Effect of single oral dose of sodium benzoate on ureagenesis in healthy men and two patients with late onset citrullinaemia

Summary Although sodium benzoate therapy is beneficial in patients with inborn error of urea cycle, it has been suggested that an accumulation of benzoyl-CoA would inhibit ureagenesis. In this study, we examined several aspects of ureagenesis after the single oral dosing of sodium benzoate in six healthy subjects who participated in the study previously reported and in two patients with citrullinaemia.Urea nitrogen appearance (UNA) did not change after the doses of 40, 80 and 160 mg·kg^–1 of sodium benzoate in the 6 healthy subjects. Sum of UNA and urinary hippurate nitrogen (UHN) increased with increasing the dose. In the 2 patients with late-onset citrullinaemia who benefit from a partially functional urea cycle, no apparent inhibitory effects on the UNA were observed after the administration of 80 mg/kg of sodium benzoate.The precursors of urea (ammonia, glutamate, glutamine and -amino nitrogen) did not increase after the benzoate administration in the 6 normal subjects as well as in the 2 patients with citrullinaemia.     

Dose-dependent pharmacokinetics of toxic metabolites is not related to increased toxicity following high-dose valproic acid in rats

It has been reported that urinary excretion of two metabolites of valproic acid (VPA), 4-ene-valproic acid (4-VPA)and 2,4-diene-valproic acid (2,4-VPA), increased exponentially with the administration of high doses of VPA, and this increased formation of toxic metabolites could be related to VPA hepatotoxicity in humans. The aim of this study was to investigate whether the plasma level of 4-VPA and 2,4-VPA in rats corresponds to the urinary data for the same metabolites in humans.After the oral administration of VPA at doses of 20, 100 and 500 mg kg-1 in rats, the AUC0–24 h, 4-VPA/AUC0–24 h, VPA ratios (0.0399,0.0120 and 0.0100 for 20, 100 and 500 mg kg-1, respectively) and AUC0–24 h, 2,4-VPA/AUC0–24 h, VPA ratios (0.00104, 0.00201 and 0.00141, respectively) did not increase with increasing doses of VPA in rats. Thus, the plasma exposure of toxic metabolites normalized by dose remained unchanged (for 2,4-VPA) or even decreased (for 4-VPA) following high-dose VPA administration;this contradicts the findings of previous studies. Our results suggest that toxicity induced by high doses of VPA cannot be explained by a nonlinear increase of toxic metabolites in rats.     

HPLC同时测定复方苯甲酸酊中的苯甲酸和水杨酸

目的 建立测定复方苯甲酸酊中苯甲酸和水杨酸含量的方法.方法 采用HPLC法,色谱柱为Kromasil C18(250 mm×4.6 mm,5 μm),流动相为甲醇-1%冰醋酸(47:53),流速为0.8 ml·min-1,检测波长为225 nm.结果 苯甲酸24.03～ 120.12 mg·L-1的线性良好(r=0.9997),平均回收率为100.66%,RSD=0.70%;水杨酸12.01～60.02 mg·L-1与峰面积的线性良好(r=0.9992),平均回收率为100.06%,RSD=0.78%.结论 所建方法简便、快速、准确,可作为复方苯甲酸酊的质量控制方法.     

反相高效液相色谱法同时测定复方苯甲酸碘酊中苯甲酸和水杨酸的含量

目的 建立同时测定复方苯甲酸碘酊中苯甲酸和水杨酸含量的反相高效液相色谱法.方法 色谱柱:ODSC18色谱柱(4.6mm×150mm,5μm);流动相:甲醇:水=60:40(pH 3.2);柱温:30℃;检测波长:242 nm;流速:0.9 ml/min.结果 苯甲酸和水杨酸的线性范围分别为30～120 mg/L(R2=0.9995)、15～60 mg/L(R2=0.9988),回收率分别为99.2％(RSD=0.95％)、99.1％(RSD=1.36％),日内RSD分别为1.57％、1.57％(n=5),日间RSD分别为1.43％、1.59％(n=5),与酸碱滴定法测定结果差异无统计学意义(P＞0.05).结论 反相高效液相色谱法适用于复方苯甲酸碘酊的含量测定,方法简便、灵敏,测定结果准确,符合制剂质量控制要求.     

