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ARV-110, a novel proteolysis-targeting chimera (PROTAC), has been reported to show satisfactory safety and tolerability for prostate cancer therapy in phase I clinical trials. However, there is a lack of bioanalytical assays for ARV-110 determination in biological samples. In this study, we developed and validated an LC-MS/MS method for the quantitation of ARV-110 in rat and mouse plasma and applied it to pharmacokinetic studies. ARV-110 and pomalidomide (internal standard) were extracted from the plasma samples using the protein precipitation method. Sample separation was performed using a C18 column and a mobile phase of 0.1% formic acid in distilled water–0.1% formic acid in acetonitrile (30:70, v/v). Multiple reaction monitoring was used to quantify ARV-110 and pomalidomide with ion transitions at m/z 813.4 → 452.2 and 273.8 → 201.0, respectively. The developed method showed good linearity in the concentration range of 2–3000 ng/mL with acceptable accuracy, precision, matrix effect, process efficiency, and recovery. ARV-110 was stable in rat and mouse plasma under long-term storage, three freeze-thaw cycles, and in an autosampler, but unstable at room temperature and 37 °C. Furthermore, the elimination of ARV-110 via phase 1 metabolism in rat, mouse, and human hepatic microsomes was shown to be unlikely. Application of the developed method to pharmacokinetic studies revealed that the oral bioavailability of ARV-110 in rats and mice was moderate (23.83% and 37.89%, respectively). These pharmacokinetic findings are beneficial for future preclinical and clinical studies of ARV-110 and/or other PROTACs.

Receptor interacting protein kinase 1 (RIPK1) plays a key role in necroptosis, which is a type of programmed necrosis that is involved in ocular diseases, including glaucoma and dry age-related macular degeneration (AMD). We previously introduced RIPK1-inhibitory compound (RIC), which has biochemical characteristics and a mode of action that are distinct from those of the prototype RIPK1 inhibitor necrostatin-1. The intraperitoneal administration of RIC exerts a protective effect on retinal ganglion cells against a glaucomatous insult. In this study, we examined the protective effect of RIC on retinal pigment epithelium (RPE) against sodium iodate (SI) insult, which is associated with dry AMD pathogenesis. The eye drop administration of RIC that reached on the retina prevented RPE loss in SI-induced retinal degeneration. RIC consistently demonstrated retinal protection in the funduscopy and electroretinogram analyses in SI-injected rabbits and iodoacetic acid-treated mini-pigs. Moreover, the in vivo protective effects of RIC were superior to those of ACU-4429 and doxycycline, which are other medications investigated in clinical trials for the treatment of dry AMD, and RIC did not induce retinal toxicity following topical administration in rats. Collectively, RIC displayed excellent retinal penetration and prevented retinal degeneration in the pathogenesis of dry AMD with a high in vivo efficacy.

Dae Hun Kim,1,* Jae Yeol Kim,1,* Rae Man Kim,1 Pooja Maharjan,1 Yu-Geun Ji,2 Dong-Jin Jang,3 Kyoung Ah Min,1 Tae-Sung Koo,2 Kwan Hyung Cho1 1Department of Pharmacy, Inje Institute of Pharmaceutical Sciences and Research, Inje University, Gimhae, Republic of Korea; 2Graduate School of New Drug Discovery and Development, Chungnam National University, Daejeon, Republic of Korea; 3Department of Pharmaceutical Engineering, Inje University, Gimhae, Republic of Korea *These authors contributed equally to this work Background: The present study aimed to develop orlistat-loaded solid self-nanoemulsifying drug delivery system preconcentrate (SSP) with the minimum use of lipid excipients for the enhanced solubility, in vitro dissolution, lipase inhibition, and in vivo performance. Materials and methods: In the screening of solubilizing vehicles, Solutol HS15 and Lauroglycol 90 were selected as the surfactant and oil phase, respectively. A pseudo-ternary phase diagram composed of Solutol HS15, Lauroglycol 90, and orlistat as an anti-obesity agent and lipid component was constructed, and the SSP regions were confirmed in terms of the particle size distribution in water, melting point by differential scanning calorimetry, and crystallinity by X-ray diffraction. Results: Physicochemical interaction between Solutol HS15 and orlistat resulted in SSP with various melting points in the range of 26°C~33°C. The representative maximum orlistat-loaded SSP (orlistat/Solutol HS15/Lauroglycol 90=55/40/5, weight ratio) showed the melting point of 32.23°C and constructed uniform nanoemulsion with the particle size of 141.7±1.1 nm dispersed in water. In the dissolution test at pH 1.2 without any detergent, the SSP reached 98.12%±0.83% until 45 minutes, whereas raw orlistat showed no significant dissolution rate. The dissolution samples containing SSP showed a lipase inhibition of 90.42%±1.58% within 45 minutes. In terms of the reduction level of fat absorption in rats, the intake group of SSP gave a significantly higher fat excretion into stool than the one observed in the raw orlistat group (P

