scholarly journals Indinavir, Efavirenz, and Abacavir Pharmacokinetics in Human Immunodeficiency Virus-Infected Subjects

2003 ◽  
Vol 47 (6) ◽  
pp. 1929-1935 ◽  
Author(s):  
Robert DiCenzo ◽  
Alan Forrest ◽  
Kathleen E. Squires ◽  
Scott M. Hammer ◽  
Margaret A. Fischl ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Wild Type Virus ◽  
Pharmacokinetic Parameters ◽  
Minimum Concentration ◽  
Immunodeficiency Virus ◽  
Aids Clinical Trials ◽  
Apparent Volume Of Distribution ◽  
Median Maximum

ABSTRACT Adult AIDS Clinical Trials Group (AACTG) Protocol 886 examined the dispositions of indinavir, efavirenz, and abacavir in human immunodeficiency virus-infected subjects who received indinavir at 1,000 mg every 8 h (q8h) and efavirenz at 600 mg q24h or indinavir at 1,200 mg and efavirenz at 300 mg q12h with or without abacavir 300 at mg q12h. Thirty-six subjects participated. The median minimum concentration in plasma (C min) for indinavir administered at 1,200 mg q12h was 88.1 nM (interquartile range [IR], 61.7 to 116.5 nM), whereas the median C min for indinavir administered at 1,000 mg q8h was 139.3 nM (IR, 68.8 to 308.7 nM) (P = 0.19). Compared to the minimum C min range for wild-type virus (80 to 120 ng/ml) estimated by the AACTG Adult Pharmacology Committee, the C min for indinavir administered at 1,200 mg q12h (54 ng/ml) is inadequate. The apparent oral clearance (CL/F) (P = 0.28), apparent volume of distribution at steady state (V ss/F) (P = 0.25), and half-life (t 1/2) (P = 0.80) of indinavir did not differ between regimens. The levels of efavirenz exposure were similar between regimens. For efavirenz administered at 600 mg q24h and 300 mg q12h, the median maximum concentrations in plasma (C maxs) were 8,968 nM (IR, 5,784 to 11,768 nM) and 8,317 nM (6,587 to 10,239 nM), respectively (P = 0.66), and the C mins were 4,289 nM (IR, 2,462 to 5,904 nM) and 4,757 nM (IR, 3,088 to 6,644 nM), respectively (P = 0.29). Efavirenz pharmacokinetic parameters such as CL/F (P = 0.62), V ss/F (P = 0.33), and t 1/2 (P = 0.37) were similar regardless of the dosing regimen. The median C max, C min, CL/F, V ss/F, and t 1/2 for abacavir were 6,852 nM (IR, 5,702 to 7,532), 21.0 nM (IR, 21.0 to 87.5), 43.7 liters/h (IR, 37.9 to 55.2), 153.9 liters (IR, 79.6 to 164.4), and 2.0 h (IR, 1.8 to 2.8), respectively. In summary, when indinavir was given with efavirenz, the trough concentration of indinavir after administration of 1,200 mg q12h was inadequate. Abacavir did not influence the pharmacokinetics or exposure parameters of either indinavir or efavirenz. The levels of efavirenz exposure were similar in subjects receiving efavirenz q12h or q24h.

Ketamine kinetics: decerebrate vs. intact cats

1979 ◽  
Vol 57 (8) ◽  
pp. 878-881 ◽  
Author(s):  
James E. Heavner ◽  
Duane C. Bloedow
Keyword(s):  
Apparent Volume ◽  
Volume Of Distribution ◽  
Drug Dose ◽  
The Body ◽  
Pharmacokinetic Parameters ◽  
Peripheral Compartment ◽  
Blood Concentrations ◽  
Open Model ◽  
Apparent Volume Of Distribution ◽  
Compartment Open Model

Pharmacokinetic parameters of a ketamine (10 mg/kg, iv) bolus in decerebrate and intact cats were compared. A two-compartment open model best described the data in both groups. The apparent volume of distribution of the peripheral compartment, the apparent volume of distribution of the drug in the body, and the half-life of the postdistributive phase were significantly less (p < 0.05) in the decerebrate animals. These results emphasize the importance of correlating behavior and neuronal activity with plasma or blood concentrations of drug in animals rather than assuming that, for a given drug dose, blood (and thus tissue) levels of the agent will be similar regardless of how the animal is prepared for study.

scholarly journals Pharmacokinetics of Ritonavir and Delavirdine in Human Immunodeficiency Virus-Infected Patients

