scholarly journals Rifampin Greatly Reduces the Plasma Concentrations of Intravenous and Oral Oxycodone

2009 ◽  
Vol 110 (6) ◽  
pp. 1371-1378 ◽  
Author(s):  
Tuija H. Nieminen ◽  
Nora M. Hagelberg ◽  
Teijo I. Saari ◽  
Antti Pertovaara ◽  
Mikko Neuvonen ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Plasma Concentrations ◽  
Parent Drug ◽  
Cytochrome P450 3A ◽  
Time Curve ◽  
Cold Pain ◽  
Visual Analog Scales ◽  
Concentration Time ◽  
Heat Pain Threshold ◽  
Oxycodone Hydrochloride

Background Oxycodone is a mu-opioid receptor agonist that is metabolized mainly in the liver by cytochrome P450 3A and 2D6 enzymes. Rifampin is a strong inducer of several drug-metabolizing enzymes. The authors studied the interaction of rifampin with oxycodone. Their hypothesis was that rifampin enhances the CYP3A-mediated metabolism of oxycodone and attenuates its pharmacologic effect. Methods The protocol was a four-session, paired crossover. Twelve volunteers were given 600 mg oral rifampin or placebo once daily for 7 days. Oxycodone was given on day 6. In the first part of the study, 0.1 mg/kg oxycodone hydrochloride was given intravenously. In the second part of the study, 15 mg oxycodone hydrochloride was given orally. Concentrations of oxycodone and its metabolites noroxycodone, oxymorphone, and noroxymorphone were determined for 48 h. Psychomotor effects were characterized for 12 h by several visual analog scales. Analgesic effects were characterized by measuring the heat pain threshold and cold pain sensitivity. Results Rifampin decreased the area under the oxycodone concentration-time curve of intravenous and oral oxycodone by 53% and 86%, respectively (P < 0.001). Oral bioavailability of oxycodone was decreased from 69% to 21% (P < 0.001). Rifampin greatly increased the plasma metabolite-to-parent drug ratios for noroxycodone and noroxymorphone (P < 0.001). Pharmacologic effects of oral oxycodone were attenuated. Conclusions Induction of cytochrome P450 3A by rifampin reduced the area under the oxycodone concentration-time curve of intravenous and oral oxycodone. The pharmacologic effects of oxycodone were modestly attenuated. To maintain adequate analgesia, dose adjustment of oxycodone may be necessary, when used concomitantly with rifampin.

scholarly journals Pharmacokinetic Interactions of Maraviroc with Darunavir-Ritonavir, Etravirine, and Etravirine-Darunavir-Ritonavir in Healthy Volunteers: Results of Two Drug Interaction Trials

2011 ◽  
Vol 55 (5) ◽  
pp. 2290-2296 ◽  
Author(s):  
Thomas N. Kakuda ◽  
Samantha Abel ◽  
John Davis ◽  
Julia Hamlin ◽  
Monika Schöller-Gyüre ◽  
...  
Keyword(s):  
Steady State ◽  
Healthy Volunteers ◽  
Potent Inhibitor ◽  
Cytochrome P450 3A ◽  
Short Term ◽  
Two Phase ◽  
Time Curve ◽  
Safety Issues ◽  
Concentration Time ◽  
Crossover Studies

ABSTRACTThe effects of darunavir-ritonavir at 600 and 100 mg twice daily (b.i.d.) alone, 200 mg of etravirine b.i.d. alone, or 600 and 100 mg of darunavir-ritonavir b.i.d. with 200 mg etravirine b.i.d. at steady state on the steady-state pharmacokinetics of maraviroc, and vice versa, in healthy volunteers were investigated in two phase I, randomized, two-period crossover studies. Safety and tolerability were also assessed. Coadministration of 150 mg maraviroc b.i.d. with darunavir-ritonavir increased the area under the plasma concentration-time curve from 0 to 12 h (AUC12) for maraviroc 4.05-fold relative to 150 mg of maraviroc b.i.d. alone. Coadministration of 300 mg maraviroc b.i.d. with etravirine decreased the maraviroc AUC12by 53% relative to 300 mg maraviroc b.i.d. alone. Coadministration of 150 mg maraviroc b.i.d. with etravirine-darunavir-ritonavir increased the maraviroc AUC123.10-fold relative to 150 mg maraviroc b.i.d. alone. Maraviroc did not significantly affect the pharmacokinetics of etravirine, darunavir, or ritonavir. Short-term coadministration of maraviroc with darunavir-ritonavir, etravirine, or both was generally well tolerated, with no safety issues reported in either trial. Maraviroc can be coadministered with darunavir-ritonavir, etravirine, or etravirine-darunavir-ritonavir. Maraviroc should be dosed at 600 mg b.i.d. with etravirine in the absence of a potent inhibitor of cytochrome P450 3A (CYP3A) (i.e., a boosted protease inhibitor) or at 150 mg b.i.d. when coadministered with darunavir-ritonavir with or without etravirine.