Dose-linear pharmacokinetics of oleanolic acid after intravenous and oral administration in rats

The pharmacokinetics of oleanolic acid was evaluated in vitro and in vivo. From Caco-2 cell permeation studies, oleanolic acid was a low permeability compound with no directional effects, suggesting a low in vivo absorption mediated by a passive diffusion. Oleanolic acid was metabolically unstable following incubation with rat liver microsomes in the presence of NADPH. After intravenous injection at doses of 0.5, 1 and 2 mg/kg doses, oleanolic acid showed dose-linear pharmacokinetics as evidenced by unaltered CL (28.6-33.0 ml/min/kg), Vss (437-583 ml/kg), dose-normalized AUC (16.0-17.9 microg min/ml based on 1 mg/kg) and t1/2 (41.9-52.7 min). Following oral administration of oleanolic acid at doses of 10, 25 and 50 mg/kg, Tmax, t1/2, dose-normalized Cmax (66-74 ng/ml based on 25 mg/kg) and dose-normalized AUC (5.4-5.9 microg min/ml based on 25 mg/kg) were comparable between 25 and 50 mg/kg dose, but the plasma concentrations at 10 mg/kg dose were not measurable as they were below the limit of quantitation (2 ng/ml). The absolute oral bioavailability was 0.7% for oral doses of 25 and 50 mg/kg. The extent of urinary excretion was minimal for both i.v. and oral doses. The very low oral bioavailability of oleanolic acid could be due to a poor absorption and extensive metabolic clearance.     

Detection and pharmacokinetics of grapiprant following oral administration to exercised Thoroughbred horses

Traditional therapeutic options for the treatment of lameness associated with inflammation in performance horses include administration of cyclooxygenase enzyme inhibiting non‐steroidal anti‐inflammatory drugs (NSAID). As long‐term use of these drugs can adversely impact the health of the horse, anti‐inflammatories with a more favorable safety profile are warranted. Grapiprant is a newly approved non‐cyclooxygenase inhibiting NSAID that has demonstrated efficacy and safety in other species and which may be a valuable alternative to traditional NSAIDs used in the horse. The objectives of the current study were to describe drug concentrations and the pharmacokinetics of grapiprant in exercised Thoroughbred horses and to develop an analytical method that could be used to regulate its use in performance horses. To that end, grapiprant, at a dose of 2 mg/kg was administered orally to 12 exercised Thoroughbred horses. Blood and urine samples were collected prior to and for up to 96 hours post drug administration. Drug concentrations were measured using liquid chromatography–tandem mass spectrometry. Grapiprant remained above the LOQ of the assay (0.005 ng/mL) in serum for 72 hours post administration and urine concentrations were above the LOQ until 96 hours. The C_max, T_max and elimination half‐life were 31.9 ± 13.9 ng/mL, 1.5 ± 0.5 hours and 5.86 ± 2.46 hours, respectively. The drug was well tolerated in all horses at a dose of 2 mg/kg. Results support further study of this compound in horses. Furthermore, development of a highly sensitive analytical method demonstrate that this compound can be adequately regulated in performance horses.     

The pharmacokinetics of anthocyanins and their metabolites in humans

BACKGROUND AND PURPOSE

Anthocyanins are phytochemicals with reported vasoactive bioactivity. However, given their instability at neutral pH, they are presumed to undergo significant degradation and subsequent biotransformation. The aim of the present study was to establish the pharmacokinetics of the metabolites of cyanidin-3-glucoside (C3G), a widely consumed dietary phytochemical with potential cardioprotective properties.

EXPERIMENTAL APPROACH

A 500 mg oral bolus dose of 6,8,10,3′,5′-¹³C₅-C3G was fed to eight healthy male participants, followed by a 48 h collection (0, 0.5, 1, 2, 4, 6, 24, 48 h) of blood, urine and faecal samples. Samples were analysed by HPLC-ESI-MS/MS with elimination kinetics established using non-compartmental pharmacokinetic modelling.

KEY RESULTS

Seventeen ¹³C-labelled compounds were identified in the serum, including ¹³C₅-C3G, its degradation products, protocatechuic acid (PCA) and phloroglucinaldehyde (PGA), 13 metabolites of PCA and 1 metabolite derived from PGA. The maximal concentrations of the phenolic metabolites (C_max) ranged from 10 to 2000 nM, between 2 and 30 h (t_max) post-consumption, with half-lives of elimination observed between 0.5 and 96 h. The major phenolic metabolites identified were hippuric acid and ferulic acid, which peaked in the serum at approximately 16 and 8 h respectively.

