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.

scholarly journals Pharmacokinetic Interaction between Darunavir Boosted with Ritonavir and Omeprazole or Ranitidine in Human Immunodeficiency Virus-Negative Healthy Volunteers

2007 ◽  
Vol 51 (3) ◽  
pp. 958-961 ◽  
Author(s):  
Vanitha J. Sekar ◽  
Eric Lefebvre ◽  
Els De Paepe ◽  
Tine De Marez ◽  
Martine De Pauw ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Plasma Concentration ◽  
Protease Inhibitor ◽  
Healthy Volunteers ◽  
Plasma Concentrations ◽  
Hiv Protease ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Serious Adverse Events ◽  
Immunodeficiency Virus

ABSTRACT Darunavir (DRV; TMC114; Prezista) is a human immunodeficiency virus (HIV) protease inhibitor used in combination with low-dose ritonavir (RTV) (DRV/r) as a pharmacokinetic enhancer. Protease inhibitor absorption may be decreased during coadministration of drugs that limit stomach acid secretion and increase gastric pH. This study was conducted to investigate the effect of ranitidine and omeprazole on the plasma pharmacokinetics of DRV and RTV in HIV-negative healthy volunteers. Sixteen volunteers completed the study and received DRV/r, DRV/r plus ranitidine, and DRV/r plus omeprazole, in three separate sessions. Treatment was given for 4 days with an additional morning dose on day 5, and regimens were separated by a washout period of 7 days. Samples were taken over a 12-h period on day 5 for the assessment of DRV and RTV plasma concentrations. Pharmacokinetic parameters assessed included DRV area under the curve, maximum plasma concentration, and trough plasma concentration. The least-squares mean ratios and 90% confidence intervals are reported with treatment of DRV/r alone as a reference. Compared with DRV/r alone, no significant changes in DRV pharmacokinetic parameters were observed during coadministration of DRV/r and either ranitidine or omeprazole. Treatment regimens were generally well tolerated, and no serious adverse events were reported. In conclusion, coadministration of DRV/r and ranitidine or omeprazole was well tolerated by the volunteers. Ranitidine and omeprazole did not have a significant influence on DRV pharmacokinetics. No dose adjustments are required when DRV/r is coadministered with omeprazole or ranitidine.

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.

Pharmacokinetics and metabolism of epidoxorubicin and doxorubicin in humans.

1988 ◽  
Vol 6 (3) ◽  
pp. 517-526 ◽  
Author(s):  
K Mross ◽  
P Maessen ◽  
W J van der Vijgh ◽  
H Gall ◽  
E Boven ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Urinary Excretion ◽  
Half Life ◽  
Enterohepatic Circulation ◽  
Plasma Concentrations ◽  
Parent Drug ◽  
Volume Of Distribution ◽  
Maximum Plasma ◽  
Cumulative Urinary Excretion ◽  
Second Peak

Pharmacokinetics of doxorubicin (DOX), epidoxorubicin (EPI), and their metabolites in plasma have been performed in eight patients receiving 40 to 56 mg/m2 of both anthracyclines as a bolus injection in two sequential cycles. Terminal half-life and volume of distribution appeared to be smaller in case of EPI, whereas plasma clearance and cumulative urinary excretion was larger in comparison to DOX. The major metabolite of DOX was doxorubicinol (Aol) followed by 7-deoxy-doxorubicinol (7d-Aolon). Metabolism to glucuronides was found in case of EPI only. The area under the curves (AUC) of the metabolites of EPI decreased in the order of the glucoronides E-glu greater than Eol-glu, 7d-Aolon greater than epirubicinol (Eol). The AUC of Eol was half of the value in its counterpart Aol. In the case of EPI, the AUC of 7d-Aolon was twice the level of that of the corresponding metabolite of DOX. The terminal half-lives of the cytostatic metabolites Aol and Eol were similar, but longer than the corresponding values of their parent drugs. Half-lives of the glucuronides (E-glu, Eol-glu) were similar to the half-life of their parent drug. 7d-Aolon had a somewhat shorter half-life in comparison to both DOX and EPI. Approximately 6.2% of EPI and 5.9% of DOX were excreted by the kidney during the initial 48 hours. Aol was found in the urine of patients treated with DOX, whereas Eol, E-glu, and Eol-glu were detected in urine of patients treated with EPI. The cumulative urinary excretion appeared to be 10.5% for EPI and its metabolites, and 6.9% for DOX and its metabolite. The plasma concentration v time curves of (7d)-aglycones showed a second peak between two and 12 hours after injection, suggesting an enterohepatic circulation for metabolites lacking the daunosamine sugar moiety. The plasma concentrations of the glucuronides were maximal at 1.2 hours for E-glu and 1.9 hours for Eol-glu. All other compounds reached their maximum plasma concentration during the first minutes after the administration of DOX and EPI. Deviating plasma kinetics were observed in one patient, probably due to prior drug administration.