Exposure to Retinoic Acids in Non-Pregnant Women Following High Vitamin A Intake with a Liver Meal

2005 ◽  
Vol 75 (3) ◽  
pp. 187-194 ◽  
Author(s):  
Hartmann ◽  
Brørs ◽  
Bock ◽  
Blomhoff ◽  
Bausch ◽  
...  
Keyword(s):  
Plasma Concentration ◽  
Vitamin A ◽  
Safety Concern ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Pregnant Female ◽  
Time Curve ◽  
High Vitamin ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

Animal liver is a rich source of vitamin A. Due to retinoic acid (RA) metabolites, vitamin A has a teratogenic potential and women are generally advised to avoid or to limit the consumption of liver during pregnancy. In a recent study in non-pregnant female volunteers following single and repeated doses of up to 30,000 IU/day of vitamin A as a supplement, the plasma concentration time curve of all-trans RA acid showed a diurnal-like profile. But, the overall exposure (AUC24h) remained essentially unaltered whereas AUC24h increased linearly with dose for 13-cis and 13-cis-4-oxo RA. The current study in non-pregnant female volunteers showed that a single high vitamin A intake with a liver meal (up to 120,000 IU) exhibited a similar diurnal-like plasma concentration time curve for all-trans RA and its overall exposure remained also unaltered, despite a temporary two-fold increase in peak plasma concentration. Concentrations of 13-cis and 13-cis-4-oxo RA increased several-fold after a liver meal, and exposure (AUC24h) increased three- to five-fold. Pooling our results with data in the literature revealed a linear relation between the mean AUC24h of 13-cis and 13-cis-4-oxo RA and vitamin A intake with liver. Metabolism to all-trans RA of vitamin A with liver seems not to be of safety concern. However, the observed increase of plasma concentrations and the dose-dependent increase in exposure to 13-cis and 13-cis-4-oxo RA support the current safety recommendations on vitamin A intake and suggest that women should be cautious regarding their consumption of liver-containing meals during pregnancy.

scholarly journals Pharmacokinetics of Daptomycin in Critically Ill Pediatric Patients

2018 ◽  
Vol 62 (6) ◽  
Author(s):  
Charalampos Antachopoulos ◽  
Stavroula Ilia ◽  
Paschalis Kadiltzoglou ◽  
Eirini Baira ◽  
Aristides Dokoumetzidis ◽  
...  
Keyword(s):  
Critically Ill ◽  
Drug Exposure ◽  
Pediatric Patients ◽  
Plasma Concentrations ◽  
Therapeutic Drug ◽  
Burn Patients ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
Optimal Drug

ABSTRACT The pharmacokinetics of daptomycin (10 mg/kg once daily) was studied in 4 critically ill pediatric patients aged 8 to 14 yrs. The area under the concentration-time curve from time zero to infinity (AUC 0–∞ ) of plasma concentrations on day 1 ranged between 123.8 to 663.9 μg · h/ml, with lower values observed in septic and burn patients; clearance ranged from 15.1 to 80.7 ml/h/kg. Higher-than-recommended doses of daptomycin may be needed in septic children to ensure optimal drug exposure. Interpatient variability may suggest a role for therapeutic drug monitoring.

scholarly journals Is the Recommended Dose of Efavirenz Optimal in Young West African Human Immunodeficiency Virus-Infected Children?