CONCLUSIONS AND IMPLICATIONS

Anthocyanins are metabolized to a structurally diverse range of metabolites that exhibit dynamic kinetic profiles. Understanding the elimination kinetics of these metabolites is key to the design of future studies examining their utility in dietary interventions or as therapeutics for disease risk reduction.     

Dose-dependent nonlinear pharmacokinetics of ethylene glycol metabolites in pregnant (GD 10) and nonpregnant Sprague-Dawley rats following oral administration of ethylene glycol.

The kinetics of orally administered ethylene glycol (EG) and its major metabolites, glycolic acid (GA) and oxalic acid (OX), in pregnant (P; gestation day 10 at dosing, GD 10) rats were compared across doses, and between pregnant and nonpregnant (NP) rats. Groups of 4 jugular vein-cannulated female rats were administered 10 (P and NP), 150 (P), 500 (P), 1000 (P), or 2500 (P and NP) mg (13)C-labelled EG/kg body weight. Serial blood samples and urine were collected over 24-hr postdosing, and analyzed for EG, GA, and OX using GC/MS techniques. Pharmacokinetic parameters including Cmax, Tmax, AUC, and betat((1/2)) were determined for EG and GA. Pregnancy status (GD 10-11) had no impact on the pharmacokinetic parameters investigated. Blood levels of GA were roughly dose-proportional from 10 to 150 mg EG/kg, but increased disproportionately from 500 to 1000 mg EG/kg. EG and GA exhibited dose-dependent urinary elimination at doses > or = 500 mg EG/kg, probably due to saturation of metabolic conversion of EG to GA, and of GA to downstream metabolites. The shift to nonlinear kinetics encompassed the NOEL (500 mg EG/kg) and LOEL (1000 mg EG/kg) for developmental toxicity of EG in rats, providing additional evidence for the role of GA in EG developmental toxicity. The peak maternal blood concentration of GA associated with the LOEL for developmental toxicity in the rat was quite high (363 microg/g or 4.8 mM blood). OX was a very minor metabolite in both blood and urine at all dose levels, suggesting that OX is not important for EG developmental toxicity.     

HPLC法测定苯甲酸软膏中水杨酸的含量

目的建立一种快速的用高效液相色谱法测定苯甲酸软膏中水扬酸（SA）的含量。方法使用C18色谱柱,流动相为甲醇：水（60：40,v/v）,检测波长为278nm。结果水杨酸在30～240μg/ml浓度范围内,r=0.9997,平均回收率为99.72%,RSD=0.75%。结论该法可快速准确的测定医用苯甲酸软膏中水杨酸的含量。     

Interspecies differences on pharmacokinetics of rebamipide following oral administration to rats and dogs

Rebamipide is used widely in East Asia for the treatment of gastric ulcers, acute gastritis, and exacerbated chronic gastritis. The objective of this study was to investigate the pharmacokinetic (PK) properties of rebamipide following single oral administration in rats and dogs. Eleven rats and dogs received single oral administrations of rebamipide (35 mg/kg and 100 mg, respectively). Blood samples were collected according to the assigned schedule, and the plasma concentration of rebamipide was determined using liquid chromatography–tandem mass spectrometry. A double-peak phenomenon was observed in the PK profile of rebamipide in rats. In contrast, rebamipide showed a conventional PK profile without double peaks in dogs. The half-life of rebamipide in rats (12.85 ± 7.86 h) was longer than that in dogs (5.62 ± 2.24 h), and the apparent total clearance (Cl_t/F) of rebamipide in rats (3.32 ± 1.18 L/h) was lower than that in dogs (105.01 ± 42.37 L/h). Simple allometric approaches showed that the correlation between body weight and Cl_t/F (R² = 0.9287) among rats, dogs, and humans appeared satisfactory. This finding will help not only in understanding the pharmacology of rebamipide but also in establishing a strategy for in vivo evaluation of novel rebamipide formulations.     

Dose proportionality and pharmacokinetics of dronedarone following intravenous and oral administration to rat

1. The aim of this study was to investigate the pharmacokinetic properties of dronedarone by using noncompartmental analysis and modeling approaches after intravenous and oral administration of dronedarone to rats.

