Safety and Pharmacokinetics of Standardized Extract of Centella asiatica (ECa 233) Capsules in Healthy Thai Volunteers: A Phase 1 Clinical Study

Planta Medica ◽  
2019 ◽  
Vol 85 (06) ◽  
pp. 483-490 ◽  
Author(s):  
Phanit Songvut ◽  
Pajaree Chariyavilaskul ◽  
Mayuree Tantisira ◽  
Phisit Khemawoot
Keyword(s):  
Clinical Laboratory ◽  
Phase 1 ◽  
Plasma Concentrations ◽  
Centella Asiatica ◽  
Fold Increase ◽  
Repeated Dose ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Asiatic Acid ◽  
Active Metabolites

AbstractThe aim of this study was to investigate the safety and pharmacokinetic profiles of a newly developed, standardized extract of Centella asiatica (ECa 233) capsule in healthy Thai volunteers. This study was designed as an open-labeled, 2-sequence dosage, single- and repeated-dose study investigated under fasting conditions. Plasma concentrations of the parent compounds and their relative acid metabolites were measured and pharmacokinetic parameters were calculated using noncompartmental analysis. Tolerability was assessed based on physical examinations, monitoring of vital signs, clinical laboratory tests, and any observed adverse events. A key finding of this study was that the pharmacokinetics of ECa 233 in healthy volunteers did not correspond with its pharmacokinetics in animal studies. As indicated in human pharmacokinetic parameters, maximum plasma concentration and area under the curve of the parent compounds (madecassoside and asiaticoside) were very low, while their respective metabolites (madecassic acid and asiatic acid) demonstrated higher values. Based on the pharmacokinetic results observed in the dose comparison, accumulation of active metabolites after repeated dose is highly suggestive. In addition, the asiatic acid profile showed 2-fold increase in Cmax and AUC(0–t) after increasing dose from 250 to 500 mg of ECa 233. Lastly, the safety and tolerability evaluation illustrated that single and multiple doses in both 250 and 500 mg oral administration of ECa 233 were well tolerated, and none of the volunteers discontinued their participation due to adverse effects during the study.

scholarly journals Phase Ib Trial To Evaluate the Safety and Pharmacokinetics of Multiple Ascending Doses of Filociclovir (MBX-400, Cyclopropavir) in Healthy Volunteers

2019 ◽  
Vol 63 (9) ◽  
Author(s):  
Nadine G. Rouphael ◽  
Selwyn J. Hurwitz ◽  
Mari Hart ◽  
Allison Beck ◽  
Evan J. Anderson ◽  
...  
Keyword(s):  
Adverse Events ◽  
Clinical Laboratory ◽  
Subcutaneous Tissue ◽  
Phase 1 ◽  
Plasma Concentrations ◽  
Pharmacokinetic Parameters ◽  
Plasma Exposure ◽  
Serious Adverse Events ◽  
Double Blind ◽  
Time Curve

ABSTRACT Filociclovir (MBX-400, cyclopropavir) is an antiviral agent with activity against cytomegalovirus (CMV). A phase 1, double-blind, randomized, placebo-controlled (3:1 ratio), single-center, multiple-ascending-dose trial was conducted to assess the safety, tolerability, and pharmacokinetics of filociclovir. Filociclovir (n = 18) or placebo (n = 6) was administered as a daily oral dose (100 mg, 350 mg, or 750 mg) for 7 days to normal healthy adults (ages, 25 to 65 years) who were monitored for 22 days. Safety assessments included clinical, laboratory, and electrocardiogram monitoring. Plasma and urine samplings were used to determine pharmacokinetic parameters. All study product-related adverse events were mild, most commonly gastrointestinal (17%), nervous system (11%), and skin and subcutaneous tissue (11%) disorders. One subject had reversible grade 3 elevation in serum creatinine and bilirubin, which was associated with an ∼1-log increase in plasma filociclovir exposure compared to levels for other subjects in the same (750-mg) cohort. No other serious adverse events were observed. Plasma exposures (area under the concentration-time curve from 0 to 24 h [AUC0–24]) on days 1 and 7 were similar, suggesting negligible dose accumulation. There was a sublinear increase in plasma exposure with dose, which plateaued at the daily dose of 350 mg. The amount of filociclovir recovered in the urine remained proportional to plasma exposure (AUC). Doses as low as 100 mg achieved plasma concentrations sufficient to inhibit CMV in vitro. (This study has been registered at ClinicalTrials.gov under identifier NCT02454699.)