Poly (ADP-ribose) polymerase 1 (PARP1)-dependent cell death in the retinal pigment epithelium (RPE) is implicated in dry age-related macular degeneration (AMD). Although PARP1 inhibitors are available for treating dry AMD, their delivery route is not ideal for patients. The aim of this study was to test the efficacy of a novel PARP1-inhibitory compound (PIC) in vitro and in vivo. This study presents PIC, a novel small molecule, with superior efficacy to PARP1 inhibitors in the market. PIC demonstrated a distinctive inhibitory profile against PARP isotypes than the FDA-approved PARP1 inhibitors. PIC inhibited PARP1 activation at an IC50 of 0.41 ± 0.15 nM in an enzyme-based assay in vitro and at IC50 and EC50 in ARPE-19 cells of 0.11 ± 0.02 nM and 0.22 ± 0.02 nM, respectively, upon H2O2 insult. PIC also moderated mitochondrial fission and depolarization and maintained cellular energy levels under oxidative stress in ARPE-19 cells. Furthermore, PIC demonstrated good corneal penetration in a rat model, presenting PIC as a promising candidate for eye drop therapeutics for dry AMD. When PIC was administered as an eye drop formulation, RPE morphology was preserved, maintaining the thickness of the outer nuclear layers under sodium iodate (SI) treatment in rats. In SI-treated rabbits, eye drop administration of PIC also retained the structural and functional integrity when analyzed using funduscopy and electroretinogram. Collectively, our data portray PIC as an attractive treatment measure for dry AMD.

Brain derived neurotrophic factor (BDNF) promotes maturation of dopaminergic (DAergic) neurons in the midbrain and positively regulates their maintenance and outgrowth. Therefore, understanding the mechanisms regulating the BDNF signaling pathway in DAergic neurons may help discover potential therapeutic strategies for neuropsychological disorders associated with dysregulation of DAergic neurotransmission. Because estrogen‐related receptor gamma (ERRγ) is highly expressed in both the fetal nervous system and adult brains during DAergic neuronal differentiation, and it is involved in regulating the DAergic neuronal phenotype, we asked in this study whether ERRγ ligand regulates BDNF signaling and subsequent DAergic neuronal phenotype. Based on the X-ray crystal structures of the ligand binding domain of ERRγ, we designed and synthesized the ERRγ agonist, (E)-4-hydroxy-N'-(4-(phenylethynyl)benzylidene)benzohydrazide (HPB2) (Kd value, 8.35 μmol/L). HPB2 increased BDNF mRNA and protein levels, and enhanced the expression of the BDNF receptor tropomyosin receptor kinase B (TrkB) in human neuroblastoma SH-SY5Y, differentiated Lund human mesencephalic (LUHMES) cells, and primary ventral mesencephalic (VM) neurons. HPB2-induced upregulation of BDNF was attenuated by GSK5182, an antagonist of ERRγ, and siRNA-mediated ERRγ silencing. HPB2-induced activation of extracellular-signal-regulated kinase (ERK) and phosphorylation of cAMP-response element binding protein (CREB) was responsible for BDNF upregulation in SH-SY5Y cells. HPB2 enhanced the DAergic neuronal phenotype, namely upregulation of tyrosine hydroxylase (TH) and DA transporter (DAT) with neurite outgrowth, both in SH-SY5Y and primary VM neurons, which was interfered by the inhibition of BDNF-TrkB signaling, ERRγ knockdown, or blockade of ERK activation. HPB2 also upregulated BDNF and TH in the striatum and induced neurite elongation in the substantia nigra of mice brain. In conclusion, ERRγ activation regulated BDNF expression and the subsequent DAergic neuronal phenotype in neuronal cells. Our results might provide new insights into the mechanism underlying the regulation of BDNF expression, leading to novel therapeutic strategies for neuropsychological disorders associated with DAergic dysregulation.