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 L-Dopa Pharmacokinetic Profile with Effervescent Melevodopa/Carbidopa versus Standard-Release Levodopa/Carbidopa Tablets in Parkinson’s Disease: A Randomised Study

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Fabrizio Stocchi ◽  
Laura Vacca ◽  
Paola Grassini ◽  
Stephen Pawsey ◽  
Holly Whale ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Plasma Concentration ◽  
Pharmacokinetic Profile ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Double Blind ◽  
Time Curve ◽  
Randomised Study ◽  
Effervescent Tablet

Objectives.To characterize the pharmacokinetic profile of levodopa (L-dopa) and carbidopa after repeated doses of the effervescent tablet of melevodopa/carbidopa (V1512; Sirio) compared with standard-release L-dopa/carbidopa in patients with fluctuating Parkinson’s disease. Few studies assessed the pharmacokinetics of carbidopa to date.Methods.This was a single-centre, randomized, double-blind, double-dummy, two-period crossover study. Patients received V1512 (melevodopa 100 mg/carbidopa 25 mg) or L-dopa 100 mg/carbidopa 25 mg, 7 doses over 24 hours (Cohort 1), 4 doses over 12 hours (Cohort 2), or 2 doses over 12 hours in combination with entacapone 200 mg (Cohort 3). Pharmacokinetic parameters included area under the plasma-concentration time curve (AUC), maximum plasma concentration (Cmax), and time toCmax(tmax).Results.Twenty-five patients received at least one dose of study medication. L-dopa absorption tended to be quicker and pharmacokinetic parameters less variable after V1512 versus L-dopa/carbidopa, both over time and between patients. Accumulation of L-dopa in plasma was less noticeable with V1512. Carbidopa exposure and interpatient variability was lower when V1512 or L-dopa/carbidopa was given in combination with entacapone. Both treatments were well tolerated.Conclusions.V1512 provides a more reliable L-dopa pharmacokinetic profile versus standard-release L-dopa/carbidopa, with less drug accumulation and less variability. This trial is registered with ClinicalTrials.govNCT00491998.

scholarly journals Severe Renal Impairment Has Minimal Impact on Doravirine Pharmacokinetics

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Wendy Ankrom ◽  
Ka Lai Yee ◽  
Rosa I. Sanchez ◽  
Adedayo Adedoyin ◽  
Li Fan ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Renal Impairment ◽  
Severe Renal Impairment ◽  
Geometric Mean ◽  
Plasma Concentrations ◽  
Area Under The Curve ◽  
Transcriptase Inhibitor ◽  
Maximum Plasma ◽  
Minor Effect ◽  
Minimal Impact

ABSTRACT Doravirine is a novel nonnucleoside reverse transcriptase inhibitor in development for use with other antiretroviral therapies to treat human immunodeficiency virus type 1 (HIV-1) infection. Doravirine metabolism predominantly occurs via cytochrome P450 3A with <10% of elimination occurring via the renal pathway. As severe renal impairment can alter the pharmacokinetics (PK) of metabolically eliminated drugs, the effect of severe renal impairment on doravirine PK was assessed. A single dose of doravirine 100 mg was administered to subjects aged 18 to 75 years with an estimated glomerular filtration rate (eGFR) of <30 ml/min/1.73 m2 (severe renal impairment group) and healthy controls with an eGFR of ≥80 ml/min/1.73 m2, matched to the mean of the renal impairment group by age (±10 years) and weight (±10 kg). Doravirine plasma concentrations were determined at regular intervals, and safety was monitored throughout. The geometric mean ratios (90% confidence interval) for severe renal impairment/healthy subjects were 1.43 (1.00, 2.04), 1.38 (0.99, 1.92), and 0.83 (0.61, 1.15) for the plasma doravirine area under the curve from zero to infinity (AUC0–∞), plasma concentration at 24 h postdose (C24), and maximum plasma concentration (Cmax), respectively. Doravirine was generally well tolerated in both groups. Based on the overall efficacy, safety, and PK profile of doravirine, the minor effect of severe renal impairment on doravirine PK observed in this study is not considered clinically meaningful. (This study has been registered at ClinicalTrials.gov under identifier NCT02641067.)