scholarly journals Multiple Oral Dosing Pharmacokinetics of Standardized Extract of Centella asiatica ECa 233 and Its Inductive Effect on Efflux Transporters in Rats

2017 ◽  
Vol 4 (02) ◽  
pp. e66-e73 ◽  
Author(s):  
Tosapol Anukunwithaya ◽  
Mayuree Tantisira ◽  
Tsutomu Shimada ◽  
Yoshimichi Sai ◽  
Phisit Khemawoot
Keyword(s):  
Inductive Effect ◽  
Area Under The Curve ◽  
Centella Asiatica ◽  
Pharmacokinetic Data ◽  
Maximum Plasma ◽  
Asiatic Acid ◽  
Multiple Dosing ◽  
Oral Dosing ◽  
Blood Biochemical ◽  
Triterpenoid Glycosides

AbstractECa 233 is a standardized extract of Centella asiatica, characterized as a white powder containing triterpenoid glycosides not less than 80% with a ratio of madecassoside to asiaticoside of 1.5±0.5:1. Although pharmacological and toxicological profiles of ECa 233 have been successively reported, the pharmacokinetic data needed for further therapeutic development are not fully elucidated. This study aimed to investigate the pharmacokinetics of multiple oral dosing of ECa 233 at 100 mg/kg/day for 7 days in rats. Plasma, tissues, urine, and feces were collected from 0 to 24 h after dosing on days 1 and 7. The concentrations of asiaticoside, madecassoside, asiatic acid, and madecassic acid were simultaneously analyzed by liquid chromatography-tandem mass spectrometry. No significant change was observed in physical and blood biochemical parameters of the animals treated with ECa 233 for 7 days. The maximum plasma concentration and area under the curve at day 7 of madecassoside and asiaticoside decreased by 70–80% from day 1. However, both triterpenoid glycosides were extensively distributed and accumulated, resulting in significantly higher concentrations at pharmacologically relevant organs. Madecasssic acid and asiatic acid are major metabolites mainly found in and excreted via feces. Moreover, multiple dosing of ECa 233 increased mRNA expression of Abcb1a and Abcc2 in the small intestine by approximately 2- to 3-fold. This is the first study to identify an inductive effect of a standardized extract of C. asiatica after multiple oral dosing in rats. Potential drug-herb interactions when ECa 233 is coadministered with Abcb1a and Abcc2 substrates calls for further investigations.

scholarly journals Pharmacokinetic Profile of μSMIN Plus™, a new Micronized Diosmin Formulation, after Oral Administration in Rats

2015 ◽  
Vol 10 (9) ◽  
pp. 1934578X1501000 ◽  
Author(s):  
Rosario Russo ◽  
Angelo Mancinelli ◽  
Michele Ciccone ◽  
Fabio Terruzzi ◽  
Claudio Pisano ◽  
...  
Keyword(s):  
Oral Administration ◽  
Plasma Concentrations ◽  
Compartmental Analysis ◽  
Pharmacokinetic Profile ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Sprague Dawley ◽  
Time Curve ◽  
Maximum Plasma Drug Concentration

Diosmin is a naturally occurring flavonoid present in citrus fruits and other plants belonging to the Rutaceae family. It is used for the treatment of chronic venous insufficiency (CVI) for its pheblotonic and vaso-active properties, safety and tolerability as well. The aim of the current in vivo study was to investigate the pharmacokinetic profile of a branded micronized diosmin (μSMIN Plus™) compared with plain micronized diosmin in male Sprague-Dawley rats. After oral administration by gastric gavage, blood samples were collected via jugular vein catheters at regular time intervals from baseline up to 24 hours. Plasma concentrations were assessed by LC/MS. For each animal, the following pharmacokinetic parameters were calculated using a non-compartmental analysis: maximum plasma drug concentration (Cmax), time to reach Cmax (Tmax), area under the plasma concentration-time curve (AUC0-last), elimination half-life (t1/2), and relative oral bioavailability (%F). The results of the current study clearly showed an improvement in the pharmacokinetic parameters in animals treated with μSMIN Plus™ compared with animals treated with micronized diosmin. In particular, μSMIN Plus™ showed a 4-fold increased bioavailability compared with micronized diosmin. In conclusion, the results from the current study provided a preliminary pharmacokinetic profile for μSMIN Plus™, which may represent a new tool for CVI management.

