Sensitive and robust UPLC–MS/MS method to determine the gender-dependent pharmacokinetics in rats of emodin and its glucuronide

In this study, a sensitive and robust ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed, validated, and applied to determine gender-dependent pharmacokinetics of total emodin (aglycone + glucuronide) in male and female Sprague–Dawley rats. The lower limit of quantification for emodin and emodin glucuronide in rat plasma was 39 and 78 ng/ml, with signal-to-noise ratio of ≥10. Precision and accuracy studies showed emodin and emodin glucuronide plasma concentrations well within the 10% range in all studies. Plasma recovery of emodin and emodin glucuronide was always above 86% for low (emodin: 39 ng/ml; glucuronide: 78 ng/ml), 92% for medium (625 ng/ml), and 97% for high (10 000 ng/ml) concentrations. Furthermore, emodin showed more than 95% plasma stability under short-term and long-term storage conditions, as well as after three freeze–thaw cycles in the experiments. The developed and validated analytical method was successfully applied to study the gender-dependent 10-fold higher oral bioavailability of total emodin in male than female rats. The oral bioavailability of emodin and emodin glucuronide was also measured separately and showed a statistically significant gender difference in oral bioavailability of emodin and emodin glucuronide in rats.     

Kinetics of genistein and its conjugated metabolites in pregnant Sprague-Dawley rats following single and repeated genistein administration.

Diets high in soy-based products are well known for their estrogenic activity. Genistein, the predominant phytoestrogen present in soy, is known to interact with estrogen receptors (ER) alpha and beta and elicits reproductive effects in developing rodents. In the rat, genistein is metabolized predominantly to glucuronide and sulfate conjugates, neither of which is capable of activating ER. Therefore, it is critical to understand the delivery of free and conjugated genistein across the placenta to the fetus following maternal genistein exposure such that the potential fetal exposure to free genistein can be assessed. Genistein (4 or 40 mg/kg) was administered to pregnant Sprague-Dawley rats by oral gavage daily from gestation day (GD) 5 through 19 or on GD 19 alone. Maternal and GD 19 fetal tissues were collected 0.5, 1, 2, 4, 6, 8, 12, and 24 h following administration of the final dose on GD 19. Concentrations of genistein, genistein glucuronide, and genistein sulfate were quantitated by LC-MS/MS. In maternal plasma, genistein glucuronide was the predominant metabolite. In the fetal plasma, genistein glucuronide and genistein sulfate were the primary metabolites. Genistein levels in maternal and fetal plasma were much lower than its conjugates. The concentration of genistein in placental tissue was higher than either conjugate. Fetal concentrations of unconjugated genistein following administration of 40 mg/kg were above the EC50 for ERbeta activation. Repeated administration of 40 mg/kg genistein resulted in minor changes in genistein kinetics in the pregnant rat compared to single administration of the same dose. These data suggest that conjugated forms of genistein are not transported across the placenta. High placental concentrations of genistein indicate the placenta is a potential target organ for genistein action during gestation.     

Intersex effect of lamotrigine on the pharmacokinetic parameters of CDRI-97/78, a novel trioxane antimalarial compound, in rats

Reports regarding drug toxicity and adverse events resulting from coadministration of multiple drugs are increasing at an alarming rate. CDRI-97/78 is an 1,2,4-trioxane antimalarial agent under development which gets metabolized to the in vivo active metabolite 97/63. In order to assess its drug interaction potential, CDRI-97/78 was administered alone and in combination with lamotrigine to male and female rats via the oral route. Quantification of the active metabolite 97/63 in rat plasma was achieved with an LC-MS/MS assay. After oral administration of 97/78, the Tmax and Cmax values of 97/63 in male rats were 1.75±0.77 h and 862±306 ng/mL while female rats showed values for Cmax of 622.75±95.09 ng/mL and for Tmax of 7.5±0.5 h. Coadministration of 97/78 and lamotrigine resulted in decreased Tmax and Cmax values in both male and female rats (Tmax and Cmax of 0.77±0.16 h and 58.58±6.43 ng/mL in male rats; 1.13±0.22 h and 62.95±12.00 ng/mL in female rats, respectively). A statistically significant difference (P<0.05) was observed for the pharmacokinetic parameters of 97/63 after oral administration of 97/78 alone and upon its coadministration with lamotrigine except for the Cmax and Tmax values in male and for the T1/2 value in female rats. Statistically, no significant difference for the pharmacokinetic parameters of 97/63 between male and female rats after oral administration of 97/78 alone or in combination with lamotrigine was determined except for Tmax. The study indicates that coadministration of 97/78, an antimalarial agent, and the antiepileptic lamotrigine may require dose adjustments. Additional clinical drug interaction trials may be required to confirm these findings.     