Phase I/IIa, randomized, open-label, drug-drug interaction study of trabectedin and rifampin in patients with advanced cancer.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e13512-e13512 ◽  
Author(s):  
Arthur P. Staddon ◽  
Trilok V. Parekh ◽  
Roland Elmar Knoblauch ◽  
Chi Keung ◽  
Apexa Bernard ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Locally Advanced ◽  
Plasma Concentrations ◽  
Systemic Exposure ◽  
Maximum Plasma ◽  
Metabolic Clearance ◽  
Open Label ◽  
Time Curve ◽  
Elimination Half ◽  
Cyp3a4 Inducer

e13512 Background: Trabectedin (Yondelis; T) is a tetrahydroisoquinoline compound initially isolated from the marine tunicate, Ecteinascidia turbinata, and currently produced synthetically. It is primarily metabolized by the cytochrome P450 (CYP)3A4 enzyme. Thus, potent inducers or inhibitors of this enzyme may alter the plasma concentrations of T. This study assessed the effects of rifampin (R), a strong CYP3A4 inducer, on the pharmacokinetics (PK) and safety of T. Methods: In this 2-way crossover study, patients (≥18 years of age) with locally advanced or metastatic disease were randomized (1:1) to receive one of the 2 treatment sequences: sequence 1: R plus T followed 28 days later by T; sequence 2: T followed 28 days later by R plus T. During each sequence, R (600 mg/day) was administered for 6 consecutive days and T (1.3 mg/m2, IV) was administered over a 3 hour infusion. Dexamethasone (20 mg, IV) was administered before T administration. PK and safety of T were evaluated with and without coadministration of R. Results: Of the 11 enrolled patients, 8 were PK evaluable. Coadministration of R with T decreased mean maximum plasma concentration (Cmax) by approximately 22% and mean area under the plasma concentration-time curve from time 0 to the last quantifiable concentration (AUClast) by approximately 31% (Table 1). Coadministration of R with T also resulted in 23% shorter elimination half-life. Overall, the safety profile of T was comparable when administered alone or with R. Conclusions: In comparison with T alone, coadministration of R resulted in reduced systemic exposure of T in these 8 patients, as measured by Cmax and AUClast. The coadministration of potent inducers of CYP3A4 with T may increase the metabolic clearance of T. Clinical trial information: NCT01273480. [Table: see text]

scholarly journals Pharmacokinetics of Telbivudine in Subjects with Various Degrees of Hepatic Impairment

2006 ◽  
Vol 50 (5) ◽  
pp. 1721-1726 ◽  
Author(s):  
Xiao-Jian Zhou ◽  
Thomas C. Marbury ◽  
Harry W. Alcorn ◽  
William B. Smith ◽  
Gloria Dubuc Patrick ◽  
...  
Keyword(s):  
Hepatitis B Virus ◽  
Plasma Concentration ◽  
Hepatitis B ◽  
Hepatic Impairment ◽  
Hepatic Function ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Concentration Time ◽  
Chronic Hepatitis B Virus ◽  
B Virus

ABSTRACT This study evaluated the effect of hepatic impairment on the pharmacokinetics of telbivudine, an investigational nucleoside antiviral for the treatment of chronic hepatitis B virus infection. Twenty-four subjects were assigned to four hepatic function groups (normal function and mild, moderate, and severe impairment, with six subjects in each group) on the basis of Child-Pugh scores. The subjects were administered a single oral dose of 600 mg telbivudine, and blood samples were collected over a 48-h interval for pharmacokinetic analyses. Telbivudine was well tolerated by all subjects. Telbivudine plasma concentration-time profiles were similar across the four hepatic function groups. The principal pharmacokinetic parameters of drug exposure, i.e., the maximum plasma concentration and area under the drug concentration-time curve, were comparable between subjects with various degrees of hepatic impairment and those with normal hepatic function. Results from this single-dose pharmacokinetic assessment therefore provide a pharmacologic rationale for further evaluation of the safety and efficacy of telbivudine in hepatitis B virus-infected patients with decompensated liver diseases.

