Safety,Pharmacokinetics and Pharmacodynamics of Hetrombopag Olamine,a Novel TPO‐R Agonist,in Healthy Individuals

Hetrombopag olamine (hetrombopag) is a novel small‐molecule, orally bioavailable, non‐peptide thrombopoietin (TPO) receptor agonist that is being developed as the treatment for thrombocytopenia. Two randomized, placebo‐controlled phase I studies were conducted in 72 healthy individuals to assess the safety, tolerability, pharmacokinetics and pharmacodynamics of hetrombopag. Hetrombopag was orally administered with a single dose in five dose cohorts (5 mg, 10 mg, 20 mg, 30 mg or 40 mg) in the first study, and given once daily for 10 days in three dose cohorts (2.5 mg, 5.0 mg or 7.5 mg) in the second study, respectively. Hetrombopag was well tolerated, and the majority of adverse events associated with medicine were platelet elevations significantly above the normal range in healthy individuals. The single dose‐escalation study revealed a T_max of approximate 8 hr, and a t_1/2 of 11.9 hr to 40.1 hr in a dose‐prolonged manner. A dose‐proportional increase in maximum concentration (C_max) of hetrombopag was observed, with area under the curve (AUC) increasing in a greater than dose‐proportional manner. The plasma concentration of hetrombopag reached the steady‐state after 7 days. The steady‐state AUC_0–24 hr and C_max were dose‐proportionally elevated from the 5.0 mg to 7.5 mg dose level. The potent pharmacological effect of the hetrombopag‐induced platelet elevation was observed in a time‐ and dose‐dependent manner. Furthermore, the thrombopoietic response was significantly (p < 0.0001) correlated to the plasma exposure level of hetrombopag in single and multiple administration studies. Taken together, results of this study support further clinical development of hetrombopag in patients with thrombocytopenia.     

Surgery‐induced changes in rat IL‐1β and acetylcholine metabolism: role of physostigmine

Pharmacological enhancement of cholinergic activity following administration of physostigmine is known to induce protective effects generally. However, it is unclear whether the effect of physostigmine on inflammation and acetylcholine (ACh) metabolism is related to different types of surgical intervention or anaesthesia alone. To investigate this, rats were subjected to partial liver resection (PLR) or sham surgery, with a control group receiving anaesthesia alone. Half of each treatment group received a single intra‐operative dose of physostigmine (0.04 mg/kg); the others received placebo. Acetylcholinesterase (AChE) activity and plasma and brain concentrations of interleukin (IL)‐1β and ACh were determined. Both PLR and sham operation induced a time‐dependent increase in plasma concentrations of IL‐1β compared with rats receiving anaesthesia alone (3.9‐ and 4.8‐fold increases, respectively). In the brain, IL‐1β concentrations had increased approximately twofold after surgery compared with the control group. Blood AChE was transiently decreased after surgery. Brain AChE activity increased 1.3‐fold (P = 0.014) only after PLR; consequently, cerebral ACh concentrations were significantly reduced. Physostigmine administration significantly reduced IL‐1β and AChE levels. Cerebral ACh concentrations were markedly increased from 544 ± 122 ng/mg protein following placebo administration to 654 ± 93 ng/mg protein after physostigmine administrations (P < 0.001). We conclude that a single dose of physostigmine intra‐operatively has a sustained anti‐inflammatory effect (up to 120 min after injection) that is especially pronounced under the conditions of PLR surgery. In addition to its protective peripheral action, physostigmine exerts a neuroprotective action by increasing levels of the neurotransmitter ACh.     

Safety,Tolerability and Pharmacokinetics of TAS‐108, a Novel Anti‐Oestrogen,in Healthy Post‐Menopausal Japanese Women: A Phase I Single Oral Dose Study

Abstract: TAS‐108 is a novel steroidal anti‐oestrogen, expected to be useful for the treatment of breast cancer. The present study was conducted to investigate the safety, tolerability and pharmacokinetics of TAS‐108 following the administration at a single oral dose of 40 mg to up to 120 mg in 12 post‐menopausal women and the effect of food on the pharmacokinetics of the drug. All adverse events were mild and involved transient symptoms that resolved without therapeutic intervention. TAS‐108 was readily absorbed and plasma levels of TAS‐108 steadily declined, apparently in a multi‐exponential manner. C_max and AUC_0‐12 were proportionally increased with increasing dose of TAS‐108. The C_max and AUC_0‐t of TAS‐108 and its metabolite, deEt‐TAS‐108, were significantly increased to approximately 150% when TAS‐108 was administered after a meal. Food did not affect the elimination half‐life of TAS‐108 or its metabolites. In this escalating dose‐study of TAS‐108, the drug was well tolerated by healthy post‐menopausal Japanese women. The pharmacokinetics of TAS‐108 indicated dose proportionality, and its bioavailability was significantly increased by food intake.     