Pharmacokinetics, in-situ absorption and protein binding studies of a new neuroleptic agent centbutindole in rats.

The present study reports the absorption kinetics, plasma protein binding and pharmacokinetic profile of the centbutindole (I) after i.v. and oral dosing in rats. In addition, an in-situ absorption study was carried out using a closed-loop technique at pH 2.6 and 7.4. The rate of absorption at pH 2.6 was 5-fold less compared to that observed at pH 7.4. In-vitro and in-vivo protein binding (ultra filtration technique) was independent of substrate concentration over a range of 1.25-10.0 microg/ml. Pharmacokinetic parameters of I were determined in male rats after administering a single 4 mg/kg oral dose and 2 mg/kg intravenous dose. The peak serum concentration of I was found to be 50.1 ng/ml at 30 min after oral administration followed by a secondary Cmax of 43.2 ng/ml at 180 min. For the hydroxy metabolite (II), a Cmax of 6.4 ng/ml was measured at 360 min after oral administration of I. After oral dosing an irregular concentration-time profile with secondary peaks was observed for both I and II. The terminal half-lives for I and II after oral dosing were 163 and 263 min, respectively. After intravenous dosing, the levels of I decreased biexponentially with a distribution (t(1/2) alpha) and elimination (t(1/2) beta) half-lives of 5.7 and 128 min, respectively. Comparison of the AUC after oral and intravenous dosing of I indicates that only about 24% of the oral dose reaches the systemic circulation. The limited bioavailability can either be due to the poor solubility of the compound and/or extensive first pass metabolism in the gastrointestinal (GI) tract. Co-administration of polyethylene glycol (PEG) at oral dosing improves solubilization and increases bioavailability.     

Absorption,distribution, metabolism and excretion of telmesteine,a mucolitic agent,in rat

1. The metabolism and disposition of telmesteine, a muco-active agent, have been investigated following single oral or intravenous administration of (14)C-telmesteine in the Sprague-Dawley rat. 2. (14)C-telmesteine was rapidly absorbed after oral dosing (20 and 50 mg kg(-1)) with an oral bioavailability of >90% both in male and female rats. The C(max) and area under the curve of the radioactivity in plasma increased proportionally to the administered dose and those values in female rats were 30% higher than in male rats. 3. Telmesteine was distributed over all organs except for brain and the tissue/plasma ratio of the radioactivity 30 min after dosing was relatively low with a range of 0.1-0.8 except for excretory organs. 4. Excretion of the radioactivity was 86% of the dose in the urine and 0.6% in the faeces up to 7 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 3% for the first 24 h. The unchanged compound mainly accounted for the radioactivity in the urine and plasma. 5. Telmesteine was hardly metabolized in microsomal incubations. A glucuronide conjugate was detected in the urine and bile, but the amount of glucuronide was less than 6% of excreted radioactivity.     

Variability of oral bioavailability for low dose methotrexate in rats.

The effects of food, antibiotics, diclofenac sodium (DS) and methotrexate (MTX) on oral bioavailability (BA) of MTX were examined in rats. Feeding didn't vary the plasma concentrations after intravenous dosing of 0.5 mg/kg MTX, but enhanced those after oral dosing, and the oral BA. The twice daily oral doses of 40 mg/kg neomycin sulfate (NS) or mixed antibiotics (200 mg/kg NS + 200 mg/kg streptomycin sulfate + 200 mg/kg bacitracin) for 5 days didn't influence the plasma concentrations after intravenous dosing of 0.5 mg/kg MTX, but induced the decreased Cmax and the delayed MRT after oral dosing. The plasma concentrations after intravenous or oral dosing of 2.5 mg/kg MTX in rats orally dosed with 1 or 5 mg/kg/day DS for 4 days were similar to those in the control rats, while the pre-treatment of 25 mg/kg/day DS delayed the elimination of MTX but didn't change the oral BA. The plasma concentrations after intravenous or oral dosing of 2.5 mg/kg MTX in rats, which received the intermittent oral doses of 7.5 mg/kg/3 doses/week MTX for 4 weeks, were comparable to those in the control rats, but the daily pre-treatment of 0.2 mg/kg/day MTX for 4 weeks increased the plasma concentrations after oral dosing, and the BA.     