2003 ◽  
Vol 47 (5) ◽  
pp. 1694-1699 ◽  
Author(s):  
Mark J. Shelton ◽  
Ross G. Hewitt ◽  
John Adams ◽  
Andrew Della-Coletta ◽  
Steven Cox ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Systemic Exposure ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Minimum Concentration ◽  
Mean Values ◽  
Immunodeficiency Virus ◽  
The Mean ◽  
Full Dosage ◽  
Delavirdine Mesylate

ABSTRACT To evaluate the pharmacokinetic effect of adding delavirdine mesylate to the antiretroviral regimens of human immunodeficiency virus (HIV)-infected patients stabilized on a full dosage of ritonavir (600 mg every 12 h), 12 HIV-1-infected subjects had delavirdine mesylate (400 mg every 8 h) added to their current antiretroviral regimens for 21 days. Ritonavir pharmacokinetics were evaluated before (day 7) and after (day 28) the addition of delavirdine, and delavirdine pharmacokinetics were evaluated on day 28. The mean values (± standard deviations) for the maximum concentration in serum (C max) of ritonavir, the area under the concentration-time curve from 0 to 12 h (AUC0-12), and the minimum concentration in serum (C min) of ritonavir before the addition of delavirdine were 14.8 ± 6.7 μM, 94 ± 36 μM · h, and 3.6 ± 2.1 μM, respectively. These same parameters were increased to 24.6 ± 13.9 μM, 154 ± 83 μM · h, and 6.52 ± 4.85 μM, respectively, after the addition of delavirdine (P is <0.05 for all comparisons). Delavirdine pharmacokinetic parameters in the presence of ritonavir included a C max of 23 ± 16 μM, an AUC0-8 of 114 ± 75 μM · h, and a C min of 9.1 ± 7.5 μM. Therefore, delavirdine increases systemic exposure to ritonavir by 50 to 80% when the drugs are coadministered.

scholarly journals Steady-State Pharmacokinetics of a Double-Boosting Regimen of Saquinavir Soft Gel plus Lopinavir plus Minidose Ritonavir in Human Immunodeficiency Virus-Infected Adults

2004 ◽  
Vol 48 (11) ◽  
pp. 4256-4262 ◽  
Author(s):  
Esteban Ribera ◽  
Rosa M. Lopez ◽  
Marjorie Diaz ◽  
Leonor Pou ◽  
Lidia Ruiz ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Steady State ◽  
Rescue Therapy ◽  
Pharmacokinetic Parameters ◽  
Time Curve ◽  
Minimum Concentration ◽  
Immunodeficiency Virus ◽  
Strong Linear Correlation ◽  
Drug Doses ◽  
Therapeutic Doses

ABSTRACT Management of treatment-experienced human immunodeficiency virus patients has become complex, and therapy may need to include two protease inhibitors at therapeutic doses. The objective of this study was to characterize the pharmacokinetics in serum of saquinavir (1,000 mg twice daily [b.i.d.]), lopinavir (400 mg b.i.d.), and ritonavir (100 mg b.i.d.) in a multidrug rescue therapy study and to investigate whether steady-state pharmacokinetics of lopinavir-ritonavir are affected by coadministration of saquinavir. Forty patients were included (25 given ritonavir, lopinavir, and saquinavir and 15 given ritonavir and lopinavir). The median pharmacokinetic parameters of lopinavir were as follows: area under the concentration-time curve from 0 to 12 h (AUC0-12), 85.1 μg/ml · h; maximum concentration of drug in serum (C max), 10.0 μg/ml; trough concentration of drug in serum (C trough), 7.3 μg/ml; and minimum concentration of drug in serum (C min), 5.5 μg/ml. Lopinavir concentrations were similar in patients with and without saquinavir. The median pharmacokinetic parameters for saquinavir were as follows: AUC0-12, 22.9 μg/ml · h; C max, 2.9 μg/ml; C trough, 1.6 μg/ml; and C min, 1.4 μg/ml. There was a strong linear correlation between lopinavir and ritonavir and between saquinavir and ritonavir concentrations in plasma. The correlation between lopinavir and saquinavir levels was weaker. We found higher saquinavir concentrations in women than in men, with no difference in lopinavir levels. Only patients with very high body weight presented lopinavir and saquinavir concentrations lower than the overall group. Ritonavir has a double-boosting function for both lopinavir and saquinavir, and in terms of pharmacokinetics, the drug doses selected seemed appropriate for combining these agents in a dual protease inhibitor-based antiretroviral regimen for patients with several prior virologic failures.