Effects of proton pump inhibitors and famotidine on elimination of plasma methotrexate: Evaluation of drug–drug interactions mediated by organic anion transporter 3

Methotrexate (MTX) is an antifolate agent used in the treatment of numerous types of cancer, and eliminated by active tubular secretion via organic anion transporter 3 (OAT3). Gastric antisecretory drugs, such as proton pump inhibitors (PPIs) and histamine H₂ receptor antagonists, are widely used among patients with cancer in clinical practice. The aim of the present study was to analyse the potential drug–drug interactions between MTX and gastric antisecretory drugs in high‐dose MTX (HD‐MTX) therapy. The impact of PPIs on the plasma MTX concentration on 73 cycles of HD‐MTX therapy was analysed retrospectively in 43 patients. Also investigated was the involvement of OAT3 in PPI–MTX drug interaction in an in vitro study using human OAT3 expressing HEK293 cells. In a retrospective study, patients who received a PPI had significantly higher MTX levels at 48 h (0.38 vs. 0.15 μmol l⁻¹, respectively, p  = 0.000018) and 72 h (0.13 vs. 0.05 μmol l⁻¹, respectively, p  = 0.0002) compared with patients who did not receive a PPI (but received famotidine). Moreover, in vitro experiments demonstrated that PPIs (esomeprazole, lansoprazole, omeprazole and rabeprazole) inhibited hOAT3‐mediated uptake of MTX in a concentration‐dependent manner (IC₅₀ values of 0.40–5.5 μ m ), with a rank order of lansoprazole > esomeprazole > rabeprazole > omeprazole. In contrast to PPIs, famotidine showed little inhibitory effect on hOAT3‐mediated MTX uptake. These results demonstrated that co‐administration of PPI, but not famotidine, could result in a pharmacokinetic interaction that increases the plasma MTX levels, at least in part, via hOAT3 inhibition.     

Drug–drug interaction study to assess the effects of atorvastatin co‐administration on pharmacokinetics and anti‐thrombotic properties of cilostazol in male Wistar rats

Cilostazol (CLZ) and atorvastatin (ATV) are often co‐prescribed to treat conditions such as peripheral arterial disease. In the present study, the drug–drug interaction potential of multi‐dose ATV co‐administration with CLZ on both pharmacokinetics and the anti‐thrombotic property of CLZ is demonstrated. The pharmacokinetic parameters of CLZ (6 mg/kg, twice daily) were determined in male Wistar rats after 7 days co‐administration with ATV (5 mg/kg, once daily) in order to assess the interaction potential between CLZ and ATV on chronic treatment. In vitro metabolic inhibition and everted gut sac studies were conducted to elucidate the mechanism of this interaction. Pharmacodynamic drug–drug interaction was evaluated on anti‐thrombotic models including time to occlusion, platelet aggregation and rat tail bleeding time. A validated LC‐MS/MS method was employed simultaneously to quantify both ATV and CLZ in rat plasma matrix. A statistically significant increase in systemic exposure (Css_max by ~1.75 fold; AUC by ~3.0 fold) to CLZ was observed in ATV pre‐treated rats. In vitro metabolism studies using liver microsomes (RLM and HLM) demonstrated statistically significant inhibition of CLZ metabolism when co‐incubated with ATV. No change in apparent permeability of CLZ was observed in the presence of ATV. Atorvastatin showed a significant delay in artery occlusion time without altering CLZ's bleeding time and platelet aggregation profile. Collectively the results of these studies provide metabolic insight into the nature of drug–drug interaction between the selected drugs. Co‐administration with ATV influences the pharmacokinetics and anti‐thrombotic property of CLZ. A thorough clinical investigation is required before extrapolation of data to humans. Copyright © 2012 John Wiley & Sons, Ltd.     