Niclosamide, which is an anti-tapeworm drug, was developed in 1958. However, recent studies have demonstrated the antiviral effects of niclosamide against the SARS-CoV-2 virus, which causes COVID-19. In this study, we developed and validated a quantitative analysis method for the determination of niclosamide in rat and dog plasma using liquid chromatography–tandem mass spectrometry (LC–MS/MS), and used this method for pharmacokinetic studies. Biological samples were prepared using the protein precipitation method with acetonitrile. Ibuprofen was used as an internal standard. The mobile phase used to quantify niclosamide in rat or dog plasma consisted of 10 mM ammonium formate in distilled water-acetonitrile (30:70, v/v) or 5 mM ammonium acetate–methanol (30:70, v/v). An XDB-phenyl column (5 µm, 2.1 × 50 mm) and a Kinetex® C18 column (5 µm, 2.1 × 500 mm) were used as reverse-phase liquid chromatography columns for rat and dog plasma analyses, respectively. Niclosamide and ibuprofen were detected under multiple reaction monitoring conditions using the electrospray ionization interface running in the negative ionization mode. Niclosamide presented linearity in the concentration ranges of 1–3000 ng/mL (r = 0.9967) and 1–1000 ng/mL (r = 0.9941) in rat and dog plasma, respectively. The intra- and inter-day precision values were 99.8%) and low metabolic stability. These results can be helpful for further developing and understanding the pharmacokinetic characteristics of niclosamide to expand its clinical use.

CKD-712 is a potential treatment for sepsis, as it exhibits protective effects against lipopolysaccharide-mediated platelet aggregation, inducible nitric oxide synthase expression, and cecum-ligation puncture-induced septic mortality in mice. In this study, we develop a rapid and sensitive LC-MS/MS method for determining CKD-712 in rat plasma. CKD-712 and papaverine hydrochloride (an internal standard) were analyzed using an LC-MS/MS system consisting of an Agilent HPLC system (HP-1100) equipped with an Atlantis HILIC Silica (2.1×50mm, 3μm) column and a API 4000 (Applied Biosystems/MDS Sciex, USA) in a positive ESI mode. We utilized multiple reaction monitoring (MRM) at m/z transitions of 306.2-164.0 to analyze CKD-712, and 340.3-202.1 m/z for IS, with a mobile phase of acetonitrile (0.025% trifluoroacetic acid):20mM ammonium acetate (94:6, v/v) at a flow rate of 0.25mL/min. The lower limit of quantification (LLOQ) was 5ng/mL, with a linearity ranging from 5 to 1000ng/mL (r>0.999). Validation parameters including specificity, precision, accuracy, matrix effect, recovery, dilution effect and stability results were well within acceptance criteria, and applied successfully on a pharmacokinetic study in rats.

Background: Esomeprazole is an S-enantiomer of omeprazole that has favorable pharmacokinetics and efficacious acid suppressant properties in humans. However, the pharmacokinetics and effects on intragastric pH of esomeprazole in dogs have not been reported. Objective: To determine the pharmacokinetics of esomeprazole administered via various routes (PK study) and to investigate the effect of esomeprazole on intragastric pH with a Bravo pH monitoring system (PD study). Animals: Seven adult male Beagle dogs and 5 adult male Beagle dogs were used for PK and PD study, respectively. Methods: Both studies used an open, randomized, and crossover design. In the PK study, 7 dogs received intravenous (IV), subcutaneous (SC), and oral doses (PO) of esomeprazole (1 mg/kg). Each treatment period was separated by a washout period of at least 10 days. Esomeprazole plasma concentrations were measured by HPLC/MS/MS. In the efficacy study, intragastric pH was recorded without medication (baseline pH) and following IV, SC, and PO esomeprazole dosing regimens (1 mg/kg) in 5 dogs. Results: The bioavailability of esomeprazole administered as PO enteric-coated granules and as SC injections was 71.4 and 106%, respectively. The half-life was approximately 1 hour. Mean +/- SD percent time intragastric pH was = 3 and = 4 was 58.9 +/- 21.1% and 40.9 +/- 17.3% for IV group, 75.8 +/- 16.4% and 62.7 +/- 17.7% for SC group, 88.2 +/- 8.9% and 82.5 +/- 7.7% for PO group, and 12.5 +/- 3.6% and 3.7 +/- 1.8% for baseline. The mean percent time with intragastric pH was >= 3 or >= 4 was significantly increased regardless of the dosing route (P