Clinical and biologic activity of the farnesyltransferase inhibitor R115777 in adults with refractory and relapsed acute leukemias: a phase 1 clinical-laboratory correlative trial

Blood ◽  
2001 ◽  
Vol 97 (11) ◽  
pp. 3361-3369 ◽  
Author(s):  
Judith E. Karp ◽  
Jeffrey E. Lancet ◽  
Scott H. Kaufmann ◽  
David W. End ◽  
John J. Wright ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Phase 1 ◽  
Area Under The Curve ◽  
Gene Mutations ◽  
Specific Inhibitor ◽  
Maximum Plasma ◽  
Protein Signaling ◽  
Ras Gene ◽  
Acute Leukemias ◽  
Dose Dependent Fashion

R115777 is a nonpeptidomimetic enzyme-specific inhibitor of farnesyl protein transferase (FT) that was developed as a potential inhibitor of Ras protein signaling, with antitumor activity in preclinical models. This study was a phase 1 trial of orally administered R115777 in 35 adults with poor-risk acute leukemias. Cohorts of patients received R115777 at doses ranging from 100 mg twice daily (bid) to 1200 mg bid for up to 21 days. Dose-limiting toxicity occurred at 1200 mg bid, with central neurotoxicity evidenced by ataxia, confusion, and dysarthria. Non–dose-limiting toxicities included reversible nausea, renal insufficiency, polydipsia, paresthesias, and myelosuppression. R115777 inhibited FT activity at 300 mg bid and farnesylation of FT substrates lamin A and HDJ-2 at 600 mg bid. Extracellular signal-regulated kinase (ERK), an effector enzyme of Ras-mediated signaling, was detected in its phosphorylated (activated) form in 8 (36.4%) of 22 pretreatment marrows and became undetectable in 4 of those 8 after one cycle of treatment. Pharmacokinetics revealed a linear relationship between dose and maximum plasma concentration or area under the curve over 12 hours at all dose levels. Weekly marrow samples demonstrated that R115777 accumulated in bone marrow in a dose-dependent fashion, with large increases in marrow drug levels beginning at 600 mg bid and with sustained levels throughout drug administration. Clinical responses occurred in 10 (29%) of the 34 evaluable patients, including 2 complete remissions. Genomic analyses failed to detect N-ras gene mutations in any of the 35 leukemias. The results of this first clinical trial of a signal transduction inhibitor in patients with acute leukemias suggest that inhibitors of FT may have important clinical antileukemic activity.

Phase 1 study of atrasentan (ABT627), novel endothelin receptor-A antagonist, in Japanese patients with hormone refractory prostate cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 14602-14602
Author(s):  
Y. Fujisaka ◽  
Y. Fujiwara ◽  
K. Yamada ◽  
T. Shimizu ◽  
A. Horiike ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Adverse Events ◽  
Half Life ◽  
Phase 1 ◽  
Plasma Concentrations ◽  
Study Drug ◽  
Japanese Patients ◽  
Maximum Plasma ◽  
Hormone Refractory Prostate Cancer ◽  
Hormone Refractory

14602 Background: Endothelin (ET)-1 and its primary receptor, the ETA receptor, contribute to tumor cell growth, survival, angiogenesis and invasion. Atrasentan is a highly potent, selective ETA receptor antagonist. This study assessed safety and pharmacokinetics (PK) in Japanese patients with hormone refractory prostate cancer. Methods: This open-label, single-center Phase I trial evaluated the safety and PK of escalating oral atrasentan doses (2.5, 10 or 20 mg) given daily on day 1 and day 4 through 27 (except day 2 and 3). Dose-limiting toxicity (DLT) was defined as Grade 3 or greater adverse events related to study drug. Results: Eighteen patients, aged 54–74 (median; 66) were treated in cohorts of 6 patients each. The compliance of all patients was 100%. The most common toxicities were rhinitis, peripheral edema, headache, hypotension and anemia, all of which were well tolerated. These events were consistent with the anticipated vasodilatory effects or with a hemodilution effect of the study drug. DLTs were not observed. Atrasentan was rapidly absorbed following oral administration of 2.5 to 20 mg, maximum plasma concentrations averaged from 0.4 to 0.8 hours. After peaking, plasma concentrations declined bi-exponentially with a terminal half-life of approximately 25 hours. In the 10 mg dosing group, the steady-state maximum plasma concentration (Cmax) and the area under the curve (AUC0–24h) averaged 135.5 ng/mL and 533 ng h/mL, respectively. The Cmax and AUC values generally increased linearly with increasing dose after single- and multiple-dose administration. Compared to baseline, PSA decreased 50% or more in 1 patient (20 mg) and increased 25% or more in 10 patients (2.5 mg;2, 10 mg;5, 20 mg;3). The PSA of the remaining 7 patients (2.5 mg;4, 10 mg;1, 20 mg;2) ranged from < 25% increase to < 50% decrease. Fourteen patients continued on study drug in an extension study. Conclusions: Atrasentan is well tolerated, with no dose-limiting adverse events observed up to 20 mg in Japanese patients. The main adverse events are consistent with the vasodilatory effect of the drug. PK are linear and dose-proportional; the half-life is appropriate for once-daily dosing. No significant financial relationships to disclose.