Pharmacokinetics of the Experimental Non‐Nucleosidic DNA Methyl Transferase Inhibitor N‐Phthalyl‐l‐Tryptophan (RG 108) in Rats

DNA methyl transferase (DNMT) inhibitors can re‐establish the expression of tumour suppressor genes in malignant diseases, but might also be useful in other diseases. Inhibitors in clinical use are nucleosidic cytotoxic agents that need to be integrated into the DNA of dividing cells. Here, we assessed the in vivo kinetics of a non‐nucleosidic inhibitor that is potentially free of cytotoxic effects and does not require cell division. The non‐specific DNMT inhibitor N‐phthalyl‐l ‐tryptophan (RG 108) was injected subcutaneously in rats. Blood was drawn 0, 0.5, 1, 2, 4, 6, 8 and 24 hr after injection and RG 108 in plasma was measured by high‐performance liquid chromatography coupled to mass spectrometry. Trough levels and area under the curve (AUC) were significantly higher with multiple‐dose administration and cytochrome inhibition. In this group, time to maximal plasma concentration (t_max, mean ± S.D.) was 37.5 ± 15 min., terminal plasma half‐life was approximately 3.7 h (60% CI: 2.1–15.6 h), maximal plasma concentration (C_max) was 61.3 ± 7.6 μM, and AUC was 200 ± 54 μmol·h/l. RG 108 peak levels were not influenced by cytochrome inhibition or multiple‐dose administration regimens. Maximal tissue levels (C_max in μmol/kg) were 6.9 ± 6.7, 1.6 ± 0.4 and 3.4 ± 1.1 in liver, skeletal and heart muscle, respectively. We conclude that despite its high lipophilicity, RG 108 can be used for in vivo experiments, appears safe and yields plasma and tissue levels in the range of the described 50% inhibitory concentration of around 1 to 5 μM. RG 108 can therefore be a useful tool for in vivo DNMT inhibition.     

Metabonomics analysis of kidneys in rats administered with chronic low‐dose cadmium by ultra‐performance liquid chromatography‐mass spectrometry

This study aimed to investigate the nephrotoxicity in rats administered with chronic low‐dose cadmium (Cd) by ultra‐performance liquid chromatography‐mass spectrometry. A total of 40 male Sprague‐Dawley rats were randomly assigned to four groups, namely: control; low‐dose (0.13 mg/kg·body weight [bw]); middle‐dose (0.80 mg/kg·bw); and high‐dose (4.89 mg/kg·bw). The rats received CdCl₂ daily via drinking water for 24 weeks. Rat kidneys were collected for metabonomics analysis. Principal components analysis and partial least‐squares discriminant analysis were used to investigate the metabonomics profile changes in the kidney samples and to screen the potential biomarkers. Ten metabolites were identified in the positive and negative ion modes. Compared with the control group, the intensities of tetranor 12‐HETE, uric acid, hypoxanthine, phenylacetylglycine, guanidinosuccinic acid and xanthosine significantly increased (P < 0.01), and those of imidazolelactic acid, lactose 6‐phosphate, l ‐urobilinogen and arachidonic acid significantly decreased (P < 0.01) in the high‐dose group. Results showed that exposure to Cd in rats induced oxidative stress to the kidneys and disrupted amino acid metabolism, fatty acid metabolism and energy metabolism.     

Effect of Carvedilol and Nebivolol on Oxidative Stress‐related Parameters and Endothelial Function in Patients with Essential Hypertension

Oxidative stress and endothelial dysfunction have been associated with essential hypertension (EH) mechanisms. The purpose of this study was to evaluate the effect of carvedilol and nebivolol on the oxidative stress‐related parameters and endothelial function in patients with EH. The studied population included 57 patients, either sex, between 30 and 75 years of age, with mild‐to‐moderate EH complications. Participants were randomized to receive either carvedilol (12.5 mg) (n = 23) or nebivolol (5 mg) (n = 21) for 12 weeks. Measurements included; 24‐hr ambulatory blood pressure (BP), flow‐mediated dilatation, levels of nitric oxide estimated as nitrite – a nitric oxide metabolite ( NO ₂ ) – in plasma, and oxidative stress‐related parameters in plasma and erythrocyte. EH patients who were treated with nebivolol or carvedilol showed systolic BP reductions of 17.4 and 19.9 mmHg, respectively, compared with baseline values (p < 0.01). Diastolic BP was reduced by 13.7 and 12.8 mmHg after the treatment with ebivolol and carvedilol, respectively (p < 0.01) (fig. 2B). Nebivolol and carvedilol showed 7.3% and 8.1% higher endothelium‐dependent dilatation in relation to baseline values (p < 0.05). Ferric‐reducing ability of plasma (FRAP) and reduced glutathione/oxidized glutathione (GSSH) ratio showed 31.5% and 29.6% higher levels in the carvedilol group compared with basal values; however, nebivolol‐treated patients did not show significant differences after treatment. On the other hand, the NO ₂ plasma concentration was not modified by the administration of carvedilol. However, nebivolol enhanced these levels in 62.1% after the treatment. In conclusion, this study demonstrated the antihypertensive effect of both beta‐blockers. However, carvedilol could mediate these effects by an increase in antioxidant capacity and nebivolol through the raise in NO ₂ concentration. Further studies are needed to determine the molecular mechanism of these effects.     

