scholarly journals Impact of Albumin and Omeprazole on Steady-State Population Pharmacokinetics of Voriconazole and Development of a Voriconazole Dosing Optimization Model in Thai Patients with Hematologic Diseases

Antibiotics ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 574
Author(s):  
Buddharat Khan-asa ◽  
Baralee Punyawudho ◽  
Noppaket Singkham ◽  
Piyawat Chaivichacharn ◽  
Ekapun Karoopongse ◽  
...  
Keyword(s):  
Steady State ◽  
Compartment Model ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Albumin Level ◽  
Hematologic Diseases ◽  
Mixed Effects Modeling ◽  
Dosing Regimens ◽  
The One ◽  
Dosing Optimization

This study aimed to identify factors that significantly influence the pharmacokinetics of voriconazole in Thai adults with hematologic diseases, and to determine optimal voriconazole dosing regimens. Blood samples were collected at steady state in 65 patients (237 concentrations) who were taking voriconazole to prevent or treat invasive aspergillosis. The data were analyzed using a nonlinear mixed-effects modeling approach. Monte Carlo simulation was applied to optimize dosage regimens. Data were fitted with the one-compartment model with first-order absorption and elimination. The apparent oral clearance (CL/F) was 3.43 L/h, the apparent volume of distribution (V/F) was 47.6 L, and the absorption rate constant (Ka) was fixed at 1.1 h−1. Albumin and omeprazole ≥ 40 mg/day were found to significantly influence CL/F. The simulation produced the following recommended maintenance doses of voriconazole: 50, 100, and 200 mg every 12 h for albumin levels of 1.5–3, 3.01–4, and 4.01–4.5 g/dL, respectively, in patients who receive omeprazole ≤ 20 mg/day. Patients who receive omeprazole ≥ 40 mg/day and who have serum albumin level 1.5–3 and 3.01–4.5 g/dL should receive voriconazole 50 and 100 mg, every 12 h, respectively. Albumin level and omeprazole dosage should be carefully considered when determining the appropriate dosage of voriconazole in Thai patients.

Letters to the Editor

PEDIATRICS ◽  
1981 ◽  
Vol 68 (4) ◽  
pp. 602-603
Author(s):  
Charles H. Feldman ◽  
Vincent E. Hutchinson ◽  
Charles E. Pippenger ◽  
Thomas A. Blumenfeld ◽  
Bernard R. Feldman ◽  
...  
Keyword(s):  
Elimination Rate ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Apparent Volume ◽  
Systemic Circulation ◽  
Volume Of Distribution ◽  
Letters To The Editor ◽  
Correct Formula ◽  
Original Report ◽  
Apparent Volume Of Distribution

We appreciate the comments of Weinberger et al and Spino et al. The equation utilized in our original report to calculate the apparent volume of distribution (V) was in error, as it was based on determinations for drugs that exhibit monoexponential elimination following a single intravenous dose. The correct formula for oral dosing at steady state with a drug obeying one-compartment model kinetics is: V = F.X0/AUCτ. K, where F is the total fraction of dose reaching systemic circulation, X0, is the dose, AUCτ is the area under the curve during a dosing interval; K is the elimination rate constant.1

scholarly journals Population Pharmacokinetics Modelling and Simulation of Mitotane in Patients with Adrenocortical Carcinoma: An Individualized Dose Regimen to Target All Patients at Three Months?

Pharmaceutics ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 566 ◽  
Author(s):  
Yoann Cazaubon ◽  
Yohann Talineau ◽  
Catherine Feliu ◽  
Céline Konecki ◽  
Jennifer Russello ◽  
...  
Keyword(s):  
Adrenocortical Carcinoma ◽  
Plasma Concentrations ◽  
Therapeutic Index ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Pharmacokinetic Analysis ◽  
Concentration Data ◽  
Starting Dose ◽  
Dosing Regimens ◽  
Data Files

Mitotane is the most effective agent in post-operative treatment of adrenocortical carcinoma. In adults, the starting dose is 2–3 g/day and should be slightly increased to reach the therapeutic index of 14–20 mg/L. This study developed a population PK model for mitotane and to simulate recommended/high dosing regimens. We retrospectively analyzed the data files of 38 patients with 503 plasma concentrations for the pharmacokinetic analysis. Monolix version 2019R1 was used for non-linear mixed-effects modelling. Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA ≥ 14 mg/L) at one month and at three months. Mitotane concentration data were best described by a linear one-compartment model. The estimated PK parameters (between-subject variability) were: 8900 L (90.4%) for central volume of distribution (V) and 70 L·h−1 (29.3%) for clearance (Cl). HDL, Triglyceride (Tg) and a latent covariate were found to influence Cl. The PTA at three months for 3, 6, 9, and 12 g per day was 10%, 55%, 76%, and 85%, respectively. For a loading dose of 15 g/day for one month then 5 g/day, the PTA in the first and third months was 57 and 69%, respectively. This is the first PKpop model of mitotane highlighting the effect of HDL and Tg covariates on the clearance as well as a subpopulation of ultrafast metabolizer. The simulations suggest that recommended dose regimens are not enough to target the therapeutic threshold in the third month.