Impact of polymorphisms in the CYP2B6 gene on the pharmacokinetics of cyclophosphamide and thiotepa

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 13062-13062
Author(s):  
C. Ekhart ◽  
A. Huitema ◽  
S. Rodenhuis ◽  
J. H. Beijnen
Keyword(s):  
A Priori ◽  
Plasma Concentrations ◽  
Hepatic Clearance ◽  
High Dose Chemotherapy ◽  
Pharmacokinetic Parameters ◽  
High Dose ◽  
Severe Toxicity ◽  
Active Metabolites ◽  
Increased Risk ◽  
Cyp2b6 Gene

13062 Background: Cyclophosphamide and thiotepa are frequently used simultaneously as part of high dose chemotherapy regimens for solid tumours. Although generally well tolerated, severe toxicity may occur. Relationships between pharmacokinetics and toxicity have been identified. Cyclophosphamide and thiotepa are both metabolised by cytochrome P450 (CYP)enzymes, resulting in the active metabolites 4-hydroxycyclophosphamide and tepa respectively. CYP2B6 and CYP3A4 are the major metabolising isozymes for both compounds. In this study we investigated the relationship between polymorphisms of the CYP2B6 gene and the hepatic clearance of cyclophosphamide and thiotepa in order to identify a priori patients at risk for severe toxicity. Methods: CYP2B6*2 (C64T) and variants A785G, C1459T and G516T were identified by PCR and sequencing samples from 82 patients receiving a high dose regimen consisting of cyclophosphamide (4–6 g/m2), thiotepa (320–480 mg/m2) and carboplatin (AUC 13–20 mg*min/ml). Plasma concentrations of thiotepa, cyclophosphamide and metabolites were determined using a validated LC-MS/MS method. Individual pharmacokinetic parameters were obtained using nonlinear mixed effects modelling. Results: A total of 82 patients was included. Not all data of the various variants were available. All investigated variants had an allele frequency of > 3% in the population. While 94% of the patients had the wildtype genotype for CYP2B6*2, 6% were heterozygous. Heterozygous patients for *2 had a lower hepatic clearance of thiotepa compared to wildtype patients (11.7 l*h−1 vs 14.4 l*h−1) (P=0.03). All other allelic variants investigated showed no effect on either hepatic clearance of thiotepa or cyclophosphamide. Conclusions: This study demonstrates that the hepatic clearance of thiotepa is reduced in patients with a heterozygous CYP2B6*2 genotype. Patients with this genotype may have an increased exposure to thiotepa and may, therefore, be at increased risk for organ toxicity. No significant financial relationships to disclose.

scholarly journals Comparative Study on Pharmacokinetics of Four Long-Acting Injectable Formulations of Enrofloxacin in Pigs

2021 ◽  
Vol 7 ◽  
Author(s):  
Salah Uddin Ahmad ◽  
Jichao Sun ◽  
Fusheng Cheng ◽  
Bing Li ◽  
Safia Arbab ◽  
...  
Keyword(s):  
Comparative Study ◽  
High Performance ◽  
Pasteurella Multocida ◽  
Plasma Concentrations ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Reference Formulation ◽  
Time Curve ◽  
Drug Concentrations ◽  
Long Acting