2009 ◽  
Vol 53 (10) ◽  
pp. 4407-4413 ◽  
Author(s):  
Déborah Hirt ◽  
Saik Urien ◽  
Mathieu Olivier ◽  
Hélène Peyrière ◽  
Boubacar Nacro ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Body Weight ◽  
Plasma Concentrations ◽  
Individual Characteristics ◽  
Population Pharmacokinetic ◽  
Ratio Test ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
Immunodeficiency Virus

ABSTRACT We aimed in this study to describe efavirenz concentration-time courses in treatment-naïve children after once-daily administration to study the effects of age and body weight on efavirenz pharmacokinetics and to test relationships between doses, plasma concentrations, and efficacy. For this purpose, efavirenz concentrations in 48 children were measured after 2 weeks of didanosine-lamivudine-efavirenz treatment, and samples were available for 9/48 children between months 2 and 5 of treatment. Efavirenz concentrations in 200 plasma specimens were measured using a validated high-performance liquid chromatography method. A population pharmacokinetic model was developed with NONMEM. The influence of individual characteristics was tested using a likelihood ratio test. The estimated minimal and maximal concentrations of efavirenz in plasma (C min and C max, respectively) and the area under the concentration-time curve (AUC) were correlated to the decrease in human immunodeficiency virus type 1 RNA levels after 3 months of treatment. The threshold C min (and AUC) that improved efficacy was determined. The target minimal concentration of 4 mg/liter was considered for toxicity. An optimized dosing schedule that would place the highest percentage of children in the interval of effective and nontoxic concentrations was simulated. The pharmacokinetics of efavirenz was best described by a one-compartment model with first-order absorption and elimination. The mean apparent clearance and volume of distribution for efavirenz were 0.211 liter/h/kg and 4.48 liters/kg, respectively. Clearance decreased significantly with age. When the recommended doses were given to 46 of the 48 children, 19% (44% of children weighing less than 15 kg) had C mins below 1 mg/liter. A significantly higher percentage of children with C mins of >1.1 mg/liter or AUCs of >51 mg/liter·h than of children with lower values had viral load decreases greater than 2 log10 copies/ml after 3 months of treatment. Therefore, to optimize the percentage of children with C mins between 1.1 and 4 mg/liter, children should receive the following once-daily efavirenz doses: 25 mg/kg of body weight from 2 to 6 years, 15 mg/kg from 6 to 10 years, and 10 mg/kg from 10 to 15 years. These assumptions should be prospectively confirmed.

scholarly journals Achieving a physiological cortisol profile with once-daily dual-release hydrocortisone: a pharmacokinetic study

2016 ◽  
Vol 175 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Gudmundur Johannsson ◽  
Hans Lennernäs ◽  
Claudio Marelli ◽  
Kevin Rockich ◽  
Stanko Skrtic
Keyword(s):  
Replacement Therapy ◽  
Plasma Concentrations ◽  
Open Label ◽  
Post Dose ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
Endogenous Cortisol ◽  
Dual Release ◽  
Dose Proportional

Objective Oral once-daily dual-release hydrocortisone (DR-HC) replacement therapy was developed to provide a cortisol exposure−time profile that closely resembles the physiological cortisol profile. This study aimed to characterize single-dose pharmacokinetics (PK) of DR-HC 5–20mg and assess intrasubject variability. Methods Thirty-one healthy Japanese or non-Hispanic Caucasian volunteers aged 20−55 years participated in this randomized, open-label, PK study. Single doses of DR-HC 5, 15 (3×5), and 20mg were administered orally after an overnight fast and suppression of endogenous cortisol secretion. After estimating the endogenous cortisol profile, PK of DR-HC over 24h were evaluated to assess dose proportionality and impact of ethnicity. Plasma cortisol concentrations were analyzed using liquid chromatography−tandem mass spectrometry. PK parameters were calculated from individual cortisol concentration−time profiles. Results DR-HC 20mg provided higher than endogenous cortisol plasma concentrations 0−4h post-dose but similar concentrations later in the profile. Cortisol concentrations and PK exposure parameters increased with increasing doses. Mean maximal serum concentration (Cmax) was 82.0 and 178.1ng/mL, while mean area under the concentration−time curve (AUC)0−∞ was 562.8 and 1180.8h×ng/mL with DR-HC 5 and 20mg respectively. Within-subject PK variability was low (<15%) for DR-HC 20mg. All exposure PK parameters were less than dose proportional (slope <1). PK differences between ethnicities were explained by body weight differences. Conclusions DR-HC replacement resembles the daily normal cortisol profile. Within-subject day-to-day PK variability was low, underpinning the safety of DR-HC for replacement therapy. DR-HC PK were less than dose proportional – an important consideration when managing intercurrent illness in patients with adrenal insufficiency.