Rifampicin has a Profound Effect on the Pharmacokinetics of Oral S‐Ketamine and Less on Intravenous S‐Ketamine

Low‐dose ketamine is currently used in several acute and chronic pain conditions as an analgesic. Ketamine undergoes extensive metabolism and is thus susceptible to drug–drug interactions. We examined the effect rifampicin, a well‐known inducer of many cytochrome P450 (CYP) enzymes and transporters, on the pharmacokinetics of intravenous and oral S‐ketamine in healthy volunteers. Eleven healthy volunteers were administered in randomized order 600 mg rifampicin or placebo orally for 6 days in a four‐session paired cross‐over study. On day 6, S‐ketamine was administered intravenously (0.1 mg/kg) in the first part of the study and orally (0.3 mg/kg) in the second part. Plasma concentrations of ketamine and norketamine were measured up to 24 hr and behavioural and analgesic effects up to 12 hr. Rifampicin treatment decreased the mean area under the plasma ketamine concentration–time curve extrapolated to infinity (AUC _0–∞) of intravenous and oral S‐ketamine by 14% (p = 0.005) and 86% (p < 0.001), respectively. Rifampicin decreased greatly the peak plasma concentration of oral S‐ketamine by 81% (p < 0.001), but shortened only moderately the elimination half‐life of intravenous and oral S‐ketamine. Rifampicin decreased the ratio of norketamine AUC _0–∞ to ketamine AUC _0–∞ after intravenous S‐ketamine by 66%, (p < 0.001) but increased the ratio by 147% (p < 0.001) after the oral administration of S‐ketamine. Rifampicin profoundly reduces the plasma concentrations of ketamine and norketamine after oral administration of S‐ketamine, by inducing mainly its first‐pass metabolism.     

Effect of salicylic acid and diclofenac on the medium‐chain and long‐chain acyl‐CoA formation in the liver and brain of mouse

Medium‐chain and long‐chain acyl‐CoA esters are key metabolites in fatty acid metabolism. Effects of salicylic acid on the in vivo formation of acyl‐CoAs in mouse liver and brain were investigated. Further, inhibition of the medium‐chain and long‐chain acyl‐CoA synthetases by salicylic acid and diclofenac was determined in mouse liver and brain mitochondria. Acyl‐CoA esters were analyzed by liquid chromatography–tandem mass spectrometry. The amounts of medium‐chain acyl‐CoAs (C₆, C₈ and C₁₀) were less than long‐chain acyl‐CoAs (C_16:0, C_18:0, C_18:1 and C_20:4) in both liver and brain. The administration of salicylic acid decreased the levels of both the medium‐chain (C₆, C₈ and C₁₀) and long‐chain acyl‐CoAs (C_16:0, C_18:0, C_18:1 and C_20:4) in liver. In brain, however, only long‐chain acyl‐CoAs were decreased. The level of salicylyl‐CoA detected in brain was about 12% of that in liver. Salicylic acid had a strong inhibitory activity (IC₅₀ = 0.1 mm ) for the liver mitochondrial formation of hexanoyl‐CoA from hexanoic acid, whereas diclofenac was weak (IC₅₀ = 4.4 mm ). In contrast, diclofenac (IC₅₀ = 1.4 mm ) inhibited the liver mitochondrial long‐chain acyl‐CoA synthetases more potently than salicylic acid (IC₅₀ = 25.5 mm ). Similar inhibitory activities for the acyl‐CoA synthetases were obtained in the case of the brain and liver mitochondria, except for the weak inhibition of brain medium‐chain acyl‐CoA synthetases by salicylic acid (IC₅₀ = 1.8 mm ). These findings suggest that salicylic acid and diclofenac exhibit different mechanisms of inhibition of fatty acid metabolism depending on the length of the acyl chain and tissues, and they may contribute to the further understanding of the toxic effects associated with these drugs. Copyright © 2009 John Wiley & Sons, Ltd.     