Meropenem, a second carbapenem antimicrobial agent with a broad spectrum of activity, is used to treat sepsis and resistant-bacterial infections in veterinary medicine. The objective of this study was to identify the pharmacokinetics of meropenem in dogs receiving intermittent hemodialysis (IHD) and to determine the proper dosing in renal failure patients receiving IHD. Five healthy beagle dogs were given a single i.v. dose of 24 mg/kg of meropenem and received IHD. The blood flow rate, dialysate flow, and ultrafiltration rate were maintained at 40 mL/min, 300 mL/min, and 40 mL/h, respectively. Blood samples were collected for 24 h from the jugular vein and from the extracorporeal arterial and venous line. Urine samples and dialysate were also collected. The concentrations of meropenem were assayed using HPLC/MS/MS determination. The peak plasma concentration was 116 ± 37 μg/mL at 15 min. The systemic clearance was 347 ± 117 mL/h/kg, and the steady-state volume of distribution was 223 ± 67 mL/kg. Dialysis clearance was 71.1 ± 34.3 mL/h/kg, and the extraction ratio by hemodialysis was 0.455 ± 0.150. The half-life (T1/2 ) in dogs with IHD decreased compared with those without IHD, and the reduction in T1/2 was greater in renal failure patients than in normal patients. Sixty-nine percent and 21% of the administered drug were recovered by urine and dialysate in the unchanged form, respectively. In conclusion, additional dosing of 24 mg/kg of meropenem after dialysis could be necessary according to the residual renal function of the patient based on the simulated data.

Motolimod (VTX-2337) is an agonist of toll-like receptor 8. In this study, a novel and sensitive liquid chromatography-tandem mass spectrometry method was developed for quantifying motolimod in rat plasma and subsequently used in a pharmacokinetic study. Proteins were precipitated from plasma samples using acetonitrile prior to the analysis. GS-9620 was used as an internal standard. High-performance liquid chromatography was performed using a Spursil C18-EP column (3 μm, 50 × 2.1 mm). Aqueous ammonium formate and acetonitrile were used as the mobile phase. Motolimod was detected using an electrospray ionization interface under multiple reaction monitoring conditions in the positive ion mode. The developed method produced a linear correlation over a concentration range of 1-1000 ng/mL (r = 0.9944). Intra- and inter-day precision values ranged from 4.8%-10.7% (the lower limit of quantification precision value was 16.3 %), whereas intra- and inter-day accuracy values ranged from 0.3%-9.1 %. The mean recovery of motolimod from rat plasma was 109.4 %. Additionally, motolimod was found to be stable under various conditions (three freeze-thaw cycles, 6-h storage at room temperature, short- and long-term stability tests, and processing). The developed method was successfully used in a pharmacokinetic study in rats. Motolimod showed non-linear pharmacokinetics following its intravenous administration to rats at 0.6-6 mg/kg. Additionally, very low exposure (1 %) was obtained following oral administration of the drug to rats. The results also showed that motolimod has a low metabolic stability in the liver microsomes and exhibits extensive binding to the plasma proteins.

The antioxidant enzyme human extracellular superoxide dismutase (SOD3) is a promising biopharmaceutical candidate for the treatment of various diseases. To support the early development of SOD3 as a biopharmaceutical, a simple, sensitive, and rapid liquid chromatography tandem mass spectrometry procedure was developed and validated for the determination of SOD3 levels in the plasma of ICR mice. After purification with Ni-NTA magnetic beads and digestion with trypsin, SOD3 signature peptides and internal standard signature peptide (ISP) were separated via high performance liquid chromatography using a Zorbax C 18 column (2.1 × 50 mm, 3.5 μm) and a mobile phase consisting of 10 mM ammonium formate, 0.1% formic acid, and acetonitrile. The analyte and ISP were detected via a tandem mass spectrometer in electrospray ionization and multiple reaction monitoring modes to select both the signature peptide for SOD3 at m/z 669 to 969 and the ISP at m/z 655 to 941 in the positive ion mode. The calibration curves were linear (r > 0.99) between 5 and 1000 μg/mL with a lower limit of quantification of 5 μg/mL. The relative standard deviation ranged from 3.08 to 8.84% while the relative error ranged from -0.13 to -9.56%. This method was successfully applied to a preclinical pharmacokinetic study of SOD3 in male ICR mice.