The Pharmacokinetics of Buserelin after Intramuscular Administration in Pigs and Cows

2021 ◽  
Author(s):  
Zhengrong Gao ◽  
Yu Liu ◽  
Yuxin Yang ◽  
Yuying Cao ◽  
Jicheng Qiu ◽  
...  
Keyword(s):  
Area Under The Curve ◽  
Apparent Volume ◽  
Ultra Performance Liquid Chromatography ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Maximum Plasma ◽  
Elimination Half ◽  
Liquid Chromatography Tandem Mass ◽  
Stability Method ◽  
Apparent Volume Of Distribution

Abstract Background: Buserelin is a LHRH agonist used for the treatment of hormone-dependent diseases in males and females. However, the pharmacokinetics of buserelin in pigs and cows are not clearly understood. This study was designed to develop a sensitive method to determine the concentration of buserelin and to investigate the pharmacokinetic parameters after intramuscular (i.m.) administration in pigs and cows. Results: A sensitive and rapid stability method based on ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed. The pharmacokinetic parameters of buserelin after i.m. administration were studies in five pigs and five cows at a single dose of 1 mg per pig and 3 mg per cow. The plasma kinetics were analyzed by WinNonlin 8.1.0 software using a non-compartmental model. The mean concentration area under the curve (AUC0-t) was 25.02 ± 6.93 h·ng/mL for pigs and 5.63 ±1.86 h·ng/mL for cows. The maximum plasma concentration (Cmax) and time to reach the maximum concentration (tmax) were 10.99 ± 2.04 ng/mL and 0.57 ± 0.18 h for pigs and 2.68 ± 0.36 ng/mL and 1.05 ±0.27 h for cows, respectively. The apparent volume of distribution (Vz) in pigs and cows was 80.49 ± 43.88 L and 839.88 ± 174.77 L, respectively. The elimination half-time (t1/2λz), and clearance (CL) were 1.29 ± 0.40 h and 41.15 ± 11.18 L/h for pigs and 1.13 ± 0.3 h and 545.04 ± 166.40 L/h for cows, respectively. No adverse effects were observed in any of the animals. Conclusion: This study extends previous studies describing the pharmacokinetics of buserelin following i.m. administration in pigs and cows. Further studies investigating other factors were needed to establish therapeutic protocol in pigs and cows and to extrapolate these parameters to others economic animals.

scholarly journals Single-Dose Pharmacokinetics and Safety of the Oral Antiviral Compound Adefovir Dipivoxil in Children Infected with Human Immunodeficiency Virus Type 1

2000 ◽  
Vol 44 (4) ◽  
pp. 1041-1046 ◽  
Author(s):  
Walter T. Hughes ◽  
Jerry L. Shenep ◽  
John H. Rodman ◽  
Arnold Fridland ◽  
Rodney Willoughby ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Adefovir Dipivoxil ◽  
Age Groups ◽  
Apparent Volume ◽  
Pharmacokinetic Parameters ◽  
Serum Samples ◽  
Antiviral Compound ◽  
Limit Of Quantitation ◽  
Immunodeficiency Virus

ABSTRACT The acyclic phosphonate analog adefovir is a potent inhibitor of retroviruses, including human immunodeficiency virus (HIV) type 1, and, unlike some antiviral nucleosides, does not require the initial phosphorylation step for its activity. Two oral dosages of the adefovir prodrug adefovir dipivoxil were evaluated in a phase I study with children with HIV infection. A total of 14 patients were stratified into age groups ranging from 6 months to 18 years of age. Eight patients received 1.5 mg of adefovir dipivoxil per kg of body weight, and six patients received 3.0 mg of adefovir dipivoxil per kg. Serum samples were obtained at intervals during the 8 h postdosing and were analyzed for adefovir concentrations. Patients were monitored for adverse effects. All samples collected resulted in quantifiable levels of adefovir (lower limit of quantitation, 25 ng/ml) from each patient. The areas under the concentration-versus-time curves (AUCs) were similar (P = 0.85) for the 1.5- and 3.0-mg/kg doses, while the apparent oral clearance (CL/F) was significantly higher (P = 0.05) for the 3-mg/kg dose. Pharmacokinetic parameters differed by patient age. In comparing those children older and younger than the median age of 5.1 years, AUC (P = 0.03), maximum concentration of drug in serum (P = 0.004), and the concentration at 8 h postdosing (P = 0.02) were significantly lower for the younger children. There were no significant differences for apparent volume of distribution and CL/F normalized to body surface area, but there was a suggestive difference in half-life (P = 0.07) among the subjects in the older and younger age groups. No significant adverse events were encountered. These data provide the basis for a multidose phase II study of adefovir dipivoxil in HIV-infected infants and children.