Assessment of methods for improving tracer estimation of non-steady-state rate of appearance

1999 ◽  
Vol 87 (5) ◽  
pp. 1813-1822 ◽  
Author(s):  
A. Gastaldelli ◽  
A. R. Coggan ◽  
R. R. Wolfe
Keyword(s):  
Steady State ◽  
Infusion Rate ◽  
Traditional Approach ◽  
Volume Of Distribution ◽  
Constant Volume ◽  
Constant Infusion ◽  
Steady State Condition ◽  
Fixed Volume ◽  
The One ◽  
Infusion Technique

The most common approach for estimating substrate rate of appearance (Ra) is use of the single-pool model first proposed by R. W. Steele, J. S. Wall, R. C. DeBodo, and N. Altszuler. ( Am. J. Physiol. 187: 15–24, 1956). To overcome the model error during highly non-steady-state conditions due to the assumption of a constant volume of distribution (V), two strategies have been proposed: 1) use of a variable tracer infusion rate to minimize tracer-to-tracee ratio (TTR) variations (fixed-volume approach) or 2) use of two tracers of the same substrate with one infused at a constant rate and the other at a variable rate (variable-volume approach or approach of T. Issekutz, R. Issekutz, and D. Elahi. Can. J. Physiol. Pharmacol. 52: 215–224, 1974). The goal of this study was to compare the results of these two strategies for the analysis of the kinetics of glycerol and glucose under the non-steady-state condition created by a constant infusion of epinephrine (50 ng ⋅ kg−1 ⋅ min−1) with the traditional approach of Steele et al., which uses a constant infusion and fixed volume. The results showed that for glucose and glycerol the estimates of Raobtained with the constant and the variable tracer infusion rate and the equation of Steele et al. were comparable. The variable tracer infusion approach was less sensitive to the choice of V in estimating Ra for glycerol and glucose, although the advantage of changing the tracer infusion rate was greater for glucose than for glycerol. The model of Issekutz et al. showed instability when the ratio TTR1/TTR2approaches a constant value, and the model is more sensitive to measurement error than the constant-volume model for glucose and glycerol. We conclude that the one-tracer constant-infusion technique is sufficient in most cases for glycerol, whereas the one-tracer variable-infusion technique is preferable for glucose. Reasonable values for glucose Ra can be obtained with the constant-infusion technique if V = 145 ml/kg.

scholarly journals Population Pharmacokinetic Study of Cefathiamidine in Infants With Augmented Renal Clearance

2021 ◽  
Vol 12 ◽  
Author(s):  
Bin Du ◽  
Yue Zhou ◽  
Bo-Hao Tang ◽  
Yue-E Wu ◽  
Xin-Mei Yang ◽  
...  
Keyword(s):  
Renal Clearance ◽  
Pharmacokinetic Study ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Pharmacokinetic Studies ◽  
Augmented Renal Clearance ◽  
Population Pharmacokinetic Study ◽  
Dosing Regimens

Objectives: Augmented renal clearance (ARC) of primarily renally eliminated antibacterial agents may result in subtherapeutic antibiotic concentrations and, as a consequence, worse clinical outcomes. Cefathiamidine is frequently used as empirical antimicrobial therapy in children with ARC, but pharmacokinetic studies in infants are lacking. This population pharmacokinetic study in infants with ARC was conducted to determine optimal dosing regimens of cefathiamidine.Methods: The population pharmacokinetics was conducted in 20 infants treated with cefathiamidine. Plasma samples of cefathiamidine were collected using opportunistic sampling, and the concentrations were detected by UPLC-MS/MS. Data analysis was performed to determine pharmacokinetic parameters and to characterize pharmacokinetic variability of cefathiamidine using nonlinear mixed effects modelling (NONMEM) software program.Results: The data (n = 36) from 20 infants (age range, 0.35–1.86 years) with ARC were fitted best with a 1-compartment model. Allometrically scaled weight and age as significant covariates influenced cefathiamidine pharmacokinetics. The median (range) values of estimated clearance and the volume of distribution were 0.22 (0.09–0.29) L/h/kg and 0.34 (0.24–0.41) L/kg, respectively. Monte Carlo simulations showed that the cefathiamidine doses of 100 mg/kg/day q12 h, 50 mg/kg/day q8 h and 75 mg/kg/day q6 h were chosen for bacteria with MIC 0.25, 0.5 and 2 mg/L, respectively.Conclusion: The population pharmacokinetic model of cefathiamidine for infants with ARC was developed. The PTA - based dosing regimens were recommended based on the final model.