Background Sildenafil citrate, a highly selective phosphodiesterase type 5 inhibitor, is used to treat pulmonary hypertension (PH) in veterinary medicine. The objective of this study was to investigate pharmacokinetic profiles by oral administration of orally disintegrating film (ODF) and film coated tablet (FCT) formulations and rectal administration of ODF formulation in healthy dogs. Twelve healthy beagle dogs were administered four separate doses of sildenafil: FCT formulation 2 mg/kg orally, ODF formulation 2 mg/kg orally, ODF formulation 2 mg/kg rectally, and ODF formulation 10 mg/kg rectally. For 24 hours following administration, blood samples were collected and the plasma concentrations of sildenafil were assayed by liquid chromatography-tandem mass spectrometry. Results There were no significant differences in all the pharmacokinetic parameters between FCT and ODF formulations when administrated orally. Cmax at the time of rectal administration was lower when the same dose was given as that orally administered. No serious systemic adverse events (AEs) were observed. Conclusions These findings suggest that sildenafil ODF formulation can be used as an alternative to FCT formulation in the treatment of canine PH patients; additionally, rectal administration of sildenafil ODF may be a beneficial treatment option for canine patients who are unable to receive medication orally.

Tafamidis is a first-in-class inhibitor of transthyretin amyloid fibril formation. It has been available in Argentina, Japan, and Mexico for the treatment of transthyretin amyloidosis in adult patients with early-stage symptomatic polyneuropathy. In this study, a rapid and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for the assay of tafamidis in rat plasma. The method was also assessed for its applicability to pharmacokinetic studies in rats. Tafamidis was extracted from rat plasma by the liquid-liquid extraction method using hydrochloric acid and ethyl acetate. A reversed-phase C18 column and a mobile phase consisting of 10mM ammonium formate and acetonitrile were used to achieve chromatographic separation. The flow rate for the mobile phase was set at 0.3mL/min. Tafamidis and 2-CBC, which was used as the internal standard (IS), were analyzed by multiple reaction monitoring in negative ESI mode at m/z transitions of 305.4→261.4 for tafamidis and 271.7→227.8 for the IS. The lower limit of quantification of tafamidis was obtained as 3ng/mL, and the calibration curve was linear over a concentration range of 3-3000ng/mL (R2>0.99). The validation parameters investigated, which were specificity, precision, accuracy, matrix effect, recovery, and stability, were well within acceptable limits. The method was successfully used for the evaluation of the pharmacokinetics of tafamidis in rats.

KR33493, a newly developed FAS-associated factor 1 (FAF1) inhibitor for Parkinson's disease, is being evaluated in a Phase I clinical trial. In the present study, the subchronic toxicity of KR33493 in Sprague-Dawley (SD) rats and beagle dogs was investigated at various oral doses for 28 and 14 days, respectively. During the study, food consumption, body weights, organ weights, gross findings, and mortality were examined; and ophthalmoscopy, electrocardiography, hematology, serum biochemistry, urinalysis, histopathology, and toxicokinetics were performed. In rats, weight gain decreased in both sexes at 500 mg/kg/day, with no significant differences. In dogs, some significant differences compared with the control were found during the trial; however, at the end of recovery periods, these were no longer observed and there was no dose correlation. Some histopathological findings were observed, but these were considered as incidental changes. Since no other significant changes were observed, doses above 500 and 1000 mg/kg KR33493 in rat and dogs, respectively, caused no observed adverse effects. Therefore, based on these results, the Phase 1 clinical trial for KR33493 was approved by the Korean Food & Drug Administration.