Estimation of Pharmacokinetic Parameters at Steady-State in Patients

1978 ◽  
Vol 12 (10) ◽  
pp. 612-616 ◽  
Author(s):  
James W. Crow ◽  
Milo Gibaldi
Keyword(s):  
Steady State ◽  
Rate Constant ◽  
Elimination Rate ◽  
Simulated Data ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Total Clearance ◽  
Dosing Intervals ◽  
Apparent Volume Of Distribution

A method to characterize the pharmacokinetics of a drug in a patient receiving it chronically is proposed. In principle, such characterization may be carried out by obtaining one or more drug concentration in plasma-time values from several different dosing intervals, combining the data to create a composite dosing interval representative of the steady-state situation and fitting the data to an appropriate equation. The method was evaluated using simulated data based on the average pharmacokinetic parameters of theophylline in children. Reasonable estimates of the elimination rate constant and apparent volume of distribution may be obtained, but the estimation of the absorption rate constant presents formidable problems. The method appears to be most useful for obtaining very accurate estimates of total clearance.

scholarly journals Population pharmacokinetics of dapsone administered biweekly to human immunodeficiency virus-infected patients.

1996 ◽  
Vol 40 (12) ◽  
pp. 2743-2748 ◽  
Author(s):  
G Gatti ◽  
M Merighi ◽  
J Hossein ◽  
S Travaini ◽  
R Casazza ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Population Pharmacokinetics ◽  
Pneumocystis Carinii ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Mixed Effect ◽  
Nonlinear Mixed Effect ◽  
Immunodeficiency Virus ◽  
Nonlinear Mixed Effect Modeling ◽  
Post Hoc

The population pharmacokinetics of dapsone were examined in human immunodeficiency virus-infected patients receiving dapsone at a dosage of 100 mg twice weekly for the prevention of Pneumocystis carinii pneumonia. Nonlinear mixed-effect modeling was used to determine the best pharmacostatistical model for the data. A one-compartment open model with first-order absorption and elimination was used as the structural pharmacokinetic model. Several covariates were tested for their influence on pharmacokinetic parameters. Rifampin was found to increase the values of clearance/bioavailability (CL/F) and volume of distribution/ bioavailability (V/F) by approximately 70%. CL/F and V/F were 1.83 liters/h and 69.6 liters, respectively, for patients not taking rifampin. The effect of rifampin on the pharmacokinetic parameters of dapsone was appreciably less than expected on the basis of studies with healthy volunteers. Increased bilirubin levels were associated with a significant decrease in the absorption rate constant (Ka). However, this finding may be considered clinically irrelevant because the post hoc Bayesian estimates of Ka for patients with high bilirubin levels ( > 1.2 mg/dl) were at the lower bound of the values for patients with normal bilirubin levels. The value of Ka was 0.957 h-1 for a patient with a bilirubin level of 0.7 mg/dl. After inclusion of covariates in the model, the interpatient variability was 35% for CL/F, not significant for V/F, and 85% for Ka. Simulation of plasma concentration-versus-time curves indicated that the administration of 100 mg of dapsone biweekly is associated with sustained dapsone levels in the plasma of the majority of the patients. Dosage adjustments for patients concomitantly treated with rifampin may be necessary.

Successful Use of Higher-Than-Recommended Dosage of Imipenem in Pseudomonas Aeruginosa Endocarditis

1992 ◽  
Vol 26 (5) ◽  
pp. 639-641 ◽  
Author(s):  
Jeffrey H. King ◽  
Elizabeth J. Kailath ◽  
Daniel B. Hrdy
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Decision ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
High Dose ◽  
Serum Concentrations ◽  
Case Summary ◽  
Apparent Volume Of Distribution