Pharmacokinetic study of the novel, synthetic trioxane antimalarial compound 97-78 in rats using an LC-MS/MS method for quantification

The present study has been designed to investigate the pharmacokinetic parameters of the novel trioxane antimalarial 97-78 (US Patent 6316493 B1, 2001) in male and female rats after single oral and intravenous administration. The pharmacokinetic profile of 97-78 was investigated in the form of its completely converted metabolite 97-63 after dose administration. Quantification of metabolite 97-63 in rat plasma was achieved using a simple and rapid LC-MS/MS method. The LC-MS/MS method has been validated in terms of accuracy, precision, sensitivity and recovery for metabolite 97-63 in rat plasma. The intra- and interday accuracy (% bias) and precision (% RSD) values of the assay were less than 10% for metabolite 97-63. The chromatographic run time was 4.0 min and the weighted (1/x2) calibration curves were linear over the range 1.56-200 ng/ml. This method was successfully applied for analysis of pharmacokinetic study samples. Maximum plasma concentrations of 97-63 at 47 mg/kg oral administration in male and female rats were 1986.6 ng/ml and 4086.7 ng/ml at time (Tmax) 0.92 h and 0.58 h, respectively. The area under the curve (AUC(0-infinity)), elimination half-life (t(1/2) beta) and mean residence time (MRT) were 4669.98 ng x h/ml, 2.8 h and 4.2 h in male and 11786.0 ng x h/ml, 4.52 h and 4.32 h in female rats respectively. After single oral and intravenous administration of 97-78 to male and female rats significant differences were observed in pharmacokinetic parameters (AUC and t (1/2) beta) for metabolite 97-63.     

Pharmacokinetics of eltoprazine in the dog

Pharmacokinetics of eltoprazine in male and female beagle dogs was studied in two separate cross-over experiments after administration of different intravenous and oral doses. After intravenous administration of 0.5 mg.kg-1, the mean volume of distribution was 5.7 +/- 1.1 l.kg-1. Clearance was 25.5 +/- 1.4 ml.min-1.kg-1. About 25% of the doses was excreted in urine, resulting ina renal clearance of 6.1 +/- 1.4 ml.min-1.kg-1. The mean elimination half-life (t1/2) after intravenous dosing was about 2.6 h. After oral dosing the plasma peak levels (Cmax) were proportional with the dose. The mean time to reach Cmax (tmax) varied between 1.5 and 1.9 h, and t1/2 was about 2.4 h, which was not significantly different (p greater than 0.05) from the half-life obtained after intravenous dosing. Plasma pharmacokinetics after single and multiple dosing of 4 mg.kg-1 showed no difference. Absolute bioavailability was 67% +/- 20%.     

Absorption,distribution, metabolism and excretion of telmesteine,amucolitic agent,in rat

1. The metabolism and disposition of telmesteine, a muco-active agent, have been investigated following single oral or intravenous administration of ¹⁴C-telmesteine in the Sprague–Dawley rat.

2. ¹⁴C-telmesteine was rapidly absorbed after oral dosing (20 and 50mg kg^-1) with an oral bioavailability of > 90% both in male and female rats. The C_max and area under the curve of the radioactivity in plasma increased proportionally to the administered dose and those values in female rats were 30% higher than in male rats.

3. Telmesteine was distributed over all organs except for brain and the tissue/plasma ratio of the radioactivity 30min after dosing was relatively low with a range of 0.1–0.8 except for excretory organs.