Wild type transthyretin (TTR) and mutant TTR misfold and misassemble into a variety of extracellular insoluble amyloid fibril and/or amorphous aggregate, which are associated with a variety of human amyloid diseases. To develop potent TTR amyloidogenesis inhibitors, we have designed and synthesized a focused library of quinoline derivatives by Pd-catalyzed coupling reaction and by the Horner–Wadsworth–Emmons reaction. The resulting 2-alkynylquinoline derivatives, (E)-2-alkenylquinoline derivatives, and (E)-3-alkenylquinoline derivatives were evaluated to inhibit TTR amyloidogenesis by utilizing the acid-mediated TTR fibril formation. Among these quinoline derivatives, compound 14c exhibited the most potent anti-TTR fibril formation activity in the screening studies, with IC50 values of 1.49 μM against WT-TTR and 1.63 μM against more amyloidogenic V30 M TTR mutant. That is comparable to that of approved therapeutic drug, tafamidis, to ameliorate transthyretin-related amyloidosis. Furthermore, rationalization of the increased efficacy of compound 14c bearing a hydrophobic substituent, such as chloride, was carried out by utilizing in silico docking study that could focus on the region of the thyroid hormone thyroxine (T4) binding sites. Additionally, the most potent compound 14c exhibited good pharmacokinetics properties. Taken together, the novel quinoline derivatives could potentially be explored as potential drug candidates to treat the human TTR amyloidosis.

The study aimed to characterize the pharmacokinetics of lacosamide, a new antiepileptic drug, in rats after intravenous and oral administration at doses of 1, 3, 10, and 30 mg/kg. Moreover, brain distribution and plasma protein binding were estimated. After intravenous injection, terminal half-life, systemic clearance, and steady state volumes of distribution remained unaltered as a function of dose with values in the range 3.01-3.53 h, 221-241 mL/h/kg and 702-732 mL/kg, respectively. Following oral administration, absolute oral bioavailability was not dose dependent and was at 93.3-106%. However, the time to peak concentration and the dose-normalized peak concentration for 30 mg/kg were significantly different with those for other doses. The extent of urinary excretion of lacosamide was 17.1% and 16.5% for intravenous and oral doses, respectively, whereas fecal excretion was negligible. The brain to plasma ratio of lacosamide was consistent regardless of post-dosing time and the brain to plasma partition coefficient was 0.553. Further, the plasma protein binding of lacosamide was concentration independent with free fraction at 95.9%. Lacosamide showed linear pharmacokinetics at an intravenous dose of 1-30 mg/kg and an oral dose of 1-10 mg/kg but non-linear pharmacokinetics at a 30 mg/kg oral dose.

This study aimed to characterise the pharmacokinetics of lurasidone, a new atypical anti-psychotic drug, in rats after intravenous and oral administration at dose range 0.5-2.5 and 2.5-10 mg/kg, respectively. Moreover, tissue distribution, liver microsomal stability and plasma protein binding were estimated. After intravenous injection, systemic clearance, steady-state volumes of distribution and half-life remained unaltered as a function of dose with values in the range 22.1-27.0 mL/min/kg, 2,380-2,850 mL/kg and 229-267 min, respectively. Following oral administration, absolute oral bioavailability was not dose dependent with approximately 23%. The recoveries of lurasidone in urine and bile were 0.286% and 0.0606%, respectively. Lurasidone was primarily distributed to nine tissues (brain, liver, kidneys, heart, spleen, lungs, gut, muscle and adipose) and tissue-to-plasma ratios of lurasidone were ranged from 1.06 (brain) to 9.16 (adipose). Further, lurasidone was unstable in rat liver microsome and the plasma protein binding of lurasidone was concentration independent with approximately 99.6%. In conclusion, lurasidone showed dose-independent pharmacokinetics at an intravenous dose of 0.5-2.5 mg/kg and an oral dose of 2.5-10 mg/kg. Lurasidone was primarily distributed to nine tissues and appeared to be primarily eliminated by its metabolism.

The purpose of this study was to examine the feasibility of applying a sample pooling method to the accelerated estimation of the uptake clearance of drugs to the brain in rats. Brain uptake clearances (CLuptake) were estimated for five model compounds using the sample pooling method and an integration plot analysis. CLuptake was also evaluated for caffeine and theophylline by brain micro-dialysis. The parameters and throughput of the pooling method were compared with those of typically used standard methods. The correlation for CLuptake was statistically significant (P < 0.005) between the integration plot and the current method; the throughput of evaluation was 15-fold higher for the sample pooling method. A comparison of CLuptake values indicated that the three methods showed comparable results for caffeine while the CLuptake of theophylline using the proposed method was significantly different from those of the other methods. A kinetic analysis indicated that a compound with a slower CLuptake and longer half-life (e.g., theophylline) is more prone to error and that the lower limit of the CLuptakeof 0.17 mL min−1 (g brain)−1 may beset so as to have an error less than 20% of the estimation. These results suggest that the sample pooling method is applicable for use in the accelerated estimation of the uptake clearance of compounds in the brain for which the value is greater than 0.17 mL min−1 (g brain)−1.