A comparative study on pharmacokinetics of four long-acting enrofloxacin injectable formulations was investigated in 36 healthy pigs after intramuscular injection according to the recommended single dose @ 2.5 mg/kg body weight. The drug concentrations in the plasma were computed using high-performance liquid chromatography (HPLC) with fluorescence detection. WinNonLin5.2.1 software was used to analyze the experimental data and compared it under one-way ANOVA using SPSS software with a 95% confidence interval (CI). The main pharmacokinetic parameters, that is, the maximum plasma concentrations (Cmax), the time to maximum concentration (Tmax), area under the time curve concentration (AUCall) and Terminal half-life (T1/2) were 733.84 ± 129.87, 917.00 ± 240.13, 694.84 ± 163.49, 621.98 ± 227.25 ng/ml, 2.19 ± 0.0.66, 1.50 ± 0.37, 2.89 ± 0.24, 0.34 ± 0.13 h, 7754.43 ± 2887.16, 8084.11 ± 1543.98, 7369.42 ± 2334.99, 4194.10 ± 1186.62 ng h/ml, 10.48 ± 2.72, 10.37 ± 2.38, 10.20 ± 2.81, and 10.61 ± 0.86 h for 10% enrofloxacin (Alkali), 20% enrofloxacin (Acidic), Yangkang and control drug Nuokang® respectively. There were significant differences among Cmax, Tmax, and AUCall of three formulations compare with that of the reference formulation. No significant differences were observed among the T1/2 for tested formulations compare with the reference formulation. The pharmacokinetic parameters showed that the tested formulations were somewhat better compared to the reference one. The calculated PK/PD indices were effective for bacteria such as Actinobacillus pleuropneumoniae and Pasteurella multocida with values higher than the cut-off points (Cmax/MIC90≥10–12 and AUC/MIC90 ≥ 125). However, they were not effective against bacteria like Haemophilus parasuis, Streptococcus suis, E. coli, and Bordetella bronchiseptica where lower values were obtained.

scholarly journals Single-Dose Pharmacokinetics and Safety of Meropenem-Vaborbactam in Subjects with Chronic Renal Impairment

2018 ◽  
Vol 62 (3) ◽  
Author(s):  
Christopher M. Rubino ◽  
Sujata M. Bhavnani ◽  
Jeffery S. Loutit ◽  
Brooke Lohse ◽  
Michael N. Dudley ◽  
...  
Keyword(s):  
Renal Function ◽  
Single Dose ◽  
Renal Impairment ◽  
Plasma Clearance ◽  
Phase 1 ◽  
Fold Increase ◽  
Pharmacokinetic Parameters ◽  
Open Label ◽  
Single Dose Study ◽  
Chronic Renal Impairment

ABSTRACTVaborbactam is a member of a new class of β-lactamase inhibitors with inhibitory activity against serine carbapenemases (e.g.,Klebsiella pneumoniaecarbapenemase) that has been developed in combination with meropenem. The pharmacokinetics of the combination was evaluated in 41 subjects with chronic renal impairment in a phase 1, open-label, single-dose study. Subjects were assigned to one of five groups based on renal function: normal (creatinine clearance of ≥90 ml/min), mild (estimated glomerular filtration rate [eGFR] of 60 to 89 ml/min/1.73 m2), moderate (eGFR of 30 to <60), or severe (eGFR of <30) impairment plus end-stage renal disease (ESRD) patients on hemodialysis. Subjects received a single intravenous dose of 1 g of meropenem plus 1 g of vaborbactam by 3-h infusion. The ESRD group received two doses (on and off dialysis) separated by a washout. Pharmacokinetic parameters were estimated by standard noncompartmental methods. For both meropenem and vaborbactam, the area under the concentration-time curve was larger and the elimination half-life was longer with decreasing renal function. Meropenem and vaborbactam total plasma clearance (CLt) rates were similar and decreased with decreasing renal function. Slopes of the linear relationship between eGFR and CLt were similar, indicating a similar proportional reduction in CLt with decreasing renal function. Hemodialysis significantly increased drug clearance of meropenem (mean of 2.21-fold increase in CLt,P< 0.001) and vaborbactam (mean of 5.11-fold increase,P= 0.0235) relative to drug administration off dialysis, consistent with dose recovery rates of 38.3% and 52.9% for meropenem and vaborbactam, respectively, in dialysate. Plasma clearance of meropenem and vaborbactam is reduced with renal impairment, requiring dose adjustment. Hemodialysis removes both drugs. (This study has been registered at ClinicalTrials.gov under identifier NCT02020434.)

