2) production in rat clotting blood (-71 and -91%); at 250 mg/kg, an area under the curve, 0 to 16 h, of 149.5 h/microg/ml and a t(1/2) of 6 h were calculated, with a C(max) value of 31.8 +/- 8.2 microg/ml. An excellent correlation between plasma concentrations and TXA(2) inhibition occurs. 2NTX-99 controls platelet function and vessel wall interaction by multifactorial mechanisms and possesses therapeutic potential.