scholarly journals Absence of Effect of Rufloxacin on Theophylline Pharmacokinetics in Steady State

1998 ◽  
Vol 42 (9) ◽  
pp. 2359-2364 ◽  
Author(s):  
Martina Kinzig-Schippers ◽  
Uwe Fuhr ◽  
Marina Cesana ◽  
Carola Müller ◽  
A. Horst Staib ◽  
...  
Keyword(s):  
Steady State ◽  
Adverse Events ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Reversed Phase ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Elimination Phase ◽  
Once Daily ◽  
Model Independent

ABSTRACT Several quinolone antibacterial agents are known to inhibit the metabolism of theophylline, with the potential to cause adverse events due to raised theophylline concentrations during coadministration. A randomized crossover study was therefore conducted with 12 healthy male volunteers (ages, 23 to 34 years; body weight, 64 to 101 kg) to evaluate a possible interaction between rufloxacin and theophylline. Both drugs were administered at steady state. Following the administration of an oral loading dose of 400 mg on day 1, rufloxacin was given orally at 200 mg once daily on days 2 to 7 during one period only. During both periods, 146 mg of theophylline was administered orally twice daily for 3 days (which were days 4 to 6 of the rufloxacin coadministration period) and intravenously once the next morning to test for an interaction. Theophylline and rufloxacin concentrations were measured by reversed-phase high-pressure liquid chromatography, the pharmacokinetics of theophylline at steady state following administration of the last dose were calculated by compartment-model-independent methods. To compare the treatments, analysis of variance-based point estimates and 90% confidence intervals (given in parentheses) were calculated for the mean ratios of the pharmacokinetic parameters from the test (rufloxacin coadministration) over those from the reference (theophylline without rufloxacin) period. These were as follows: maximum concentration at steady state, 1.01 (0.96 to 1.07); area under the concentration-time curve from 0 to 12 h, 0.98 (0.94 to 1.02); half-life, 0.99 (0.95 to 1.03); total clearance at steady state, 1.02 (0.99 to 1.06); and volume of distribution in the elimination phase, 1.01 (0.97 to 1.05). In conclusion, rufloxacin did not affect theophylline pharmacokinetics at steady state. Therefore, therapeutic coadministration of rufloxacin and theophylline is not expected to cause an increased incidence of theophylline-related adverse events.

scholarly journals A Semimechanistic Pharmacokinetic-Enzyme Turnover Model for Rifampin Autoinduction in Adult Tuberculosis Patients

2012 ◽  
Vol 56 (4) ◽  
pp. 2091-2098 ◽  
Author(s):  
Wynand Smythe ◽  
Akash Khandelwal ◽  
Corinne Merle ◽  
Roxana Rustomjee ◽  
Martin Gninafon ◽  
...  
Keyword(s):  
Steady State ◽  
Hiv Infection ◽  
Selection Procedure ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Oral Clearance ◽  
Time Curve ◽  
Turnover Model ◽  
Enzyme Turnover ◽  
Apparent Volume Of Distribution

ABSTRACTThe currently recommended doses of rifampin are believed to be at the lower end of the dose-response curve. Rifampin induces its own metabolism, although the effect of dose on the extent of autoinduction is not known. This study aimed to investigate rifampin autoinduction using a semimechanistic pharmacokinetic-enzyme turnover model. Four different structural basic models were explored to assess whether different scaling methods affected the final covariate selection procedure. Covariates were selected by using a linearized approach. The final model included the allometric scaling of oral clearance and apparent volume of distribution. Although HIV infection was associated with a 30% increase in the apparent volume of distribution, simulations demonstrated that the effect of HIV on rifampin exposure was slight. Model-based simulations showed close-to-maximum induction achieved after 450-mg daily dosing, since negligible increases in oral clearance were observed following the 600-mg/day regimen. Thus, dosing above 600 mg/day is unlikely to result in higher magnitudes of autoinduction. In a typical 55-kg male without HIV infection, the oral clearance, which was 7.76 liters · h−1at the first dose, increased 1.82- and 1.85-fold at steady state after daily dosing with 450 and 600 mg, respectively. Corresponding reductions of 41 and 42%, respectively, in the area under the concentration-versus-time curve from 0 to 24 h were estimated. The turnover of the inducible process was estimated to have a half-life of approximately 8 days in a typical patient. Assuming 5 half-lives to steady state, this corresponds to a duration of approximately 40 days to reach the induced state for rifampin autoinduction.

scholarly journals Phase I Study To Evaluate the Pharmacokinetics, Safety, and Tolerability of Two Dosing Regimens of Oral Fosfomycin Tromethamine in Healthy Adult Participants