scholarly journals Pharmacokinetic Interaction between Nevirapine and Nortriptyline in Rats: Inhibition of Nevirapine Metabolism by Nortriptyline

2014 ◽  
Vol 58 (12) ◽  
pp. 7041-7048 ◽  
Author(s):  
Iris Usach ◽  
Virginia Melis ◽  
Patricia Gandía ◽  
José-Esteban Peris
Keyword(s):  
Plasma Concentrations ◽  
Pharmacokinetic Interaction ◽  
Hepatic Metabolism ◽  
Transcriptase Inhibitor ◽  
Tricyclic Antidepressant ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Hepatic Microsomes

ABSTRACTOne of the most frequent comorbidities of HIV infection is depression, with a lifetime prevalence of 22 to 45%. Therefore, it was decided to study a potential pharmacokinetic interaction between the nonnucleoside reverse transcriptase inhibitor nevirapine (NVP) and the tricyclic antidepressant nortriptyline (NT). NVP and NT were administered to rats either orally, intraduodenally, or intravenously, and the changes in plasma levels and pharmacokinetic parameters were analyzed. Experiments with rat and human hepatic microsomes were carried out to evaluate the inhibitory effects of NT on NVP metabolism. NVP plasma concentrations were significantly higher when this drug was coadministered with NT. The maximum plasma concentrations of NVP were increased 2 to 5 times and the total plasma clearance was decreased 7-fold in the presence of NT. However, statistically significant differences in the pharmacokinetic parameters of NT in the absence and presence of NVP were not found.In vitrostudies with rat and human hepatic microsomes confirmed the inhibition of NVP hepatic metabolism by NT in a concentration-dependent way, with the inhibition being more intense in the case of rat microsomes. In conclusion, a pharmacokinetic interaction between NVP and NT was detected. This interaction was a consequence of the inhibition of hepatic metabolism of NVP by NT.In vivohuman studies are required to evaluate the effects of this interaction on the pharmacokinetics of NVP before it can be taken into account for patients receiving NVP.

scholarly journals Absorption and pharmacokinetics of grapefruit flavanones in beagles

2007 ◽  
Vol 98 (1) ◽  
pp. 86-92 ◽  
Author(s):  
Maria de Lourdes Mata-Bilbao ◽  
Cristina Andrés-Lacueva ◽  
Elena Roura ◽  
Olga Jáuregui ◽  
Elvira Escribano ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Biological Activities ◽  
Plasma Concentrations ◽  
Oral Intake ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Blood Samples ◽  
Dog Plasma ◽  
Citrus Flavonoids ◽  
L 14

The present study evaluated the pharmacokinetics of three different grapefruit flavanone forms in dog plasma and demonstrated their absorption after an oral intake of a grapefruit extract; pharmacokinetic parameters of these forms were also determined. Ten healthy beagles were administered 70 mg citrus flavonoids as a grapefruit extract contained in capsules, while two additional dogs were used as controls and given an excipient. The grapefruit flavanone naringin, along with its metabolites naringenin and naringenin glucuronide, was detected in dog plasma. Blood samples were collected between 0 and 24 h after administration of the extract. Naringin reached its maximun plasma concentration at around 80 min, whereas naringenin and naringenin glucuronide reached their maximun plasma concentrations at around 20 and 30 min, respectively. Maximum plasma concentrations of naringin, naringenin and naringenin glucuronide (medians and ranges) were 0·24 (0·05–2·08), 0·021 (0·001–0·3) and 0·09 (0·034–0·12) μmol/l, respectively. The areas under the curves were 23·16 l (14·04–70·62) min × μmol/for nariningin, 1·78 (0·09–4·95) min × μmol/l for naringenin and 22·5 (2·74–99·23) min × μmol/l for naringenin glucuronide. The median and range values for mean residence time were 3·3 (1·5–9·3), 2·8 (0·8–11·2) and 8·0 (2·3–13·1) h for naringin, naringenin and naringenin glucuronide, respectively. The results of the present study demonstrate the absorption of grapefruit flavanones via the presence of their metabolites in plasma, thus making an important contribution to the field since the biological activities ascribed to these compounds rely on their specific forms of absorption.

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