4. Excretion of the radioactivity was 86% of the dose in the urine and 0.6% in the faeces up to 7 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 3% for the first 24 h. The unchanged compound mainly accounted for the radioactivity in the urine and plasma.

5. Telmesteine was hardly metabolized in microsomal incubations. A glucuronide conjugate was detected in the urine and bile, but the amount of glucuronide was less than 6% of excreted radioactivity.     

Influence of grapefruit juice on scopolamine pharmacokinetics and pharmacodynamics in healthy male and female subjects

OBJECTIVES: To investigate the effects of grapefruit juice on absolute bioavailability of scopolamine in healthy subjects and to evaluate differences in pharmacokinetics and pharmacodynamics between genders. SUBJECTS, MATERIAL AND METHODS: 14 healthy subjects (7 men and 7 women) received scopolamine 0.5 mg as intravenous infusion, and as oral ingestion with and without grapefruit juice on separate occasions. Serum and urine samples were analyzed using gas chromatography-ion trap tandem mass spectrometry. Changes in subjective state were determined up to 24 hours after drug administration. RESULTS: After oral administration, pretreatment with grapefruit juice led to a 30% increase in systemic bioavailability of scopolamine (p = 0.005) and a significant increase in time to reach peak serum concentration (tmax) of scopolamine (p < 0.001). The Cmax value (6.61+/-0.63 ng/ml) of scopolamine after i.v. administration in male subjects was significant higher compared with the value in female subjects (3.93+/-0.04 ng/ml; geometric mean +/- SEM; p = 0.007). No differences were found in urinary excretion rate of scopolamine and scopolamine glucuronide across genders and between the three different routes of scopolamine administration. Scopolamine produced time-dependent decrements in subjective alertness while contentment and calmness were not influenced. CONCLUSIONS: Pretreatment with grapefruit juice delayed the absorption and increased the bioavailability of scopolamine, whereas elimination was not significantly affected. This study identified an influence of gender on Cmax of scopolamine after i.v. infusion.     

High-performance liquid chromatographic determination of oxatomide and its metabolite and its application to pharmacokinetic study in rat plasma

Oxatomide (CAS 60607-34-3) is an antiallergic agent effective against allergic rhinitis, urticaria, pruritus dermatitis, eczema dermatitis and bronchial asthma. The aim of this study was to establish the method for simultaneously determining oxatomide and its major metabolite M-11 in human serum, human plasma and rat plasma by high-performance liquid chromatography (HPLC). The method was applied to study the influences of alimentation on pharmacokinetics of oxatomide in rats. After extracting oxatomide and its metabolite M-11 from human serum, human plasma or rat plasma with diethyl ether under alkaline condition, sulfuric acid was added to the organic layer and oxatomide and M-11 were back-extracted. The aqueous layers were analysed by HPLC equipped with a fluorimetric detector. The method was highly sensitive and precise for quantitation of oxatomide and M-11 in human serum, human plasma and rat plasma in the concentration range of 1 to 125 ng/ml. Plasma concentration of oxatomide decreased biphasically with an elimination half-life (T1/2) of 1.59 h after intravenous administration of oxatomide (1 mg/kg) to non-fasting male rats. After oral administration of oxatomide (30 mg/kg) to fasting male rats, plasma concentration of oxatomide increased rapidly, and reached the maximum concentration of 188 ng/ml (Cmax) at 1.0 h. Plasma concentration of oxatomide decreased monophasically. The T1/2 was 2.58 h. The bioavailability was 6.74%. Plasma concentration of M-11 increased rapidly, and reached Cmax of 64.3 ng/ml at 0.7 h, and decreased monophasically with T1/2 of 3.79 h. After oral administration of oxatomide to non-fasting male rats, plasma concentration of oxatomide reached Cmax of 378 ng/ml at 3.3 h. The T1/2 was 3.27 h and the bioavailability was 17.5%. The Cmax and AUC0-infinity of M-11 were larger than those after oral administration of oxatomide to fasting male rats. These results demonstrated the usefulness of this method for monitoring and basic examination of biological samples and the influence of alimentation on absorption of oxatomide. Determination of plasma oxatomide concentrations would provide a useful indication of therapeutic efficacy.     

Pharmacokinetics of dibutylphthalate in pregnant rats.