Clinical Rules for Phenytoin Dosing

1993 ◽  
Vol 27 (10) ◽  
pp. 1169-1173 ◽  
Author(s):  
Michael D. Privitera
Keyword(s):  
Plasma Concentration ◽  
Plasma Concentrations ◽  
Test Group ◽  
Patient Data ◽  
Pharmacokinetic Parameters ◽  
Concentration Data ◽  
Simple Method ◽  
Actual Patient ◽  
Initial Plasma ◽  
Clinical Rules

OBJECTIVE: To develop simple clinical rules for dosing phenytoin (PHT) using computer simulations, then to test the rules for accuracy and safety on actual patient data. DESIGN: Patients with steady-state PHT plasma concentrations at least two different PHT doses were identified from three separate sources of patient data. A computerized dosing program calculated pharmacokinetic parameters using Bayesian methodology, then predicted how many patients were likely to reach potentially toxic PHT plasma concentrations when their daily dosage was increased by 30, 50, or 100 mg. Dosing rules were developed to allow fewer than ten percent of resultant plasma concentrations to exceed 25 μg/mL. The dosing rules then were tested on dose/plasma concentration data from a separate group of patients. SETTING: All patients were being treated by neurologists either as outpatients or inpatients. PATIENTS: All patients were adults with epilepsy being treated with PHT; none had clinically significant renal or hepatic disease. Patients for the computer simulation were from three sources: (1) patients who had an initial PHT plasma concentration <10 μg/mL and required a dosage increase; (2) patients admitted to the hospital for PHT intoxication; and (3) patients who required consultations specifically for PHT dosing. Patients on whom the dosing rules were tested were part of a prospective, randomized trial of antiepileptic drug safety and efficacy. MAIN OUTCOME MEASURES: Successful dosing rules allowing fewer than ten percent of resulting plasma concentrations in the test group to exceed 25 μg/mL. RESULTS: The simulations used 167 actual dose/plasma concentration pairs from 45 patients. The resulting dosing rules were: increase the dosage by 100 mg/d if the initial plasma concentration was <7 μg/mL; increase the dosage by 50 mg/d if the initial plasma concentration is 7 to <12 μg/mL; increase the dosage by 30 mg/d if the initial plasma concentration is ≥12 μg/mL. The rules were tested on 129 50- or 100-mg dosage increases in 77 patients. All 53 dosage increases that were within the dosing rules produced plasma concentrations <25 μg/mL, whereas 36 percent (27 of 74) of the dosage increases that exceeded the dosing rules produced plasma concentrations >25 μg/mL. CONCLUSIONS: The proposed dosing rules are a simple method for clinicians to estimate PHT dosage changes and appear to be safe and accurate when applied retrospectively to actual patient data.

scholarly journals The Effects of Formaldehyde on Cytochrome P450 Isoform Activity in Rats

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Min Xu ◽  
Huaqiao Tang ◽  
Qian Rong ◽  
Yuanli Zhang ◽  
Yinglun Li ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Plasma Concentrations ◽  
Pharmacokinetic Parameters ◽  
Control Group ◽  
High Dose ◽  
Blood Samples ◽  
Time Points ◽  
Indoor Pollutant ◽  
Carcinogenic Effects

Formaldehyde (FA) is an occupational and indoor pollutant. Long-term exposure to FA can irritate the respiratory mucosa, with potential carcinogenic effects on the airways. The effects of acute FA poisoning on the activities of CYP450 isoforms CYP1A2, CYP2C11, CYP2E1, and CYP3A2 were assessed by determining changes in the pharmacokinetic parameters of the probe drugs phenacetin, tolbutamide, chlorzoxazone, and testosterone, respectively. Rats were randomly divided into three groups: control, low FA dose (exposure to 110 ppm for 2 h for 3 days), and high FA dose (exposure to 220 ppm for 2 h for 3 days). A mixture of the four probe drugs was injected into rats and blood samples were taken at a series of time points. Plasma concentrations of the probe drugs were measured by HPLC. The pharmacokinetic parameters t1/2, AUC(0-t), and Cmax of tolbutamide, chlorzoxazone, and testosterone increased significantly in the high dose versus control group (P<0.05), whereas the CL of chlorzoxazone and testosterone decreased significantly (P<0.05). However, t1/2, AUC(0-t), and Cmax of phenacetin decreased significantly (P<0.05), whereas the CL of phenacetin increased significantly (P<0.05) compared to controls. Thus, acute FA poisoning suppressed the activities of CYP2C11, CYP2E1, and CYP3A2 and induced the activity of CYP1A2 in rats. And the change of CYP450 activity caused by acute FA poisoning may be associated with FA potential carcinogenic effects on the airways.

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