Efavirenz does not meaningfully affect the single dose pharmacokinetics of 1200 mg raltegravir

Raltegravir is a human immunodeficiency virus (HIV)‐1 integrase strand transfer inhibitor currently marketed at a dose of 400 mg twice daily (BID). Raltegravir for once daily regimen (QD) at a dose of 1200 mg (2 x 600 mg) is under development and offers a new treatment option for HIV‐1 infected treatment‐naive subjects. Since raltegravir is eliminated mainly by metabolism via an UDP‐glucuronosyltransferase (UGT) 1 A1‐mediated glucuronidation pathway, co‐administration of UGT1A1 inducers may alter plasma levels of raltegravir. Efavirenz, an UGT1A1 inducer, was used to assess the impact of altered UGT activity on a 1200 mg QD dose of raltegravir. An open label, randomized, 2‐period fixed‐sequence Phase 1 study was performed in adult healthy male and female subjects (non‐childbearing potential) ≥ 19 and ≤55 years of age, with a body mass index (BMI) ≥ 18.5 and ≤32.0 kg/m². Subjects (n = 21) received a single oral dose of 1200 mg raltegravir at bedtime on an empty stomach on Day 1 in Period 1. After a washout period of at least 7 days, subjects received oral doses of 600 mg efavirenz QD at bedtime for 14 consecutive days in Period 2. Subjects received a single oral dose of 1200 mg raltegravir co‐administered with 600 mg efavirenz on Day 12 of Period 2. Pharmacokinetic (PK) samples were collected for 72 hours following raltegravir dosing and analyzed using a validated bioanalytical method to quantify raltegravir plasma concentrations. PK parameters were estimated using non‐compartmental analysis. Administration of single 1200 mg oral doses of raltegravir alone and co‐administered with multiple oral doses of efavirenz were generally well tolerated in healthy subjects. Co‐administration with efavirenz yielded geometric mean ratios (GMRs) and their associated 90% confidence intervals (90% CIs) for raltegravir AUC_0‐∞, C_max, and C₂₄ of 0.86 (0.73, 1.01), 0.91 (0.70, 1.17), and 0.94 (0.76, 1.17), respectively. The results show that efavirenz modestly reduced the exposure of raltegravir. The reduction in raltegravir exposure is not considered clinically meaningful. Copyright © 2016 John Wiley & Sons, Ltd.     

Population pharmacokinetic‐pharmacodynamic modelling of liquid and controlled‐release formulations of oxycodone in healthy volunteers

Oral controlled‐release formulations are playing an ever‐increasing role in opioid therapy; however, little is known about their influence on the relationship between pharmacokinetics and pharmacodynamics. The study aim was to characterize the pharmacokinetic‐pharmacodynamics of two controlled‐release tablet formulations and a liquid formulation of oxycodone in healthy, opioid‐naïve volunteers, which can serve as a reference for future patient studies. A semi‐double‐blinded, three‐way crossover study was conducted, with fifteen healthy volunteers receiving two differently designed 20 mg monophasic controlled‐release oxycodone tablets and 10 mg oral solution oxycodone in a randomized order. Venous plasma concentrations and pupil diameter were determined pre‐dose and 0.25, 0.5, 0.75, 1, 1.5, 2, 2.33, 2.66, 3, 3.33, 3.66, 4, 5, 6, 8, 12 and 24 hour post‐dose. Oxycodone pharmacokinetics was best described by a two‐compartment model with first‐order absorption. The controlled‐release formulations had an absorption lag of 0.23 hour and a slower absorption rate constant (k_aCR = 0.19 hour^‐1) compared to the oral solution (k_aSOL = 0.94 hour^‐1). Effects on pupil diameter were delayed relative to plasma (14 minutes half‐life) for all formulations and were best described by a proportional E_max model. The plasma concentration of oxycodone at half‐maximum effect was lower in males (31.1 μg/L) compared to females (52.8 μg/L; P < .001). The absorption profile of controlled‐release oxycodone formulations provided a prolonged onset and offset of action compared to oral solution oxycodone. The controlled‐release formulations showed no differences in pharmacokinetic and pharmacodynamic parameters suggesting that both may be used interchangeably in human beings with normal gastrointestinal function.     