Dibutylphthalate (DBP) can cause adverse effects on the developing male reproductive tract when administered late in gestation to pregnant rats. The objectives of this study were to evaluate the metabolism of DBP in female rats, and the pharmacokinetics of DBP in pregnant rats on gestational day (g.d.) 20. The identities of DBP metabolites in urine and in maternal and fetal plasma were confirmed by LC-MS/MS, as monobutylphthalate (MBP) and its glucuronide, monohydroxybutylphthalate and its glucuronide, and butanoic acid phthalate and its glucuronide. An LC-MS/MS method was developed for the quantitation of MBP and its glucuronide. MBP and MBP glucuronide were quantitated in maternal and fetal plasma, and in amniotic fluid from pregnant rats administered a single dose of DBP (50, 100, or 250 mg/kg by gavage in corn oil) on g.d. 20. The pharmacokinetics of MBP and MBP glucuronide were determined. MBP was the major metabolite in maternal and fetal plasma. With increasing dose, there was a nonlinear increase in area under the curve (AUC) for MBP, with a ten-fold increase in maternal plasma, and an eight-fold increase in fetal plasma between 50 mg/kg and 250 mg/kg. In amniotic fluid, the major metabolite initially was MBP, but by 24 h after dosing, the major metabolite was MBP glucuronide. Isomers of the MBP glucuronide were detected in amniotic fluid, suggesting acyl group migration, known to occur with acyl glucuronides. This study indicated that MBP, thought to be the active metabolite of DBP, can cross the placenta in late gestation, and that the metabolism of MBP is saturable.     

Pharmacokinetics, absorption and tissue distribution of tanshinone IIA solid dispersion

This study was designed to elucidate the pharmacokinetics, absorption, tissue distribution and plasma protein binding properties of tanshinone IIA, a highly lipophilic compound isolated from Salvia miltiorrhiza. Tanshinone IIA was isolated using a previously well developed LC-MS/MS method. Its pharmacokinetic characteristics, absolute bioavailability, tissue distribution and plasma protein binding properties were determined. The membrane permeability was evaluated using Caco-2 cells in monolayer. The pharmacokinetic plasma profile of tanshinone IIA after a single intravenous dosing exhibited a triexponential pattern consisting of rapid distribution (t1/2 alpha, 0.024 h), slow redistribution (t1/2 beta, 0.34 h) and terminal elimination phase (t1/2 gamma, 7.5 h). Tanshinone IIA preferentially distributed into the reticuloendothelial system, especially into liver and lung, after either intravenous or oral doses. Tanshinone IIA (99.2 %) bound highly to plasma proteins, among which lipoprotein played an important role (77.5 %). Tanshinone IIA absorption was extremely poor with an absolute bioavailability below 3.5 %. Absorptive saturation was deduced from the fact that the AUC and Cmax increased less proportionally to dose and Tmax was significantly prolonged. The poor absorption of tanshinone IIA may be caused by its low aqueous solubility and limited membrane permeability. There were no significant differences of the apparent permeability coefficient for all tested concentrations and for the apical to basolateral and reverse direction transport, suggesting a passive transport mode and no involvement of an efflux protein. In conclusion, tanshinone IIA has a suitable pharmacokinetic behavior except for its poor absorption. A pharmaceutical strategy for promoting its absorption should be designed to develop tanshinone IIA as a new drug candidate.     

Absolute bioavailability and pharmacokinetics of treprostinil sodium administered by acute subcutaneous infusion