OBJECTIVE: To report a case of Pseudomonas aeruginosa endocarditis that was successfully treated with high-dose imipenem/cilastatin and to discuss dosage modification based on individual pharmacokinetic parameters. DATA SOURCES: Clinical studies, review articles, and relevant laboratory and pharmacokinetic information. CASE SUMMARY: A 27-year-old man with right-sided P. aeruginosa endocarditis was successfully treated with long-term imipenem/cilastatin and tobramycin. The imipenem dose required to achieve therapeutic serum concentrations and cidal activity was 6 g/d. The manufacturer's recommended maximum dose is 4.0 g/d or 50 mg/kg/d. Because of the patient's large apparent volume of distribution, low serum imipenem concentrations, and lack of serum cidal activity, the clinical decision was made to increase the dose to 6 g/d or 54 mg/kg/d. Treatment was tolerated for seven weeks without any adverse effects. The patient remains free of symptoms 24 months after the diagnosis. CONCLUSIONS: Careful and discriminate use of larger-than-recommended doses of imipenem may be indicated in certain clinical situations. Dosage may need to be adjusted to body size in order to obtain optimal serum concentrations and activity.

Safety of a Higher Loading Dose of Phenobarbital in the Term Newborn

PEDIATRICS ◽  
1985 ◽  
Vol 75 (6) ◽  
pp. 1061-1064 ◽  
Author(s):  
Steven M. Donn ◽  
Thaddeus H. Grasela ◽  
Gary W. Goldstein
Keyword(s):  
Newborn Infants ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Loading Dose ◽  
Cardiorespiratory Function ◽  
Term Newborns ◽  
The Mean ◽  
Spontaneously Breathing ◽  
Apparent Volume Of Distribution

The conventional loading dose of phenobarbital for newborn infants with hypoxic-ischemic seizures, 20 mg/kg, often fails to control convulsive activity. To determine the safety of a higher loading dose and to establish the pharmacokinetic parameters of a higher loading dose, ten severely asphyxiated term newborns were given 30 mg/kg of phenobarbital intravenously over 15 minutes. The mean serum concentration of phenobarbital two hours after loading was 30.0 ± 3.2 µg/mL, the apparent volume of distribution was 0.97 ± 0.18 L/kg, total clearance was 0.08 ± 0.03 mL/min/kg, and mean serum half-life was 148 ± 55 hours. The higher loading dose was not associated with any short-term adverse effects on cardiorespiratory function, even in spontaneously breathing infants.

Metabolism and acid secretory effect of sulfated and nonsulfated gastrin-6 in humans

2000 ◽  
Vol 279 (5) ◽  
pp. G903-G909 ◽  
Author(s):  
C. Palnæs Hansen ◽  
F. Stadil ◽  
J. F. Rehfeld
Keyword(s):  
Clearance Rate ◽  
Main Product ◽  
Acid Output ◽  
Normal Subjects ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Metabolic Clearance ◽  
Metabolic Clearance Rate ◽  
Apparent Volume Of Distribution

The antral hormone gastrin is synthesized by processing progastrin into different peptides that stimulate gastric secretion. The effect on acid secretion depends mainly on the metabolic clearance rate of the peptides, but some of them may differ in potency and maximum acid output at similar concentrations in plasma. Sulfated and nonsulfated gastrin-6 are the smallest circulating bioactive gastrins in humans. Their effect and metabolism have now been investigated in nine normal subjects and compared with nonsulfated gastrin-17, a main product of progastrin. Maximum acid output after stimulation with gastrin-17, sulfated gastrin-6, and nonsulfated gastrin-6 were 28.3 ± 2.0, 24.5 ± 2.0 ( P < 0.02), and 19.3 ± 2.3 ( P < 0.05) mmol H+/50 min, respectively, and the corresponding EC50values were 43 ± 6, 24 ± 2 ( P < 0.01), and 25 ± 2 (not significant) pmol/l. The half-life of gastrin-17 was 5.3 ± 0.3 min, the metabolic clearance rate (MCR) was 16.5 ± 1.3 ml · kg−1· min−1, and the apparent volume of distribution (Vd) was 124.3 ± 9.6 ml/kg. The half-lives of sulfated and nonsulfated gastrin-6 were 2.1 ± 0.3 and 1.9 ± 0.3 min, the MCRs were 42.8 ± 3.7 and 139.4 ± 9.6 ml kg−1min−1( P < 0.01), and the Vdwere 139.0 ± 30.5 and 392.0 ± 81.6 ( P < 0.01) ml kg−1. All pharmacokinetic parameters differed significantly from gastrin-17 ( P < 0.01). We conclude that gastrin 6 has a higher potency but a lower efficacy than gastrin-17. The efficacy of gastrin-6 is increased by tyrosine O-sulfation, which also enhances the protection against elimination.

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