Identification and disposition of novel mono‐hydroxyl mefenamic acid and their potentially toxic 1‐O‐acyl‐glucuronides in vivo

Mefenamic acid (MEF) is a widely prescribed non‐steroidal anti‐inflammatory drug that has been found associated with rare but severe cases of hepatotoxicity, nephrotoxicity and gastrointestinal toxicity. The formation of protein‐reactive acylating metabolites such as 1‐O‐acyl‐MEF glucuronide (MEFG) and 3′‐hydroxymethyl‐MEF 1‐O‐acyl‐glucuronide is one proposed cause. In addition to the well‐reported 3′‐hydroxymethyl‐MEF, two mono‐hydroxyl‐MEF (OH‐MEFs) were recently identified in vitro. However, in vivo evidence is lacking and whether these OH‐MEFs would be further glucuronidated to the potentially reactive 1‐O‐acyl‐glucuronides (OH‐MEFGs) is unknown. Utilizing UPLC‐Q‐TOF/MS and LC‐MS/MS, the current study identified, for the first time, four OH‐MEFs and their corresponding OH‐MEFGs from plasma after a single oral administration of MEF (40 mg/kg) to rats, including an OH‐MEF that has not been reported previously. The systemic exposure of these identified metabolites was high, with metabolic to parent AUC_0→24h ratios reaching 23–52% (OH‐MEFs) and 8–29% (OH‐MEFGs). These metabolites also had a long systemic exposure time in both single and 5 day multiple oral MEF‐treated rats, with elimination half‐lives between 9 h and > 24 h. In addition to these novel metabolites, the previously reported MEFG was also identified and its systemic exposure was found to be doubled after multiple MEF administrations. These pharmacokinetic results suggest that systemic toxicities caused by the potentially reactive MEFG and OH‐MEFGs could be considerable, especially after repeated MEF treatment. Nevertheless, MEFG and OH‐MEFGs had negligible uptake in the brain, indicating a minimal risk of brain toxicities. Furthermore, an in situ intestinal perfusion study revealed that during MEF absorption, it was extensively metabolized to MEFG while < 5% was metabolized to OH‐MEFs and OH‐MEFGs. Copyright © 2015 John Wiley & Sons, Ltd.     

The Interference of Ethanol with Heroin‐Stimulated Psychomotor Activation in Mice is not Related to Changed Brain Concentrations of the Active Metabolites 6MAM or Morphine

It has been suggested that the potentiating effect observed in human beings when combining alcohol and heroin may be due to an interference of ethanol with the pharmacokinetics of heroin, leading to accumulation of the biologically active metabolites, 6‐monoacetylmorphine (6MAM) and morphine. However, experimental evidence for this hypothesis is lacking. In this study, we used mice and examined the effect of ethanol on the metabolism of heroin by combining a locomotor activity test, which is a behaviour model representative of psychomotor stimulation, with pharmacokinetic studies in blood and brain tissue. Pre‐treatment with ethanol (1 and 2.5 g/kg, po) affected heroin‐stimulated (2.5 and 15 μmol/kg, sc) locomotor activation significantly, resulting in a dose‐dependent reduction in run distance. However, the change in the activity profiles did not indicate any increase in the concentration of active metabolites. Pharmacokinetic studies in blood and brain supported the behavioural findings, showing no change in the time‐versus‐concentration curves of either 6MAM or morphine after administration of heroin (15 μmol/kg, sc) to mice pre‐treated with ethanol (2.5 g/kg, po). The concentration of heroin itself was elevated, but is probably of minor importance because heroin has low biological activity by itself. The in vivo pharmacokinetic findings were supported by experiments in vitro. In conclusion, studies in mice do not support the hypothesis from epidemiological studies of a pharmacokinetic interaction between alcohol and heroin.     

β‐asarone and levodopa co‐administration increase striatal dopamine level in 6‐hydroxydopamine induced rats by modulating P‐glycoprotein and tight junction proteins at the blood‐brain barrier and promoting levodopa into the brain

Levodopa (L‐dopa) is widely considered as one of the most effective drug constituents in the treatment of Parkinson's disease (PD), but the blood‐brain barrier (BBB) permeability of L‐dopa is <5%, which causes low efficacy. Neuroprotective effects of β‐asarone on 6‐hydroxydopamine (6‐OHDA)‐induced PD rats were demonstrated by our previous studies. Co‐administration of β‐asarone and L‐dopa has not been explored until being investigated on PD rats in this study. PD rats were divided into four groups: untreated, L‐dopa‐treated, β‐asarone‐treated and co‐administered‐treated groups. All of the treatments were administered to the rats twice per day for 30 days. The L‐dopa, dopamine (DA), 3,4‐dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), S100β and neuron‐specific enolase (NSE) levels were subsequently determined. The P‐glycoprotein (P‐gp), zonula occludens‐1 (ZO‐1), claudin‐5, occludin and actin expression was also assessed in cortex. Changes in BBB ultrastructure were observed using transmission electron microscopy. Our results showed that the co‐administered treatment increased levels of L‐dopa, DA, DOPAC and HVA in striatum, and S100β in plasma, but down‐regulated NSE, P‐gp, ZO‐1, occludin, actin and claudin‐5 in cortex. Crevices were observed between capillary endothelial cells at intercellular tight junction of the striatum in co‐administered‐treated group, while the endothelial cells in untreated group were tightly jointing each other. In addition, the correlations of L‐dopa or DA and P‐gp or tight junction proteins respectively were significantly negative in co‐administered‐ and β‐asarone‐treated groups. These findings suggest that co‐administered treatment may enhance the L‐dopa BBB permeability and attenuate brain injury, which may be beneficial to PD treatment.     