2. Twenty-eight male Sprague-Dawley rats were randomly divided into four groups, and dronedarone was administered intravenously (1?mg/kg) and orally (5, 10 and 40?mg/kg) based on a parallel design. Blood samples were collected before and 0.083 (intravenous administration only), 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 12 and 24?h after drug administration. The plasma concentration of dronedarone was determined by using LC-MS/MS.

3. The oral bioavailability of dronedarone was evaluated as approximately 16% in rats, similar to that in humans. The assessment of dose proportionality by using the power model showed that AUC_inf increased in a dose-proportional manner, whereas AUC_24h and C_max exhibited a lack of dose proportionality over the dose range between 5 and 40?mg/kg. The two-compartment model, with first-order absorption and elimination rate constants, was sufficient to explain the pharmacokinetics of dronedarone with biexponential decay.

4. These findings will help to understand the pharmacology of dronedarone to develop the new formulation and therapeutics optimization linked to pharmacokinetic/pharmacodynamic study.

     

Effects of bile salts on the lovastatin pharmacokinetics following oral administration to rats

This study aimed to examine the effects of bile salts on pharmacokinetics of lovastatin, which has low bioavailability. Lovastatin solid dispersions were prepared using sodium deoxycholate (NaDC) and sodium glycholate (NaGC) at ratios of 1:19, 1:49, and 1:69. The formulated solid dispersions and control (commercial tablet) were administered to rats and plasma concentrations were determined by a validated LC-MS/MS method. Statistically significant differences were found in C_max, AUC_0–10, and AUC_0–∞ values among lovastatin formulations (p?<?0.05). NaDC-containing formulations revealed higher bioavailabilities than NaGC-containing solid dispersions at ratios of 1:19 and 1:49. Especially, NaDC-containing formulation at a ratio of 1:19 (NaDC19) showed the highest bioavailability. The AUC (both AUC_0–10 and AUC_0–∞) of NaDC19 was statistically higher than control and NaDC69 (p?<?0.05). The AUC values decreased as bile salt concentrations increased. Overall, formulations containing bile salts showed higher AUC values than control, even though all formulations did not show significantly higher AUC. In conclusion, the addition of bile salts to lovastatin could enhance drug bioavailabilities. However, too high concentrations of bile salts could decrease bioavailabilities of lovastatin.     

The pharmacokinetics of tiopronin and its principal metabolite (2-mercaptopropionic acid) after oral administration to healthy volunteers

Summary We have studied the pharmacokinetics of tiopronin and its principal metabolite, 2-mercaptopropionic acid (2-MPA) in healthy volunteers after the oral administration of 500 mg (2 Acadione® tablets), followed by simultaneous assay of the two compounds in plasma over a period of 48 h using a new method (emission of fluorescence after HPLC and post-column derivatization by pyrene-maleimide). The absorption of tiopronin was slow (t_max between 4 and 6 h) and the plasma concentrations subsequently fell biexponentially. The principal metabolite 2-MPA appeared later in the plasma (t_max between 10 and 12 h after a lag-time of 3 h) then disappeared monoexponentially. About 15% of the tiopronin was metabolized to 2-MPA.     

The pharmacokinetics of diclofenac sodium following intravenous and oral administration

Summary The pharmacokinetics of diclofenac were examined following single rapid intravenous injection and also following single oral doses to healthy female volunteers. After intravenous injection plasma levels of diclofenac fell rapidly and were below the limits of detection at 5.5 h postdosing. Individual drug profiles were described by a triexponential function and mean half-lives of the three exponential phases were 0.05, 0.26 and 1.1 h. After oral doses of enteric-coated tablets, the lag time between dosing and the appearance of drug in plasma varied between 1.0 and 4.5 h. However once drug absorption had commenced similar plasma drug profiles were obtained in different individuals. Peak plasma diclofenac levels ranged from 1.4 to 3.0 µg · ml^–1. The mean terminal drug half-life in plasma was 1.8 h after oral doses. This value was not significantly greater than the value of 1.1 h following intravenous doses. Fifty percent of orally dosed diclofenac did not reach the systemic circulation due, predominantly, to first-pass metabolism.     