2018 ◽  
Vol 62 (8) ◽  
Author(s):  
Eric Wenzler ◽  
Susan C. Bleasdale ◽  
Monica Sikka ◽  
Kristen L. Bunnell ◽  
Matthew Finnemeyer ◽  
...  
Keyword(s):  
Phase I ◽  
Healthy Adult ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Open Label ◽  
Time Curve ◽  
Elimination Half ◽  
Apparent Clearance ◽  
Dosing Regimens ◽  
Repeated Dosing

ABSTRACTThe pharmacokinetics (PK), safety, and tolerability of two repeated dosing regimens of oral fosfomycin tromethamine were evaluated in 18 healthy adult subjects. Subjects received 3 g every other day (QOD) for 3 doses and then every day (QD) for 7 doses, or vice versa, in a phase I, randomized, open-label, two-period-crossover study. Serial blood (n= 11) and urine (n= 4 collection intervals) samples were collected before and up to 24 h after dosing on days 1 and 5, along with predose concentrations on days 3 and 7. PK parameters were similar between days 1 and 5 within and between dosing regimens. The mean (± standard deviation [SD]) PK parameters for fosfomycin in plasma on day 5 during the respective QOD and QD dosing regimens were as follows: maximum concentration of drug in serum (Cmax) = 24.4 ± 6.2 versus 23.8 ± 5.6 μg/ml, time toCmax(Tmax) = 2.2 ± 0.7 versus 2.0 ± 0.4 h, apparent volume of distribution (V/F) = 141 ± 67.9 versus 147 ± 67.6 liters, apparent clearance (CL/F) = 21.4 ± 8.0 versus 20.4 ± 5.3 liters/h, renal clearance (CLR) = 7.5 ± 4.1 versus 7.3 ± 3.5 liters/h, area under the concentration-time curve from 0 to 24 h (AUC0–24) = 151.6 ± 35.6 versus 156.6 ± 42.5 μg · h/ml, and elimination half-life (t1/2) = 4.5 ± 1.1 versus 5.0 ± 1.7 h. Urine concentrations peaked at approximately 600 μg/ml through the 0- to 8-h urine collection intervals but displayed significant interindividual variability. Roughly 35 to 40% of the 3-g dose was excreted in the urine by 24 h postdose. No new safety concerns were identified during this study. The proportion of diarrhea-free days during the study was significantly lower with the QD regimen than with the QOD regimen (61% versus 77%;P< 0.0001). Further studies to establish the clinical benefit/risk ratio for repeated dosing regimens of oral fosfomycin tromethamine are warranted. (This trial is registered at ClinicalTrials.gov under registration no. NCT02570074.)

Steady-State Pharmacokinetics of Cefoperazone and Sulbactam in Patients with Acute Appendicitis

1994 ◽  
Vol 28 (6) ◽  
pp. 703-707
Author(s):  
Larry H. Danziger ◽  
Stephen C. Piscitelli ◽  
Donna J. Occhipinti ◽  
Daniel J. Resnick ◽  
Keith A. Rodvold
Keyword(s):  
Steady State ◽  
Acute Appendicitis ◽  
Dosage Reduction ◽  
Area Under The Curve ◽  
Compartment Model ◽  
Hepatic Function ◽  
Volume Of Distribution ◽  
Two Compartment Model ◽  
Elimination Half ◽  
G Prior

OBJECTIVE: To determine the steady-state pharmacokinetics of intravenously administered cefoperazone and sulbactam when given in combination to patients with acute appendicitis. METHODS: Six patients with normal renal and hepatic function received cefoperazone 2 g with sulbactam 1 g prior to appendectomy and then every 12 hours. Serial blood samples were collected after each patient received at least three doses of cefoperazone/sulbactam. RESULTS: Cefoperazone and sulbactam could be best described by a two-compartment model. Mean ± SD values for cefoperazone steady-state volume of distribution (Vssd), elimination half-life (t1/2β), clearance (Cl), and area under the curve (AUC0-t) were 19.8 ± 8.0 L, 3.97 ± 1.06 h, 62.6 ± 16.3 mL/min, and 556.9 ± 122.0 mg·h/L, respectively. Sulbactam Vssd, t1/2β, Cl, and AUC0-t were 34.7 ± 13.9 L, 1.39 ± 0.4 h, 288.6 ± 68.2 mL/min, and 64.8 ± 24.5 mg·h/L, respectively. CONCLUSIONS: Compared with data from healthy volunteers, cefoperazone exhibited a decreased Cl and increased Vssd and t1/2β in patients with acute appendicitis. An increased Vssd also was observed for sulbactam. The disposition of cefoperazone/sulbactam is altered in this group of patients; however, these changes are not likely to warrant a dosage reduction.

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