The objective of this study was to evaluate the absolute bioavailability and acute pharmacokinetics of treprostinil sodium administered by continuous, short-term subcutaneous infusion in normal subjects. Fifteen healthy volunteers received treprostinil via an intravenous infusion at 15 ng/kg/min over 150 minutes, followed by a 5- to 7-day washout and a subcutaneous infusion at the same rate administered over 150 minutes. Serial plasma samples were collected predosing, during dosing, and postdosing, and plasma treprostinil concentration levels were measured by a validated liquid chromatography atmospheric pressure ionization tandem mass spectrometry (LC/MS/MS) method with a lower limit of quantitation (LLOQ) of 25 pg/mL. Acute administration of treprostinil administered by subcutaneous infusion at a rate of 15 ng/kg/min for 150 minutes achieved a mean Cmax of 1.47 ng/mL. Mean AUC infinity values for intravenous and subcutaneous dosing were 3.52 and 3.97 ng.h/mL, respectively, resulting in a mean apparent absolute bioavailability of 113% for subcutaneous administration. It was possible that the area under of the curve for the intravenous administration was underestimated because most of the terminal elimination phase could not be documented due to the LLOQ of the assay. The mean apparent elimination half-life of treprostinil following subcutaneous administration was 1.38 hours, compared to 0.87 hours following intravenous administration. It was concluded that treprostinil administered by subcutaneous administration is completely absorbed, with a slightly longer half-life compared to intravenously administered treprostinil.     

LC-MS/MS快速测定人血浆中氯沙坦浓度及其生物等效性研究

目的建立人血浆中氯沙坦LC-MS/MS测定方法,计算氯沙坦人体药动学参数并评价两制剂生物等效性。方法采用单剂量双周期交叉试验设计,完成试验的23例受试者空腹口服受试或参比制剂氯沙坦钾片100 mg后,用甲醇一步沉淀血浆蛋白,并用LC-MS/MS法测定人血浆中氯沙坦浓度。用DAS 3.2.3软件计算氯沙坦人体药动学参数,并评价两制剂生物等效性。结果服用受试和参比制剂后,血浆中氯沙坦的Cmax分别为(697.3±301.7)和(674.1±350.5)ng/m L,AUC0-12 h分别为(994±240)和(1 005±287)ng·h/m L,tmax分别为(1.23±0.38)和(1.37±0.75)h,t1/2分别为(2.04±0.28)和(2.00±0.40)h,生物利用度为102.4%±21.1%。结论建立的分析测试方法灵敏、简便、准确,受试制剂与参比制剂生物等效。     

Disposition and metabolism of a new benzothiophene antiestrogen in rats, dogs and monkeys

A new benzothiophene-derived antiestrogen (LY156758) when orally administered was well absorbed in rats and monkeys while approx. 20% was absorbed in dogs. In the rat the compound was subject to first-pass hepatic metabolism which led to low levels of parent drug in the systematic circulation together with a small amount as the glucuronide conjugate. In monkeys the compound occurred primarily as the glucuronide conjugate of parent drug with very little circulating free drug. The systemic bioavailability of free parent drug in plasma was 39% in rats, 17% in dogs and 5% in monkeys. Excretion of the drug in rats and dogs was primarily via the bile. Approx. 1% of the dose was excreted in the urine of rats and dogs after oral dosing. In rats, at least 50% of an oral dose was excreted in bile as the glucuronide conjugate of parent drug.     

Intravenous pharmacokinetics, oral bioavailability and dose proportionality of ragaglitazar, a novel PPAR-dual activator in rats

Pharmacokinetics of ragaglitazar (a novel phenoxazine derivative of aryl propanoic acid), a potent insulin sensitizing and lipid-lowering compound was studied in Wistar rats. A single dose of 1, 3 or 10 mg/kg of ragaglitazar was given orally to male rats (n=4 per dose level) to evaluate dose proportionality. In another study, a single intravenous bolus dose of ragaglitazar was given to rats (n=4) at 3 mg/kg dose following administration through the lateral tail vein in order to obtain the absolute oral bioavailability and clearance parameters. Blood samples were drawn at predetermined intervals and the concentration of ragaglitazar in plasma was determined by a validated HPLC method. Plasma concentration versus time data were generated following oral and intravenous dosing and pharmacokinetic analysis was performed using non-compartmental analysis. The results revealed that Cmax and AUC(0-infinity) increased more than proportionally to the administered oral doses. As dose increased in the ratio of 1:3:10, the mean Cmax and AUC(0-infinity) increased in the ratio of 1:3.2:13 and 1:3.2:16, respectively. After intravenous administration the systemic clearance and volume of distribution of ragaglitazar in rats were 139+/-30 ml/h/kg and 463+/-51 ml/kg, respectively (mean+/-SD). Plasma concentrations declined mono-exponentially following intravenous administration and elimination half-life (t1/2) was about 2.6 h and not significantly different (p > 0.05) from the value from oral administration. Mean residence time (MRT) values for ragaglitazar were found to be 4.15+/-0.52 h (3.5 to 4.6 h). Absolute oral bioavailability of ragaglitazar across the doses tested was in the range of 68%-93%. In conclusion, ragaglitazar exhibits promising pharmacokinetic properties in rats.     