Enhancing effects of different dosages of borneol on pharmacokinetics of salvanic acid B after oral administration to rats

The main purpose of this study was to illustrate the effect of borneol on pharmacokinetics of salvianolic acid B (SalB) in rats after oral administration of SalB with different doses of borneol. The concentrations of SalB in rat plasma were determined by an established and validated LC-MS/MS method. Our data showed that when 20, 40, and 80 mg kg^? 1 of borneol were orally administrated with SalB at 50 mg kg^? 1, C _max of SalB was increased by 18.4%, 55.8%, and 103.2% compared with that of SalB alone. And AUC_0 ? t of SalB in plasma was increased by 14.4%, 48.5%, and 123.3%, respectively. The results indicated that borneol is able to enhance the intestinal absorption and relative bioavailability of SalB, with a positive dose-dependent relationship. The described herb–drug interactions might prove the scientific rationality of the compatible ratio of traditional Chinese medicines.     

反相高效液相色谱法测定复方土槿皮酊中水杨酸和苯甲酸的含量

本文报道了反相高效液相色谱法测定复方土槿皮酊中水杨酸和苯甲酸含量，以对氨基苯甲酸为内标，该法简便、快速，每个样品测试在１０ｍｉｎ内完成。其中水杨酸平均回收率为１００．８５％，变异系数为０．１９％；苯甲酸平均回收率为９９．５０％，变异系数为０．２４％。     

Dose-independent pharmacokinetics of torasemide after intravenous and oral administration to rats

After intravenous (at doses of 1, 2, 5, and 10 mg/kg) and oral (at doses of 1, 5, and 10 mg/kg) administration of torasemide, the pharmacokinetic parameters were dose-independent. Hence, the extent of absolute oral bioavailability (F) was also independent of oral doses; the values were 95.6, 98.8, and 97.3% for oral doses of 1, 5, and 10 mg/kg, respectively. The high F values indicated that the first-pass (gastric, intestinal, and hepatic) effects of torasemide in rats could be almost negligible. After intravenous administration, the total body clearances of torasemide were extensively slower than the reported cardiac output in rats and hepatic extraction ratio was only 3-4% suggesting almost negligible first-pass effects of torasemide in the heart, lung, and liver in rats. Based on in vitro rat tissue homogenate studies, the tissues studied also showed negligible metabolic activities for torasemide. Equilibrium of torasemide between plasma and blood cells of rat blood reached fast and plasma-to-blood cells concentration ratio was independent of initial blood concentrations of torasemide, 1, 5, and 10 microg/ml; the mean value was 0.279. Protein binding of torasemide to fresh rat plasma was 93.9 +/- 1.53% using an equilibrium dialysis technique.     

Plasma levels of ethaverine after oral administration to humans

Fourteen healthy human subjects received a 200 mg oral dose of ethaverine hydrochloride as an elixir. Blood samples were obtained for 12 h after dosing. Plasma ethaverine concentrations were determined using a paired-ion, reversed-phase high performance liquid chromatographic method. Individual plasma concentration-time profiles were fitted to a two-compartment model with first-order absorption. The ethaverine was rapidly absorbed, based on a time of maximum plasma concentration of 0.75 h, a time-lag of 8.4 min, and an apparent first-order absorption half-life of 8.6 min. The mean terminal elimination half-life was 3.3 h.     

Effect of severe renal impairment on the pharmacokinetics of azimilide following single dose oral administration

AIMS: To assess the influence of severe renal impairment on azimilide pharmacokinetics. METHODS: A single oral dose of 125 mg azimilide dihydrochloride was administered to subjects with normal and severely impaired renal function. Blood and urine samples were collected for 22-28 and 10 days, respectively. RESULTS: Azimilide renal clearance decreased in subjects with renal impairment (mean 14 vs 4.8 ml h-1 kg-1, 95% confidence interval on the ratio 0.23, 0.50). However, no change in any other pharmacokinetic parameter including oral clearance (mean 109 vs 104 ml h-1 kg-1, 95% confidence interval on the ratio 0.67, 1.36) was observed. CONCLUSIONS: Since azimilide blood concentrations are essentially unaffected by renal function, an a priori dosage regimen adjustment is not required in patients with renal impairment.     

Plasma levels and pharmacokinetics of cyclofenil after oral administration to man

Summary Cyclofenil was given as a single oral dose of 200 mg, and also as 200 mg/day for eight days, to seven healthy female volunteers. Plasma was analyzed for the active metabolite and pharmacokinetic modelling was performed. A biological half life of 29 h was bound after the single dose and 18 h after the eighth day of continuous treatment. No significant difference was found in any of the calculated parameters when comparing the values from Day 1 and Day 8. The theoretically constructed steady-state curve fitted the experimented values.