Pre‐incubation with cyclosporine A potentiates its inhibitory effects on pitavastatin uptake mediated by recombinantly expressed cynomolgus monkey hepatic organic anion transporting polypeptide

Cyclosporine A, an inhibitor of hepatic organic anion transporting polypeptides (OATPs), reportedly increased plasma concentrations of probe substrates, although its maximum unbound blood concentrations were lower than the experimental half‐maximal inhibitory (IC₅₀) concentrations. Pre‐incubation with cyclosporine A in vitro before simultaneous incubation with probes has been reported to potentiate its inhibitory effects on recombinant human OATP‐mediated probe uptake. In the present study, the effects of cyclosporine A and rifampicin on recombinant cynomolgus monkey OATP‐mediated pitavastatin uptake were investigated in pre‐ and simultaneous incubation systems. Pre‐incubation with cyclosporine A, but not with rifampicin, decreased the apparent IC₅₀ values on recombinant cynomolgus monkey OATP1B1‐ and OATP1B3‐mediated pitavastatin uptake. Application of the co‐incubated IC₅₀ values toward R values (1 + [unbound inhibitor]_{inlet to the liver, theoretically maximum}/inhibition constant) in static models, 1.1 in monkeys and 1.3 in humans, for recombinant cynomolgus monkey and human OATP1B1‐mediated pitavastatin uptake might result in the poor prediction of drug interaction magnitudes. In contrast, the lowered IC₅₀ values after pre‐incubation with cyclosporine A provided better prediction with R values of 3.9 for monkeys and 2.7 for humans when the estimated maximum cyclosporine A concentrations at the inlet to the liver were used. These results suggest that the enhanced inhibitory potential of perpetrator medicines by pre‐incubation on cynomolgus monkey OATP‐mediated pitavastatin uptake in vitro could be of value for the precise estimation of drug interaction magnitudes in silico, in accordance with the findings from pre‐administration of inhibitors on pitavastatin pharmacokinetics validated in monkeys. Copyright © 2016 John Wiley & Sons, Ltd.     

Identification of non‐reported bupropion metabolites in human plasma

Bupropion and its three active metabolites exhibit clinical efficacy in the treatment of major depression, seasonal depression and smoking cessation. The pharmacokinetics of bupropion in humans is highly variable. It is not known if there are any non‐reported metabolites formed in humans in addition to the three known active metabolites. This paper reports newly identified and non‐reported metabolites of bupropion in human plasma samples. Human subjects were dosed with a single oral dose of 75 mg of an immediate release bupropion HCl tablet. Plasma samples were collected and analysed by LC–MS/MS at 0, 6 and 24 h. Two non‐reported metabolites (M1 and M3) were identified with mass‐to‐charge (m/z) ratios of 276 (M1, hydration of bupropion) and 258 (M3, hydroxylation of threo/erythrohydrobupropion) from human plasma in addition to the known hydroxybupropion, threo/erythrohydrobupropion and the glucuronidation products of the major metabolites (M2 and M4–M7). These new metabolites may provide new insight and broaden the understanding of bupropion's variability in clinical pharmacokinetics. © 2016 The Authors Biopharmaceutics & Drug Disposition Published by John Wiley & Sons Ltd.     