In‐situ absorption,protein binding and pharmacokinetic studies of S002‐853, a novel antidiabetic and antidyslipidaemic flavone derivative in rats

Objectives The aim of the study was to investigate the in‐situ absorption kinetics, plasma protein binding and pharmacokinetic characteristics of a novel synthetic flavone derivative, S002‐853, which shows pronounced antidiabetic and antidyslipidaemic activity. Methods Quantification of S002‐853 in plasma was performed by the LC‐MS/MS method and in‐situ sample analysis was carried out by the HPLC‐UV method. Key findings The absorption rate constant was 0.274/h in a mild alkaline environment, which S002‐853 experiences in the intestine following oral dose administration. Plasma protein binding was found to be 26.37 ± 2.58% at a concentration of 1 μg/ml. The pharmacokinetic parameters were determined in male rats after administration of a single 40 mg/kg oral dose and 10 mg/kg intravenous dose. The peak plasma concentration (C_max) was found to be 60.93 ng/ml at 8 h after oral administration. Irregular concentration–time profiles with secondary peaks were observed after oral dose administration. The elimination half‐life of the compound was 19.56 h and 16.30 h after oral and intravenous doses, respectively. Comparison of the AUC after oral and intravenous dosing of S002‐853 indicates that only about 29.48% (bioavailability) of the oral dose reaches the systemic circulation. Conclusions In‐situ study of S002‐853 shows slow absorption from the gastrointestinal tract. S002‐853 also shows low plasma protein binding. The pharmacokinetic parameters after oral and intravenous dose reveal low oral bioavailability and high mean residence time.     

Disposition and metabolism of a new benzothiophene antiestrogen in rats,dogs and monkeys

1. A new benzothiophene-derived antiestrogen (LY156758) when orally administered was well absorbed in rats and monkeys while approx. 20% was absorbed in dogs.

2. In the rat the compound was subject to first-pass hepatic metabolism which led to low levels of parent drug in the systematic circulation together with a small amount as the glucuronide conjugate.

3. In monkeys the compound occurred primarily as the glucuronide conjugate of parent drug with very little circulating free drug.

4. The systemic bioavailability of free parent drug in plasma was 39% in rats, 17% in dogs and 5% in monkeys.

5. Excretion of the drug in rats and dogs was primarily via the bile. Approx. 1% of the dose was excreted in the urine of rats and dogs after oral dosing. In rats, at least 50% of an oral dose was excreted in bile as the glucuronide conjugate of parent drug.     

Pharmacokinetics of tramadol in rat plasma and cerebrospinal fluid after intranasal administration

We have evaluated the potential of intranasal administration of tramadol. The pharmacokinetic behaviour of tramadol in rat plasma and cerebrospinal fluid (CSF) after intranasal administration was determined and compared with those after intravenous and oral administration. Serial plasma and CSF samples were collected for 6 h, and the drug concentrations were assayed by an HPLC-fluorescence method. The plasma absolute bioavailability values of tramadol after intranasal and oral administration were 73.8% and 32.4%, respectively, in conscious rats. The Cmax (maximum concentration) value after the intranasal dose was lower (P<0.05), and the MRT (mean retention time) was longer (P<0.05) than the values obtained after intravenous administration. A pharmacokinetic study of tramadol in plasma and CSF was undertaken in anaesthetized rats. The absolute bioavailability values in plasma and CSF after intranasal administration were 66.7% and 87.3%, respectively. The Cmax values in plasma and CSF after a nasal dose were lower (P<0.05) than after the intravenous dose. The values of Cmax and AUC0-->6 h in plasma and CSF after intranasal administration were higher than after the oral dose. The mean drug-targeting efficiency after intranasal administration was significantly greater than after the oral dose. In conclusion, intranasal administration of tramadol appeared to be a promising alternative to the traditional administration modes for this drug.