Pharmacogenomics of Tamoxifen Therapy

2009 ◽  
Vol 55 (10) ◽  
pp. 1770-1782 ◽  
Author(s):  
Hiltrud Brauch ◽  
Thomas E Mürdter ◽  
Michel Eichelbaum ◽  
Matthias Schwab
Keyword(s):  
Cytochrome P450 ◽  
Selective Serotonin Reuptake Inhibitors ◽  
Plasma Concentrations ◽  
Hot Flashes ◽  
Parent Drug ◽  
Endocrine Treatment ◽  
Active Metabolites ◽  
Recurrence Rates ◽  
Hormone Receptor Positive ◽  
Cyp2d6 Inhibitors

Abstract Background: Tamoxifen is a standard endocrine therapy for the prevention and treatment of steroid hormone receptor–positive breast cancer. Content: Tamoxifen requires enzymatic activation by cytochrome P450 (CYP) enzymes for the formation of active metabolites 4-hydroxytamoxifen and endoxifen. As compared with the parent drug, both metabolites have an approximately 100-fold greater affinity for the estrogen receptor and the ability to inhibit cell proliferation. The polymorphic CYP2D6 is the key enzyme in this biotransformation, and recent mechanistic, pharmacologic, and clinical evidence suggests that genetic variants and drug interaction by CYP2D6 inhibitors influence the plasma concentrations of active tamoxifen metabolites and the outcomes of tamoxifen-treated patients. In particular, nonfunctional (poor metabolizer) and severely impaired (intermediate metabolizer) CYP2D6 alleles are associated with higher recurrence rates. Summary: Accordingly, CYP2D6 (cytochrome P450, family 2, subfamily D, polypeptide 6) genotyping before treatment to predict metabolizer status may open new avenues for individualizing endocrine treatment, with the maximum benefit being expected for extensive metabolizers. Moreover, strong CYP2D6 inhibitors such as the selective serotonin reuptake inhibitors paroxetine and fluoxetine, which are used to treat hot flashes, should be avoided because they severely impair formation of the active metabolites.

Interaction of Metoprolol, Propranolol and Atenolol with Cimetidine

1982 ◽  
Vol 63 (s8) ◽  
pp. 451s-453s ◽  
Author(s):  
W. Kirch ◽  
H. Spahn ◽  
H. Köhler ◽  
E. Mutschler
Keyword(s):  
Plasma Concentration ◽  
Healthy Volunteers ◽  
Peak Plasma ◽  
Plasma Concentrations ◽  
Concurrent Administration ◽  
Time Curve ◽  
Concentration Time ◽  
Plasma Concentration Time Curve

1. Pharmacokinetics of metoprolol, propranolol and atenolol were investigated in six healthy volunteers after 7 days of oral monotherapy with these drugs and after 7 days concurrent administration, with each of these β-adrenoceptor antagonists with cimetidine. 2. Cimetidine did not interact with atenolol, whereas mean peak plasma concentrations of metoprolol were increased by 70%, and those of propranolol by 95% with concurrent administration of cimetidine (P < 0.05). 3. The area under the plasma concentration-time curve for propranolol and metoprolol was similarly increased (P < 0.05).

scholarly journals Rifampin Reduces Concentrations of Trimethoprim and Sulfamethoxazole in Serum in Human Immunodeficiency Virus-Infected Patients

2001 ◽  
Vol 45 (11) ◽  
pp. 3238-3241 ◽  
Author(s):  
Esteban Ribera ◽  
Leonor Pou ◽  
Antoni Fernandez-Sola ◽  
Francisco Campos ◽  
Rosa M. Lopez ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
High Performance Liquid Chromatography ◽  
High Performance ◽  
Parent Drug ◽  
Time Curve ◽  
Once Daily ◽  
Concentration Time ◽  
Antituberculosis Treatment ◽  
Immunodeficiency Virus ◽  
Before And After

ABSTRACT To determine whether rifampin reduces concentrations of trimethoprim (TMP) and sulfamethoxazole (SMX) in serum of human immunodeficiency virus (HIV)-infected persons, levels of these agents were determined by high-performance liquid chromatography before and after more than 12 days of standard antituberculosis treatment for 10 patients who had been taking one double-strength tablet of co-trimoxazole once daily for more than 1 month. Statistically significant, 47 and 23% decreases in TMP and SMX mean areas under the concentration-time curve from 0 to 24 h (AUC0–24), respectively, were observed after administration of rifampin.N-Acetyl-SMX profiles without and with rifampin were similar. The steady-state AUC0–24 metabolite/parent drug ratio increased by 32% with rifampin administration. Our study shows that rifampin reduces profiles of TMP and SMX in serum of HIV-infected patients.

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