The objective of this study was to characterize the extent of the formation of the active ( trans -alcohol form) and inactive ( cis -alcohol) metabolites of loxoprofen and to compare the kinetics after its intragastric, intravenous, and intramuscular administrations in rats. After intravenous administration of the drug at doses of 5–20mg/kg, the clearance and the volume of distribution for loxoprofen, and the ratios of the AUC for the metabolites to the parent drug were not statistically different with the dosage; the formation clearances were 1.08 and 0.87mL/min/kg for the active and its isomeric metabolite, respectively. After the intragastric, intravenous, or intramuscular administration, AUC for loxoprofen and the metabolites at a dose of 10mg/kg were not statistically different for the different routes of administration. The formation of the metabolites with the concomitant loss of loxoprofen was found in incubations with liver homogenates and blood but not with a muscle homogenate or plasma, indicating that the conversion of loxoprofen to the metabolites may occur both in the liver and extraheptic tissue(s). Thus, approximately 22% of the loxoprofen may have been converted to the active metabolite in the liver and the extraheptic tissue(s) and the pharmacokinetics of the active metabolite was independent of the route of administration. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association

This report details a method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) that allows one to determine the concentration of an atypical anticancer drug, enzalutamide, in rat plasma. Specifically, this method involves the addition of an acetonitrile and bicalutamide (internal standard) solution to plasma samples. Following centrifugation of this mixture, an aliquot of the supernatant was directly injected into the LC-MS/MS system. Separation was achieved using a column packed with octadecylsilica (5 µm, 2.1 × 50 mm) with 10 mM ammonium acetate in acetonitrile as the mobile phase; detection was accomplished using MS/MS by multiple-reaction monitoring via an electrospray ionization source. This method demonstrated a linear standard curve (r = 0.997) over a concentration range of 0.001-1 µg/mL, as well as an intra- and inter-assay precision of 2.7 and 5.1%, respectively, and an accuracy range from 100.8 to 105.6%. The lower limit of quantification was 1.0 ng/mL in 50 μL of rat plasma sample. We also demonstrated that this analytical method could be successfully applied to the pharmacokinetic study of enzalutamide in rats.

A simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of methylene blue (MB) and its major metabolite, azure B (AZB), in rat plasma. A simple protein precipitation using acetonitrile was followed by injection of the supernatant on to a Zorbax HILIC Plus column (3.5 µm, 2.1 × 100 mm) with isocratic mobile phase consisting of 5 mM ammonium acetate in 10:90 (v/v) water:methanol at a flow rate of 0.3 mL/min and detection in positive ionization mode. The standard curve was linear over the concentration range from 1 to 1000 ng/mL for MB and AZB with coefficient of determination above 0.9930. The lower limit of quantification was 1 ng/mL using 20 μL of rat plasma sample. The intra- and inter-assay precision and accuracy were12%. The developed analytical method was successfully applied to the pharmacokinetic study of MB and AZB in rats.

In this study, we synthesized the BF-3 binding small molecules, a series of pyridazinone-based compounds, as a novel class of non-LBP antiandrogens for treating prostate cancer by inhibiting androgen receptor. The new class compound was discovered to inhibitor the viability of AR-dependent human prostate LNCap cells and AR activity combining with the computational method. It showed a good physicochemical and PK property.

A liquid chromatography-tandem mass spectrometric (LC/MS/MS) method was developed for the determination of an atypical antipsychotic drug, lurasidone, in rat plasma. The method involves the addition of acetonitrile and ziprasidone (internal standard) solution to plasma samples, followed by centrifugation. An aliquot of the supernatant was diluted with water and directly injected into the LC/MS/MS system. The separations were performed on a column packed with octadecylsilica (5 μm, 2.0 × 50 mm) with 0.1% formic acid and 0.1% formic acid in acetonitrile as mobile phase and the detection was performed using tandem mass spectrometry by multiple-reaction monitoring via an electrospray ionization source. The standard curve was linear (r = 0.9982) over the concentration range 0.002-1 μg/mL. The intra- and inter-assay precisions were 1.7 and 8.6%, respectively. The accuracy range was from 90.3 to 101.8%. The lower limit of quantification was 2.0 ng/mL using 50 μL of rat plasma sample. The developed analytical method was successfully applied to the pharmacokinetic study of lurasidone in rats.