Toxicological Investigation and Antinociceptive Property of Potassium Thiophene‐3‐Trifluoroborate

Abstract: The aim of the present study was to evaluate pharmacological and toxicological properties of potassium thiophene‐3‐trifluoroborate (RBF₃K). The acute effect of RBF₃K was evaluated on mice. To this end, mice received a single dose of RBF₃K (25, 50, and 100 mg/kg, by oral route, p.o.) and after 72 hrs, blood, liver, and kidney samples were collected. δ‐Aminolevulinate dehydratase, catalase and glutathione‐S‐transferase activities, thiobarbituric acid‐reactive substances and vitamin C levels, as well as plasma aspartate and alanine aminotransferase activities and creatinine levels were determined. Hepatic and renal lipid peroxidation levels in treated mice did not differ from those in control mice. No significant differences between treated and control mice were detected in hepatic and renal δ‐aminolevulinate dehydratase activity. Aspartate and alanine aminotransferase activities as well as urea and creatinine levels were similar among the groups. In contrast, results obtained from in vivo experiments revealed that RBF₃K, orally administered, reduced peritoneovisceral pain induced by acetic acid administered i.p. Doses of 1, 5, 10, 25, 50, and 100 mg/kg of RBF₃K were assessed in the antinociceptive investigation and the effect was significantly different than control groups from 5 mg/kg. It was observed that α_2‐adrenergic and serotonergic, but not opioidergic, receptors appear to be involved in orally administered RBF₃K. Mice treated with RBF₃K did not reveal any motor impairment in the open field. This is a promising compound for more detailed pharmacological studies involving organotrifluoroborate compounds.     

(E)‐2‐Benzylidene‐4‐phenyl‐1,3‐diselenole ameliorates signals of renal injury induced by cisplatin in rats

The present study investigated the protective role of antioxidant (E)‐2‐benzylidene‐4‐phenyl‐1,3‐diselenole (BPD), an organoselenium compound, against the renal injury induced by cisplatin in rats. Canola oil or BPD (50 mg kg^?1) was administered orally by gavage once a day for 6 days to rats. The first dose of BPD was given 24 h before a single intraperitoneal injection of saline or cisplatin (7 mg kg^?1). At day 7, animals were killed and parameters related to renal injury were determined. The histological analysis showed that cisplatin caused renal injury in rats, which was accompanied by an increase in urea and creatinine levels in plasma. The increase of plasma creatinine levels negatively correlated with renal antioxidant defenses including ascorbic acid (AA) and reduced glutathione (GSH) content as well as glutathione S‐transferase (GST), glutathione peroxidase (GPx) and catalase (CAT) activities. As revealed by histological analysis, BPD ameliorated tubular injury in rat kidney and reduced plasma markers altered by cisplatin. The administration of BPD to rats attenuated the reduction of renal AA and GSH content in animals exposed to cisplatin. The decrease of GST activity, but not GPx and CAT activities, in rats exposed to cisplatin was totally reversed by BPD administration. BPD was also effective in attenuating the inhibition of a sulfhydryl enzyme sensitive to oxidative stress, δ‐aminolevulinic dehydratase, in kidneys of rats exposed to cisplatin. The present study demonstrated that BPD reduced renal injury induced by cisplatin in rats and this effect seems to be related to antioxidant mechanisms. Copyright © 2012 John Wiley & Sons, Ltd.     

Effects of Ojeok‐san on the Pharmacokinetics of Celecoxib at Steady‐state in Healthy Volunteers

Ojeok‐san is a frequently used herbal medication for the management of osteoarthritic pain. We evaluated the effect of Ojeok‐san on the pharmacokinetics of celecoxib at steady‐state in healthy individuals. An open‐label, fixed‐sequence, two‐period, two‐treatment cross‐over study was conducted. In period I, the individuals received celecoxib capsule 200 mg once daily for 4 days. In period II, only Ojeok‐san (14.47 g/pack, three times daily) was administered for 4 days, followed by co‐administration with celecoxib for 4 days. On the fourth (final) day of administration, Ojeok‐san was administered as a single dose. The blood samples for pharmacokinetic evaluation were collected for up to 48 hr after the administration of celecoxib in each study period. Of the 22 enrolled individuals, 20 individuals completed the study. In the presence of Ojeok‐san, the systemic exposure of celecoxib was decreased. The geometric mean ratios ([celecoxib + Ojeok‐san]/celecoxib) and the 90% confidence intervals for the maximum plasma concentration (C_max) and the area under the plasma concentration–time curve during dosing interval (AUC_τ) of celecoxib at steady‐state were 0.725 (0.620–0.848) and 0.885 (0.814–0.962), respectively. The changes in the mean of the C_max and AUC_τ of celecoxib were greater in intermediate metabolizers of cytochrome 2C9 (CYP2C9) than in normal metabolizers. Our results suggested that the C_max and AUC_τ of celecoxib were reduced by Ojeok‐san co‐administration. This finding may be beneficial to determine the required adjustment of celecoxib dosage when co‐administered with Ojeok‐san.